package daikon;

import daikon.chicory.DaikonVariableInfo;
import daikon.derive.Derivation;
import daikon.derive.binary.BinaryDerivation;
import daikon.derive.binary.SequenceFloatSubscript;
import daikon.derive.binary.SequenceScalarSubscript;
import daikon.derive.binary.SequenceStringSubscript;
import daikon.derive.binary.SequenceSubsequence;
import daikon.derive.ternary.SequenceFloatArbitrarySubsequence;
import daikon.derive.ternary.SequenceScalarArbitrarySubsequence;
import daikon.derive.ternary.SequenceStringArbitrarySubsequence;
import daikon.derive.unary.SequenceLength;
import daikon.derive.unary.UnaryDerivation;
import daikon.inv.OutputFormat;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;
import java.util.StringJoiner;
import java.util.WeakHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.checkerframework.checker.interning.qual.InternMethod;
import org.checkerframework.checker.interning.qual.Interned;
import org.checkerframework.checker.lock.qual.GuardSatisfied;
import org.checkerframework.checker.nullness.qual.EnsuresNonNullIf;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.dataflow.qual.Pure;
import org.checkerframework.dataflow.qual.SideEffectFree;
import org.plumelib.util.StringsPlume;

// This class is deprecated.  It should be removed as soon as Daikon no
// longer supports the old decl format.

// If you change this file, also change class daikon.test.VarInfoNameTest.

/**
 * VarInfoName represents the "name" of a variable. Calling it a "name", however, is somewhat
 * misleading. It can be some expression that includes more than one variable, term, etc. We
 * separate this from the VarInfo itself because clients wish to manipulate names into new
 * expressions independent of the VarInfo that they might be associated with. VarInfoName's child
 * classes are specific types of names, like applying a function to something. For example, "a" is a
 * name, and "sin(a)" is a name that is the name "a" with the function "sin" applied to it.
 */
@SuppressWarnings({"nullness", "interning"}) // deprecated file
public abstract @Interned class VarInfoName implements Serializable, Comparable<VarInfoName> {

  /** Debugging Logger. */
  public static Logger debug = Logger.getLogger("daikon.VarInfoName");

  static final long serialVersionUID = 20020614L;

  /**
   * When true, apply orig directly to variables, do not apply orig to derived variables. For
   * example, create 'size(orig(a[]))' rather than 'orig(size(a[]))'.
   */
  public static boolean dkconfig_direct_orig = false;

  /**
   * Given the standard String representation of a variable name (like what appears in the normal
   * output format), return the corresponding VarInfoName. This method can't parse all the strings
   * that the VarInfoName name() method might produce, but it should be able to handle anything that
   * appears in a decls file. Specifically, it can only handle a subset of the grammar of derived
   * variables. For some values of "name", "name.equals(parse(e.name()))" might throw an exception,
   * but if it completes normally, the result should be true.
   */
  public static VarInfoName parse(String name) {

    // Remove the array indication from the new decl format
    name = name.replace("[..]", "[]");

    // orig(x)
    if (name.startsWith("orig(")) {
      // throw new Error("orig() variables shouldn't appear in .decls files");
      assert name.endsWith(")") : name;
      return parse(name.substring(5, name.length() - 1)).applyPrestate();
    }

    // x.class
    if (name.endsWith(DaikonVariableInfo.class_suffix)) {
      return parse(name.substring(0, name.length() - DaikonVariableInfo.class_suffix.length()))
          .applyTypeOf();
    }

    // a quoted string
    if (name.startsWith("\"") && name.endsWith("\"")) {
      String content = name.substring(1, name.length() - 1);
      if (content.equals(StringsPlume.escapeJava(StringsPlume.unescapeJava(content)))) {
        return new Simple(name).intern();
      }
    }

    // x or this.x
    if ((name.indexOf('[') == -1) && (name.indexOf('(') == -1)) {
      // checking for only legal characters would be more robust
      int dot = name.lastIndexOf('.');
      int arrow = name.lastIndexOf("->");
      if (dot >= 0 && dot > arrow) {
        String first = name.substring(0, dot);
        String field = name.substring(dot + 1);
        return parse(first).applyField(field);
      } else if (arrow >= 0 && arrow > dot) {
        String first = name.substring(0, arrow);
        String field = name.substring(arrow + 2);
        return parse(first).applyField(field);
      } else {
        return new Simple(name).intern();
      }
    }

    // a[]
    if (name.endsWith("[]")) {
      return parse(name.substring(0, name.length() - 2)).applyElements();
    }

    // foo[bar] -- IOA input only (pre-derived)
    if (name.endsWith("]")) {
      // This isn't quite right:  we really want the matching open bracket,
      // not the last open bracket.
      int lbracket = name.lastIndexOf('[');
      if (lbracket >= 0) {
        String seqname = name.substring(0, lbracket) + "[]";
        String idxname = name.substring(lbracket + 1, name.length() - 1);
        VarInfoName seq = parse(seqname);
        VarInfoName idx = parse(idxname);
        return seq.applySubscript(idx);
      }
    }

    // a[].foo or a[].foo.bar
    if (name.indexOf("[]") >= 0) {
      int brackets = name.lastIndexOf("[]");
      int dot = name.lastIndexOf('.');
      int arrow = name.lastIndexOf("->");
      if (dot >= brackets && dot > arrow) {
        String first = name.substring(0, dot);
        String field = name.substring(dot + 1);
        return parse(first).applyField(field);
      } else if (arrow >= brackets && arrow > dot) {
        String first = name.substring(0, arrow);
        String field = name.substring(arrow + 2);
        return parse(first).applyField(field);
      }
    }

    // A.B, where A is complex: foo(x).y, x[7].y, etc.
    int dot = name.lastIndexOf('.');
    int arrow = name.lastIndexOf("->");
    if (dot >= 0 && dot > arrow) {
      String first = name.substring(0, dot);
      String field = name.substring(dot + 1);
      return parse(first).applyField(field);
    }

    // A->B, where A is complex: foo(x)->y, x[7]->y, etc.
    if (arrow >= 0 && arrow > dot) {
      String first = name.substring(0, arrow);
      String field = name.substring(arrow + 2);
      return parse(first).applyField(field);
    }

    // New decl format permits arbitrary uninterpreted strings as names
    if (FileIO.new_decl_format) {
      return new Simple(name).intern();
    } else {
      throw new UnsupportedOperationException("parse error: '" + name + "'");
    }
  }

  /**
   * Returns the String representation of this name in the default output format.
   *
   * @return the string representation (interned) of this name, in the default output format
   */
  @Pure
  public @Interned String name(@GuardSatisfied VarInfoName this) {
    if (name_cached == null) {
      try {
        name_cached = name_impl().intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    return name_cached;
  }

  private @Interned String name_cached = null; // interned

  /**
   * Returns the String representation of this name in the default output format. Result is not
   * interned; the client (name()) does so, then caches the interned value.
   */
  protected abstract String name_impl(@GuardSatisfied VarInfoName this);

  /**
   * Returns the String representation of this name in the esc style output format.
   *
   * @return the string representation (interned) of this name, in the esc style output format
   */
  public @Interned String esc_name() {
    if (esc_name_cached == null) {
      try {
        esc_name_cached = esc_name_impl().intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    // System.out.println("esc_name = " + esc_name_cached + " for " + name() + " of class " +
    // this.getClass().getName());
    return esc_name_cached;
  }

  private @Interned String esc_name_cached = null; // interned

  /**
   * Returns the String representation of this name in the ESC style output format. Cached by {@link
   * #esc_name()}.
   */
  protected abstract String esc_name_impl();

  /**
   * Returns the string representation (interned) of this name, in the Simplify tool output format
   * in the pre-state context.
   *
   * @return the string representation (interned) of this name, in the Simplify tool output format
   *     in the pre-state context
   */
  public @Interned String simplify_name() {
    return simplify_name(false);
  }

  /**
   * Returns the string representation (interned) of this name, in the Simplify tool output format,
   * in the given pre/post-state context.
   *
   * @param prestate if true, return the variable in a prestate context; if false, return the
   *     variable in a poststate context
   * @return the string representation (interned) of this name, in the Simplify tool output format,
   *     in the given pre/post-state context
   */
  protected @Interned String simplify_name(boolean prestate) {
    int which = prestate ? 0 : 1;
    if (simplify_name_cached[which] == null) {
      try {
        simplify_name_cached[which] = simplify_name_impl(prestate).intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    return simplify_name_cached[which];
  }

  // each element is interned
  private @Interned String[] simplify_name_cached = new @Interned String[2];

  /**
   * Returns the String representation of this name in the simplify output format in either prestate
   * or poststate context.
   */
  protected abstract String simplify_name_impl(boolean prestate);

  /**
   * Returns the String representation of this name in the java style output format.
   *
   * @return the string representation (interned) of this name, in the java style output format
   */
  public @Interned String java_name(VarInfo v) {
    if (java_name_cached == null) {
      try {
        java_name_cached = java_name_impl(v).intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    return java_name_cached;
  }

  private @Interned String java_name_cached = null; // interned

  /**
   * Returns the String representation of this name in java format. Cached and interned by {@link
   * #java_name}.
   */
  protected abstract String java_name_impl(VarInfo v);

  /** Returns the String representation of this name in the JML style output format. */
  public @Interned String jml_name(VarInfo v) {
    if (jml_name_cached == null) {
      try {
        jml_name_cached = jml_name_impl(v).intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    // System.out.println("jml_name = " + jml_name_cached + " for " + name() + " of class " +
    // this.getClass().getName());
    return jml_name_cached;
  }

  private @Interned String jml_name_cached = null; // interned

  /** Returns the name in JML style output format. Cached and interned by {@link #jml_name}. */
  protected abstract String jml_name_impl(VarInfo v);

  // For DBC, Java and JML formats, the formatting methods take as
  // argument the VarInfo related to the VarInfoName in question. This
  // causes trouble with VarInfoNameDriver (a class for testing
  // VarInfoName), because there are no VarInfo's to pass to the
  // formatting methods. So in places where the VarInfo argument is
  // required by the formatting code, we use this variable to check
  // whether we're doing testing. If we are, then we know that the
  // VarInfo being passed is probably null, and we do something other
  // than the normal thing (which would probably be to signal an
  // error). Unfortunately, this prevents testing of some of those
  // formats that make use of VarInfo information.
  public static boolean testCall = false;

  /**
   * Returns the String representation of this name in the dbc style output format.
   *
   * @param var the VarInfo which goes along with this VarInfoName. Used to determine the type of
   *     the variable.
   *     <p>If var is null, the only repercussion is that if `this' is an "orig(x)" expression, it
   *     will be formatted in jml-style, something like "\old(x)".
   *     <p>If var is not null and `this' is an "orig(x)" expressions, it will be formatted in
   *     Jtest's DBC style, as "$pre(<em>type</em>, x)".
   * @return the string representation (interned) of this name, in the dbc style output format
   */
  public @Interned String dbc_name(VarInfo var) {
    if (dbc_name_cached == null) {
      try {
        dbc_name_cached = dbc_name_impl(var).intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    return dbc_name_cached;
  }

  private @Interned String dbc_name_cached = null; // interned

  /**
   * Returns the name in the DBC style output format. If v is null, uses JML style instead. Cached
   * and interned by {@link #dbc_name}.
   */
  protected abstract String dbc_name_impl(VarInfo v);

  /**
   * Returns the String representation of this name using only letters, numbers, and underscores.
   */
  public @Interned String identifier_name() {
    if (identifier_name_cached == null) {
      try {
        identifier_name_cached = identifier_name_impl().intern();
      } catch (RuntimeException e) {
        System.err.println("repr = " + repr());
        throw e;
      }
    }
    // System.out.println("identifier_name = " + identifier_name_cached + " for " + name() + " of
    // class " + this.getClass().getName());
    return identifier_name_cached;
  }

  private @Interned String identifier_name_cached = null; // interned

  /**
   * Returns the name using only letters, numbers, and underscores. Cached and interned by {@link
   * #identifier_name()}.
   *
   * @return the name using only letters, numbers, and underscores
   */
  protected abstract String identifier_name_impl();

  /**
   * Returns name of this in the specified format.
   *
   * @param format the format in which to return this variable name
   * @param vi the VarInfo for this variable name
   * @return name of this in the specified format
   */
  public String name_using(OutputFormat format, VarInfo vi) {

    if (format == OutputFormat.DAIKON) {
      return name();
    }
    if (format == OutputFormat.SIMPLIFY) {
      return simplify_name();
    }
    if (format == OutputFormat.ESCJAVA) {
      return esc_name();
    }
    if (format == OutputFormat.JAVA) {
      return java_name(vi);
    }
    if (format == OutputFormat.JML) {
      return jml_name(vi);
    }
    if (format == OutputFormat.DBCJAVA) {
      return dbc_name(vi);
    }
    throw new UnsupportedOperationException("Unknown format requested: " + format);
  }

  /**
   * Returns the name, in a debugging format.
   *
   * @return the name, in a debugging format
   */
  public String repr(@GuardSatisfied VarInfoName this) {
    // AAD: Used to be interned for space reasons, but removed during
    // profiling when it was determined that the interns are unique
    // anyway.
    if (repr_cached == null) {
      repr_cached = repr_impl(); // .intern();
    }
    return repr_cached;
  }

  /** The cached output of {@link #repr_impl}, or null. */
  private String repr_cached = null;

  /**
   * Returns the name in a verbose debugging format. Cached by {@link #repr}.
   *
   * @return the name in a verbose debugging format
   */
  protected abstract String repr_impl(@GuardSatisfied VarInfoName this);

  // It would be nice if a generalized form of the mechanics of
  // interning were abstracted out somewhere.
  private static final WeakHashMap<VarInfoName, WeakReference<VarInfoName>> internTable =
      new WeakHashMap<>();

  // This does not make any guarantee that the components of the
  // VarInfoName are themselves interned.  Should it?  (I suspect so...)
  @InternMethod
  public VarInfoName intern() {
    WeakReference<VarInfoName> ref = internTable.get(this);
    if (ref != null) {
      VarInfoName result = ref.get();
      return result;
    } else {
      @SuppressWarnings("interning") // intern method
      @Interned VarInfoName this_interned = this;
      internTable.put(this_interned, new WeakReference<>(this_interned));
      return this_interned;
    }
  }

  // ============================================================
  // Constants

  public static final VarInfoName ZERO = parse("0");
  public static final VarInfoName THIS = parse("this");
  public static final VarInfoName ORIG_THIS = parse("this").applyPrestate();

  // ============================================================
  // Observers

  /**
   * Returns true when this is "0", "-1", "1", etc.
   *
   * @return true when this is "0", "-1", "1", etc
   */
  @Pure
  public boolean isLiteralConstant() {
    return false;
  }

  /**
   * Returns the nodes of this, as given by an inorder traversal.
   *
   * @return the nodes of this, as given by an inorder traversal
   */
  public Collection<VarInfoName> inOrderTraversal(@Interned VarInfoName this) {
    return Collections.unmodifiableCollection(new InorderFlattener(this).nodes());
  }

  /**
   * Returns true iff the given node can be found in this. If the node has children, the whole
   * subtree must match.
   *
   * @param node a variable name
   * @return true iff the given node can be found in this. If the node has children, the whole
   *     subtree must match
   */
  public boolean hasNode(VarInfoName node) {
    return inOrderTraversal().contains(node);
  }

  /**
   * Returns true iff a node of the given type exists in this.
   *
   * @param type the type to search for
   * @return true iff a node of the given type exists in this
   */
  public boolean hasNodeOfType(Class<?> type) {
    for (VarInfoName vin : inOrderTraversal()) {
      if (type.equals(vin.getClass())) {
        return true;
      }
    }
    return false;
  }

  /**
   * Returns true iff a TypeOf node exists in this.
   *
   * @return true iff a TypeOf node exists in this
   */
  public boolean hasTypeOf() {
    return hasNodeOfType(VarInfoName.TypeOf.class);
  }

  /**
   * Returns true if this name refers to the 'this' variable of a class. True for both normal and
   * prestate versions of the variable.
   */
  @Pure
  public boolean isThis() {
    if (name() == "this") { // interned
      return true;
    }
    if (this instanceof VarInfoName.Prestate
        && ((VarInfoName.Prestate) this).term.name() == "this") { // interned
      return true;
    }

    return false;
  }

  /**
   * Returns true if the given node is in a prestate context within this tree.
   *
   * @param node a member of this tree
   * @return true if the given node is in a prestate context within this tree
   */
  public boolean inPrestateContext(@Interned VarInfoName this, VarInfoName node) {
    return new NodeFinder(this, node).inPre();
  }

  /**
   * Returns true if every variable in the name is an orig(...) variable.
   *
   * @return true if every variable in the name is an orig(...) variable
   */
  @Pure
  public boolean isAllPrestate(@Interned VarInfoName this) {
    return new IsAllPrestateVisitor(this).result();
  }

  /**
   * Returns true if this VarInfoName contains a simple variable whose name is NAME.
   *
   * @param name the name to search for in this VarInfoName
   * @return true if this VarInfoName contains a simple variable whose name is NAME
   */
  public boolean includesSimpleName(@Interned VarInfoName this, String name) {
    return new SimpleNamesVisitor(this).simples().contains(name);
  }

  // ============================================================
  // Special producers, or other helpers

  /** Replace the first instance of node by replacement, in the data structure rooted at this. */
  public VarInfoName replace(
      @Interned VarInfoName this, VarInfoName node, VarInfoName replacement) {
    if (node == replacement) { // "interned": equality optimization pattern
      return this;
    }
    Replacer r = new Replacer(node, replacement);
    return r.replace(this).intern();
  }

  /** Replace all instances of node by replacement, in the data structure rooted at this. */
  public VarInfoName replaceAll(
      @Interned VarInfoName this, VarInfoName node, VarInfoName replacement) {
    if (node == replacement) { // "interned": equality optimization pattern
      return this;
    }

    // assert ! replacement.hasNode(node); // no infinite loop

    // It doesn't make sense to assert this as we have plenty of times when
    // we want to replace x by y where y may contain x.

    Replacer r = new Replacer(node, replacement);

    // This code used to loop as long as node was in result, but this isn't
    // necessary -- all occurrences are replaced by replacer.

    VarInfoName result = r.replace(this).intern();
    return result;
  }

  // ============================================================
  // The usual Object methods

  @EnsuresNonNullIf(result = true, expression = "#1")
  @Pure
  @Override
  public boolean equals(@GuardSatisfied VarInfoName this, @GuardSatisfied @Nullable Object o) {
    return (o instanceof VarInfoName) && equalsVarInfoName((VarInfoName) o);
  }

  @EnsuresNonNullIf(result = true, expression = "#1")
  @Pure
  public boolean equalsVarInfoName(
      @GuardSatisfied @Interned VarInfoName this, @GuardSatisfied VarInfoName other) {
    return ((other == this) // "interned": equality optimization pattern
        || ((other != null) && this.repr().equals(other.repr())));
  }

  // This should be safe even in the absence of caching, because "repr()"
  // returns a new string each time, but it is equal() to any other
  // returned string, so their hashCode()s should be the same.
  @Pure
  @Override
  public int hashCode(@GuardSatisfied VarInfoName this) {
    return repr().hashCode();
  }

  @Pure
  @Override
  public int compareTo(@GuardSatisfied VarInfoName this, VarInfoName other) {
    int nameCmp = name().compareTo(other.name());
    if (nameCmp != 0) {
      return nameCmp;
    }
    int reprCmp = repr().compareTo(other.repr());
    return reprCmp;
  }

  // This is a debugging method, not intended for ordinary output.
  // Code producing output should usually call name() rather than
  // calling toString (perhaps implicitly).
  @SideEffectFree
  @Override
  public String toString(@GuardSatisfied VarInfoName this) {
    return repr();
  }

  // Interning is lost when an object is serialized and deserialized.
  // Manually re-intern any interned fields upon deserialization.
  private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
    in.defaultReadObject();
    if (name_cached != null) {
      name_cached = name_cached.intern();
    }
    if (esc_name_cached != null) {
      esc_name_cached = esc_name_cached.intern();
    }
    if (simplify_name_cached[0] != null) {
      simplify_name_cached[0] = simplify_name_cached[0].intern();
    }
    if (simplify_name_cached[1] != null) {
      simplify_name_cached[1] = simplify_name_cached[1].intern();
    }
    if (java_name_cached != null) {
      java_name_cached = java_name_cached.intern();
    }
    if (jml_name_cached != null) {
      jml_name_cached = jml_name_cached.intern();
    }
    if (dbc_name_cached != null) {
      dbc_name_cached = dbc_name_cached.intern();
    }
  }

  // ============================================================
  // Static inner classes that form the expression language

  /** A simple identifier like "a", etc. */
  public static @Interned class Simple extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final String name;

    public Simple(String name) {
      assert name != null;
      this.name = name;
    }

    @Pure
    @Override
    public boolean isLiteralConstant() {
      try {
        Integer.parseInt(name);
        return true;
      } catch (NumberFormatException e) {
        return false;
      }
    }

    @Override
    protected String repr_impl(@GuardSatisfied Simple this) {
      return name;
    }

    @Override
    protected String name_impl(@GuardSatisfied Simple this) {
      return name;
    }

    @Override
    protected String esc_name_impl() {
      return "return".equals(name) ? "\\result" : name;
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      if (isLiteralConstant()) {
        return name;
      } else {
        return simplify_name_impl(name, prestate);
      }
    }

    // Names must be either a legal C/Java style identifier, or
    // surrounded by vertical bars (Simplify's quoting mechanism);
    // other than that, they only have to be consistent within one
    // execution of Daikon.
    protected static String simplify_name_impl(String s, boolean prestate) {
      if (s.startsWith("~") && s.endsWith("~")) {
        s = s.substring(1, s.length() - 2) + ":closure";
      }
      if (prestate) {
        s = "__orig__" + s;
      }
      return "|" + s + "|";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return "return".equals(name) ? "\\result" : name;
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return "return".equals(name) ? "\\result" : name;
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      if (name.equals("return")) {
        return "$result";
      } else {
        return name;
      }
    }

    @Override
    protected String identifier_name_impl() {
      if (name.equals("return")) {
        return "Daikon_return";
      } else if (name.equals("this")) {
        return "Daikon_this";
      } else {
        StringBuilder buf = new StringBuilder();
        for (int i = 0; i < name.length(); i++) {
          char c = name.charAt(i);
          if (Character.isLetterOrDigit(c)) buf.append(c);
          else if (c == '_') buf.append("__");
          else if (c == '$') buf.append("_dollar_");
          else if (c == ':') buf.append("_colon_");
          else if (c == '*') buf.append("star_");
          else {
            throw new Error("Unexpected character in VarInfoName$Simple");
          }
        }
        return buf.toString();
      }
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitSimple(this);
    }
  }

  /**
   * Returns true iff applySize will not throw an exception.
   *
   * @return true iff applySize will not throw an exception
   * @see #applySize
   */
  @Pure
  public boolean isApplySizeSafe() {
    return new ElementsFinder(this).elems() != null;
  }

  /**
   * Returns a name for the size of this (this object should be a sequence). Form is like
   * "size(a[])" or "a.length".
   *
   * @return a name for the size of this
   */
  public VarInfoName applySize(@Interned VarInfoName this) {
    // The simple approach:
    //   return new SizeOf((Elements) this).intern();
    // is wrong because this might be "orig(a[])".
    if (dkconfig_direct_orig) {
      return new SizeOf(this).intern();
    } else {
      Elements elems = new ElementsFinder(this).elems();
      if (elems == null) {
        throw new Error(
            "applySize should have elements to use in "
                + name()
                + ";"
                + Global.lineSep
                + "that is, "
                + name()
                + " does not appear to be a sequence/collection."
                + Global.lineSep
                + "Perhaps its name should be suffixed by \"[]\"?"
                + Global.lineSep
                + " this.class = "
                + getClass().getName());
      }

      // If this is orig, replace the elems with sizeof, leaving orig
      // where it is.  If it is not orig, simply return the sizeof the
      // elems (ignoring anything outside of the elems (like additional
      // fields or typeof)).  This allows this code to work correctly
      // for variables such as a[].b.c (returns size(a[])) or
      // a[].getClass().getName() (returns size(a[]))
      if (this instanceof Prestate) {
        VarInfoName size = new SizeOf(elems).intern();
        return new Prestate(size).intern();
        // Replacer r = new Replacer(elems, new SizeOf(elems).intern());
        // return r.replace(this).intern();
      } else {
        return new SizeOf(elems).intern();
      }
    }
  }

  /**
   * If this is a slice, (potentially in pre-state), return its lower and upper bounds, which can be
   * subtracted to get one less than its size.
   */
  public @Interned VarInfoName[] getSliceBounds(@Interned VarInfoName this) {
    VarInfoName vin = this;
    boolean inPrestate = false;
    if (vin instanceof Prestate) {
      inPrestate = true;
      vin = ((Prestate) vin).term;
    }
    while (vin instanceof Field) {
      vin = ((Field) vin).term;
    }
    if (!(vin instanceof Slice)) {
      return null;
    }
    Slice slice = (Slice) vin;
    @Interned VarInfoName[] ret = new @Interned VarInfoName[2];
    if (slice.i != null) {
      ret[0] = slice.i;
    } else {
      ret[0] = ZERO;
    }
    if (slice.j != null) {
      ret[1] = slice.j;
    } else {
      ret[1] = slice.sequence.applySize().applyAdd(-1);
    }
    if (inPrestate) {
      ret[0] = ret[0].applyPrestate();
      ret[1] = ret[1].applyPrestate();
    }
    return ret;
  }

  /** The size of a contained sequence; form is like "size(sequence)" or "sequence.length". */
  public static @Interned class SizeOf extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName sequence;

    public SizeOf(VarInfoName sequence) {
      assert sequence != null;
      this.sequence = sequence;
    }

    @Override
    protected String repr_impl(@GuardSatisfied SizeOf this) {
      return "SizeOf[" + sequence.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied SizeOf this) {
      return "size(" + sequence.name() + ")";

      // I'm not sure how to get this right; seems to require info about
      // the variable type.
      // // The result could be either "sequence.length" or "sequence.size()",
      // // depending on the type of "sequence".
      // String seqname = sequence.name();
      // if (seqname.endsWith("[]")
      //     // This clause is too confusing for C output, where some
      //     // variables get "size(seq)" and some get seq.length.
      //     // && ! seqname.startsWith("::")
      //     ) {
      //   return sequence.term.name() + ".length";
      // } else {
      //   return seqname + ".size()";
      // }
    }

    /** Returns the hashcode that is the base of the array. */
    @Pure
    public VarInfoName get_term() {
      if (sequence instanceof Elements) {
        return ((Elements) sequence).term;
      } else if (sequence instanceof Prestate) {
        VarInfoName term = ((Prestate) sequence).term;
        return ((Elements) term).term;
      }
      throw new RuntimeException("unexpected term in sizeof " + this);
    }

    @Override
    protected String esc_name_impl() {
      return get_term().esc_name() + ".length";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(arrayLength " + get_term().simplify_name(prestate) + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return java_family_impl(OutputFormat.JAVA, v);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return java_family_impl(OutputFormat.JML, v);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return java_family_impl(OutputFormat.DBCJAVA, v);
    }

    protected String java_family_impl(OutputFormat format, VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      assert v != null;
      assert v.isDerived();
      Derivation derived = v.derived;
      assert derived instanceof SequenceLength;
      VarInfo seqVarInfo = ((SequenceLength) derived).base;
      String prefix = get_term().name_using(format, seqVarInfo);
      return "daikon.Quant.size(" + prefix + ")";
      //       if (seqVarInfo.type.pseudoDimensions() > seqVarInfo.type.dimensions()) {
      //         if (prefix.startsWith("daikon.Quant.collect")) {
      //           // Quant collect methods returns an array
      //           return prefix  + ".length";
      //         } else {
      //           // It's a Collection
      //           return prefix  + ".size()";
      //         }
      //       } else {
      //         // It's an array
      //         return prefix + ".length";
      //       }
    }

    @Override
    protected String identifier_name_impl() {
      return "size_of" + sequence.identifier_name() + "___";
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitSizeOf(this);
    }
  }

  /**
   * Returns a name for a unary function applied to this object. The result is like "sum(this)".
   *
   * @param function the function to apply
   * @return a name for the function applied to this
   */
  public VarInfoName applyFunction(@Interned VarInfoName this, String function) {
    return new FunctionOf(function, this).intern();
  }

  /**
   * Returns a name for a function applied to more than one argument. The result is like "sum(var1,
   * var2)".
   *
   * @param function the name of the function
   * @param vars the arguments to the function, of type VarInfoName
   * @return a name for a function applied to multiple arguments
   */
  public static VarInfoName applyFunctionOfN(String function, List<VarInfoName> vars) {
    return new FunctionOfN(function, vars).intern();
  }

  /**
   * Returns a name for a function of more than one argument. The result is like "sum(var1, var2)".
   *
   * @param function the name of the function
   * @param vars the arguments to the function
   */
  public static VarInfoName applyFunctionOfN(String function, @Interned VarInfoName[] vars) {
    // This causes an odd error with the Interned checker:
    // return applyFunctionOfN(function, Arrays.<@Interned VarInfoName>asList(vars));
    return applyFunctionOfN(function, Arrays.asList(vars));
  }

  /** A function over a term, like "sum(argument)". */
  public static @Interned class FunctionOf extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final String function;
    public final VarInfoName argument;

    public FunctionOf(String function, VarInfoName argument) {
      assert function != null;
      assert argument != null;
      this.function = function;
      this.argument = argument;
    }

    @Override
    protected String repr_impl(@GuardSatisfied FunctionOf this) {
      return "FunctionOf{" + function + "}[" + argument.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied FunctionOf this) {
      return function + "(" + argument.name() + ")";
    }

    @Override
    protected String esc_name_impl() {
      return "(warning: format_esc() needs to be implemented: "
          + function
          + " on "
          + argument.repr()
          + ")";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(warning: format_simplify() needs to be implemented: "
          + function
          + " on "
          + argument.repr()
          + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return java_family_name_impl(OutputFormat.JAVA, v);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return java_family_name_impl(OutputFormat.JML, v);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return java_family_name_impl(OutputFormat.DBCJAVA, v);
    }

    protected String java_family_name_impl(OutputFormat format, VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      assert v != null;
      assert v.isDerived();
      Derivation derived = v.derived;
      assert derived instanceof UnaryDerivation;
      VarInfo argVarInfo = ((UnaryDerivation) derived).base;
      return "daikon.Quant." + function + "(" + argument.name_using(format, argVarInfo) + ")";
    }

    @Override
    protected String identifier_name_impl() {
      return function + "_of_" + argument.identifier_name() + "___";
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitFunctionOf(this);
    }
  }

  /** A function of multiple parameters. */
  public static @Interned class FunctionOfN extends VarInfoName {
    /** If you add or remove fields, change this number to the current date. */
    static final long serialVersionUID = 20020130L;

    /** The function being invoked. */
    public final String function;

    /** The parameters. */
    @SuppressWarnings("serial")
    public final List<VarInfoName> args;

    /**
     * Construct a new function of multiple arguments.
     *
     * @param function the name of the function
     * @param args the arguments to the function, of type VarInfoName
     */
    public FunctionOfN(String function, List<VarInfoName> args) {
      assert function != null;
      assert args != null;
      this.args = args;
      this.function = function;
    }

    /**
     * Returns a string representation of the elements of this.
     *
     * @return a string representation of the elements of this
     */
    private List<String> elts_repr(@GuardSatisfied FunctionOfN this) {
      List<String> elts = new ArrayList<>(args.size());
      for (VarInfoName vin : args) {
        elts.add(vin.repr());
      }
      return elts;
    }

    /**
     * Returns a comma-separated list of element names.
     *
     * @return comma-separated list of element names
     */
    private String elts_repr_commas(@GuardSatisfied FunctionOfN this) {
      return String.join(", ", elts_repr());
    }

    @Override
    protected String repr_impl(@GuardSatisfied FunctionOfN this) {
      return "FunctionOfN{" + function + "}[" + elts_repr_commas() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied FunctionOfN this) {
      return function + "(" + elts_repr_commas() + ")";
    }

    @Override
    protected String esc_name_impl() {
      return "(warning: format_esc() needs to be implemented: "
          + function
          + " on "
          + elts_repr_commas()
          + ")";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(warning: format_simplify() needs to be implemented: "
          + function
          + " on "
          + elts_repr_commas()
          + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return java_family_name_impl(OutputFormat.JAVA, v);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return java_family_name_impl(OutputFormat.JML, v);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return java_family_name_impl(OutputFormat.DBCJAVA, v);
    }

    // Only works for two-argument functions.  There are currently no
    // ternary (or greater) function applications in Daikon.
    protected String java_family_name_impl(OutputFormat format, VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      assert v != null;
      assert v.isDerived();
      Derivation derived = v.derived;
      assert derived instanceof BinaryDerivation;
      // || derived instanceof TernaryDerivation);
      assert args.size() == 2;
      VarInfo arg1VarInfo = ((BinaryDerivation) derived).base1;
      VarInfo arg2VarInfo = ((BinaryDerivation) derived).base2;
      return "daikon.Quant."
          + function
          + "("
          + args.get(0).name_using(format, arg1VarInfo)
          + ", "
          + args.get(1).name_using(format, arg2VarInfo)
          + ")";
    }

    @Override
    protected String identifier_name_impl() {
      List<String> elts = new ArrayList<>(args.size());
      for (VarInfoName vin : args) {
        elts.add(vin.identifier_name());
      }
      return function + "_of_" + String.join("_comma_", elts) + "___";
    }

    /** Shortcut getter to avoid repeated type casting. */
    public VarInfoName getArg(int n) {
      return args.get(n);
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitFunctionOfN(this);
    }
  }

  /**
   * Returns a name for the intersection of with another sequence, like "intersect(a[], b[])".
   *
   * @param seq2 the variable to intersect with
   * @return the name for the intersection of this and seq2
   */
  public VarInfoName applyIntersection(@Interned VarInfoName this, VarInfoName seq2) {
    assert seq2 != null;
    return new Intersection(this, seq2).intern();
  }

  /**
   * Intersection of two sequences. Extends FunctionOfN, and the only change is that it does special
   * formatting for IOA.
   */
  public static @Interned class Intersection extends FunctionOfN {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public Intersection(VarInfoName seq1, VarInfoName seq2) {
      super("intersection", Arrays.asList(seq1, seq2));
    }
  }

  /**
   * Returns a name for the union of this with another sequence, like "union(a[], b[])".
   *
   * @param seq2 the variable to union with
   * @return the name for the intersection of this and seq2
   */
  public VarInfoName applyUnion(@Interned VarInfoName this, VarInfoName seq2) {
    assert seq2 != null;
    return new Union(this, seq2).intern();
  }

  /**
   * Union of two sequences. Extends FunctionOfN, and the only change is that it does special
   * formatting for IOA.
   */
  public static @Interned class Union extends FunctionOfN {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public Union(VarInfoName seq1, VarInfoName seq2) {
      super("intersection", Arrays.asList(seq1, seq2));
    }
  }

  /**
   * Returns a 'getter' operation for some field of this name, like a.foo if this is a.
   *
   * @param field the field
   * @return the name for the given field of this
   */
  public VarInfoName applyField(@Interned VarInfoName this, String field) {
    return new Field(this, field).intern();
  }

  /** A 'getter' operation for some field, like a.foo. */
  public static @Interned class Field extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName term;
    public final String field;

    public Field(VarInfoName term, String field) {
      assert term != null;
      assert field != null;
      this.term = term;
      this.field = field;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Field this) {
      return "Field{" + field + "}[" + term.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Field this) {
      return term.name() + "." + field;
    }

    @Override
    protected String esc_name_impl() {
      return term.esc_name() + "." + field;
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(select "
          + Simple.simplify_name_impl(field, false)
          + " "
          + term.simplify_name(prestate)
          + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return java_family_name(OutputFormat.JAVA, v);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return java_family_name(OutputFormat.JML, v);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return java_family_name(OutputFormat.DBCJAVA, v);
    }

    // Special case: the fake "toString" field in Daikon is output
    // with parens, so that it's legal Java.
    protected String java_field(String f) {
      if (f.equals("toString")) {
        return "toString()";
      } else {
        return f;
      }
    }

    // For JAVA, JML and DBC formats.
    protected String java_family_name(OutputFormat format, VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      if (term.name().indexOf("..") != -1) {
        // We cannot translate arr[i..].x because this translates into
        //
        //    "daikon.Quant.collect(daikon.Quant.slice(arr,i,arr.length),"x")"
        //
        // but slice() returns an array of Objects, so an error will
        // occur when method collect() tries to query for field "x".
        return "(warning: "
            + format
            + " format cannot express a field applied to a slice:"
            + " [repr="
            + repr()
            + "])";
      }

      boolean hasBrackets = (term.name().indexOf("[]") != -1);

      if (format == OutputFormat.JAVA) {
        assert !hasBrackets || v.type.dimensions() > 0
            : "hasBrackets:" + hasBrackets + ", dimensions:" + v.type.dimensions() + ", v:" + v;
      }

      if (!hasBrackets && format != OutputFormat.JAVA) {
        // Case 1: Not an array collection
        String term_name = null;
        if (format == OutputFormat.JML) {
          term_name = term.jml_name(v);
        } else {
          term_name = term.dbc_name(v);
        }
        return term_name + "." + java_field(field);
      }

      // Case 2: An array collection

      // How to translate foo[].f, which is the array obtained from
      // collecting o.f for every element o in the array foo?  Just as
      // we did for slices, we'll translate this into a call of an
      // external function to do the job:

      // x.y.foo[].bar.f
      // ---translates-into--->
      // daikon.Quant.collect_TYPE_(x, "y.foo[].bar.f")

      // The method Quant.collect takes care of the "y.foo[].bar.f"
      // mess for object x.

      if (field.equals("toString")) {
        return "(warning: "
            + format
            + " format cannot express a slice with String objects:"
            + " obtained by toString():  [repr="
            + repr()
            + "])";
      }

      String term_name_no_brackets = term.name().replaceAll("\\[\\]", "") + "." + field;

      @SuppressWarnings("keyfor") // PACKAGE_NAME is always a key
      String packageName = v.aux.getValue(VarInfoAux.PACKAGE_NAME);
      if (packageName.equals(VarInfoAux.NO_PACKAGE_NAME)) {
        packageName = "";
      }

      String[] splits;
      boolean isStatic = false;
      String packageNamePrefix = null;
      // if (isStatic) {
      if (term_name_no_brackets.startsWith(packageName + ".")) {
        //           throw new Error("packageName=" + packageName + ", term_name_no_brackets=" +
        //                           term_name_no_brackets);
        //         }
        // Before splitting, remove the package name.
        packageNamePrefix = (packageName.equals("") ? "" : packageName + ".");
        isStatic = true;
        splits = term_name_no_brackets.substring(packageNamePrefix.length()).split("\\.");
      } else {
        packageNamePrefix = "";
        isStatic = false;
        splits = term_name_no_brackets.split("\\.");
      }

      String object = splits[0];
      if (isStatic) {
        object += DaikonVariableInfo.class_suffix;
      }
      if (object.equals("return")) {
        if (format == OutputFormat.DBCJAVA) {
          object = "$return";
        } else {
          object = "\\result";
        }
      }

      String fields = "";
      for (int j = 1; j < splits.length; j++) {
        if (j != 1) {
          fields += ".";
        }
        fields += splits[j];
      }

      String collectType = (v.type.baseIsPrimitive() ? v.type.base() : "Object");

      if (format == OutputFormat.JAVA) {
        return
        // On one line to enable searches for "collect.*_field".
        "daikon.Quant.collect"
            + collectType
            + (!v.is_array() ? "_field" : "")
            + "("
            + packageNamePrefix
            + object
            + ", "
            + "\""
            + fields
            + "\""
            + ")";
      } else {
        return "daikon.Quant.collect"
            + collectType
            + "("
            + packageNamePrefix
            + object
            + ", "
            + "\""
            + fields
            + "\""
            + ")";
      }
    }

    @Override
    protected String identifier_name_impl() {
      return term.identifier_name() + "_dot_" + field;
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitField(this);
    }
  }

  /**
   * Returns a name for the type of this object; form is like "this.getClass().getName()" or
   * "\typeof(this)".
   *
   * @return the name for the type of this object
   */
  public VarInfoName applyTypeOf(@Interned VarInfoName this) {
    return new TypeOf(this).intern();
  }

  /** The type of the term, like "term.getClass().getName()" or "\typeof(term)". */
  public static @Interned class TypeOf extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName term;

    public TypeOf(VarInfoName term) {
      assert term != null;
      this.term = term;
    }

    @Override
    protected String repr_impl(@GuardSatisfied TypeOf this) {
      return "TypeOf[" + term.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied TypeOf this) {
      return term.name() + DaikonVariableInfo.class_suffix;
    }

    @Override
    protected String esc_name_impl() {
      return "\\typeof(" + term.esc_name() + ")";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(typeof " + term.simplify_name(prestate) + ")";
    }

    @SideEffectFree
    protected String javaFamilyFormat(String varname, boolean isArray) {
      if (isArray) {
        return "daikon.Quant.typeArray(" + varname + ")";
      } else {
        return varname + DaikonVariableInfo.class_suffix;
      }
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      if (testCall) {
        return "no format when testCall.";
      }
      return javaFamilyFormat(term.java_name(v), v.type.isArray());
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      if (testCall) {
        return "no format when testCall.";
      }
      return javaFamilyFormat(term.jml_name(v), v.type.isArray());
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      if (testCall) {
        return "no format when testCall.";
      }
      return javaFamilyFormat(term.dbc_name(v), v.type.isArray());
    }

    @Override
    protected String identifier_name_impl() {
      return "type_of_" + term.identifier_name() + "___";
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitTypeOf(this);
    }
  }

  /**
   * Returns a name for a the prestate value of this object; form is like "orig(this)" or
   * "\old(this)".
   *
   * @return a name for the prestate value of this object
   */
  public VarInfoName applyPrestate(@Interned VarInfoName this) {
    if (this instanceof Poststate) {
      return ((Poststate) this).term;
    } else if ((this instanceof Add) && ((Add) this).term instanceof Poststate) {
      Add a = (Add) this;
      Poststate p = (Poststate) a.term;
      return p.term.applyAdd(a.amount);
    } else {
      return new Prestate(this).intern();
    }
  }

  /** The prestate value of a term, like "orig(term)" or "\old(term)". */
  public static @Interned class Prestate extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName term;

    public Prestate(VarInfoName term) {
      assert term != null;
      this.term = term;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Prestate this) {
      return "Prestate[" + term.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Prestate this) {
      return "orig(" + term.name() + ")";
    }

    @Override
    protected String esc_name_impl() {
      return "\\old(" + term.esc_name() + ")";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return term.simplify_name(true);
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      if (PrintInvariants.dkconfig_replace_prestate) {
        return PrintInvariants.addPrestateExpression(term.java_name(v));
      }
      return "\\old(" + term.java_name(v) + ")";
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return "\\old(" + term.jml_name(v) + ")";
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      String brackets = "";
      assert v != null;
      String preType = v.type.base();
      if ((term instanceof Slice)
          // Slices are obtained by calling daikon.Quant.slice(...)
          // which returns things of type java.lang.Object
          && v.type.dimensions() > 0
          && v.type.base().equals("java.lang.Object")) {
        preType = "java.lang.Object";
      }
      for (int i = 0; i < v.type.dimensions(); i++) {
        brackets += "[]";
      }
      return "$pre(" + preType + brackets + ", " + term.dbc_name(v) + ")";
    }

    @Override
    protected String identifier_name_impl() {
      return "orig_of_" + term.identifier_name() + "___";
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitPrestate(this);
    }
  }

  // sansOrig()
  //      int origpos = s.indexOf("orig(");
  //      assert origpos != -1;
  //      int rparenpos = s.lastIndexOf(')');
  //      return s.substring(0, origpos)
  //        + s.substring(origpos+5, rparenpos)
  //        + s.substring(rparenpos+1);

  //      int origpos = s.indexOf("\\old(");
  //      assert origpos != -1;
  //      int rparenpos = s.lastIndexOf(')');
  //      return s.substring(0, origpos)
  //        + s.substring(origpos+5, rparenpos)
  //        + s.substring(rparenpos+1);

  /**
   * Returns a name for a the poststate value of this object; form is like "new(this)" or
   * "\new(this)".
   *
   * @return the name for the poststate value of this object
   */
  public VarInfoName applyPoststate(@Interned VarInfoName this) {
    return new Poststate(this).intern();
  }

  /**
   * The poststate value of a term, like "new(term)". Only used within prestate, so like
   * "orig(this.myArray[new(index)]".
   */
  public static @Interned class Poststate extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName term;

    public Poststate(VarInfoName term) {
      assert term != null;
      this.term = term;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Poststate this) {
      return "Poststate[" + term.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Poststate this) {
      return "post(" + term.name() + ")";
    }

    @Override
    protected String esc_name_impl() {
      return "\\new(" + term.esc_name() + ")";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return term.simplify_name(false);
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return "\\post(" + term.java_name(v) + ")";
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return "\\new(" + term.jml_name(v) + ")";
      // return "(warning: JML format cannot express a Poststate"
      //  + " [repr=" + repr() + "])";
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return "(warning: DBC format cannot express a Poststate [repr=" + repr() + "])";
    }

    @Override
    protected String identifier_name_impl() {
      return "post_of_" + term.identifier_name() + "___";
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitPoststate(this);
    }
  }

  /** Returns a name for the this term plus a constant, like "this-1" or "this+1". */
  public VarInfoName applyAdd(@Interned VarInfoName this, int amount) {
    if (amount == 0) {
      return this;
    } else {
      return new Add(this, amount).intern();
    }
  }

  /** An integer amount more or less than some other value, like "x+2". */
  public static @Interned class Add extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName term;
    public final int amount;

    public Add(VarInfoName term, int amount) {
      assert term != null;
      this.term = term;
      this.amount = amount;
    }

    private String amount(@GuardSatisfied Add this) {
      return (amount < 0) ? String.valueOf(amount) : "+" + amount;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Add this) {
      return "Add{" + amount() + "}[" + term.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Add this) {
      return term.name() + amount();
    }

    @Override
    protected String esc_name_impl() {
      return term.esc_name() + amount();
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return (amount < 0)
          ? "(- " + term.simplify_name(prestate) + " " + -amount + ")"
          : "(+ " + term.simplify_name(prestate) + " " + amount + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return term.java_name(v) + amount();
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return term.jml_name(v) + amount();
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return term.dbc_name(v) + amount();
    }

    @Override
    protected String identifier_name_impl() {
      if (amount >= 0) {
        return term.identifier_name() + "_plus" + amount;
      } else {
        return term.identifier_name() + "_minus" + -amount;
      }
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitAdd(this);
    }

    // override for cleanliness
    @Override
    public VarInfoName applyAdd(int _amount) {
      int amt = _amount + this.amount;
      return (amt == 0) ? term : term.applyAdd(amt);
    }
  }

  /** Returns a name for the decrement of this term, like "this-1". */
  public VarInfoName applyDecrement(@Interned VarInfoName this) {
    return applyAdd(-1);
  }

  /** Returns a name for the increment of this term, like "this+1". */
  public VarInfoName applyIncrement(@Interned VarInfoName this) {
    return applyAdd(+1);
  }

  /**
   * Returns a name for the elements of a container (as opposed to the identity of the container)
   * like "this[]" or "(elements this)".
   *
   * @return the name for the elements of this container
   */
  public VarInfoName applyElements(@Interned VarInfoName this) {
    return new Elements(this).intern();
  }

  /** The elements of a container, like "term[]". */
  public static @Interned class Elements extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final VarInfoName term;

    public Elements(VarInfoName term) {
      assert term != null;
      this.term = term;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Elements this) {
      return "Elements[" + term.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Elements this) {
      return name_impl("");
    }

    protected String name_impl(@GuardSatisfied Elements this, String index) {
      return term.name() + "[" + index + "]";
    }

    @Override
    protected String esc_name_impl() {
      throw new UnsupportedOperationException(
          "ESC cannot format an unquantified sequence of elements [repr=" + repr() + "]");
    }

    protected String esc_name_impl(String index) {
      return term.esc_name() + "[" + index + "]";
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(select elems " + term.simplify_name(prestate) + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return term.java_name(v);
    }

    protected String java_name_impl(String index, VarInfo v) {
      return java_family_impl(OutputFormat.JAVA, v, index);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return term.jml_name(v);
    }

    protected String jml_name_impl(String index, VarInfo v) {
      return java_family_impl(OutputFormat.JML, v, index);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return term.dbc_name(v);
    }

    protected String dbc_name_impl(String index, VarInfo v) {
      return java_family_impl(OutputFormat.DBCJAVA, v, index);
    }

    protected String java_family_impl(OutputFormat format, VarInfo v, String index) {

      // If the collection goes through daikon.Quant.collect___, then
      // it will be returned as an array no matter what.
      String formatted = term.name_using(format, v);
      String collectType = (v.type.baseIsPrimitive() ? v.type.base() : "Object");
      return "daikon.Quant.getElement_" + collectType + "(" + formatted + ", " + index + ")";
      //       // XXX temporary fix: sometimes long is passed as index.
      //       // I can't find where the VarInfo for "index" is found. Wherever that is,
      //       // we should check if its type is long, and do the casting only for that
      //       // case.
      //       if (formatted.startsWith("daikon.Quant.collect")) {
      //         return formatted + "[(int)" + index + "]";
      //       } else {
      //         if (v.type.pseudoDimensions() > v.type.dimensions()) {
      //           // it's a collection
      //           return formatted + ".get((int)" + index + ")";
      //         } else {
      //           // it's an array
      //           return formatted + "[(int)" + index + "]";
      //         }
      //       }
    }

    protected String identifier_name_impl(String index) {
      if (index.equals("")) {
        return term.identifier_name() + "_elems";
      } else {
        return term.identifier_name() + "_in_" + index + "_dex_";
      }
    }

    @Override
    protected String identifier_name_impl() {
      return identifier_name_impl("");
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitElements(this);
    }

    public VarInfoName getLowerBound() {
      return ZERO;
    }

    public VarInfoName getUpperBound() {
      return applySize().applyDecrement();
    }

    public VarInfoName getSubscript(VarInfoName index) {
      return applySubscript(index);
    }
  }

  /**
   * Caller is subscripting an orig(a[]) array. Take the requested index and make it useful in that
   * context.
   *
   * @param index an index into an orig array
   * @return a name for the indexed orig item
   */
  static VarInfoName indexToPrestate(VarInfoName index) {
    // 1 orig(a[]) . orig(index) -> orig(a[index])
    // 2 orig(a[]) . index       -> orig(a[post(index)])
    if (index instanceof Prestate) {
      index = ((Prestate) index).term; // #1
    } else if (index instanceof Add) {
      Add add = (Add) index;
      if (add.term instanceof Prestate) {
        index = ((Prestate) add.term).term.applyAdd(add.amount); // #1
      } else {
        index = index.applyPoststate(); // #2
      }
    } else if (index.isLiteralConstant()) {
      // we don't want orig(a[post(0)]), so leave index alone
    } else {
      index = index.applyPoststate(); // #2
    }
    return index;
  }

  /** Returns a name for an element selected from a sequence, like "this[i]". */
  public VarInfoName applySubscript(@Interned VarInfoName this, VarInfoName index) {
    assert index != null;
    ElementsFinder finder = new ElementsFinder(this);
    Elements elems = finder.elems();
    assert elems != null : "applySubscript should have elements to use in " + this;
    if (finder.inPre()) {
      index = indexToPrestate(index);
    }
    Replacer r = new Replacer(elems, new Subscript(elems, index).intern());
    return r.replace(this).intern();
  }

  // Given a sequence and subscript index, convert the index to an
  // explicit form if necessary (e.g. a[-1] becomes a[a.length-1]).
  // Result is not interned, because it is only ever used for printing.
  static VarInfoName indexExplicit(Elements sequence, VarInfoName index) {
    if (!index.isLiteralConstant()) {
      return index;
    }

    int i = Integer.parseInt(index.name());
    if (i >= 0) {
      return index;
    }

    return sequence.applySize().applyAdd(i);
  }

  /** An element from a sequence, like "sequence[index]". */
  public static @Interned class Subscript extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final Elements sequence;
    public final VarInfoName index;

    public Subscript(Elements sequence, VarInfoName index) {
      assert sequence != null;
      assert index != null;
      this.sequence = sequence;
      this.index = index;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Subscript this) {
      return "Subscript{" + index.repr() + "}[" + sequence.repr() + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Subscript this) {
      return sequence.name_impl(index.name());
    }

    @Override
    protected String esc_name_impl() {
      return sequence.esc_name_impl(indexExplicit(sequence, index).esc_name());
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      return "(select "
          + sequence.simplify_name(prestate)
          + " "
          + indexExplicit(sequence, index).simplify_name(prestate)
          + ")";
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return java_family_impl(OutputFormat.JAVA, v);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return java_family_impl(OutputFormat.JML, v);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return java_family_impl(OutputFormat.DBCJAVA, v);
    }

    protected String java_family_impl(OutputFormat format, VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      assert v != null;
      assert v.isDerived();
      Derivation derived = v.derived;
      assert derived instanceof SequenceScalarSubscript
          || derived instanceof SequenceStringSubscript
          || derived instanceof SequenceFloatSubscript;
      VarInfo indexVarInfo = ((BinaryDerivation) derived).base2;
      VarInfo seqVarInfo = ((BinaryDerivation) derived).base1;
      if (format == OutputFormat.JAVA) {
        return sequence.java_name_impl(index.java_name_impl(indexVarInfo), seqVarInfo);
      } else if (format == OutputFormat.JML) {
        return sequence.jml_name_impl(index.jml_name_impl(indexVarInfo), seqVarInfo);
      } else { // format == OutputFormat.DBCJAVA
        return sequence.dbc_name_impl(index.dbc_name_impl(indexVarInfo), seqVarInfo);
      }
    }

    @Override
    protected String identifier_name_impl() {
      return sequence.identifier_name_impl(index.identifier_name());
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitSubscript(this);
    }
  }

  /**
   * Returns a name for a slice of element selected from a sequence, like "this[i..j]". If an
   * endpoint is null, it means "from the start" or "to the end".
   */
  public VarInfoName applySlice(
      @Interned VarInfoName this, @Nullable VarInfoName i, @Nullable VarInfoName j) {
    // a[] -> a[index..]
    // orig(a[]) -> orig(a[post(index)..])
    ElementsFinder finder = new ElementsFinder(this);
    Elements elems = finder.elems();
    assert elems != null;
    if (finder.inPre()) {
      if (i != null) {
        i = indexToPrestate(i);
      }
      if (j != null) {
        j = indexToPrestate(j);
      }
    }
    Replacer r = new Replacer(finder.elems(), new Slice(elems, i, j).intern());
    return r.replace(this).intern();
  }

  /** A slice of elements from a sequence, like "sequence[i..j]". */
  public static @Interned class Slice extends VarInfoName {
    // We are Serializable, so we specify a version to allow changes to
    // method signatures without breaking serialization.  If you add or
    // remove fields, you should change this number to the current date.
    static final long serialVersionUID = 20020130L;

    public final Elements sequence;
    public final VarInfoName i;
    public final VarInfoName j;

    public Slice(Elements sequence, VarInfoName i, VarInfoName j) {
      assert sequence != null;
      assert (i != null) || (j != null);
      this.sequence = sequence;
      this.i = i;
      this.j = j;
    }

    @Override
    protected String repr_impl(@GuardSatisfied Slice this) {
      return "Slice{"
          + ((i == null) ? "" : i.repr())
          + ","
          + ((j == null) ? "" : j.repr())
          + "}["
          + sequence.repr()
          + "]";
    }

    @Override
    protected String name_impl(@GuardSatisfied Slice this) {
      return sequence.name_impl(
          ((i == null) ? "0" : i.name()) + ".." + ((j == null) ? "" : j.name()));
    }

    @Override
    protected String esc_name_impl() {
      // return the default implementation for now.
      // return name_impl();
      throw new UnsupportedOperationException(
          "ESC cannot format an unquantified slice of elements");
    }

    @Override
    protected String simplify_name_impl(boolean prestate) {
      System.out.println(" seq: " + sequence + " " + i + " " + j);
      throw new UnsupportedOperationException(
          "Simplify cannot format an unquantified slice of elements");
    }

    @Override
    protected String java_name_impl(VarInfo v) {
      return slice_helper(OutputFormat.JAVA, v);
    }

    @Override
    protected String jml_name_impl(VarInfo v) {
      return slice_helper(OutputFormat.JML, v);
    }

    @Override
    protected String dbc_name_impl(VarInfo v) {
      return slice_helper(OutputFormat.DBCJAVA, v);
    }

    // Helper for JML, Java and DBC formats
    protected String slice_helper(OutputFormat format, VarInfo v) {

      // See declaration of testCall for explanation of this flag.
      if (testCall) {
        return "no format when testCall.";
      }

      assert v != null;
      assert v.isDerived();
      Derivation derived = v.derived;
      assert derived instanceof SequenceSubsequence
          || derived instanceof SequenceScalarArbitrarySubsequence
          || derived instanceof SequenceFloatArbitrarySubsequence
          || derived instanceof SequenceStringArbitrarySubsequence;
      if (derived instanceof SequenceSubsequence) {
        assert i == null || j == null;
        if (i == null) { // sequence[0..j]
          assert j != null;
          return "daikon.Quant.slice("
              + sequence.name_using(format, ((SequenceSubsequence) derived).seqvar())
              + ", 0, "
              + j.name_using(format, ((SequenceSubsequence) derived).sclvar())
              + ")";
        } else {
          VarInfo seqVarInfo = ((SequenceSubsequence) derived).seqvar();
          String prefix = sequence.name_using(format, seqVarInfo);
          String lastIdxString = "daikon.Quant.size(" + prefix + ")";
          //           if (seqVarInfo.type.pseudoDimensions() > seqVarInfo.type.dimensions()) {
          //             if (prefix.startsWith("daikon.Quant.collect")) {
          //               // Quant collect methods returns an array
          //               lastIdxString = prefix + ".length-1";
          //             } else {
          //               // it's a collection
          //               lastIdxString = prefix + ".size()-1";
          //             }
          //           } else {
          //             // it's an array
          //             lastIdxString = prefix + ".length-1";
          //           }
          return "daikon.Quant.slice("
              + sequence.name_using(format, ((SequenceSubsequence) derived).seqvar())
              + ", "
              + i.name_using(format, ((SequenceSubsequence) derived).sclvar())
              + ", "
              + lastIdxString
              + ")";
        }
      } else {
        assert i != null && j != null;
        if (derived instanceof SequenceScalarArbitrarySubsequence) {
          SequenceScalarArbitrarySubsequence derived2 =
              (SequenceScalarArbitrarySubsequence) derived;
          return "daikon.Quant.slice("
              + sequence.name_using(format, derived2.seqvar())
              + ", "
              + i.name_using(format, derived2.startvar())
              + ", "
              + j.name_using(format, derived2.endvar())
              + ")";
        } else if (derived instanceof SequenceFloatArbitrarySubsequence) {
          SequenceFloatArbitrarySubsequence derived2 = (SequenceFloatArbitrarySubsequence) derived;
          return "daikon.Quant.slice("
              + sequence.name_using(format, derived2.seqvar())
              + ", "
              + i.name_using(format, derived2.startvar())
              + ", "
              + j.name_using(format, derived2.endvar())
              + ")";
        } else {
          SequenceStringArbitrarySubsequence derived2 =
              (SequenceStringArbitrarySubsequence) derived;
          return "daikon.Quant.slice("
              + sequence.name_using(format, derived2.seqvar())
              + ", "
              + i.name_using(format, derived2.startvar())
              + ", "
              + j.name_using(format, derived2.endvar())
              + ")";
        }
      }
    }

    @Override
    protected String identifier_name_impl() {
      String start = (i == null) ? "0" : i.identifier_name();
      String end = (j == null) ? "" : j.identifier_name();
      return sequence.identifier_name_impl(start + "_to_" + end);
    }

    @Override
    public <T> T accept(Visitor<T> v) {
      return v.visitSlice(this);
    }

    public VarInfoName getLowerBound() {
      return (i != null) ? i : ZERO;
    }

    public VarInfoName getUpperBound() {
      return (j != null) ? j : sequence.getUpperBound();
    }

    public VarInfoName getSubscript(VarInfoName index) {
      return sequence.getSubscript(index);
    }
  }

  /** Accept the actions of a visitor. */
  public abstract <T> T accept(Visitor<T> v);

  /** Visitor framework for processing of VarInfoNames. */
  public static interface Visitor<T> {
    public T visitSimple(Simple o);

    public T visitSizeOf(SizeOf o);

    public T visitFunctionOf(FunctionOf o);

    public T visitFunctionOfN(FunctionOfN o);

    public T visitField(Field o);

    public T visitTypeOf(TypeOf o);

    public T visitPrestate(Prestate o);

    public T visitPoststate(Poststate o);

    public T visitAdd(Add o);

    public T visitElements(Elements o);

    public T visitSubscript(Subscript o);

    public T visitSlice(Slice o);
  }

  /**
   * Traverse the tree elements that have exactly one branch (so the traversal order doesn't
   * matter). Visitors need to implement methods for traversing elements (e.g. FunctionOfN) with
   * more than one branch.
   */
  public abstract static class AbstractVisitor<T> implements Visitor<T> {
    @Override
    public T visitSimple(Simple o) {
      // nothing to do; leaf node
      return null;
    }

    @Override
    public T visitSizeOf(SizeOf o) {
      return o.sequence.accept(this);
    }

    @Override
    public T visitFunctionOf(FunctionOf o) {
      return o.argument.accept(this);
    }

    /** By default, return effect on first argument, but traverse all, backwards. */
    @Override
    public T visitFunctionOfN(FunctionOfN o) {
      T retval = null;
      for (ListIterator<VarInfoName> i = o.args.listIterator(o.args.size()); i.hasPrevious(); ) {
        VarInfoName vin = i.previous();
        retval = vin.accept(this);
      }
      return retval;
    }

    @Override
    public T visitField(Field o) {
      return o.term.accept(this);
    }

    @Override
    public T visitTypeOf(TypeOf o) {
      return o.term.accept(this);
    }

    @Override
    public T visitPrestate(Prestate o) {
      return o.term.accept(this);
    }

    @Override
    public T visitPoststate(Poststate o) {
      return o.term.accept(this);
    }

    @Override
    public T visitAdd(Add o) {
      return o.term.accept(this);
    }

    @Override
    public T visitElements(Elements o) {
      return o.term.accept(this);
    }

    // leave abstract; traversal order and return values matter
    @Override
    public abstract T visitSubscript(Subscript o);

    // leave abstract; traversal order and return values matter
    @Override
    public abstract T visitSlice(Slice o);
  }

  /**
   * Use to report whether a node is in a pre- or post-state context. Throws an assertion error if a
   * given goal isn't present.
   */
  public static class NodeFinder extends AbstractVisitor<VarInfoName> {
    /**
     * Creates a new NodeFinder.
     *
     * @param root the root of the tree to search
     * @param goal the goal to find
     */
    public NodeFinder(VarInfoName root, VarInfoName goal) {
      this.goal = goal;
      assert root.accept(this) != null;
    }

    // state and accessors
    private final VarInfoName goal;
    private boolean pre;

    public boolean inPre() {
      return pre;
    }

    // visitor methods that get the job done
    @Override
    public VarInfoName visitSimple(Simple o) {
      return (o == goal) ? goal : null;
    }

    @Override
    public VarInfoName visitSizeOf(SizeOf o) {
      return (o == goal) ? goal : super.visitSizeOf(o);
    }

    @Override
    public VarInfoName visitFunctionOf(FunctionOf o) {
      return (o == goal) ? goal : super.visitFunctionOf(o);
    }

    @Override
    public VarInfoName visitFunctionOfN(FunctionOfN o) {
      VarInfoName retval = null;
      for (VarInfoName vin : o.args) {
        retval = vin.accept(this);
        if (retval != null) {
          return retval;
        }
      }
      return retval;
    }

    @Override
    public VarInfoName visitField(Field o) {
      return (o == goal) ? goal : super.visitField(o);
    }

    @Override
    public VarInfoName visitTypeOf(TypeOf o) {
      return (o == goal) ? goal : super.visitTypeOf(o);
    }

    @Override
    public VarInfoName visitPrestate(Prestate o) {
      pre = true;
      return super.visitPrestate(o);
    }

    @Override
    public VarInfoName visitPoststate(Poststate o) {
      pre = false;
      return super.visitPoststate(o);
    }

    @Override
    public VarInfoName visitAdd(Add o) {
      return (o == goal) ? goal : super.visitAdd(o);
    }

    @Override
    public VarInfoName visitElements(Elements o) {
      return (o == goal) ? goal : super.visitElements(o);
    }

    @Override
    public VarInfoName visitSubscript(Subscript o) {
      if (o == goal) {
        return goal;
      }
      if (o.sequence.accept(this) != null) {
        return goal;
      }
      if (o.index.accept(this) != null) {
        return goal;
      }
      return null;
    }

    @Override
    public VarInfoName visitSlice(Slice o) {
      if (o == goal) {
        return goal;
      }
      if (o.sequence.accept(this) != null) {
        return goal;
      }
      if ((o.i != null) && (o.i.accept(this) != null)) {
        return goal;
      }
      if ((o.j != null) && (o.j.accept(this) != null)) {
        return goal;
      }
      return null;
    }
  }

  /**
   * Finds if a given VarInfoName is contained in a set of nodes in the VarInfoName tree using ==
   * comparison. Recurse through everything except fields, so in x.a, we don't look at a.
   */
  public static class Finder extends AbstractVisitor<VarInfoName> {
    // state and accessors
    private final Set<VarInfoName> goals;

    /**
     * Creates a new Finder. Uses equals() to find.
     *
     * @param argGoals the goals to find
     */
    public Finder(Set<VarInfoName> argGoals) {
      goals = new HashSet<VarInfoName>();
      for (VarInfoName name : argGoals) {
        this.goals.add(name.intern());
      }
    }

    /** Returns true iff some part of root is contained in this.goals. */
    @EnsuresNonNullIf(result = true, expression = "getPart(#1")
    public boolean contains(VarInfoName root) {
      VarInfoName o = getPart(root);
      return (o != null);
    }

    /** Returns the part of root that is contained in this.goals, or null if not found. */
    public @Nullable VarInfoName getPart(VarInfoName root) {
      VarInfoName o = root.intern().accept(this);
      return o;
    }

    // visitor methods that get the job done
    @Override
    public VarInfoName visitSimple(Simple o) {
      return goals.contains(o) ? o : null;
    }

    @Override
    public VarInfoName visitSizeOf(SizeOf o) {
      return goals.contains(o) ? o : o.sequence.intern().accept(this);
    }

    @Override
    public VarInfoName visitFunctionOf(FunctionOf o) {
      return goals.contains(o) ? o : super.visitFunctionOf(o);
    }

    @Override
    public VarInfoName visitFunctionOfN(FunctionOfN o) {
      VarInfoName result = null;
      if (goals.contains(o)) {
        return o;
      }
      for (VarInfoName vin : o.args) {
        result = vin.accept(this);
        if (result != null) {
          return result;
        }
      }
      return result;
    }

    @Override
    public VarInfoName visitField(Field o) {
      return goals.contains(o) ? o : super.visitField(o);
    }

    @Override
    public VarInfoName visitTypeOf(TypeOf o) {
      return goals.contains(o) ? o : super.visitTypeOf(o);
    }

    @Override
    public VarInfoName visitPrestate(Prestate o) {
      if (goals.contains(o)) {
        return o;
      }
      return super.visitPrestate(o);
    }

    @Override
    public VarInfoName visitPoststate(Poststate o) {
      if (goals.contains(o)) {
        return o;
      }
      return super.visitPoststate(o);
    }

    @Override
    public VarInfoName visitAdd(Add o) {
      return goals.contains(o) ? o : super.visitAdd(o);
    }

    @Override
    public VarInfoName visitElements(Elements o) {
      return goals.contains(o) ? o : super.visitElements(o);
    }

    @Override
    public VarInfoName visitSubscript(Subscript o) {
      if (goals.contains(o)) {
        return o;
      }
      VarInfoName temp = o.sequence.accept(this);
      if (temp != null) {
        return temp;
      }
      temp = o.index.accept(this);
      if (temp != null) {
        return temp;
      }
      return null;
    }

    @Override
    public VarInfoName visitSlice(Slice o) {
      if (goals.contains(o)) {
        return o;
      }
      VarInfoName temp = o.sequence.accept(this);
      if (temp != null) {
        return temp;
      }
      if (o.i != null) {
        temp = o.i.accept(this);
        if (temp != null) {
          return temp;
        }
      }
      if (o.j != null) {
        temp = o.j.accept(this);
        if (temp != null) {
          return temp;
        }
      }
      return null;
    }
  }

  // An abstract base class for visitors that compute some predicate
  // of a conjunctive nature (true only if true on all subparts),
  // returning Boolean.FALSE or Boolean.TRUE.
  public abstract static class BooleanAndVisitor extends AbstractVisitor<Boolean> {
    private boolean result;

    protected BooleanAndVisitor(VarInfoName name) {
      result = (name.accept(this) != null);
    }

    public boolean result() {
      return result;
    }

    @Override
    public Boolean visitFunctionOfN(FunctionOfN o) {
      Boolean retval = null;
      for (ListIterator<VarInfoName> i = o.args.listIterator(o.args.size()); i.hasPrevious(); ) {
        VarInfoName vin = i.previous();
        retval = vin.accept(this);
        if (retval != null) {
          return null;
        }
      }
      return retval;
    }

    @Override
    public Boolean visitSubscript(Subscript o) {
      Boolean temp = o.sequence.accept(this);
      if (temp == null) {
        return temp;
      }
      temp = o.index.accept(this);
      return temp;
    }

    @Override
    public Boolean visitSlice(Slice o) {
      Boolean temp = o.sequence.accept(this);
      if (temp == null) {
        return temp;
      }
      if (o.i != null) {
        temp = o.i.accept(this);
        if (temp == null) {
          return temp;
        }
      }
      if (o.j != null) {
        temp = o.j.accept(this);
        if (temp == null) {
          return temp;
        }
      }
      return temp;
    }
  }

  public static class IsAllPrestateVisitor extends BooleanAndVisitor {

    public IsAllPrestateVisitor(VarInfoName vin) {
      super(vin);
    }

    @Override
    public Boolean visitSimple(Simple o) {
      // Any var not inside an orig() isn't prestate
      return null;
    }

    @Override
    public Boolean visitPrestate(Prestate o) {
      // orig(...) is all prestate unless it contains post(...)
      return new IsAllNonPoststateVisitor(o).result() ? Boolean.TRUE : null;
    }
  }

  public static class IsAllNonPoststateVisitor extends BooleanAndVisitor {
    public IsAllNonPoststateVisitor(VarInfoName vin) {
      super(vin);
    }

    @Override
    public Boolean visitSimple(Simple o) {
      // Any var not inside a post() isn't poststate
      return Boolean.TRUE;
    }

    @Override
    public Boolean visitPoststate(Poststate o) {
      // If we see a post(...), we aren't all poststate.
      return null;
    }
  }

  /**
   * Use to traverse a tree, find the first (elements ...) node, and report whether it's in pre or
   * post-state.
   */
  public static class ElementsFinder extends AbstractVisitor<Elements> {
    public ElementsFinder(VarInfoName name) {
      elems = name.accept(this);
    }

    // state and accessors
    private boolean pre = false;
    private Elements elems = null;

    public boolean inPre() {
      return pre;
    }

    public Elements elems() {
      return elems;
    }

    // visitor methods that get the job done
    @Override
    public Elements visitFunctionOfN(FunctionOfN o) {
      Elements retval = null;
      for (VarInfoName vin : o.args) {
        retval = vin.accept(this);
        if (retval != null) {
          return retval;
        }
      }
      return retval;
    }

    @Override
    public Elements visitPrestate(Prestate o) {
      pre = true;
      return super.visitPrestate(o);
    }

    @Override
    public Elements visitPoststate(Poststate o) {
      pre = false;
      return super.visitPoststate(o);
    }

    @Override
    public Elements visitElements(Elements o) {
      return o;
    }

    @Override
    public Elements visitSubscript(Subscript o) {
      // skip the subscripted sequence
      Elements tmp = o.sequence.term.accept(this);
      if (tmp == null) {
        tmp = o.index.accept(this);
      }
      return tmp;
    }

    @Override
    public Elements visitSlice(Slice o) {
      // skip the sliced sequence
      Elements tmp = o.sequence.term.accept(this);
      if (tmp == null && o.i != null) {
        tmp = o.i.accept(this);
      }
      if (tmp == null && o.j != null) {
        tmp = o.j.accept(this);
      }
      return tmp;
    }
  }

  /**
   * A Replacer is a Visitor that makes a copy of a tree, but replaces some node (and its children)
   * with another. The result is *not* interned; the client must do that if desired.
   */
  public static class Replacer extends AbstractVisitor<VarInfoName> {
    private final VarInfoName old;
    private final VarInfoName _new;

    public Replacer(VarInfoName old, VarInfoName _new) {
      this.old = old;
      this._new = _new;
    }

    public VarInfoName replace(VarInfoName root) {
      return root.accept(this);
    }

    @Override
    public VarInfoName visitSimple(Simple o) {
      return (o == old) ? _new : o;
    }

    @Override
    public VarInfoName visitSizeOf(SizeOf o) {
      return (o == old) ? _new : super.visitSizeOf(o).applySize();
    }

    @Override
    public VarInfoName visitFunctionOf(FunctionOf o) {
      return (o == old) ? _new : super.visitFunctionOf(o).applyFunction(o.function);
    }

    @Override
    public VarInfoName visitFunctionOfN(FunctionOfN o) {
      // If o is getting replaced, then just replace it
      // otherwise, create a new function and check if arguments get replaced
      if (o == old) {
        return _new;
      }
      ArrayList<VarInfoName> newArgs = new ArrayList<>();
      for (VarInfoName vin : o.args) {
        VarInfoName retval = vin.accept(this);
        newArgs.add(retval);
      }
      return VarInfoName.applyFunctionOfN(o.function, newArgs);
    }

    @Override
    public VarInfoName visitField(Field o) {
      return (o == old) ? _new : super.visitField(o).applyField(o.field);
    }

    @Override
    public VarInfoName visitTypeOf(TypeOf o) {
      return (o == old) ? _new : super.visitTypeOf(o).applyTypeOf();
    }

    @Override
    public VarInfoName visitPrestate(Prestate o) {
      return (o == old) ? _new : super.visitPrestate(o).applyPrestate();
    }

    @Override
    public VarInfoName visitPoststate(Poststate o) {
      return (o == old) ? _new : super.visitPoststate(o).applyPoststate();
    }

    @Override
    public VarInfoName visitAdd(Add o) {
      return (o == old) ? _new : super.visitAdd(o).applyAdd(o.amount);
    }

    @Override
    public VarInfoName visitElements(Elements o) {
      return (o == old) ? _new : super.visitElements(o).applyElements();
    }

    @Override
    public VarInfoName visitSubscript(Subscript o) {
      return (o == old) ? _new : o.sequence.accept(this).applySubscript(o.index.accept(this));
    }

    @Override
    public VarInfoName visitSlice(Slice o) {
      return (o == old)
          ? _new
          : o.sequence
              .accept(this)
              .applySlice(
                  (o.i == null) ? null : o.i.accept(this), (o.j == null) ? null : o.j.accept(this));
    }
  }

  /**
   * Replace pre states by normal variables, and normal variables by post states. We should do this
   * for all variables except for variables derived from return. This piggybacks on replacer but the
   * actual replacement is done elsewhere.
   */
  public static class PostPreConverter extends Replacer {

    public PostPreConverter() {
      super(null, null);
    }

    @Override
    public VarInfoName visitSimple(Simple o) {
      if (o.name.equals("return")) {
        return o;
      }
      return o.applyPoststate();
    }

    @Override
    public VarInfoName visitPrestate(Prestate o) {
      return o.term;
    }
  }

  public static class NoReturnValue {}

  /**
   * Use to collect all elements in a tree into an inorder-traversal list. Result includes the root
   * element. All methods return null; to obtain the result, call nodes().
   */
  public static class InorderFlattener extends AbstractVisitor<NoReturnValue> {
    public InorderFlattener(VarInfoName root) {
      root.accept(this);
    }

    // state and accessors
    private final List<VarInfoName> result = new ArrayList<>();

    /** Method returning the actual results (the nodes in order). */
    public List<VarInfoName> nodes() {
      return Collections.unmodifiableList(result);
    }

    // visitor methods that get the job done
    @Override
    public NoReturnValue visitSimple(Simple o) {
      result.add(o);
      return super.visitSimple(o);
    }

    @Override
    public NoReturnValue visitSizeOf(SizeOf o) {
      result.add(o);
      return super.visitSizeOf(o);
    }

    @Override
    public NoReturnValue visitFunctionOf(FunctionOf o) {
      result.add(o);
      return super.visitFunctionOf(o);
    }

    @Override
    public NoReturnValue visitFunctionOfN(FunctionOfN o) {
      result.add(o);
      for (VarInfoName vin : o.args) {
        vin.accept(this);
      }
      return null;
    }

    @Override
    public NoReturnValue visitField(Field o) {
      result.add(o);
      return super.visitField(o);
    }

    @Override
    public NoReturnValue visitTypeOf(TypeOf o) {
      result.add(o);
      return super.visitTypeOf(o);
    }

    @Override
    public NoReturnValue visitPrestate(Prestate o) {
      result.add(o);
      return super.visitPrestate(o);
    }

    @Override
    public NoReturnValue visitPoststate(Poststate o) {
      result.add(o);
      return super.visitPoststate(o);
    }

    @Override
    public NoReturnValue visitAdd(Add o) {
      result.add(o);
      return super.visitAdd(o);
    }

    @Override
    public NoReturnValue visitElements(Elements o) {
      result.add(o);
      return super.visitElements(o);
    }

    @Override
    public NoReturnValue visitSubscript(Subscript o) {
      result.add(o);
      o.sequence.accept(this);
      o.index.accept(this);
      return null;
    }

    @Override
    public NoReturnValue visitSlice(Slice o) {
      result.add(o);
      o.sequence.accept(this);
      if (o.i != null) {
        o.i.accept(this);
      }
      if (o.j != null) {
        o.j.accept(this);
      }
      return null;
    }
  }

  // ============================================================
  // Quantification for formatting in ESC or Simplify

  public static class SimpleNamesVisitor extends AbstractVisitor<NoReturnValue> {
    public SimpleNamesVisitor(VarInfoName root) {
      assert root != null;
      simples = new HashSet<String>();
      root.accept(this);
    }

    /**
     * See {@link #simples()}.
     *
     * @see #simples()
     */
    private Set<String> simples;

    /**
     * Returns collection of simple identifiers used in this expression, as Strings. (Used, for
     * instance, to check for conflict with a quantifier variable name.)
     *
     * @return collection of simple identifiers used in this expression, as Strings
     */
    public Set<String> simples() {
      return Collections.unmodifiableSet(simples);
    }

    // visitor methods that get the job done
    @Override
    public NoReturnValue visitSimple(Simple o) {
      simples.add(o.name);
      return super.visitSimple(o);
    }

    @Override
    public NoReturnValue visitElements(Elements o) {
      return super.visitElements(o);
    }

    @Override
    public NoReturnValue visitFunctionOf(FunctionOf o) {
      simples.add(o.function);
      return super.visitFunctionOf(o);
    }

    @Override
    public NoReturnValue visitFunctionOfN(FunctionOfN o) {
      simples.add(o.function);
      return super.visitFunctionOfN(o);
    }

    @Override
    public NoReturnValue visitSubscript(Subscript o) {
      o.sequence.accept(this);
      return o.index.accept(this);
    }

    @Override
    public NoReturnValue visitSlice(Slice o) {
      if (o.i != null) {
        o.i.accept(this);
      }
      if (o.j != null) {
        o.j.accept(this);
      }
      return o.sequence.accept(this);
    }
  }

  /**
   * A quantifier visitor can be used to search a tree and return all unquantified sequences (e.g.
   * a[] or a[i..j]).
   */
  public static class QuantifierVisitor extends AbstractVisitor<NoReturnValue> {
    public QuantifierVisitor(VarInfoName root) {
      assert root != null;
      unquant = new HashSet<VarInfoName>();
      root.accept(this);
    }

    // state and accessors
    /**
     * See {@link #unquants()}.
     *
     * @see #unquants()
     */
    private Set<VarInfoName> /*actually <Elements || Slice>*/ unquant;

    /**
     * Returns a collection of the nodes under the root that need quantification. Each node
     * represents an array; in particular, the values are either of type Elements or Slice.
     *
     * @return the nodes under the root that need quantification
     */
    // Here are some inputs and the corresponding output sets:
    //  terms[index].elts[num]   ==> { }
    //  terms[index].elts[]      ==> { terms[index].elts[] }
    //  terms[].elts[]           ==> { terms[], terms[].elts[] }
    //  ary[row][col]            ==> { }
    //  ary[row][]               ==> { ary[row][] }
    //  ary[][]                  ==> { ary[], ary[][] }
    public Set<VarInfoName> unquants() {
      if (QuantHelper.debug.isLoggable(Level.FINE)) {
        QuantHelper.debug.fine("unquants: " + unquant);
      }
      return Collections.unmodifiableSet(unquant);
    }

    // visitor methods that get the job done
    @Override
    public NoReturnValue visitSimple(Simple o) {
      return super.visitSimple(o);
    }

    @Override
    public NoReturnValue visitElements(Elements o) {
      unquant.add(o);
      return super.visitElements(o);
    }

    @Override
    public NoReturnValue visitFunctionOf(FunctionOf o) {
      return null;
      // return o.args.get(0).accept(this); // Return value doesn't matter
      // We only use one of them because we don't want double quantifiers
    }

    /**
     * We do *not* want to pull out array members of FunctionOfN because a FunctionOfN creates a
     * black-box array with respect to quantification. (Also, otherwise, there may be two or more
     * arrays that are returned, making the quantification engine think it's working with 2-d
     * arrays.)
     */
    @Override
    public NoReturnValue visitFunctionOfN(FunctionOfN o) {
      return null;
      // return o.args.get(0).accept(this); // Return value doesn't matter
      // We only use one of them because we don't want double quantifiers
    }

    @Override
    public NoReturnValue visitSizeOf(SizeOf o) {
      // don't visit the sequence; we aren't using the elements of it,
      // just the length, so we don't want to include it in the results
      return o.get_term().accept(this);
    }

    @Override
    public NoReturnValue visitSubscript(Subscript o) {
      o.index.accept(this);
      // don't visit the sequence; it is fixed with an exact
      // subscript, so we don't want to include it in the results
      return o.sequence.term.accept(this);
    }

    @Override
    public NoReturnValue visitSlice(Slice o) {
      unquant.add(o);
      if (o.i != null) {
        o.i.accept(this);
      }
      if (o.j != null) {
        o.j.accept(this);
      }
      // don't visit the sequence; we will replace the slice with the
      // subscript, so we want to leave the elements alone
      return o.sequence.term.accept(this);
    }
  }

  // ============================================================
  // Quantification for formatting in ESC or Simplify:  QuantHelper

  /**
   * Helper for writing parts of quantification expressions. Formatting methods in invariants call
   * the formatting methods in this class to get commonly-used parts, like how universal
   * quanitifiers look in the different formatting schemes.
   */
  public static class QuantHelper {

    /** Do not instantiate. */
    private QuantHelper() {
      throw new Error("Do not instantiate");
    }

    /** Debug tracer. */
    public static final Logger debug = Logger.getLogger("daikon.inv.Invariant.print.QuantHelper");

    /**
     * A FreeVar is very much like a Simple, except that it doesn't care if it's in prestate or
     * poststate for simplify formatting.
     */
    public static class FreeVar extends Simple {
      // We are Serializable, so we specify a version to allow changes to
      // method signatures without breaking serialization.  If you add or
      // remove fields, you should change this number to the current date.
      static final long serialVersionUID = 20020130L;

      public FreeVar(String name) {
        super(name);
      }

      @Override
      protected String repr_impl(@GuardSatisfied FreeVar this) {
        return "Free[" + super.repr_impl() + "]";
      }

      @Override
      protected String jml_name_impl(VarInfo v) {
        return super.jml_name_impl(v);
      }

      // protected String esc_name_impl() {
      //   return super.esc_name_impl();
      // }
      @Override
      protected String simplify_name_impl(boolean prestate) {
        return super.simplify_name_impl(false);
      }
    }

    // <root, needy, index> -> <root', lower, upper>
    /**
     * Replaces a needy (unquantified term) with its subscripted equivalent, using the given index
     * variable.
     *
     * @param root the root of the expression to be modified. Substitution occurs only in the
     *     subtree reachable from root.
     * @param needy the term to be subscripted (must be of type Elements or Slice)
     * @param index the variable to place in the subscript
     * @return a 3-element array consisting of the new root, the lower bound for the index
     *     (inclusive), and the upper bound for the index (inclusive), in that order
     */
    public static VarInfoName[] replace(VarInfoName root, VarInfoName needy, VarInfoName index) {
      assert root != null;
      assert needy != null;
      assert index != null;
      assert (needy instanceof Elements) || (needy instanceof Slice);

      // Figure out what to replace needy with, and the appropriate
      // bounds to use
      VarInfoName replace_with;
      VarInfoName lower;
      VarInfoName upper;
      if (needy instanceof Elements) {
        Elements sequence = (Elements) needy;
        replace_with = sequence.getSubscript(index);
        lower = sequence.getLowerBound();
        upper = sequence.getUpperBound();
      } else if (needy instanceof Slice) {
        Slice slice = (Slice) needy;
        replace_with = slice.getSubscript(index);
        lower = slice.getLowerBound();
        upper = slice.getUpperBound();
      } else {
        // unreachable; placate javac
        throw new IllegalStateException();
      }
      assert replace_with != null;

      // If needy was in prestate, adjust bounds appropriately
      if (root.inPrestateContext(needy)) {
        if (!lower.isLiteralConstant()) {
          if (lower instanceof Poststate) {
            lower = ((Poststate) lower).term;
          } else {
            lower = lower.applyPrestate();
          }
        }
        if (!upper.isLiteralConstant()) {
          if (upper instanceof Poststate) {
            upper = ((Poststate) upper).term;
          } else {
            upper = upper.applyPrestate();
          }
        }
      }

      // replace needy
      VarInfoName root_prime = new Replacer(needy, replace_with).replace(root).intern();

      assert root_prime != null;
      assert lower != null;
      assert upper != null;

      return new VarInfoName[] {root_prime, lower, upper};
    }

    /**
     * Assuming that root is a sequence, return a VarInfoName representing the
     * (index_base+index_off)-th element of that sequence. index_base may be null, to represent 0.
     */
    public static VarInfoName selectNth(
        VarInfoName root, @Nullable VarInfoName index_base, int index_off) {
      QuantifierVisitor qv = new QuantifierVisitor(root);
      List<VarInfoName> unquants = new ArrayList<>(qv.unquants());
      if (unquants.isEmpty()) {
        // Nothing to do?
        return null;
      } else if (unquants.size() == 1) {
        VarInfoName index_vin;
        if (index_base != null) {
          index_vin = index_base;
          if (index_off != 0) {
            index_vin = index_vin.applyAdd(index_off);
          }
        } else {
          index_vin = new Simple(Integer.toString(index_off)).intern();
        }
        VarInfoName to_replace = unquants.get(0);
        @Interned VarInfoName[] replace_result = replace(root, to_replace, index_vin);
        return replace_result[0];
      } else {
        throw new Error("Can't handle multi-dim array in VarInfoName.QuantHelper.select_nth()");
      }
    }

    /**
     * Assuming that root is a sequence, return a VarInfoName representing the
     * (index_base+index_off)-th element of that sequence. index_base may be null, to represent 0.
     */
    public static VarInfoName selectNth(
        VarInfoName root, String index_base, boolean free, int index_off) {
      QuantifierVisitor qv = new QuantifierVisitor(root);
      List<VarInfoName> unquants = new ArrayList<>(qv.unquants());
      if (unquants.isEmpty()) {
        // Nothing to do?
        return null;
      } else if (unquants.size() == 1) {
        VarInfoName index_vin;
        if (index_base != null) {
          if (index_off != 0) {
            index_base += "+" + index_off;
          }
          if (free) {
            index_vin = new FreeVar(index_base);
          } else {
            index_vin = VarInfoName.parse(index_base);
          }
          // if (index_base.contains ("a"))
          //  System.out.printf("selectNth: '%s' '%s'%n", index_base,
          //                     index_vin);
        } else {
          index_vin = new Simple(Integer.toString(index_off));
        }
        VarInfoName to_replace = unquants.get(0);
        VarInfoName[] replace_result = replace(root, to_replace, index_vin);
        // if ((index_base != null) && index_base.contains ("a"))
        //   System.out.printf("root = %s, to_replace = %s, index_vin = %s%n",
        //                      root, to_replace, index_vin);
        return replace_result[0];
      } else {
        throw new Error("Can't handle multi-dim array in VarInfoName.QuantHelper.select_nth()");
      }
    }

    // Return a string distinct from any of the strings in "taken".
    private static String freshDistinctFrom(Set<String> taken) {
      char c = 'i';
      String name;
      do {
        name = String.valueOf(c++);
      } while (taken.contains(name));
      return name;
    }

    /** Returns a fresh variable name that doesn't appear in the given variable names. */
    public static VarInfoName getFreeIndex(VarInfoName... vins) {
      Set<String> simples = new HashSet<>();
      for (VarInfoName vin : vins) {
        simples.addAll(new SimpleNamesVisitor(vin).simples());
      }
      return new FreeVar(freshDistinctFrom(simples));
    }

    /** Record type for return value of the quantify method below. */
    public static class QuantifyReturn {
      public @Interned VarInfoName[] root_primes;
      public List<@Interned VarInfoName[]>
          bound_vars; // each element is VarInfoName[3] = <variable, lower, upper>
    }

    // <root*> -> <root'*, <index, lower, upper>*>
    // (The lengths of root* and root'* are the same; not sure about <i,l,u>*.)
    /**
     * Given a list of roots, changes all Elements and Slice terms to Subscripts by inserting a new
     * free variable; also return bounds for the new variables.
     */
    public static QuantifyReturn quantify(VarInfoName[] roots) {
      assert roots != null;

      if (QuantHelper.debug.isLoggable(Level.FINE)) {
        QuantHelper.debug.fine("roots: " + Arrays.asList(roots));
      }

      // create empty result
      QuantifyReturn result = new QuantifyReturn();
      result.root_primes = new VarInfoName[roots.length];
      result.bound_vars = new ArrayList<VarInfoName[]>();

      // all of the simple identifiers used by these roots
      Set<String> simples = new HashSet<>();

      // build helper for each roots; collect identifiers
      QuantifierVisitor[] helper = new QuantifierVisitor[roots.length];
      for (int i = 0; i < roots.length; i++) {
        if (QuantHelper.debug.isLoggable(Level.FINE)) {
          QuantHelper.debug.fine("Calling quanthelper on: " + i + " " + roots[i]);
        }

        helper[i] = new QuantifierVisitor(roots[i]);
        simples.addAll(new SimpleNamesVisitor(roots[i]).simples());
      }

      // choose names for the indices that don't conflict, and then
      // replace the right stuff in the term
      char tmp = 'i';
      for (int i = 0; i < roots.length; i++) {
        List<VarInfoName> uq = new ArrayList<>(helper[i].unquants());
        if (uq.isEmpty()) {
          // nothing needs quantification
          result.root_primes[i] = roots[i];
        } else {
          if (QuantHelper.debug.isLoggable(Level.FINE)) {
            QuantHelper.debug.fine("root: " + roots[i]);
            QuantHelper.debug.fine("uq_elts: " + uq.toString());
          }

          // We assume that the input was one unquantified sequence
          // variable.  If uq has more than one element, then the
          // sequence had more than one dimension.
          assert uq.size() == 1 : "We can only handle 1D arrays for now";

          VarInfoName uq_elt = uq.get(0);

          String idx_name;
          do {
            idx_name = String.valueOf(tmp++);
          } while (simples.contains(idx_name));
          assert tmp <= 'z' : "Ran out of letters in quantification";
          VarInfoName idx = new FreeVar(idx_name).intern();

          if (QuantHelper.debug.isLoggable(Level.FINE)) {
            QuantHelper.debug.fine("idx: " + idx);
          }

          // call replace and unpack results
          VarInfoName[] replace_result = replace(roots[i], uq_elt, idx);
          VarInfoName root_prime = replace_result[0];
          VarInfoName lower = replace_result[1];
          VarInfoName upper = replace_result[2];

          result.root_primes[i] = root_prime;
          result.bound_vars.add(new VarInfoName[] {idx, lower, upper});
        }
      }

      return result;
    }

    // <root*> -> <string string* string>
    /**
     * Given a list of roots, return a String array where the first element is a ESC-style
     * quantification over newly-introduced bound variables, the last element is a closer, and the
     * other elements are esc-named strings for the provided roots (with sequences subscripted by
     * one of the new bound variables).
     */
    public static String[] format_esc(VarInfoName[] roots) {
      return format_esc(roots, false);
    }

    public static String[] format_esc(VarInfoName[] roots, boolean elementwise) {
      // The call to format_esc is now handled by the combined formatter format_java_style
      return format_java_style(roots, elementwise, true, OutputFormat.ESCJAVA);
    }

    // <root*> -> <string string*>
    // /**
    //  * Given a list of roots, return a String array where the first element is a JML-style
    //  * quantification over newly-introduced bound variables, the last element is a closer, and
    // the
    //  * other elements are jml-named strings for the provided roots (with sequenced subscripted by
    //  * one of the new bound variables).
    //  */
    // public static String[] format_jml(VarInfoName[] roots) {
    //   return format_jml(roots, false);
    // }
    // public static String[] format_jml(VarInfoName[] roots, boolean elementwise) {
    //   return format_jml(roots, elementwise, true);
    // }
    // public static String[] format_jml(VarInfoName[] roots, boolean elementwise, boolean forall) {
    //   return format_java_style(roots, elementwise, forall, OutputFormat.JML);
    // }

    /* CP: Quantification for DBC: We would like quantified expression
     * to always return a boolean value, and in the previous
     * implementation (commented out below), quantification was
     * expressed as a for-loop, which does not return boolean
     * values. An alternative solution would be to use Jtest's $forall
     * and $exists constructs, but testing showed that Jtest does not
     * allow these constructs in @post annotations (!). The current
     * implementation uses helper methods defined in a separate class
     * daikon.Quant (not currently included with Daikon's
     * distribution). These methods always return a boolean value and
     * look something like this:
     *
     *   Quant.eltsEqual(this.theArray, null)
     *   Quant.subsetOf(this.arr, new int[] { 1, 2, 3 })
     *
     */
    //     /**
    //      * vi is the Varinfo corresponding to the VarInfoName var. Uses
    //      * the variable i to iterate. This could mean a conflict with the
    //      * name of the argument var.
    //      */
    //     public static String dbcForalli(VarInfoName.Elements var, VarInfo vi,
    //                                     String condition) {
    //       if (vi.type.isArray()) {
    //         return
    //           "(java.util.Arrays.asList(" + var.term.dbc_name(vi)
    //           + ")).$forall(" + vi.type.base() + " i, "
    //           + condition + ")";
    //       }
    //       return var.term.dbc_name(vi)
    //         + ".$forall(" + vi.type.base() + " i, "
    //         + condition + ")";
    //     }

    //     /**
    //      * vi is the Varinfo corresponding to the VarInfoName var. Uses
    //       * the variable i to iterate. This could mean a conflict with the
    //       * name of the argument var.
    //      */
    //     public static String dbcExistsi(VarInfoName.Elements var, VarInfo vi,
    //                                     String condition) {
    //       if (vi.type.isArray()) {
    //         return
    //           "(java.util.Arrays.asList(" + var.term.dbc_name(vi)
    //           + ")).$exists(" + vi.type.base() + " i, "
    //           + condition + ")";
    //       }
    //       return var.term.dbc_name(vi)
    //         + ".$exists(" + vi.type.base() + " i, "
    //         + condition + ")";
    //     }

    //     //@tx
    //     public static String[] format_dbc(VarInfoName[] roots, VarInfo[] varinfos) {
    //       return format_dbc(roots, true, varinfos);
    //     }
    //     public static String[] format_dbc(VarInfoName[] roots, boolean elementwise,
    //                                       VarInfo[] varinfos) {
    //       return format_dbc(roots, elementwise, true, varinfos);
    //     }
    //     public static String[] format_dbc(VarInfoName[] roots, boolean elementwise,
    //                                       boolean forall, VarInfo[] varinfos) {
    //       assert roots != null;

    //       QuantifyReturn qret = quantify(roots);

    //       // build the "\forall ..." predicate
    //       String[] result = new String[roots.length + 2];
    //       StringBuilder int_list, conditions, closing;
    //       StringBuilder tempResult;
    //       {
    //         tempResult = new StringBuilder();
    //         // "i, j, ..."
    //         int_list = new StringBuilder();
    //         // "ai <= i && i <= bi && aj <= j && j <= bj && ..."
    //         // if elementwise, also do "(i-ai) == (b-bi) && ..."
    //         conditions = new StringBuilder();
    //         closing = new StringBuilder();
    //         for (int i = 0; i < qret.bound_vars.size(); i++) {
    //           int_list.setLength(0);
    //           conditions.setLength(0);
    //           closing.setLength(0);

    //           VarInfoName[] boundv = qret.bound_vars.get(i);
    //           VarInfoName idx = boundv[0], low = boundv[1], high = boundv[2];
    //           if (i != 0) {
    //             //int_list.append(", ");
    //             //conditions.append(" && ");
    //             //closing.append(", ");
    //             closing.append(idx.dbc_name(null));
    //             closing.append("++");
    //           } else {
    //             closing.append(idx.dbc_name(null));
    //             closing.append("++");
    //           }
    //           int_list.append(idx.dbc_name(null));
    //           int_list.append(" = "); //@TX
    //           int_list.append(low.dbc_name(null));

    //           conditions.append(idx.dbc_name(null));
    //           conditions.append(" <= ");
    //           conditions.append(high.dbc_name(null));

    //           if (elementwise && (i >= 1)) {
    //             VarInfoName[] _boundv = qret.bound_vars.get(i - 1);
    //             VarInfoName _idx = _boundv[0], _low = _boundv[1];
    //             conditions.append(" && ");
    //             if (ZERO.equals(_low)) {
    //               conditions.append(_idx);
    //             } else {
    //               conditions.append("(");
    //               conditions.append(_idx.dbc_name(null));
    //               conditions.append("-(");
    //               conditions.append(_low.dbc_name(null));
    //               conditions.append("))");
    //             }
    //             conditions.append(" == ");
    //             if (ZERO.equals(low)) {
    //               conditions.append(idx.dbc_name(null));
    //             } else {
    //               conditions.append("(");
    //               conditions.append(idx.dbc_name(null));
    //               conditions.append("-(");
    //               conditions.append(low.dbc_name(null));
    //               conditions.append("))");
    //             }
    //           }
    //           tempResult.append(" for (int " + int_list + " ; " + conditions + "; " + closing +
    // ") ");
    //         }
    //       }
    //       //result[0] = "{ for (int " + int_list + " ; " + conditions + "; "
    //                     + closing + ") $assert ("; //@TX
    //       result[0] = "{ " + tempResult + " $assert ("; //@TX
    //       result[result.length - 1] = "); }";

    //       // stringify the terms
    //       for (int i = 0; i < roots.length; i++) {
    //         result[i + 1] = qret.root_primes[i].dbc_name(null);
    //       }

    //       return result;
    //     }

    // //////////////////////////

    public static String[] simplifyNameAndBounds(VarInfoName name) {
      String[] results = new String[3];
      boolean preState = false;
      if (name instanceof Prestate) {
        Prestate wrapped = (Prestate) name;
        name = wrapped.term;
        preState = true;
      }
      if (name instanceof Elements) {
        Elements sequence = (Elements) name;
        VarInfoName array = sequence.term;
        results[0] = array.simplify_name(preState);
        results[1] = sequence.getLowerBound().simplify_name(preState);
        results[2] = sequence.getUpperBound().simplify_name(preState);
        return results;
      } else if (name instanceof Slice) {
        Slice slice = (Slice) name;
        VarInfoName array = slice.sequence.term;
        results[0] = array.simplify_name(preState);
        results[1] = slice.getLowerBound().simplify_name(preState);
        results[2] = slice.getUpperBound().simplify_name(preState);
        return results;
      } else {
        // There are some other cases this scheme can't handle.
        // For instance, if every Book has an ISBN, a front-end
        // might distribute the access to that field over an array
        // of books, so that "books[].isbn" is an array of ISBNs,
        // though its name has type Field.
        return null;
      }
    }

    // <root*> -> <string string*>
    /**
     * Given a list of roots, return a String array where the first element is a simplify-style
     * quantification over newly-introduced bound variables, the last element is a closer, and the
     * other elements are simplify-named strings for the provided roots (with sequences subscripted
     * by one of the new bound variables).
     *
     * <p>If elementwise is true, include the additional constraint that the indices (there must be
     * exactly two in this case) refer to corresponding positions. If adjacent is true, include the
     * additional constraint that the second index be one more than the first. If distinct is true,
     * include the constraint that the two indices are different. If includeIndex is true, return
     * additional strings, after the roots but before the closer, with the names of the index
     * variables.
     */
    // XXX This argument list is starting to get out of hand. -smcc
    public static String[] format_simplify(VarInfoName[] roots) {
      return format_simplify(roots, false, false, false, false);
    }

    public static String[] format_simplify(VarInfoName[] roots, boolean eltwise) {
      return format_simplify(roots, eltwise, false, false, false);
    }

    public static String[] format_simplify(VarInfoName[] roots, boolean eltwise, boolean adjacent) {
      return format_simplify(roots, eltwise, adjacent, false, false);
    }

    public static String[] format_simplify(
        VarInfoName[] roots, boolean eltwise, boolean adjacent, boolean distinct) {
      return format_simplify(roots, eltwise, adjacent, distinct, false);
    }

    public static String[] format_simplify(
        VarInfoName[] roots,
        boolean elementwise,
        boolean adjacent,
        boolean distinct,
        boolean includeIndex) {
      assert roots != null;

      if (adjacent || distinct) {
        assert roots.length == 2;
      }

      QuantifyReturn qret = quantify(roots);

      // build the forall predicate
      String[] result = new String[(includeIndex ? 2 : 1) * roots.length + 2];

      StringJoiner int_list;
      StringJoiner conditions;
      {
        // "i j ..."
        int_list = new StringJoiner(" ");
        // "(AND (<= ai i) (<= i bi) (<= aj j) (<= j bj) ...)"
        // if elementwise, also insert "(EQ (- i ai) (- j aj)) ..."
        conditions = new StringJoiner(" ");
        for (int i = 0; i < qret.bound_vars.size(); i++) {
          VarInfoName[] boundv = qret.bound_vars.get(i);
          VarInfoName idx = boundv[0];
          VarInfoName low = boundv[1];
          VarInfoName high = boundv[2];
          int_list.add(idx.simplify_name());
          conditions.add("(<= " + low.simplify_name() + " " + idx.simplify_name() + ")");
          conditions.add("(<= " + idx.simplify_name() + " " + high.simplify_name() + ")");
          if (elementwise && (i >= 1)) {
            VarInfoName[] _boundv = qret.bound_vars.get(i - 1);
            VarInfoName _idx = _boundv[0];
            VarInfoName _low = _boundv[1];
            if (_low.simplify_name().equals(low.simplify_name())) {
              conditions.add("(EQ " + _idx.simplify_name() + " " + idx.simplify_name() + ")");
            } else {
              conditions.add(" (EQ (- " + _idx.simplify_name() + " " + _low.simplify_name() + ")");
              conditions.add("(- " + idx.simplify_name() + " " + low.simplify_name() + "))");
            }
          }
          if (i == 1 && (adjacent || distinct)) {
            VarInfoName[] _boundv = qret.bound_vars.get(i - 1);
            VarInfoName prev_idx = _boundv[0];
            if (adjacent) {
              conditions.add(
                  "(EQ (+ " + prev_idx.simplify_name() + " 1) " + idx.simplify_name() + ")");
            }
            if (distinct) {
              conditions.add("(NEQ " + prev_idx.simplify_name() + " " + idx.simplify_name() + ")");
            }
          }
        }
      }
      result[0] = "(FORALL (" + int_list + ") (IMPLIES (AND " + conditions + ") ";

      // stringify the terms
      for (int i = 0; i < qret.root_primes.length; i++) {
        result[i + 1] = qret.root_primes[i].simplify_name();
      }

      // stringify the indices, if requested
      // note that the index should be relative to the slice, not relative
      // to the original array (we used to get this wrong)
      if (includeIndex) {
        for (int i = 0; i < qret.root_primes.length; i++) {
          VarInfoName[] boundv = qret.bound_vars.get(i);
          VarInfoName idx_var = boundv[0];
          String idx_var_name = idx_var.simplify_name();
          String lower_bound = qret.bound_vars.get(i)[1].simplify_name();
          String idx_expr = "(- " + idx_var_name + " " + lower_bound + ")";
          result[i + qret.root_primes.length + 1] = idx_expr;
        }
      }

      result[result.length - 1] = "))"; // close IMPLIES, FORALL

      return result;
    }

    // Important Note: The Java quantification style actually makes no
    // sense as is.  The resultant quantifications are statements as
    // opposed to expressions, and thus no value can be derived from
    // them. This must be fixed before the java statements are of any
    // value. However, the ESC and JML quantifications are fine because
    // they actually produce expressions with values.

    // <root*> -> <string string* string>
    /**
     * Given a list of roots, return a String array where the first element is a Java-style
     * quantification over newly-introduced bound variables, the last element is a closer, and the
     * other elements are java-named strings for the provided roots (with sequences subscripted by
     * one of the new bound variables).
     */
    //     public static String[] format_java(VarInfoName[] roots) {
    //       return format_java(roots, false);
    //     }
    //     public static String[] format_java(VarInfoName[] roots, boolean elementwise) {
    //       return format_java_style(roots, false, true, OutputFormat.JAVA);
    //     }

    // This set of functions quantifies in the same manner to the ESC quantification, except that
    // JML names are used instead of ESC names, and minor formatting changes are incorporated
    //     public static String[] format_jml(QuantifyReturn qret) {
    //       return format_java_style(qret, false, true, OutputFormat.JML);
    //     }
    //     public static String[] format_jml(QuantifyReturn qret, boolean elementwise) {
    //       return format_java_style(qret, elementwise, true, OutputFormat.JML);
    //     }
    //     public static String[] format_jml(QuantifyReturn qret, boolean elementwise, boolean
    // forall) {
    //       return format_java_style(qret, elementwise, forall, OutputFormat.JML);
    //     }

    // This set of functions assists in quantification for all of the java style
    // output formats, that is, Java, ESC, and JML. It does the actual work behind
    // those formatting functions. This function was meant to be called only through
    // the other public formatting functions.
    //
    // The OutputFormat must be one of those three previously mentioned.
    // Also, if the Java format is selected, forall must be true.

    protected static String[] format_java_style(VarInfoName[] roots, OutputFormat format) {
      return format_java_style(roots, false, true, format);
    }

    protected static String[] format_java_style(
        VarInfoName[] roots, boolean elementwise, OutputFormat format) {
      return format_java_style(roots, elementwise, true, format);
    }

    protected static String[] format_java_style(
        VarInfoName[] roots, boolean elementwise, boolean forall, OutputFormat format) {
      assert roots != null;

      QuantifyReturn qret = quantify(roots);

      return format_java_style(qret, elementwise, forall, format);
    }

    // This form allows the indices and bounds to be modified before quantification
    protected static String[] format_java_style(QuantifyReturn qret, OutputFormat format) {
      return format_java_style(qret, false, true, format);
    }

    protected static String[] format_java_style(
        QuantifyReturn qret, boolean elementwise, OutputFormat format) {
      return format_java_style(qret, elementwise, true, format);
    }

    protected static String[] format_java_style(
        QuantifyReturn qret, boolean elementwise, boolean forall, OutputFormat format) {
      // build the "\forall ..." predicate
      String[] result = new String[qret.root_primes.length + 2];
      StringBuilder int_list;
      StringBuilder conditions;
      StringBuilder closing;
      {
        // "i, j, ..."
        int_list = new StringBuilder();
        // "ai <= i && i <= bi && aj <= j && j <= bj && ..."
        // if elementwise, also do "(i-ai) == (b-bi) && ..."
        conditions = new StringBuilder();
        closing = new StringBuilder();
        for (int i = 0; i < qret.bound_vars.size(); i++) {
          VarInfoName[] boundv = qret.bound_vars.get(i);
          VarInfoName idx = boundv[0];
          VarInfoName low = boundv[1];
          VarInfoName high = boundv[2];
          if (i != 0) {
            int_list.append(", ");
            conditions.append(" && ");
          }
          closing.append(quant_increment(idx, i, format));

          int_list.append(quant_var_initial_state(idx, low, format));
          conditions.append(quant_execution_condition(low, idx, high, format));

          if (elementwise && (i >= 1)) {
            VarInfoName[] _boundv = qret.bound_vars.get(i - 1);
            VarInfoName _idx = _boundv[0];
            VarInfoName _low = _boundv[1];
            if (format == OutputFormat.JAVA) {
              conditions.append(" || ");
            } else {
              conditions.append(" && ");
            }

            conditions.append(quant_element_conditions(_idx, _low, idx, low, format));
          }
        }
      }

      if (forall) {
        result[0] = quant_format_forall(format);
      } else {
        result[0] = quant_format_exists(format);
      }

      result[0] +=
          (int_list
              + quant_separator1(format)
              + conditions
              + quant_separator2(format)
              + closing
              + quant_step_terminator(format));
      result[result.length - 1] = ")";

      // stringify the terms
      for (int i = 0; i < qret.root_primes.length; i++) {
        result[i + 1] = qret.root_primes[i].name_using(format, null);
      }

      return result;
    }

    // This set of functions are helper functions to the quantification function.

    /**
     * This function creates a string that represents how to increment the variables involved in
     * quantification. Since the increment is not stated explicitly in the JML and ESC formats this
     * function merely returns an empty string for those formats.
     */
    protected static String quant_increment(VarInfoName idx, int i, OutputFormat format) {
      if (format != OutputFormat.JAVA) {
        return "";
      } else {
        if (i != 0) {
          return (", " + idx.esc_name() + "++");
        } else {
          return (idx.esc_name() + "++");
        }
      }
    }

    /**
     * This function returns a string that represents the initial condition for the index variable.
     */
    protected static String quant_var_initial_state(
        VarInfoName idx, VarInfoName low, OutputFormat format) {
      if (format == OutputFormat.JAVA) {
        return idx.esc_name() + " == " + low.esc_name();
      } else {
        return idx.name_using(format, null);
      }
    }

    /**
     * This function returns a string that represents the execution condition for the
     * quantification.
     */
    protected static String quant_execution_condition(
        VarInfoName low, VarInfoName idx, VarInfoName high, OutputFormat format) {
      if (format == OutputFormat.JAVA) {
        return idx.esc_name() + " <= " + high.esc_name();
      } else {
        return low.name_using(format, null)
            + " <= "
            + idx.name_using(format, null)
            + " && "
            + idx.name_using(format, null)
            + " <= "
            + high.name_using(format, null);
      }
    }

    /**
     * This function returns a string representing the extra conditions necessary if the
     * quantification is element-wise.
     */
    protected static String quant_element_conditions(
        VarInfoName _idx, VarInfoName _low, VarInfoName idx, VarInfoName low, OutputFormat format) {
      StringBuilder conditions = new StringBuilder();

      if (ZERO.equals(_low)) {
        conditions.append(_idx.name_using(format, null));
      } else {
        conditions.append("(");
        conditions.append(_idx.name_using(format, null));
        conditions.append("-(");
        conditions.append(_low.name_using(format, null));
        conditions.append("))");
      }
      conditions.append(" == ");
      if (ZERO.equals(low)) {
        conditions.append(idx.name_using(format, null));
      } else {
        conditions.append("(");
        conditions.append(idx.name_using(format, null));
        conditions.append("-(");
        conditions.append(low.name_using(format, null));
        conditions.append("))");
      }

      return conditions.toString();
    }

    /**
     * This function returns a string representing how to format a forall statement in a given
     * output mode.
     */
    protected static String quant_format_forall(OutputFormat format) {
      if (format == OutputFormat.JAVA) {
        return "(for (int ";
      } else {
        return "(\\forall int ";
      }
    }

    /**
     * This function returns a string representing how to format an exists statement in a given
     * output mode.
     */
    protected static String quant_format_exists(OutputFormat format) {
      return "(\\exists int ";
    }

    /**
     * This function returns a string representing how to format the first separation in the
     * quantification, that is, the one between the initial condition and the execution condition.
     */
    protected static String quant_separator1(OutputFormat format) {
      if (format == OutputFormat.JML) {
        return "; ";
      } else {
        return "; (";
      }
    }

    /**
     * This function returns a string representing how to format the second separation in the
     * quantification, that is, the one between the execution condition and the assertion.
     */
    protected static String quant_separator2(OutputFormat format) {
      if (format == OutputFormat.ESCJAVA) {
        return ") ==> ";
      } else {
        return "; ";
      }
    }

    /**
     * This function returns a string representing how to format the final separation in the
     * quantification, that is, the one between the assertion and any closing symbols.
     */
    protected static String quant_step_terminator(OutputFormat format) {
      if (format == OutputFormat.JAVA) {
        return ")";
      }
      return "";
    }
  } // QuantHelper

  // Special JML capability, since JML cannot format a sequence of elements,
  // often what is wanted is the name of the reference (we have a[], we want
  // a. This function provides the appropriate name for these circumstances.
  public VarInfoName JMLElementCorrector() {
    if (this instanceof Elements) {
      return ((Elements) this).term;
    } else if (this instanceof Slice) {
      return ((Slice) this).sequence.term;
    } else if (this instanceof Prestate) {
      return ((Prestate) this).term.JMLElementCorrector().applyPrestate();
    } else if (this instanceof Poststate) {
      return ((Poststate) this).term.JMLElementCorrector().applyPoststate();
    }
    return this;
  }

  // ============================================================
  // Transformation framework

  /** Specifies a function that performs a transformation on VarInfoNames. */
  public interface Transformer {
    /** Perform a transformation on the argument. */
    public VarInfoName transform(VarInfoName v);
  }

  /** A pass-through transformer. */
  public static final Transformer IDENTITY_TRANSFORMER =
      new Transformer() {
        @Override
        public VarInfoName transform(VarInfoName v) {
          return v;
        }
      };

  /** Compare VarInfoNames alphabetically. */
  public static class LexicalComparator implements Comparator<VarInfoName> {
    @Pure
    @Override
    public int compare(VarInfoName name1, VarInfoName name2) {
      return name1.compareTo(name2);
    }
  }
}
