Package it.unive.lisa.program.cfg.statement

Class Expression

java.lang.Object

it.unive.lisa.program.cfg.statement.Statement

it.unive.lisa.program.cfg.statement.Expression

All Implemented Interfaces:

ProgramPoint, CodeElement, CodeNode<CFG,Statement,Edge>, Node<CFG,Statement,Edge>, java.lang.Comparable<Statement>

Direct Known Subclasses:

DefaultParamInitialization, Literal, NaryExpression, VariableRef

public abstract class Expression
extends Statement

An expression that is part of a statement of the program.

Field Summary

Fields inherited from class it.unive.lisa.program.cfg.statement.Statement

offset

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	Expression(CFG cfg, CodeLocation location)	Builds an untyped expression happening at the given source location, that is its type is Untyped.INSTANCE.
protected	Expression(CFG cfg, CodeLocation location, Type staticType)	Builds a typed expression happening at the given source location.

Method Summary

Modifier and Type	Method	Description
boolean	equals(java.lang.Object obj)
java.util.Collection<Identifier>	getMetaVariables()	Yields the meta variables that are generated by the evaluation of this expression.
Statement	getParentStatement()	Yields the Statement that contains this expression, if any.
Statement	getRootStatement()	Yields the outer-most Statement containing this expression, that is used as a node in the cfg.
Statement	getStatementEvaluatedAfter(Statement other)	Yields the Statement that follows the given one, assuming that other is contained into this statement.
Statement	getStatementEvaluatedBefore(Statement other)	Yields the Statement that precedes the given one, assuming that other is contained into this statement.
Type	getStaticType()	Yields the static type of this expression.
int	hashCode()
void	setParentStatement(Statement st)	Sets the Statement that contains this expression.

Methods inherited from class it.unive.lisa.program.cfg.statement.Statement

backwardSemantics, compareTo, forwardSemantics, getCFG, getEvaluationPredecessor, getEvaluationSuccessor, getLocation, getOffset, stopsExecution, throwsError, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unive.lisa.util.datastructures.graph.code.CodeNode

setOffset

Methods inherited from interface it.unive.lisa.util.datastructures.graph.Node

accept

Methods inherited from interface it.unive.lisa.program.cfg.ProgramPoint

getProgram

Constructor Detail

Expression

protected Expression(CFG cfg,
                     CodeLocation location)

Builds an untyped expression happening at the given source location, that is its type is Untyped.INSTANCE.

Parameters:

cfg - the cfg that this expression belongs to

location - the location where the expression is defined within the program

Expression

protected Expression(CFG cfg,
                     CodeLocation location,
                     Type staticType)

Builds a typed expression happening at the given source location.

Parameters:

cfg - the cfg that this expression belongs to

location - the location where this expression is defined within the program

staticType - the static type of this expression

Method Detail

getStaticType

public final Type getStaticType()

Yields the static type of this expression.

Returns:

the static type of this expression

getMetaVariables

public java.util.Collection<Identifier> getMetaVariables()

Yields the meta variables that are generated by the evaluation of this expression. These should be removed as soon as the values computed by those gets out of scope (e.g., popped from the stack). The returned collection will be filled while evaluating this expression semantics, thus invoking this method before computing the semantics will yield an empty collection. Variables added here should represent stack values that cannot be re-computed at a later time (e.g., call return values).

Returns:

the meta variables

hashCode

public int hashCode()

Overrides:

hashCode in class Statement

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class Statement

setParentStatement

public final void setParentStatement(Statement st)

Sets the Statement that contains this expression.

Parameters:

st - the containing statement

getParentStatement

public final Statement getParentStatement()

Yields the Statement that contains this expression, if any. If this method returns null, than this expression is used as a command: it is the root statement of a node in the cfg, and its returned value is discarded.

Returns:

the statement that contains this expression, if any

getRootStatement

public final Statement getRootStatement()

Yields the outer-most Statement containing this expression, that is used as a node in the cfg. If this expression is used a command, then this method return this. If this expression is a Call built as a resolved version of an UnresolvedCall uc, then uc.getRootStatement() is returned.

Returns:

the outer-most statement containing this expression, or this

getStatementEvaluatedBefore

public Statement getStatementEvaluatedBefore(Statement other)

Description copied from class: Statement

Yields the Statement that precedes the given one, assuming that other is contained into this statement. If this method returns null, then other is the first expression evaluated when this statement is evaluated.

Overrides:

getStatementEvaluatedBefore in class Statement

Parameters:

other - the other statement

Returns:

the previous statement, or null

getStatementEvaluatedAfter

public Statement getStatementEvaluatedAfter(Statement other)

Description copied from class: Statement

Yields the Statement that follows the given one, assuming that other is contained into this statement. If this method returns null, then other is the last expression evaluated when this statement is evaluated.

Overrides:

getStatementEvaluatedAfter in class Statement

Parameters:

other - the other statement

Returns:

the next statement, or null