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   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v1.0
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v10.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  *******************************************************************************/
  11 package net.sourceforge.phpeclipse.internal.compiler.ast;
  12
  13 import net.sourceforge.phpdt.internal.compiler.IAbstractSyntaxTreeVisitor;
  14 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  15 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  16 import net.sourceforge.phpdt.internal.compiler.flow.InitializationFlowContext;
  17 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  18 import net.sourceforge.phpdt.internal.compiler.lookup.LocalVariableBinding;
  19 import net.sourceforge.phpdt.internal.compiler.lookup.MethodBinding;
  20 import net.sourceforge.phpdt.internal.compiler.lookup.MethodScope;
  21 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  22
  23 public class ReturnStatement extends Statement {
  24         public Expression expression;
  25
  26         public TypeBinding expressionType;
  27         public boolean isSynchronized;
  28         public ASTNode[] subroutines;
  29         public LocalVariableBinding saveValueVariable;
  30
  31 public ReturnStatement(Expression expr, int s, int e ) {
  32         sourceStart = s;
  33         sourceEnd = e;
  34         expression = expr ;
  35 }
  36 public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) {      // here requires to generate a sequence of finally blocks invocations depending corresponding
  37         // to each of the traversed try statements, so that execution will terminate properly.
  38
  39         // lookup the label, this should answer the returnContext
  40
  41         if (expression != null) {
  42                 flowInfo = expression.analyseCode(currentScope, flowContext, flowInfo);
  43         }
  44         // compute the return sequence (running the finally blocks)
  45         FlowContext traversedContext = flowContext;
  46         int subIndex = 0, maxSub = 5;
  47         boolean saveValueNeeded = false;
  48         boolean hasValueToSave = expression != null && expression.constant == NotAConstant;
  49         do {
  50                 ASTNode sub;
  51                 if ((sub = traversedContext.subRoutine()) != null) {
  52                         if (this.subroutines == null){
  53                                 this.subroutines = new ASTNode[maxSub];
  54                         }
  55                         if (subIndex == maxSub) {
  56                                 System.arraycopy(this.subroutines, 0, (this.subroutines = new ASTNode[maxSub *= 2]), 0, subIndex); // grow
  57                         }
  58                         this.subroutines[subIndex++] = sub;
  59                         if (sub.cannotReturn()) {
  60                                 saveValueNeeded = false;
  61                                 break;
  62                         }
  63                 }
  64                 traversedContext.recordReturnFrom(flowInfo.unconditionalInits());
  65
  66                 ASTNode node;
  67                 if ((node = traversedContext.associatedNode) instanceof SynchronizedStatement) {
  68                         isSynchronized = true;
  69
  70                 } else if (node instanceof TryStatement) {
  71                         TryStatement tryStatement = (TryStatement) node;
  72                         flowInfo.addInitializationsFrom(tryStatement.subRoutineInits); // collect inits
  73                         if (hasValueToSave) {
  74                                 if (this.saveValueVariable == null){ // closest subroutine secret variable is used
  75                                         prepareSaveValueLocation(tryStatement);
  76                                 }
  77                                 saveValueNeeded = true;
  78                         }
  79
  80                 } else if (traversedContext instanceof InitializationFlowContext) {
  81                                 currentScope.problemReporter().cannotReturnInInitializer(this);
  82                                 return FlowInfo.DEAD_END;
  83                 }
  84         } while ((traversedContext = traversedContext.parent) != null);
  85
  86         // resize subroutines
  87         if ((subroutines != null) && (subIndex != maxSub)) {
  88                 System.arraycopy(subroutines, 0, (subroutines = new ASTNode[subIndex]), 0, subIndex);
  89         }
  90
  91         // secret local variable for return value (note that this can only occur in a real method)
  92         if (saveValueNeeded) {
  93                 if (this.saveValueVariable != null) {
  94                         this.saveValueVariable.useFlag = LocalVariableBinding.USED;
  95                 }
  96         } else {
  97                 this.saveValueVariable = null;
  98                 if ((!isSynchronized) && (expressionType == BooleanBinding)) {
  99                         this.expression.bits |= ValueForReturnMASK;
 100                 }
 101         }
 102         return FlowInfo.DEAD_END;
 103 }
 104
 105 /**
 106  * Retrun statement code generation
 107  *
 108  *   generate the finallyInvocationSequence.
 109  *
 110  * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
 111  * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
 112  */
 113 //public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 114 //      if ((bits & IsReachableMASK) == 0) {
 115 //              return;
 116 //      }
 117 //      int pc = codeStream.position;
 118 //      // generate the expression
 119 //      if ((expression != null) && (expression.constant == NotAConstant)) {
 120 //              expression.generateCode(currentScope, codeStream, needValue()); // no value needed if non-returning subroutine
 121 //              generateStoreSaveValueIfNecessary(codeStream);
 122 //      }
 123 //
 124 //      // generation of code responsible for invoking the finally blocks in sequence
 125 //      if (subroutines != null) {
 126 //              for (int i = 0, max = subroutines.length; i < max; i++) {
 127 //                      ASTNode sub;
 128 //                      if ((sub = subroutines[i]) instanceof SynchronizedStatement) {
 129 //                              codeStream.load(((SynchronizedStatement) sub).synchroVariable);
 130 //                              codeStream.monitorexit();
 131 //                      } else {
 132 //                              TryStatement trySub = (TryStatement) sub;
 133 //                              if (trySub.subRoutineCannotReturn) {
 134 //                                      codeStream.goto_(trySub.subRoutineStartLabel);
 135 //                                      codeStream.recordPositionsFrom(pc, this.sourceStart);
 136 //                                      return;
 137 //                              } else {
 138 //                                      codeStream.jsr(trySub.subRoutineStartLabel);
 139 //                              }
 140 //                      }
 141 //              }
 142 //      }
 143 //      if (saveValueVariable != null) codeStream.load(saveValueVariable);
 144 //
 145 //      if ((expression != null) && (expression.constant != NotAConstant)) {
 146 //              codeStream.generateConstant(expression.constant, expression.implicitConversion);
 147 //              generateStoreSaveValueIfNecessary(codeStream);
 148 //      }
 149 //      // output the suitable return bytecode or wrap the value inside a descriptor for doits
 150 //      this.generateReturnBytecode(codeStream);
 151 //
 152 //      codeStream.recordPositionsFrom(pc, this.sourceStart);
 153 //}
 154 /**
 155  * Dump the suitable return bytecode for a return statement
 156  *
 157  */
 158 //public void generateReturnBytecode(CodeStream codeStream) {
 159 //
 160 //      if (expression == null) {
 161 //              codeStream.return_();
 162 //      } else {
 163 //              switch (expression.implicitConversion >> 4) {
 164 //                      case T_boolean :
 165 //                      case T_int :
 166 //                              codeStream.ireturn();
 167 //                              break;
 168 //                      case T_float :
 169 //                              codeStream.freturn();
 170 //                              break;
 171 //                      case T_long :
 172 //                              codeStream.lreturn();
 173 //                              break;
 174 //                      case T_double :
 175 //                              codeStream.dreturn();
 176 //                              break;
 177 //                      default :
 178 //                              codeStream.areturn();
 179 //              }
 180 //      }
 181 //}
 182 //public void generateStoreSaveValueIfNecessary(CodeStream codeStream){
 183 //      if (saveValueVariable != null) codeStream.store(saveValueVariable, false);
 184 //}
 185 public boolean needValue(){
 186         return (subroutines == null) || (saveValueVariable != null) || isSynchronized;
 187 }
 188 public void prepareSaveValueLocation(TryStatement targetTryStatement){
 189
 190         this.saveValueVariable = targetTryStatement.secretReturnValue;
 191 }
 192 public void resolve(BlockScope scope) {
 193         MethodScope methodScope = scope.methodScope();
 194         MethodBinding methodBinding;
 195         TypeBinding methodType =
 196                 (methodScope.referenceContext instanceof AbstractMethodDeclaration)
 197                         ? ((methodBinding = ((AbstractMethodDeclaration) methodScope.referenceContext).binding) == null
 198                                 ? null
 199                                 : methodBinding.returnType)
 200                         : VoidBinding;
 201         if (methodType == VoidBinding) {
 202                 // the expression should be null
 203                 if (expression == null)
 204                         return;
 205                 if ((expressionType = expression.resolveType(scope)) != null)
 206                         scope.problemReporter().attemptToReturnNonVoidExpression(this, expressionType);
 207                 return;
 208         }
 209         if (expression == null) {
 210                 if (methodType != null) scope.problemReporter().shouldReturn(methodType, this);
 211                 return;
 212         }
 213         if ((expressionType = expression.resolveType(scope)) == null)
 214                 return;
 215
 216         if (methodType != null && expression.isConstantValueOfTypeAssignableToType(expressionType, methodType)) {
 217                 // dealing with constant
 218                 expression.implicitWidening(methodType, expressionType);
 219                 return;
 220         }
 221         if (expressionType == VoidBinding) {
 222                 scope.problemReporter().attemptToReturnVoidValue(this);
 223                 return;
 224         }
 225         if (methodType != null && expressionType.isCompatibleWith(methodType)) {
 226                 expression.implicitWidening(methodType, expressionType);
 227                 return;
 228         }
 229         if (methodType != null){
 230                 scope.problemReporter().typeMismatchErrorActualTypeExpectedType(expression, expressionType, methodType);
 231         }
 232 }
 233 public String toString(int tab){
 234
 235         String s = tabString(tab) ;
 236         s = s + "return "; //$NON-NLS-1$
 237         if (expression != null )
 238                 s = s + expression.toStringExpression() ;
 239         return s;
 240 }
 241 public void traverse(IAbstractSyntaxTreeVisitor visitor, BlockScope scope) {
 242         if (visitor.visit(this, scope)) {
 243                 if (expression != null)
 244                         expression.traverse(visitor, scope);
 245         }
 246         visitor.endVisit(this, scope);
 247 }
 248 }