IntLiteral.java

/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;

import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.codegen.CodeStream;
import org.eclipse.jdt.internal.compiler.impl.IntConstant;
import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.eclipse.jdt.internal.compiler.parser.ScannerHelper;

public class IntLiteral extends NumberLiteral {

	public int value;

	public static final IntLiteral One= new IntLiteral(new char[] { '1' }, 0, 0, 1);//used for ++ and --

	public IntLiteral(char[] token, int s, int e) {
		super(token, s, e);
	}

	public IntLiteral(char[] token, int s, int e, int value) {
		this(token, s, e);
		this.value= value;
	}

	public IntLiteral(int intValue) {
		//special optimized constructor : the cst is the argument
		//value that should not be used
		//	tokens = null ;
		//	sourceStart = 0;
		//	sourceEnd = 0;
		super(null, 0, 0);
		this.constant= IntConstant.fromValue(intValue);
		this.value= intValue;
	}

	public void computeConstant() {
		//a special constant is use for the potential Integer.MAX_VALUE+1
		//which is legal if used with a - as prefix....cool....
		//notice that Integer.MIN_VALUE  == -2147483648
		long MAX= Integer.MAX_VALUE;
		if (this == One) {
			this.constant= IntConstant.fromValue(1);
			return;
		}
		int length= this.source.length;
		long computedValue= 0L;
		if (this.source[0] == '0') {
			MAX= 0xFFFFFFFFL; //a long in order to be positive !
			if (length == 1) {
				this.constant= IntConstant.fromValue(0);
				return;
			}
			final int shift, radix;
			int j;
			if ((this.source[1] == 'x') || (this.source[1] == 'X')) {
				shift= 4;
				j= 2;
				radix= 16;
			} else {
				shift= 3;
				j= 1;
				radix= 8;
			}
			while (this.source[j] == '0') {
				j++; //jump over redondant zero
				if (j == length) {
					//watch for 000000000000000000
					this.constant= IntConstant.fromValue(this.value= (int)computedValue);
					return;
				}
			}
			while (j < length) {
				int digitValue;
				if ((digitValue= ScannerHelper.digit(this.source[j++], radix)) < 0) {
					return; /*constant stays null*/
				}
				computedValue= (computedValue << shift) | digitValue;
				if (computedValue > MAX)
					return; /*constant stays null*/
			}
		} else {
			//-----------regular case : radix = 10-----------
			for (int i= 0; i < length; i++) {
				int digitValue;
				if ((digitValue= ScannerHelper.digit(this.source[i], 10)) < 0) {
					return; /*constant stays null*/
				}
				computedValue= 10 * computedValue + digitValue;
				if (computedValue > MAX)
					return /*constant stays null*/;
			}
		}
		this.constant= IntConstant.fromValue(this.value= (int)computedValue);

	}

	/**
	 * Code generation for int literal
	 * 
	 * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
	 * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
	 * @param valueRequired boolean
	 */
	public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) {
		int pc= codeStream.position;
		if (valueRequired) {
			codeStream.generateConstant(this.constant, this.implicitConversion);
		}
		codeStream.recordPositionsFrom(pc, this.sourceStart);
	}

	public TypeBinding literalType(BlockScope scope) {
		return TypeBinding.INT;
	}

	public final boolean mayRepresentMIN_VALUE() {
		//a special autorized int literral is 2147483648
		//which is ONE over the limit. This special case
		//only is used in combinaison with - to denote
		//the minimal value of int -2147483648
		return ((this.source.length == 10) &&
				(this.source[0] == '2') &&
				(this.source[1] == '1') &&
				(this.source[2] == '4') &&
				(this.source[3] == '7') &&
				(this.source[4] == '4') &&
				(this.source[5] == '8') &&
				(this.source[6] == '3') &&
				(this.source[7] == '6') &&
				(this.source[8] == '4') &&
				(this.source[9] == '8') && (((this.bits & ASTNode.ParenthesizedMASK) >> ASTNode.ParenthesizedSHIFT) == 0));
	}

	public StringBuffer printExpression(int indent, StringBuffer output) {
		if (this.source == null) {
			/* special optimized IntLiteral that are created by the compiler */
			return output.append(String.valueOf(this.value));
		}
		return super.printExpression(indent, output);
	}

	public void traverse(ASTVisitor visitor, BlockScope scope) {
		visitor.visit(this, scope);
		visitor.endVisit(this, scope);
	}
}