src/org/eclipse/jdt/internal/compiler/ast/CompoundAssignment.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2004 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 org.eclipse.jdt.internal.compiler.ast;
  12
  13 import org.eclipse.jdt.internal.compiler.ASTVisitor;
  14 import org.eclipse.jdt.internal.compiler.codegen.*;
  15 import org.eclipse.jdt.internal.compiler.flow.*;
  16 import org.eclipse.jdt.internal.compiler.lookup.*;
  17
  18 public class CompoundAssignment extends Assignment implements OperatorIds {
  19         public int operator;
  20         public int assignmentImplicitConversion;
  21
  22         //  var op exp is equivalent to var = (varType) var op exp
  23         // assignmentImplicitConversion stores the cast needed for the assignment
  24
  25         public CompoundAssignment(Expression lhs, Expression expression,int operator, int sourceEnd) {
  26                 //lhs is always a reference by construction ,
  27                 //but is build as an expression ==> the checkcast cannot fail
  28
  29                 super(lhs, expression, sourceEnd);
  30                 lhs.bits &= ~IsStrictlyAssignedMASK; // tag lhs as NON assigned - it is also a read access
  31                 lhs.bits |= IsCompoundAssignedMASK; // tag lhs as assigned by compound
  32                 this.operator = operator ;
  33         }
  34
  35         public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) {
  36                 // record setting a variable: various scenarii are possible, setting an array reference,
  37                 // a field reference, a blank final field reference, a field of an enclosing instance or
  38                 // just a local variable.
  39
  40                 return  ((Reference) lhs).analyseAssignment(currentScope, flowContext, flowInfo, this, true).unconditionalInits();
  41         }
  42
  43         public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) {
  44
  45                 // various scenarii are possible, setting an array reference,
  46                 // a field reference, a blank final field reference, a field of an enclosing instance or
  47                 // just a local variable.
  48
  49                 int pc = codeStream.position;
  50                  ((Reference) lhs).generateCompoundAssignment(currentScope, codeStream, expression, operator, assignmentImplicitConversion, valueRequired);
  51                 if (valueRequired) {
  52                         codeStream.generateImplicitConversion(implicitConversion);
  53                 }
  54                 codeStream.recordPositionsFrom(pc, this.sourceStart);
  55         }
  56
  57         public String operatorToString() {
  58                 switch (operator) {
  59                         case PLUS :
  60                                 return "+="; //$NON-NLS-1$
  61                         case MINUS :
  62                                 return "-="; //$NON-NLS-1$
  63                         case MULTIPLY :
  64                                 return "*="; //$NON-NLS-1$
  65                         case DIVIDE :
  66                                 return "/="; //$NON-NLS-1$
  67                         case AND :
  68                                 return "&="; //$NON-NLS-1$
  69                         case OR :
  70                                 return "|="; //$NON-NLS-1$
  71                         case XOR :
  72                                 return "^="; //$NON-NLS-1$
  73                         case REMAINDER :
  74                                 return "%="; //$NON-NLS-1$
  75                         case LEFT_SHIFT :
  76                                 return "<<="; //$NON-NLS-1$
  77                         case RIGHT_SHIFT :
  78                                 return ">>="; //$NON-NLS-1$
  79                         case UNSIGNED_RIGHT_SHIFT :
  80                                 return ">>>="; //$NON-NLS-1$
  81                 }
  82                 return "unknown operator"; //$NON-NLS-1$
  83         }
  84
  85         public StringBuffer printExpressionNoParenthesis(int indent, StringBuffer output) {
  86
  87                 lhs.printExpression(indent, output).append(' ').append(operatorToString()).append(' ');
  88                 return expression.printExpression(0, output) ;
  89         }
  90
  91         public TypeBinding resolveType(BlockScope scope) {
  92                 constant = NotAConstant;
  93                 if (!(this.lhs instanceof Reference) || this.lhs.isThis()) {
  94                         scope.problemReporter().expressionShouldBeAVariable(this.lhs);
  95                         return null;
  96                 }
  97                 TypeBinding lhsType = lhs.resolveType(scope);
  98                 TypeBinding expressionType = expression.resolveType(scope);
  99                 if (lhsType == null || expressionType == null)
 100                         return null;
 101
 102                 int lhsId = lhsType.id;
 103                 int expressionId = expressionType.id;
 104                 if (restrainUsageToNumericTypes() && !lhsType.isNumericType()) {
 105                         scope.problemReporter().operatorOnlyValidOnNumericType(this, lhsType, expressionType);
 106                         return null;
 107                 }
 108                 if (lhsId > 15 || expressionId > 15) {
 109                         if (lhsId != T_String) { // String += Thread is valid whereas Thread += String  is not
 110                                 scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 111                                 return null;
 112                         }
 113                         expressionId = T_Object; // use the Object has tag table
 114                 }
 115
 116                 // the code is an int
 117                 // (cast)  left   Op (cast)  rigth --> result
 118                 //  0000   0000       0000   0000      0000
 119                 //  <<16   <<12       <<8     <<4        <<0
 120
 121                 // the conversion is stored INTO the reference (info needed for the code gen)
 122                 int result = OperatorExpression.OperatorSignatures[operator][ (lhsId << 4) + expressionId];
 123                 if (result == T_undefined) {
 124                         scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 125                         return null;
 126                 }
 127                 if (operator == PLUS){
 128                         if(lhsId == T_JavaLangObject) {
 129                                 // <Object> += <String> is illegal (39248)
 130                                 scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 131                                 return null;
 132                         } else {
 133                                 // <int | boolean> += <String> is illegal
 134                                 if ((lhsType.isNumericType() || lhsId == T_boolean) && !expressionType.isNumericType()){
 135                                         scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 136                                         return null;
 137                                 }
 138                         }
 139                 }
 140                 lhs.implicitConversion = result >>> 12;
 141                 expression.implicitConversion = (result >>> 4) & 0x000FF;
 142                 assignmentImplicitConversion = (lhsId << 4) + (result & 0x0000F);
 143                 return this.resolvedType = lhsType;
 144         }
 145
 146         public boolean restrainUsageToNumericTypes(){
 147                 return false ;
 148         }
 149
 150         public void traverse(ASTVisitor visitor, BlockScope scope) {
 151                 if (visitor.visit(this, scope)) {
 152                         lhs.traverse(visitor, scope);
 153                         expression.traverse(visitor, scope);
 154                 }
 155                 visitor.endVisit(this, scope);
 156         }
 157 }