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trait IsNullValue extends IsBaseReferenceValue

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  1. IsNullValue
  2. IsBaseReferenceValue
  3. IsReferenceValue
  4. KnownTypedValue
  5. KnownValue
  6. ValueInformation
  7. AnyRef
  8. Any
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Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. final def allValues: Iterable[IsNullValue.this.type]

    The set of base values (IsReferenceValue) this value abstracts over.

    The set of base values (IsReferenceValue) this value abstracts over. This set is never empty and contains this value if this value does not (further) abstract over other reference values; otherwise it only contains the base values, but not this value.

    Definition Classes
    IsBaseReferenceValueIsReferenceValue
    Note

    Primarily defined as a convenience interface.

  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def asPrimitiveValue: IsPrimitiveValue[_ <: BaseType]
    Definition Classes
    ValueInformation
  7. final def asReferenceType: ReferenceType

    Returns the type of the upper type bound if the upper type bound contains exactly one element.

    Returns the type of the upper type bound if the upper type bound contains exactly one element. That is, the function is only always defined iff the type is precise.

    Definition Classes
    IsReferenceValue
  8. final def asReferenceValue: IsReferenceValue
    Definition Classes
    IsReferenceValueValueInformation
  9. final def baseValues: Iterable[IsNullValue.this.type]

    In general an IsReferenceValue abstracts over all potential values and this information is sufficient for subsequent analyses; but in some cases, analyzing the set of underlying values may increase the overall precision and this set is returned by this function.

    In general an IsReferenceValue abstracts over all potential values and this information is sufficient for subsequent analyses; but in some cases, analyzing the set of underlying values may increase the overall precision and this set is returned by this function. In other words: if baseValues is nonEmpty, then the properties returned by this value are derived from the base values, but still maybe more specific. For example,

    Object o = _;
    if(...) o = f() else o = g();
    // when we reach this point, we generally don't know if the values returned by f and g
    // are non-null; hence, o is potentially null.
    if(o != null)
     // Now, we know that o is not null, but we still don't know if the values returned
     // by f OR g were null and we cannot establish that when we don't know to which value
     // o is actually referring to.
     u(o);
    returns

    The set of values this reference value abstracts over. The set is empty if this value is already a base value and it does not abstract over other values.

    Definition Classes
    IsBaseReferenceValueIsReferenceValue
    Note

    A reference value which belongs to the base values by some other reference value never has itself as a direct base value.

  10. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native() @IntrinsicCandidate()
  11. final def computationalType: ComputationalType

    The computational type of the value if this object represents a legal value.

    The computational type of the value if this object represents a legal value.

    The precise computational type is, e.g., needed to calculate the effect of generic stack manipulation instructions (e.g., DUP_... and SWAP) on the stack as well as to calculate the jump targets of RET instructions and to determine which values are actually copied by, e.g., the dup_XX instructions.

    Definition Classes
    IsReferenceValueValueInformation
    Exceptions thrown

    IllegalStateException if this value is illegal or void.

    Note

    The computational type has to be precise/correct.

  12. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  13. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  14. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native() @IntrinsicCandidate()
  15. final def hasCategory2ComputationalType: Boolean

    Returns true if and only if the value has the computational type 2; false in all other cases (including the case where this value is illegal!).

    Returns true if and only if the value has the computational type 2; false in all other cases (including the case where this value is illegal!).

    Definition Classes
    IsReferenceValueValueInformation
  16. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native() @IntrinsicCandidate()
  17. final def isArrayValue: Answer

    Returns Yes if the value is _not null_ and the least upper type bound is an ArrayType; the value is Unknown if the least upper type bound is ArrayType but the value may be null; in all other cases No is returned; in particular if the value is known to be null.

    Returns Yes if the value is _not null_ and the least upper type bound is an ArrayType; the value is Unknown if the least upper type bound is ArrayType but the value may be null; in all other cases No is returned; in particular if the value is known to be null. No is also returned if the value's type is Object or Seriablizable or Cloneable.

    Definition Classes
    IsNullValueValueInformation
  18. final def isIllegalValue: Boolean

    Returns true iff this value is not a legal value according to the JVM specification.

    Returns true iff this value is not a legal value according to the JVM specification. Such values cannot be used to perform any computations and will generally not occur in static analyses unless the analysis or the bytecode is buggy.

    Definition Classes
    KnownValueValueInformation
    Note

    An IsIllegalValue can always be distinguished from a void value.

  19. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  20. final def isNull: Answer

    If Yes the value is known to always be null at runtime.

    If Yes the value is known to always be null at runtime. In this case the upper bound is (has to be) empty. If the answer is Unknown then the analysis was not able to statically determine whether the value is null or is not null. In this case the upper bound is expected to be non-empty. If the answer is No then the value is statically known not to be null. In this case, the upper bound may precisely identify the runtime type or still just identify an upper bound.

    Definition Classes
    IsNullValueIsReferenceValue
  21. final def isPrecise: Boolean

    Returns true if the type information is precise.

    Returns true if the type information is precise. I.e., the type returned by upperTypeBound precisely models the runtime type of the value. If, isPrecise returns true, the type of this value can generally be assumed to represent a class type (not an interface type) or an array type. However, this domain also supports the case that isPrecise returns true even though the associated type identifies an interface type or an abstract class type. The later case may be interesting in the context of classes that are generated at run time.

    Definition Classes
    IsNullValueIsReferenceValue
  22. final def isPrimitiveValue: Boolean

    Returns true in case of a value with primitive type.

    Returns true in case of a value with primitive type.

    Definition Classes
    IsReferenceValueValueInformation
    Exceptions thrown

    IllegalStateException if this value is illegal.

  23. final def isReferenceValue: Boolean

    Returns true if the value has a reference type.

    Returns true if the value has a reference type.

    Definition Classes
    IsReferenceValueValueInformation
    Exceptions thrown

    IllegalStateException if this value is illegal.

  24. final def isValueASubtypeOf(referenceType: ReferenceType)(implicit classHierarchy: ClassHierarchy): Answer

    Tests if the type of this value is potentially a subtype of the specified reference type under the assumption that this value is not null.

    Tests if the type of this value is potentially a subtype of the specified reference type under the assumption that this value is not null. This test takes the precision of the type information into account. That is, if the currently available type information is not precise and the given type has a subtype that is always a subtype of the current upper type bound, then Unknown is returned. Given that it may be computationally intensive to determine whether two types have a common subtype it may be better to just return Unknown in case that this type and the given type are not in a direct inheritance relationship.

    Basically, this method implements the same semantics as the ClassHierarchy's isSubtypeOf method, but it additionally checks if the type of this value could be a subtype of the given supertype. I.e., if this value's type identifies a supertype of the given supertype and that type is not known to be precise, the answer is Unknown.

    For example, assume that the type of this reference value is java.util.Collection and we know/have to assume that this is only an upper bound. In this case an answer is No if and only if it is impossible that the runtime type is a subtype of the given supertype. This condition holds, for example, for java.io.File which is not a subclass of java.util.Collection and which does not have any further subclasses (in the JDK). I.e., the classes java.io.File and java.util.Collection are not in an inheritance relationship. However, if the specified supertype would be java.util.List the answer would be unknown.

    Definition Classes
    IsNullValueIsReferenceValue
    Note

    The function isValueASubtypeOf is not defined if isNull returns Yes; if isNull is Unknown then the result is given under the assumption that the value is not null at runtime. In other words, if this value represents null this method is not supported. If the value is null, the effect/interpretation of a subtype of query is context dependent (isInstanceOf/checkCast).

  25. final def isVoid: Boolean

    Returns true if this value represents void.

    Returns true if this value represents void.

    Definition Classes
    KnownTypedValueValueInformation
  26. final def leastUpperType: None.type

    The least upper type bound of the value.

    The least upper type bound of the value.

    None if and only if the underlying value is null.

    Definition Classes
    IsNullValueIsReferenceValue
  27. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  28. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @IntrinsicCandidate()
  29. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @IntrinsicCandidate()
  30. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  31. def toCanonicalForm: IsNullValue

    Returns a ValueInformation object that just captures the basic information as defined by this value framework.

    Returns a ValueInformation object that just captures the basic information as defined by this value framework. The returned value information object will be independent of the underlying representation from which it was derived.

    Definition Classes
    IsNullValueIsBaseReferenceValueIsReferenceValueValueInformation
  32. def toString(): String
    Definition Classes
    AnyRef → Any
  33. final def upperTypeBound: UIDSet[_ <: ReferenceType]

    The upper bound of the value's type.

    The upper bound of the value's type. The upper bound is empty if this value is null (i.e., isNull == Yes). The upper bound is only guaranteed to contain exactly one type if the type is precise. (i.e., isPrecise == true). Otherwise, the upper type bound may contain one or more types that are not known to be in an inheritance relation, but which will correctly approximate the runtime type.

    Definition Classes
    IsNullValueIsReferenceValue
    Note

    If only a part of a project is analyzed, the class hierarchy may be fragmented and it may happen that two classes that are indeed in an inheritance relation – if we would analyze the complete project – are part of the upper type bound.

  34. final def verificationTypeInfo: VerificationTypeInfo

    The type of this value as used by the org.opalj.br.StackMapTable attribute.

    The type of this value as used by the org.opalj.br.StackMapTable attribute.

    Definition Classes
    IsNullValueValueInformation
    Exceptions thrown

    IllegalStateException if this value represents void or a return address value.

  35. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  36. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  37. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])

Deprecated Value Members

  1. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable]) @Deprecated
    Deprecated

Inherited from IsBaseReferenceValue

Inherited from IsReferenceValue

Inherited from KnownTypedValue

Inherited from KnownValue

Inherited from ValueInformation

Inherited from AnyRef

Inherited from Any

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