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.CodeStream;
  15 import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
  16 import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
  17 import net.sourceforge.phpdt.internal.compiler.lookup.BaseTypeBinding;
  18 import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
  19 import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;
  20
  21 public class Assignment extends Expression {
  22
  23         public Reference lhs;
  24         public Expression expression;
  25         public TypeBinding lhsType;
  26
  27         public Assignment(Expression lhs, Expression expression, int sourceEnd) {
  28                 //lhs is always a reference by construction ,
  29                 //but is build as an expression ==> the checkcast cannot fail
  30
  31                 this.lhs = (Reference) lhs;
  32                 this.expression = expression;
  33
  34                 this.sourceStart = lhs.sourceStart;
  35                 this.sourceEnd = sourceEnd;
  36         }
  37
  38         public FlowInfo analyseCode(
  39                 BlockScope currentScope,
  40                 FlowContext flowContext,
  41                 FlowInfo flowInfo) {
  42                 // record setting a variable: various scenarii are possible, setting an array reference,
  43                 // a field reference, a blank final field reference, a field of an enclosing instance or
  44                 // just a local variable.
  45
  46                 return lhs
  47                         .analyseAssignment(currentScope, flowContext, flowInfo, this, false)
  48                         .unconditionalInits();
  49         }
  50
  51         public void generateCode(
  52                 BlockScope currentScope,
  53                 CodeStream codeStream,
  54                 boolean valueRequired) {
  55
  56                 // various scenarii are possible, setting an array reference,
  57                 // a field reference, a blank final field reference, a field of an enclosing instance or
  58                 // just a local variable.
  59
  60                 int pc = codeStream.position;
  61                 lhs.generateAssignment(currentScope, codeStream, this, valueRequired);
  62                 // variable may have been optimized out
  63                 // the lhs is responsible to perform the implicitConversion generation for the assignment since optimized for unused local assignment.
  64                 codeStream.recordPositionsFrom(pc, this.sourceStart);
  65         }
  66
  67         public TypeBinding resolveType(BlockScope scope) {
  68
  69                 // due to syntax lhs may be only a NameReference, a FieldReference or an ArrayReference
  70                 constant = NotAConstant;
  71                 this.lhsType = lhs.resolveType(scope);
  72                 TypeBinding expressionTb = expression.resolveType(scope);
  73                 if (this.lhsType == null || expressionTb == null)
  74                         return null;
  75
  76                 // Compile-time conversion of base-types : implicit narrowing integer into byte/short/character
  77                 // may require to widen the rhs expression at runtime
  78                 if ((expression.isConstantValueOfTypeAssignableToType(expressionTb, this.lhsType)
  79                         || (this.lhsType.isBaseType() && BaseTypeBinding.isWidening(this.lhsType.id, expressionTb.id)))
  80                         || (BlockScope.areTypesCompatible(expressionTb, this.lhsType))) {
  81                         expression.implicitWidening(this.lhsType, expressionTb);
  82                         return this.lhsType;
  83                 }
  84                 scope.problemReporter().typeMismatchErrorActualTypeExpectedType(
  85                         expression,
  86                         expressionTb,
  87                         this.lhsType);
  88                 return null;
  89         }
  90
  91         public String toString(int tab) {
  92
  93                 //no () when used as a statement
  94                 return tabString(tab) + toStringExpressionNoParenthesis();
  95         }
  96
  97         public String toStringExpression() {
  98
  99                 //subclass redefine toStringExpressionNoParenthesis()
 100                 return "(" + toStringExpressionNoParenthesis() + ")"; //$NON-NLS-2$ //$NON-NLS-1$
 101         }
 102
 103         public String toStringExpressionNoParenthesis() {
 104
 105                 return lhs.toStringExpression() + " " //$NON-NLS-1$
 106                         + "=" //$NON-NLS-1$
 107                         + ((expression.constant != null) && (expression.constant != NotAConstant)
 108                                 ? " /*cst:" + expression.constant.toString() + "*/ " //$NON-NLS-1$ //$NON-NLS-2$
 109                                 : " ")  //$NON-NLS-1$
 110                         + expression.toStringExpression();
 111         }
 112         public void traverse(IAbstractSyntaxTreeVisitor visitor, BlockScope scope) {
 113
 114                 if (visitor.visit(this, scope)) {
 115                         lhs.traverse(visitor, scope);
 116                         expression.traverse(visitor, scope);
 117                 }
 118                 visitor.endVisit(this, scope);
 119         }
 120 }