net.sourceforge.phpeclipse/src/net/sourceforge/phpeclipse/internal/compiler/ast/ReturnStatement.java

   1 /***********************************************************************************************************************************
   2  * Copyright (c) 2000, 2003 IBM Corporation and others. All rights reserved. This program and the accompanying materials are made
   3  * available under the terms of the Common Public License v1.0 which accompanies this distribution, and is available at
   4  * http://www.eclipse.org/legal/cpl-v10.html
   5  *
   6  * Contributors: IBM Corporation - initial API and implementation
   7  **********************************************************************************************************************************/
   8 package net.sourceforge.phpeclipse.internal.compiler.ast;
   9
  10 import net.sourceforge.phpdt.internal.compiler.ASTVisitor;
  11 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  12 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  13 import net.sourceforge.phpdt.internal.compiler.flow.InitializationFlowContext;
  14 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  15 import net.sourceforge.phpdt.internal.compiler.lookup.LocalVariableBinding;
  16 import net.sourceforge.phpdt.internal.compiler.lookup.MethodBinding;
  17 import net.sourceforge.phpdt.internal.compiler.lookup.MethodScope;
  18 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  19
  20 public class ReturnStatement extends Statement {
  21   public Expression expression;
  22
  23   public TypeBinding expressionType;
  24
  25   public boolean isSynchronized;
  26
  27   public ASTNode[] subroutines;
  28
  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
  37   public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) { // here requires to generate a
  38                                                                                                      // sequence of finally blocks
  39                                                                                                      // invocations depending
  40                                                                                                      // corresponding
  41     // to each of the traversed try statements, so that execution will terminate properly.
  42
  43     // lookup the label, this should answer the returnContext
  44
  45     if (expression != null) {
  46       flowInfo = expression.analyseCode(currentScope, flowContext, flowInfo);
  47     }
  48     // compute the return sequence (running the finally blocks)
  49     FlowContext traversedContext = flowContext;
  50     int subIndex = 0, maxSub = 5;
  51     boolean saveValueNeeded = false;
  52     boolean hasValueToSave = expression != null && expression.constant == NotAConstant;
  53     do {
  54       ASTNode sub;
  55       if ((sub = traversedContext.subRoutine()) != null) {
  56         if (this.subroutines == null) {
  57           this.subroutines = new ASTNode[maxSub];
  58         }
  59         if (subIndex == maxSub) {
  60           System.arraycopy(this.subroutines, 0, (this.subroutines = new ASTNode[maxSub *= 2]), 0, subIndex); // grow
  61         }
  62         this.subroutines[subIndex++] = sub;
  63         if (sub.cannotReturn()) {
  64           saveValueNeeded = false;
  65           break;
  66         }
  67       }
  68       traversedContext.recordReturnFrom(flowInfo.unconditionalInits());
  69
  70       ASTNode node = traversedContext.associatedNode;
  71 //      if ((node = traversedContext.associatedNode) instanceof SynchronizedStatement) {
  72 //        isSynchronized = true;
  73 //
  74 //      } else
  75       if (node instanceof TryStatement) {
  76         TryStatement tryStatement = (TryStatement) node;
  77         flowInfo.addInitializationsFrom(tryStatement.subRoutineInits); // collect inits
  78         if (hasValueToSave) {
  79           if (this.saveValueVariable == null) { // closest subroutine secret variable is used
  80             prepareSaveValueLocation(tryStatement);
  81           }
  82           saveValueNeeded = true;
  83         }
  84
  85       } else if (traversedContext instanceof InitializationFlowContext) {
  86         currentScope.problemReporter().cannotReturnInInitializer(this);
  87         return FlowInfo.DEAD_END;
  88       }
  89     } while ((traversedContext = traversedContext.parent) != null);
  90
  91     // resize subroutines
  92     if ((subroutines != null) && (subIndex != maxSub)) {
  93       System.arraycopy(subroutines, 0, (subroutines = new ASTNode[subIndex]), 0, subIndex);
  94     }
  95
  96     // secret local variable for return value (note that this can only occur in a real method)
  97     if (saveValueNeeded) {
  98       if (this.saveValueVariable != null) {
  99         this.saveValueVariable.useFlag = LocalVariableBinding.USED;
 100       }
 101     } else {
 102       this.saveValueVariable = null;
 103       if ((!isSynchronized) && (expressionType == BooleanBinding)) {
 104         this.expression.bits |= ValueForReturnMASK;
 105       }
 106     }
 107     return FlowInfo.DEAD_END;
 108   }
 109
 110   /**
 111    * Retrun statement code generation
 112    *
 113    * generate the finallyInvocationSequence.
 114    *
 115    * @param currentScope
 116    *          net.sourceforge.phpdt.internal.compiler.lookup.BlockScope
 117    * @param codeStream
 118    *          net.sourceforge.phpdt.internal.compiler.codegen.CodeStream
 119    */
 120   //public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 121   //    if ((bits & IsReachableMASK) == 0) {
 122   //            return;
 123   //    }
 124   //    int pc = codeStream.position;
 125   //    // generate the expression
 126   //    if ((expression != null) && (expression.constant == NotAConstant)) {
 127   //            expression.generateCode(currentScope, codeStream, needValue()); // no value needed if non-returning subroutine
 128   //            generateStoreSaveValueIfNecessary(codeStream);
 129   //    }
 130   //
 131   //    // generation of code responsible for invoking the finally blocks in sequence
 132   //    if (subroutines != null) {
 133   //            for (int i = 0, max = subroutines.length; i < max; i++) {
 134   //                    ASTNode sub;
 135   //                    if ((sub = subroutines[i]) instanceof SynchronizedStatement) {
 136   //                            codeStream.load(((SynchronizedStatement) sub).synchroVariable);
 137   //                            codeStream.monitorexit();
 138   //                    } else {
 139   //                            TryStatement trySub = (TryStatement) sub;
 140   //                            if (trySub.subRoutineCannotReturn) {
 141   //                                    codeStream.goto_(trySub.subRoutineStartLabel);
 142   //                                    codeStream.recordPositionsFrom(pc, this.sourceStart);
 143   //                                    return;
 144   //                            } else {
 145   //                                    codeStream.jsr(trySub.subRoutineStartLabel);
 146   //                            }
 147   //                    }
 148   //            }
 149   //    }
 150   //    if (saveValueVariable != null) codeStream.load(saveValueVariable);
 151   //
 152   //    if ((expression != null) && (expression.constant != NotAConstant)) {
 153   //            codeStream.generateConstant(expression.constant, expression.implicitConversion);
 154   //            generateStoreSaveValueIfNecessary(codeStream);
 155   //    }
 156   //    // output the suitable return bytecode or wrap the value inside a descriptor for doits
 157   //    this.generateReturnBytecode(codeStream);
 158   //
 159   //    codeStream.recordPositionsFrom(pc, this.sourceStart);
 160   //}
 161   /**
 162    * Dump the suitable return bytecode for a return statement
 163    *
 164    */
 165   //public void generateReturnBytecode(CodeStream codeStream) {
 166   //
 167   //    if (expression == null) {
 168   //            codeStream.return_();
 169   //    } else {
 170   //            switch (expression.implicitConversion >> 4) {
 171   //                    case T_boolean :
 172   //                    case T_int :
 173   //                            codeStream.ireturn();
 174   //                            break;
 175   //                    case T_float :
 176   //                            codeStream.freturn();
 177   //                            break;
 178   //                    case T_long :
 179   //                            codeStream.lreturn();
 180   //                            break;
 181   //                    case T_double :
 182   //                            codeStream.dreturn();
 183   //                            break;
 184   //                    default :
 185   //                            codeStream.areturn();
 186   //            }
 187   //    }
 188   //}
 189   //public void generateStoreSaveValueIfNecessary(CodeStream codeStream){
 190   //    if (saveValueVariable != null) codeStream.store(saveValueVariable, false);
 191   //}
 192   public boolean needValue() {
 193     return (subroutines == null) || (saveValueVariable != null) || isSynchronized;
 194   }
 195
 196   public void prepareSaveValueLocation(TryStatement targetTryStatement) {
 197
 198     this.saveValueVariable = targetTryStatement.secretReturnValue;
 199   }
 200
 201   public void resolve(BlockScope scope) {
 202     MethodScope methodScope = scope.methodScope();
 203     MethodBinding methodBinding;
 204     TypeBinding methodType = (methodScope.referenceContext instanceof AbstractMethodDeclaration) ? ((methodBinding = ((AbstractMethodDeclaration) methodScope.referenceContext).binding) == null ? null
 205         : methodBinding.returnType)
 206         : VoidBinding;
 207     if (methodType == VoidBinding) {
 208       // the expression should be null
 209       if (expression == null)
 210         return;
 211       if ((expressionType = expression.resolveType(scope)) != null)
 212         scope.problemReporter().attemptToReturnNonVoidExpression(this, expressionType);
 213       return;
 214     }
 215     if (expression == null) {
 216       if (methodType != null)
 217         scope.problemReporter().shouldReturn(methodType, this);
 218       return;
 219     }
 220     if ((expressionType = expression.resolveType(scope)) == null)
 221       return;
 222
 223     if (methodType != null && expression.isConstantValueOfTypeAssignableToType(expressionType, methodType)) {
 224       // dealing with constant
 225       expression.implicitWidening(methodType, expressionType);
 226       return;
 227     }
 228     if (expressionType == VoidBinding) {
 229       scope.problemReporter().attemptToReturnVoidValue(this);
 230       return;
 231     }
 232     if (methodType != null && expressionType.isCompatibleWith(methodType)) {
 233       expression.implicitWidening(methodType, expressionType);
 234       return;
 235     }
 236     if (methodType != null) {
 237       scope.problemReporter().typeMismatchErrorActualTypeExpectedType(expression, expressionType, methodType);
 238     }
 239   }
 240
 241   public StringBuffer printStatement(int tab, StringBuffer output) {
 242
 243     printIndent(tab, output).append("return "); //$NON-NLS-1$
 244     if (expression != null)
 245       expression.printExpression(0, output);
 246     return output.append(';');
 247   }
 248
 249   public String toString(int tab) {
 250
 251     String s = tabString(tab);
 252     s = s + "return "; //$NON-NLS-1$
 253     if (expression != null)
 254       s = s + expression.toStringExpression();
 255     return s;
 256   }
 257
 258   public void traverse(ASTVisitor visitor, BlockScope scope) {
 259     if (visitor.visit(this, scope)) {
 260       if (expression != null)
 261         expression.traverse(visitor, scope);
 262     }
 263     visitor.endVisit(this, scope);
 264   }
 265 }