src/org/eclipse/jdt/internal/compiler/ast/NullLiteral.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.FlowInfo;
  16 import org.eclipse.jdt.internal.compiler.lookup.*;
  17
  18 public class NullLiteral extends MagicLiteral {
  19
  20         static final char[] source = {'n' , 'u' , 'l' , 'l'};
  21
  22         public NullLiteral(int s , int e) {
  23
  24                 super(s,e);
  25         }
  26
  27         public void computeConstant() {
  28
  29                 constant = NotAConstant;
  30         }
  31
  32         /**
  33          * Code generation for the null literal
  34          *
  35          * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
  36          * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
  37          * @param valueRequired boolean
  38          */
  39         public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) {
  40                 int pc = codeStream.position;
  41                 if (valueRequired) {
  42                         codeStream.aconst_null();
  43                         codeStream.generateImplicitConversion(this.implicitConversion);
  44                 }
  45                 codeStream.recordPositionsFrom(pc, this.sourceStart);
  46         }
  47         public TypeBinding literalType(BlockScope scope) {
  48                 return NullBinding;
  49         }
  50
  51         public int nullStatus(FlowInfo flowInfo) {
  52                 return FlowInfo.NULL;
  53         }
  54
  55         /**
  56          *
  57          */
  58         public char[] source() {
  59                 return source;
  60         }
  61
  62         public void traverse(ASTVisitor visitor, BlockScope scope) {
  63                 visitor.visit(this, scope);
  64                 visitor.endVisit(this, scope);
  65         }
  66 }