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/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.codegen.*;
import org.eclipse.jdt.internal.compiler.flow.*;
import org.eclipse.jdt.internal.compiler.lookup.*;
public class ReturnStatement extends Statement {
public Expression expression;
public TypeBinding expressionType;
public boolean isSynchronized;
public SubRoutineStatement[] subroutines;
public boolean isAnySubRoutineEscaping = false;
public LocalVariableBinding saveValueVariable;
public ReturnStatement(Expression expr, int s, int e ) {
sourceStart = s;
sourceEnd = e;
expression = expr ;
}
public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) { // here requires to generate a sequence of finally blocks invocations depending corresponding
// to each of the traversed try statements, so that execution will terminate properly.
// lookup the label, this should answer the returnContext
if (expression != null) {
flowInfo = expression.analyseCode(currentScope, flowContext, flowInfo);
}
// compute the return sequence (running the finally blocks)
FlowContext traversedContext = flowContext;
int subIndex = 0, maxSub = 5;
boolean saveValueNeeded = false;
boolean hasValueToSave = expression != null && expression.constant == NotAConstant;
do {
SubRoutineStatement sub;
if ((sub = traversedContext.subRoutine()) != null) {
if (this.subroutines == null){
this.subroutines = new SubRoutineStatement[maxSub];
}
if (subIndex == maxSub) {
System.arraycopy(this.subroutines, 0, (this.subroutines = new SubRoutineStatement[maxSub *= 2]), 0, subIndex); // grow
}
this.subroutines[subIndex++] = sub;
if (sub.isSubRoutineEscaping()) {
saveValueNeeded = false;
isAnySubRoutineEscaping = true;
break;
}
}
traversedContext.recordReturnFrom(flowInfo.unconditionalInits());
ASTNode node;
if ((node = traversedContext.associatedNode) instanceof SynchronizedStatement) {
isSynchronized = true;
} else if (node instanceof TryStatement) {
TryStatement tryStatement = (TryStatement) node;
flowInfo.addInitializationsFrom(tryStatement.subRoutineInits); // collect inits
if (hasValueToSave) {
if (this.saveValueVariable == null){ // closest subroutine secret variable is used
prepareSaveValueLocation(tryStatement);
}
saveValueNeeded = true;
}
} else if (traversedContext instanceof InitializationFlowContext) {
currentScope.problemReporter().cannotReturnInInitializer(this);
return FlowInfo.DEAD_END;
}
} while ((traversedContext = traversedContext.parent) != null);
// resize subroutines
if ((subroutines != null) && (subIndex != maxSub)) {
System.arraycopy(subroutines, 0, (subroutines = new SubRoutineStatement[subIndex]), 0, subIndex);
}
// secret local variable for return value (note that this can only occur in a real method)
if (saveValueNeeded) {
if (this.saveValueVariable != null) {
this.saveValueVariable.useFlag = LocalVariableBinding.USED;
}
} else {
this.saveValueVariable = null;
if ((!isSynchronized) && (expressionType == BooleanBinding)) {
this.expression.bits |= ValueForReturnMASK;
}
}
return FlowInfo.DEAD_END;
}
/**
* Retrun statement code generation
*
* generate the finallyInvocationSequence.
*
* @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
* @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
*/
public void generateCode(BlockScope currentScope, CodeStream codeStream) {
if ((bits & IsReachableMASK) == 0) {
return;
}
int pc = codeStream.position;
// generate the expression
if ((expression != null) && (expression.constant == NotAConstant)) {
expression.generateCode(currentScope, codeStream, needValue()); // no value needed if non-returning subroutine
generateStoreSaveValueIfNecessary(codeStream);
}
// generation of code responsible for invoking the finally blocks in sequence
if (subroutines != null) {
for (int i = 0, max = subroutines.length; i < max; i++) {
SubRoutineStatement sub = subroutines[i];
sub.generateSubRoutineInvocation(currentScope, codeStream);
if (sub.isSubRoutineEscaping()) {
codeStream.recordPositionsFrom(pc, this.sourceStart);
SubRoutineStatement.reenterExceptionHandlers(subroutines, i, codeStream);
return;
}
sub.exitAnyExceptionHandler();
}
}
if (saveValueVariable != null) codeStream.load(saveValueVariable);
if ((expression != null) && (expression.constant != NotAConstant)) {
codeStream.generateConstant(expression.constant, expression.implicitConversion);
generateStoreSaveValueIfNecessary(codeStream);
}
// output the suitable return bytecode or wrap the value inside a descriptor for doits
this.generateReturnBytecode(codeStream);
codeStream.recordPositionsFrom(pc, this.sourceStart);
SubRoutineStatement.reenterExceptionHandlers(subroutines, -1, codeStream);
}
/**
* Dump the suitable return bytecode for a return statement
*
*/
public void generateReturnBytecode(CodeStream codeStream) {
if (expression == null) {
codeStream.return_();
} else {
switch (expression.implicitConversion >> 4) {
case T_boolean :
case T_int :
codeStream.ireturn();
break;
case T_float :
codeStream.freturn();
break;
case T_long :
codeStream.lreturn();
break;
case T_double :
codeStream.dreturn();
break;
default :
codeStream.areturn();
}
}
}
public void generateStoreSaveValueIfNecessary(CodeStream codeStream){
if (saveValueVariable != null) codeStream.store(saveValueVariable, false);
}
public boolean needValue(){
return (subroutines == null) || (saveValueVariable != null) || isSynchronized;
}
public void prepareSaveValueLocation(TryStatement targetTryStatement){
this.saveValueVariable = targetTryStatement.secretReturnValue;
}
public StringBuffer printStatement(int tab, StringBuffer output){
printIndent(tab, output).append("return "); //$NON-NLS-1$
if (expression != null )
expression.printExpression(0, output) ;
return output.append(';');
}
public void resolve(BlockScope scope) {
MethodScope methodScope = scope.methodScope();
MethodBinding methodBinding;
TypeBinding methodType =
(methodScope.referenceContext instanceof AbstractMethodDeclaration)
? ((methodBinding = ((AbstractMethodDeclaration) methodScope.referenceContext).binding) == null
? null
: methodBinding.returnType)
: VoidBinding;
if (methodType == VoidBinding) {
// the expression should be null
if (expression == null)
return;
if ((expressionType = expression.resolveType(scope)) != null)
scope.problemReporter().attemptToReturnNonVoidExpression(this, expressionType);
return;
}
if (expression == null) {
if (methodType != null) scope.problemReporter().shouldReturn(methodType, this);
return;
}
if ((expressionType = expression.resolveType(scope)) == null)
return;
if (methodType != null && expression.isConstantValueOfTypeAssignableToType(expressionType, methodType)) {
// dealing with constant
expression.implicitWidening(methodType, expressionType);
return;
}
if (expressionType == VoidBinding) {
scope.problemReporter().attemptToReturnVoidValue(this);
return;
}
if (methodType != null && expressionType.isCompatibleWith(methodType)) {
expression.implicitWidening(methodType, expressionType);
return;
}
if (methodType != null){
scope.problemReporter().typeMismatchErrorActualTypeExpectedType(expression, expressionType, methodType);
}
}
public void traverse(ASTVisitor visitor, BlockScope scope) {
if (visitor.visit(this, scope)) {
if (expression != null)
expression.traverse(visitor, scope);
}
visitor.endVisit(this, scope);
}
}
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