net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/compiler/ast/Assignment.java

   1 /*******************************************************************************
   2  * Copyright (c) 2000, 2001, 2002 International Business Machines Corp. and others.
   3  * All rights reserved. This program and the accompanying materials
   4  * are made available under the terms of the Common Public License v0.5
   5  * which accompanies this distribution, and is available at
   6  * http://www.eclipse.org/legal/cpl-v05.html
   7  *
   8  * Contributors:
   9  *     IBM Corporation - initial API and implementation
  10  ******************************************************************************/
  11 package net.sourceforge.phpdt.internal.compiler.ast;
  12
  13 import net.sourceforge.phpdt.internal.compiler.IAbstractSyntaxTreeVisitor;
  14 import net.sourceforge.phpdt.internal.compiler.codegen.*;
  15 import net.sourceforge.phpdt.internal.compiler.flow.*;
  16 import net.sourceforge.phpdt.internal.compiler.lookup.*;
  17
  18 public class Assignment extends Expression {
  19
  20         public Reference lhs;
  21         public Expression expression;
  22         public TypeBinding lhsType;
  23
  24         public Assignment(Expression lhs, Expression expression, int sourceEnd) {
  25                 //lhs is always a reference by construction ,
  26                 //but is build as an expression ==> the checkcast cannot fail
  27
  28                 this.lhs = (Reference) lhs;
  29                 this.expression = expression;
  30
  31                 this.sourceStart = lhs.sourceStart;
  32                 this.sourceEnd = sourceEnd;
  33         }
  34
  35         public FlowInfo analyseCode(
  36                 BlockScope currentScope,
  37                 FlowContext flowContext,
  38                 FlowInfo flowInfo) {
  39                 // record setting a variable: various scenarii are possible, setting an array reference,
  40                 // a field reference, a blank final field reference, a field of an enclosing instance or
  41                 // just a local variable.
  42
  43                 return lhs
  44                         .analyseAssignment(currentScope, flowContext, flowInfo, this, false)
  45                         .unconditionalInits();
  46         }
  47
  48         public void generateCode(
  49                 BlockScope currentScope,
  50                 CodeStream codeStream,
  51                 boolean valueRequired) {
  52
  53                 // various scenarii are possible, setting an array reference,
  54                 // a field reference, a blank final field reference, a field of an enclosing instance or
  55                 // just a local variable.
  56
  57                 int pc = codeStream.position;
  58                 lhs.generateAssignment(currentScope, codeStream, this, valueRequired);
  59                 // variable may have been optimized out
  60                 // the lhs is responsible to perform the implicitConversion generation for the assignment since optimized for unused local assignment.
  61                 codeStream.recordPositionsFrom(pc, this.sourceStart);
  62         }
  63
  64         public TypeBinding resolveType(BlockScope scope) {
  65
  66                 // due to syntax lhs may be only a NameReference, a FieldReference or an ArrayReference
  67                 constant = NotAConstant;
  68                 this.lhsType = lhs.resolveType(scope);
  69                 TypeBinding expressionTb = expression.resolveType(scope);
  70                 if (this.lhsType == null || expressionTb == null)
  71                         return null;
  72
  73                 // Compile-time conversion of base-types : implicit narrowing integer into byte/short/character
  74                 // may require to widen the rhs expression at runtime
  75                 if ((expression.isConstantValueOfTypeAssignableToType(expressionTb, this.lhsType)
  76                         || (this.lhsType.isBaseType() && BaseTypeBinding.isWidening(this.lhsType.id, expressionTb.id)))
  77                         || (scope.areTypesCompatible(expressionTb, this.lhsType))) {
  78                         expression.implicitWidening(this.lhsType, expressionTb);
  79                         return this.lhsType;
  80                 }
  81                 scope.problemReporter().typeMismatchErrorActualTypeExpectedType(
  82                         expression,
  83                         expressionTb,
  84                         this.lhsType);
  85                 return null;
  86         }
  87
  88         public String toString(int tab) {
  89
  90                 //no () when used as a statement
  91                 return tabString(tab) + toStringExpressionNoParenthesis();
  92         }
  93
  94         public String toStringExpression() {
  95
  96                 //subclass redefine toStringExpressionNoParenthesis()
  97                 return "(" + toStringExpressionNoParenthesis() + ")"; //$NON-NLS-2$ //$NON-NLS-1$
  98         }
  99
 100         public String toStringExpressionNoParenthesis() {
 101
 102                 return lhs.toStringExpression() + " " //$NON-NLS-1$
 103                         + "=" //$NON-NLS-1$
 104                         + ((expression.constant != null) && (expression.constant != NotAConstant)
 105                                 ? " /*cst:" + expression.constant.toString() + "*/ " //$NON-NLS-1$ //$NON-NLS-2$
 106                                 : " ")  //$NON-NLS-1$
 107                         + expression.toStringExpression();
 108         }
 109         public void traverse(IAbstractSyntaxTreeVisitor visitor, BlockScope scope) {
 110
 111                 if (visitor.visit(this, scope)) {
 112                         lhs.traverse(visitor, scope);
 113                         expression.traverse(visitor, scope);
 114                 }
 115                 visitor.endVisit(this, scope);
 116         }
 117 }