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

Class Substring

java.lang.Object

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

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

it.unive.lisa.program.cfg.statement.NaryExpression

it.unive.lisa.program.cfg.statement.TernaryExpression

it.unive.lisa.program.cfg.statement.string.Substring

All Implemented Interfaces:

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

public class Substring
extends TernaryExpression

An expression modeling the string substring operation. The type of the first operand must be StringType, while the other two operands' types must be NumericType. The type of this expression is the StringType.

Since in most languages string operations are provided through calls to library functions, this class contains a field originating whose purpose is to optionally store a Statement that is rewritten to an instance of this class (i.e., a call to a NativeCFG modeling the library function). If present, such statement will be used as ProgramPoint for semantics computations. This allows subclasses to implement PluggableStatement easily without redefining the semantics provided by this class.

Field Summary

Fields

Modifier and Type	Field	Description
protected Statement	originating	Statement that has been rewritten to this operation, if any.

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

offset

Constructor Summary

Constructors

Constructor	Description
Substring(CFG cfg, CodeLocation location, Expression left, Expression middle, Expression right)	Builds the substring.

Method Summary

Modifier and Type	Method	Description
<A extends AbstractState<A,H,V,T>,H extends HeapDomain<H>,V extends ValueDomain<V>,T extends TypeDomain<T>> AnalysisState<A,H,V,T>	ternarySemantics(InterproceduralAnalysis<A,H,V,T> interprocedural, AnalysisState<A,H,V,T> state, SymbolicExpression left, SymbolicExpression middle, SymbolicExpression right, StatementStore<A,H,V,T> expressions)	Computes the semantics of the expression, after the semantics of the sub-expressions have been computed.

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

expressionSemantics, getLeft, getMiddle, getRight

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

accept, equals, getConstructName, getOrder, getStatementEvaluatedBefore, getSubExpressions, hashCode, semantics, setOffset, toString

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

getMetaVariables, getParentStatement, getRootStatement, getStaticType, setParentStatement

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

compareTo, getCFG, getEvaluationPredecessor, getLocation, getOffset, stopsExecution, throwsError

Methods inherited from class java.lang.Object

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

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

getProgram

Field Detail

originating

protected Statement originating

Statement that has been rewritten to this operation, if any. This is to accomodate the fact that, in most languages, string operations are performed through calls, and one might want to provide the semantics of those calls through NativeCFG that rewrites to instances of this class.

Constructor Detail

Substring

public Substring(CFG cfg,
                 CodeLocation location,
                 Expression left,
                 Expression middle,
                 Expression right)

Builds the substring.

Parameters:

cfg - the CFG where this operation lies

location - the location where this literal is defined

left - the left-hand side of this operation

middle - the middle operand of this operation

right - the right-hand side of this operation

Method Detail

ternarySemantics

public <A extends AbstractState<A,H,V,T>,H extends HeapDomain<H>,V extends ValueDomain<V>,T extends TypeDomain<T>> AnalysisState<A,H,V,T> ternarySemantics(InterproceduralAnalysis<A,H,V,T> interprocedural,
                                                                                                                                                                                                                 AnalysisState<A,H,V,T> state,
                                                                                                                                                                                                                 SymbolicExpression left,
                                                                                                                                                                                                                 SymbolicExpression middle,
                                                                                                                                                                                                                 SymbolicExpression right,
                                                                                                                                                                                                                 StatementStore<A,H,V,T> expressions)
                                                                                                                                                                                                          throws SemanticException

Description copied from class: TernaryExpression

Computes the semantics of the expression, after the semantics of the sub-expressions have been computed. Meta variables from the sub-expressions will be forgotten after this expression returns.

Specified by:

ternarySemantics in class TernaryExpression

Type Parameters:

A - the type of AbstractState

H - the type of the HeapDomain

V - the type of the ValueDomain

T - the type of TypeDomain

Parameters:

interprocedural - the interprocedural analysis of the program to analyze

state - the state where the expression is to be evaluated

left - the symbolic expression representing the computed value of the first sub-expression of this expression

middle - the symbolic expression representing the computed value of the second sub-expression of this expression

right - the symbolic expression representing the computed value of the third sub-expression of this expression

expressions - the cache where analysis states of intermediate expressions are stored and that can be accessed to query for post-states of parameters expressions

Returns:

the AnalysisState representing the abstract result of the execution of this expression

Throws:

SemanticException - if something goes wrong during the computation