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 int nullStatus(FlowInfo flowInfo) {
  58                 return FlowInfo.NON_NULL;
  59         }
  60
  61         public String operatorToString() {
  62                 switch (operator) {
  63                         case PLUS :
  64                                 return "+="; //$NON-NLS-1$
  65                         case MINUS :
  66                                 return "-="; //$NON-NLS-1$
  67                         case MULTIPLY :
  68                                 return "*="; //$NON-NLS-1$
  69                         case DIVIDE :
  70                                 return "/="; //$NON-NLS-1$
  71                         case AND :
  72                                 return "&="; //$NON-NLS-1$
  73                         case OR :
  74                                 return "|="; //$NON-NLS-1$
  75                         case XOR :
  76                                 return "^="; //$NON-NLS-1$
  77                         case REMAINDER :
  78                                 return "%="; //$NON-NLS-1$
  79                         case LEFT_SHIFT :
  80                                 return "<<="; //$NON-NLS-1$
  81                         case RIGHT_SHIFT :
  82                                 return ">>="; //$NON-NLS-1$
  83                         case UNSIGNED_RIGHT_SHIFT :
  84                                 return ">>>="; //$NON-NLS-1$
  85                 }
  86                 return "unknown operator"; //$NON-NLS-1$
  87         }
  88
  89         public StringBuffer printExpressionNoParenthesis(int indent, StringBuffer output) {
  90
  91                 lhs.printExpression(indent, output).append(' ').append(operatorToString()).append(' ');
  92                 return expression.printExpression(0, output) ;
  93         }
  94
  95         public TypeBinding resolveType(BlockScope scope) {
  96                 constant = NotAConstant;
  97                 if (!(this.lhs instanceof Reference) || this.lhs.isThis()) {
  98                         scope.problemReporter().expressionShouldBeAVariable(this.lhs);
  99                         return null;
 100                 }
 101                 TypeBinding originalLhsType = lhs.resolveType(scope);
 102                 TypeBinding originalExpressionType = expression.resolveType(scope);
 103                 if (originalLhsType == null || originalExpressionType == null)
 104                         return null;
 105
 106                 // autoboxing support
 107                 LookupEnvironment env = scope.environment();
 108                 TypeBinding lhsType = originalLhsType, expressionType = originalExpressionType;
 109                 boolean use15specifics = scope.environment().options.sourceLevel >= JDK1_5;
 110                 boolean unboxedLhs = false;
 111                 if (use15specifics) {
 112                         if (!lhsType.isBaseType() && expressionType.id != T_JavaLangString && expressionType.id != T_null) {
 113                                 TypeBinding unboxedType = env.computeBoxingType(lhsType);
 114                                 if (unboxedType != lhsType) {
 115                                         lhsType = unboxedType;
 116                                         unboxedLhs = true;
 117                                 }
 118                         }
 119                         if (!expressionType.isBaseType() && lhsType.id != T_JavaLangString  && lhsType.id != T_null) {
 120                                 expressionType = env.computeBoxingType(expressionType);
 121                         }
 122                 }
 123
 124                 if (restrainUsageToNumericTypes() && !lhsType.isNumericType()) {
 125                         scope.problemReporter().operatorOnlyValidOnNumericType(this, lhsType, expressionType);
 126                         return null;
 127                 }
 128                 int lhsID = lhsType.id;
 129                 int expressionID = expressionType.id;
 130                 if (lhsID > 15 || expressionID > 15) {
 131                         if (lhsID != T_JavaLangString) { // String += Thread is valid whereas Thread += String  is not
 132                                 scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 133                                 return null;
 134                         }
 135                         expressionID = T_JavaLangObject; // use the Object has tag table
 136                 }
 137
 138                 // the code is an int
 139                 // (cast)  left   Op (cast)  rigth --> result
 140                 //  0000   0000       0000   0000      0000
 141                 //  <<16   <<12       <<8     <<4        <<0
 142
 143                 // the conversion is stored INTO the reference (info needed for the code gen)
 144                 int result = OperatorExpression.OperatorSignatures[operator][ (lhsID << 4) + expressionID];
 145                 if (result == T_undefined) {
 146                         scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 147                         return null;
 148                 }
 149                 if (operator == PLUS){
 150                         if(lhsID == T_JavaLangObject) {
 151                                 // <Object> += <String> is illegal (39248)
 152                                 scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 153                                 return null;
 154                         } else {
 155                                 // <int | boolean> += <String> is illegal
 156                                 if ((lhsType.isNumericType() || lhsID == T_boolean) && !expressionType.isNumericType()){
 157                                         scope.problemReporter().invalidOperator(this, lhsType, expressionType);
 158                                         return null;
 159                                 }
 160                         }
 161                 }
 162                 this.lhs.implicitConversion = (unboxedLhs ? UNBOXING : 0) | (result >>> 12);
 163                 this.expression.computeConversion(scope, TypeBinding.wellKnownType(scope, (result >>> 8) & 0x0000F), originalExpressionType);
 164                 this.assignmentImplicitConversion =  (unboxedLhs ? BOXING : 0) | (lhsID << 4) | (result & 0x0000F);
 165                 return this.resolvedType = originalLhsType;
 166         }
 167
 168         public boolean restrainUsageToNumericTypes(){
 169                 return false ;
 170         }
 171
 172         public void traverse(ASTVisitor visitor, BlockScope scope) {
 173                 if (visitor.visit(this, scope)) {
 174                         lhs.traverse(visitor, scope);
 175                         expression.traverse(visitor, scope);
 176                 }
 177                 visitor.endVisit(this, scope);
 178         }
 179 }