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.call.Call

it.unive.lisa.program.cfg.statement.call.NativeCall

it.unive.lisa.program.cfg.statement.call.TernaryNativeCall

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

All Implemented Interfaces:

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

public class Substring
extends TernaryNativeCall

An expression modeling the string substring operation. The type of the first operand must be StringType, while the other two operands' types must be Int32. 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
protected <A extends AbstractState<A,H,V>,H extends HeapDomain<H>,V extends ValueDomain<V>> AnalysisState<A,H,V>	ternarySemantics(AnalysisState<A,H,V> entryState, InterproceduralAnalysis<A,H,V> interprocedural, AnalysisState<A,H,V> leftState, SymbolicExpression leftExp, AnalysisState<A,H,V> middleState, SymbolicExpression middleExp, AnalysisState<A,H,V> rightState, SymbolicExpression rightExp)	Computes the semantics of the call, after the semantics of the parameters have been computed.

Methods inherited from class it.unive.lisa.program.cfg.statement.call.TernaryNativeCall

callSemantics

Methods inherited from class it.unive.lisa.program.cfg.statement.call.NativeCall

equals, getConstructName, hashCode, toString

Methods inherited from class it.unive.lisa.program.cfg.statement.call.Call

accept, getParameters, semantics, setOffset

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

getDynamicType, getMetaVariables, getParentStatement, getRootStatement, getRuntimeTypes, getStaticType, setParentStatement, setRuntimeTypes

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

compareTo, getCFG, getLocation, getOffset, stopsExecution, throwsError

Methods inherited from class java.lang.Object

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

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

protected <A extends AbstractState<A,H,V>,H extends HeapDomain<H>,V extends ValueDomain<V>> AnalysisState<A,H,V> ternarySemantics(AnalysisState<A,H,V> entryState,
                                                                                                                                                                      InterproceduralAnalysis<A,H,V> interprocedural,
                                                                                                                                                                      AnalysisState<A,H,V> leftState,
                                                                                                                                                                      SymbolicExpression leftExp,
                                                                                                                                                                      AnalysisState<A,H,V> middleState,
                                                                                                                                                                      SymbolicExpression middleExp,
                                                                                                                                                                      AnalysisState<A,H,V> rightState,
                                                                                                                                                                      SymbolicExpression rightExp)
                                                                                                                                                               throws SemanticException

Description copied from class: TernaryNativeCall

Computes the semantics of the call, after the semantics of the parameters have been computed. Meta variables from the parameters will be forgotten after this call returns.

Specified by:

ternarySemantics in class TernaryNativeCall

Type Parameters:

A - the type of AbstractState

H - the type of the HeapDomain

V - the type of the ValueDomain

Parameters:

entryState - the entry state of this binary call

interprocedural - the interprocedural analysis of the program to analyze

leftState - the state obtained by evaluating left in entryState

leftExp - the symbolic expression representing the computed value of the first parameter of this call

middleState - the state obtained by evaluating middle in leftState

middleExp - the symbolic expression representing the computed value of the second parameter of this call

rightState - the state obtained by evaluating right in middleState

rightExp - the symbolic expression representing the computed value of the third parameter of this call

Returns:

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

Throws:

SemanticException - if something goes wrong during the computation