Package it.unive.lisa.symbolic

Class SymbolicExpression

java.lang.Object

it.unive.lisa.symbolic.SymbolicExpression

All Implemented Interfaces:

ScopedObject<SymbolicExpression>

Direct Known Subclasses:

HeapExpression, ValueExpression

public abstract class SymbolicExpression
extends java.lang.Object
implements ScopedObject<SymbolicExpression>

A symbolic expression that can be evaluated by SemanticDomains.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SymbolicExpression(Type staticType, CodeLocation location)	Builds the symbolic expression.

Method Summary

Modifier and Type	Method	Description
abstract <T> T	accept(ExpressionVisitor<T> visitor, java.lang.Object... params)	Accepts an ExpressionVisitor, visiting this expression recursively.
boolean	equals(java.lang.Object obj)
CodeLocation	getCodeLocation()	Yields the code location of the statement that has generated this symbolic expression.
Type	getStaticType()	Yields the static type of this expression, as provided during construction.
int	hashCode()
abstract boolean	mightNeedRewriting()	Yields whether or not this expression can be considered safe to be processed by domains that only focus on ValueExpressions, or if it might need rewriting.
abstract SymbolicExpression	popScope(ScopeToken token)	Pops the scope identified by the given token from the expression.
abstract SymbolicExpression	pushScope(ScopeToken token)	Pushes a new scope, identified by the give token, in the expression.
abstract java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SymbolicExpression

protected SymbolicExpression(Type staticType,
                             CodeLocation location)

Builds the symbolic expression.

Parameters:

staticType - the static type of this expression, determined at its construction

location - the code location of the statement that has generated this expression

Method Detail

getStaticType

public Type getStaticType()

Yields the static type of this expression, as provided during construction. The returned type should (but might not) be a supertype of all the runtime types determined during the analysis, with the exception of HeapLocations representing more memory locations.

Returns:

the static type

pushScope

public abstract SymbolicExpression pushScope(ScopeToken token)
                                      throws SemanticException

Pushes a new scope, identified by the give token, in the expression. This causes all Identifiers where Identifier.canBeScoped() holds to become OutOfScopeIdentifiers associated with the given token.

Specified by:

pushScope in interface ScopedObject<SymbolicExpression>

Parameters:

token - the token identifying the scope to push

Returns:

a copy of this expression where the local variables have gone out of scope

Throws:

SemanticException - if an error occurs during the computation

popScope

public abstract SymbolicExpression popScope(ScopeToken token)
                                     throws SemanticException

Pops the scope identified by the given token from the expression. This causes all the invisible variables (i.e. OutOfScopeIdentifiers) mapped to the given scope to become visible (e.g. Variables) again. Note that invoking this method on Identifiers where Identifier.canBeScoped() holds will return null if (i) the identifier is not scoped, or (ii) the identifier is scoped by a different token.

Specified by:

popScope in interface ScopedObject<SymbolicExpression>

Parameters:

token - the token of the scope to be restored

Returns:

a copy of this expression where the local variables associated with the given scope are visible again

Throws:

SemanticException - if an error occurs during the computation

accept

public abstract <T> T accept(ExpressionVisitor<T> visitor,
                             java.lang.Object... params)
                      throws SemanticException

Accepts an ExpressionVisitor, visiting this expression recursively.

Type Parameters:

T - the type of value produced by the visiting callbacks

Parameters:

visitor - the visitor

params - additional optional parameters to pass to each visiting callback

Returns:

the value produced by the visiting operation

Throws:

SemanticException - if an error occurs during the visiting

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

getCodeLocation

public CodeLocation getCodeLocation()

Yields the code location of the statement that has generated this symbolic expression. The code location is not used for the equality between two symbolic expressions.

Returns:

the code location of the statement that has generated this symbolic expression

toString

public abstract java.lang.String toString()

Overrides:

toString in class java.lang.Object

mightNeedRewriting

public abstract boolean mightNeedRewriting()

Yields whether or not this expression can be considered safe to be processed by domains that only focus on ValueExpressions, or if it might need rewriting. This is a definite answer: if this method returns true, than this expression is sure to not contain anything that deals with, or points to, the memory.

Returns:

whether or not this expression might need rewriting