| package org.eclipse.jdt.internal.compiler.ast; |
| |
| /* |
| * (c) Copyright IBM Corp. 2000, 2001. |
| * All Rights Reserved. |
| */ |
| import org.eclipse.jdt.internal.compiler.IAbstractSyntaxTreeVisitor; |
| 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 AstNode[] subroutines; |
| 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; |
| while (true) { |
| AstNode sub; |
| if ((sub = traversedContext.subRoutine()) != null) { |
| if (this.subroutines == null){ |
| this.subroutines = new AstNode[maxSub]; |
| } |
| if (subIndex == maxSub) { |
| System.arraycopy(this.subroutines, 0, (this.subroutines = new AstNode[maxSub *= 2]), 0, subIndex); // grow |
| } |
| this.subroutines[subIndex++] = sub; |
| if (sub.cannotReturn()) { |
| saveValueNeeded = false; |
| break; |
| } |
| } |
| AstNode node; |
| |
| if ((node = traversedContext.associatedNode) instanceof SynchronizedStatement) { |
| isSynchronized = true; |
| |
| } else if (node instanceof TryStatement && hasValueToSave) { |
| if (this.saveValueVariable == null){ // closest subroutine secret variable is used |
| prepareSaveValueLocation((TryStatement)node); |
| } |
| saveValueNeeded = true; |
| |
| } else if (traversedContext instanceof InitializationFlowContext) { |
| currentScope.problemReporter().cannotReturnInInitializer(this); |
| return FlowInfo.DeadEnd; |
| } |
| |
| // remember the initialization at this |
| // point for dealing with blank final variables. |
| traversedContext.recordReturnFrom(flowInfo.unconditionalInits()); |
| |
| FlowContext parentContext; |
| if ((parentContext = traversedContext.parent) == null) { // top-context |
| break; |
| } else { |
| traversedContext = parentContext; |
| } |
| } |
| // resize subroutines |
| if ((subroutines != null) && (subIndex != maxSub)) { |
| System.arraycopy(subroutines, 0, (subroutines = new AstNode[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.used = true; |
| } |
| } else { |
| this.saveValueVariable = null; |
| if ((!isSynchronized) && (expressionType == BooleanBinding)) { |
| this.expression.bits |= ValueForReturnMASK; |
| } |
| } |
| return FlowInfo.DeadEnd; |
| } |
| /** |
| * 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(currentScope, 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++) { |
| AstNode sub; |
| if ((sub = subroutines[i]) instanceof SynchronizedStatement) { |
| codeStream.load(((SynchronizedStatement) sub).synchroVariable); |
| codeStream.monitorexit(); |
| } else { |
| TryStatement trySub = (TryStatement) sub; |
| if (trySub.subRoutineCannotReturn) { |
| codeStream.goto_(trySub.subRoutineStartLabel); |
| codeStream.recordPositionsFrom(pc, this); |
| return; |
| } else { |
| codeStream.jsr(trySub.subRoutineStartLabel); |
| } |
| } |
| } |
| } |
| if (saveValueVariable != null) codeStream.load(saveValueVariable); |
| |
| if ((expression != null) && (expression.constant != NotAConstant)) { |
| codeStream.generateConstant(expression.constant, expression.implicitConversion); |
| generateStoreSaveValueIfNecessary(currentScope, codeStream); |
| } |
| // output the suitable return bytecode or wrap the value inside a descriptor for doits |
| this.generateReturnBytecode(currentScope, codeStream); |
| |
| codeStream.recordPositionsFrom(pc, this); |
| } |
| /** |
| * Dump the suitable return bytecode for a return statement |
| * |
| */ |
| public void generateReturnBytecode(BlockScope currentScope, 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(BlockScope currentScope, CodeStream codeStream){ |
| |
| if (saveValueVariable != null) codeStream.store(saveValueVariable, false); |
| } |
| public boolean needValue(){ |
| return (subroutines == null) || (saveValueVariable != null) || isSynchronized; |
| } |
| public void prepareSaveValueLocation(TryStatement targetTryStatement){ |
| |
| saveValueVariable = targetTryStatement.secretReturnValue; |
| } |
| public void resolve(BlockScope scope) { |
| MethodScope methodScope = scope.methodScope(); |
| TypeBinding methodType = |
| (methodScope.referenceContext instanceof AbstractMethodDeclaration) |
| ? ((AbstractMethodDeclaration) methodScope.referenceContext).binding.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) { |
| scope.problemReporter().shouldReturn(methodType, this); |
| return; |
| } |
| if ((expressionType = expression.resolveType(scope)) == null) |
| return; |
| |
| if (expression.isConstantValueOfTypeAssignableToType(expressionType, methodType)) { |
| // dealing with constant |
| expression.implicitWidening(methodType, expressionType); |
| return; |
| } |
| if (expressionType == VoidBinding) { |
| scope.problemReporter().attemptToReturnVoidValue(this); |
| return; |
| } |
| if (scope.areTypesCompatible(expressionType, methodType)) { |
| expression.implicitWidening(methodType, expressionType); |
| return; |
| } |
| scope.problemReporter().typeMismatchErrorActualTypeExpectedType(expression, expressionType, methodType); |
| } |
| public String toString(int tab){ |
| /* slow code */ |
| |
| String s = tabString(tab) ; |
| s = s + "return "/*nonNLS*/; |
| if (expression != null ) |
| s = s + expression.toStringExpression() ; |
| return s; |
| } |
| public void traverse(IAbstractSyntaxTreeVisitor visitor, BlockScope scope) { |
| if (visitor.visit(this, scope)) { |
| if (expression != null) |
| expression.traverse(visitor, scope); |
| } |
| visitor.endVisit(this, scope); |
| } |
| } |