Object
- Invariant
- - UnaryInvariant
  - - SingleScalar
    - - IsPointer

All Implemented Interfaces:

Serializable, Cloneable
```
public class IsPointer
extends SingleScalar
```
IsPointer is an invariant that heuristically determines whether an integer represents a pointer (a 32-bit memory address). Since both a 32-bit integer and an address have the same representation, sometimes a a pointer can be mistaken for an integer. When this happens, several scalar invariants are computed for integer variables. Most of them would not make any sense for pointers. Determining whether a 32-bit variable is a pointer can thus spare the computation of many irrelevant invariants.
The basic approach is to discard the invariant if any values that are not valid pointers are encountered. By default values between -100,000 and 100,000 (except 0) are considered to be invalid pointers. This approach has been experimentally confirmed on Windows x86 executables.

See Also:

Serialized Form

Nested Class Summary
- Nested classes/interfaces inherited from class Invariant
  Invariant.ClassVarnameComparator, Invariant.ClassVarnameFormulaComparator, Invariant.InvariantComparatorForPrinting, Invariant.Match

Field Summary

Fields
Modifier and Type Field Description

static boolean dkconfig_enabled
Boolean.
- Fields inherited from class Invariant
  CONFIDENCE_JUSTIFIED, CONFIDENCE_NEVER, CONFIDENCE_UNJUSTIFIED, debug, debugFlow, debugGuarding, debugIsObvious, debugIsWorthPrinting, debugPrint, debugPrintEquality, dkconfig_confidence_limit, dkconfig_fuzzy_ratio, dkconfig_simplify_define_predicates, falsified, invariantEnabledDefault, isGuardingPredicate, min_mod_non_missing_samples, ppt, PROBABILITY_JUSTIFIED, PROBABILITY_NEVER, PROBABILITY_UNJUSTIFIED

Constructor Summary

Constructors
Modifier Constructor Description

protected IsPointer()

protected IsPointer(PptSlice ppt)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`InvariantStatus`	`add_modified(long value, int count)`	Similar to `SingleScalar.check_modified(long, int)` except that it can change the state of the invariant if necessary.
`InvariantStatus`	`check_modified(long v, int count)`	Presents a sample to the invariant.
`protected double`	`computeConfidence()`	This method computes the confidence that this invariant occurred by chance.
`protected double`	`computeProbability()`
`boolean`	`enabled()`	Returns whether or not this class of invariants is currently enabled.
`String`	`format_using(OutputFormat format)`	Return a printed representation of this invariant, in the given format.
`static IsPointer`	`get_proto()`	Returns the prototype invariant for IsPointer.
`protected IsPointer`	`instantiate_dyn(PptSlice slice)`	Instantiates (creates) an invariant of the same class on the specified slice.
`boolean`	`instantiate_ok(VarInfo[] vis)`	Returns true if it makes sense to instantiate this invariant over the specified variables.
`boolean`	`isSameFormula(Invariant other)`	Returns true iff the two invariants represent the same mathematical formula.

Methods inherited from class SingleScalar
add, add_unmodified, check, check_unmodified, valid_types, valid_types_static, var

Methods inherited from class UnaryInvariant
resurrect_done

Methods inherited from class Invariant
add_sample, asInvClass, checkRep, clear_falsified, clone, clone_and_permute, conf_is_ge, confidence_and, confidence_and, confidence_or, createGuardedInvariant, createGuardingPredicate, enoughSamples, falsify, find, format, format_classname, format_too_few_samples, format_unimplemented, formatFuzzy, get_comparability, get_ni_suppressions, getConfidence, getGuardingList, getGuardingList, hasUninterestingConstant, instantiate, is_false, is_ni_suppressed, isActive, isAllPrestate, isEqualityComparison, isExact, isExclusiveFormula, isObvious, isObviousDynamically, isObviousDynamically, isObviousDynamically_SomeInEquality, isObviousDynamically_SomeInEqualityHelper, isObviousStatically, isObviousStatically, isObviousStatically_AllInEquality, isObviousStatically_SomeInEquality, isObviousStatically_SomeInEqualityHelper, isReflexive, isSameInvariant, isValidEscExpression, isValidExpression, isWorthPrinting, justified, log, log, logDetail, logOn, match, merge, mergeFormulasOk, permute, prob_and, prob_and, prob_is_ge, prob_or, repCheck, repr, repr_prob, resurrect, simplify_format_double, simplify_format_long, simplify_format_string, state_match, toString, toString, transfer, usesVar, usesVar, usesVarDerived, varNames

Methods inherited from class Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - dkconfig_enabled
```
public static boolean dkconfig_enabled
```
    Boolean. True iff IsPointer invariants should be considered.
- Constructor Detail
  - IsPointer
```
protected IsPointer(PptSlice ppt)
```
  - IsPointer
```
protected IsPointer()
```
- Method Detail
  - get_proto
```
public static IsPointer get_proto()
```
    Returns the prototype invariant for IsPointer.
  - instantiate_dyn
```
protected IsPointer instantiate_dyn(PptSlice slice)
```
    Description copied from class: Invariant
    
    Instantiates (creates) an invariant of the same class on the specified slice. Must be overridden in each class. Must be used rather than Invariant.clone() so that checks in Invariant.instantiate(daikon.PptSlice) for reasonable invariants are done.
    The implementation of this method is almost always return new <em>InvName</em>(slice);
    
    Specified by:
    
    instantiate_dyn in class Invariant
    
    Returns:
    
    the new invariant
  - enabled
```
public boolean enabled()
```
    Description copied from class: Invariant
    
    Returns whether or not this class of invariants is currently enabled.
    Its implementation is almost always return dkconfig_enabled;.
    
    Specified by:
    
    enabled in class Invariant
  - instantiate_ok
```
public boolean instantiate_ok(VarInfo[] vis)
```
    Description copied from class: Invariant
    
    Returns true if it makes sense to instantiate this invariant over the specified variables. Checks details beyond what is provided by Invariant.valid_types(daikon.VarInfo[]). This should never be called without calling valid_types() first (implementations should be able to presume that valid_types() returns true).
    This method does not have to be overridden; the default implementation in Invariant returns true.
    
    Overrides:
    
    instantiate_ok in class Invariant
    
    See Also:
    
    Invariant.valid_types(VarInfo[])
  - add_modified
```
public InvariantStatus add_modified(long value,
                                    int count)
```
    Description copied from class: SingleScalar
    
    Similar to SingleScalar.check_modified(long, int) except that it can change the state of the invariant if necessary. If the invariant doesn't have any state, then the implementation should simply call SingleScalar.check_modified(long, int). This method need not check for falsification; that is done by the caller.
    
    Specified by:
    
    add_modified in class SingleScalar
  - check_modified
```
public InvariantStatus check_modified(long v,
                                      int count)
```
    Description copied from class: SingleScalar
    
    Presents a sample to the invariant. Returns whether the sample is consistent with the invariant. Does not change the state of the invariant.
    
    Specified by:
    
    check_modified in class SingleScalar
    
    count - how many identical samples were observed in a row. For example, three calls to check_modified with a count parameter of 1 is equivalent to one call to check_modified with a count parameter of 3.
    
    Returns:
    
    whether or not the sample is consistent with the invariant
  - format_using
```
@SideEffectFree
public String format_using(@GuardSatisfied IsPointer this,
                           OutputFormat format)
```
    Description copied from class: Invariant
    
    Return a printed representation of this invariant, in the given format.
    
    Specified by:
    
    format_using in class Invariant
  - computeConfidence
```
protected double computeConfidence()
```
    Description copied from class: Invariant
    
    This method computes the confidence that this invariant occurred by chance. Clients should call Invariant.getConfidence() instead.
    This method need not check the value of field "falsified", as the caller does that.
    
    Specified by:
    
    computeConfidence in class Invariant
    
    Returns:
    
    confidence of this invariant
    
    See Also:
    
    Invariant.getConfidence()
  - computeProbability
```
protected double computeProbability()
```
  - isSameFormula
```
@Pure
public boolean isSameFormula(Invariant other)
```
    Description copied from class: Invariant
    
    Returns true iff the two invariants represent the same mathematical formula. Does not consider the context such as variable names, confidences, sample counts, value counts, or related quantities. As a rule of thumb, if two invariants format the same, this method returns true. Furthermore, in many cases, if an invariant does not involve computed constants (as "x>c" and "y=ax+b" do for constants a, b, and c), then this method vacuously returns true.
    
    Specified by:
    
    isSameFormula in class Invariant
    
    Parameters:
    
    other - the invariant to compare to this one
    
    Returns:
    
    true iff the two invariants represent the same mathematical formula. Does not consider

Modifier	Constructor	Description
`protected`	`IsPointer()`
`protected`	`IsPointer(PptSlice ppt)`

Class IsPointer

Nested Class Summary

Nested classes/interfaces inherited from class Invariant

Field Summary

Fields inherited from class Invariant

Constructor Summary

Method Summary

Methods inherited from class SingleScalar

Methods inherited from class UnaryInvariant

Methods inherited from class Invariant

Methods inherited from class Object

Field Detail

dkconfig_enabled

Constructor Detail

IsPointer

IsPointer

Method Detail

get_proto

instantiate_dyn

enabled

instantiate_ok

add_modified

check_modified

format_using

computeConfidence

computeProbability

isSameFormula