keywords.java

是一款用JAVA 编写的编译器 具有很强的编译功能

/*
 * Copyright 2002-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.tools.javac.parser;

import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.Log;
import com.sun.tools.javac.util.Name;

import static com.sun.tools.javac.parser.Token.*;

/**
 * Map from Name to Token and Token to String.
 * 
 * <p><b>This is NOT part of any API supported by Sun Microsystems.
 * If you write code that depends on this, you do so at your own risk.
 * This code and its internal interfaces are subject to change or
 * deletion without notice.</b>
 */
public class Keywords {
    public static final Context.Key<Keywords> keywordsKey =
	new Context.Key<Keywords>();

    public static Keywords instance(Context context) {
	Keywords instance = context.get(keywordsKey);
	if (instance == null)
	    instance = new Keywords(context);
	return instance;
    }

    private final Log log;
    private final Name.Table names;

    protected Keywords(Context context) {
	context.put(keywordsKey, this);
	log = Log.instance(context);
	names = Name.Table.instance(context);

	for (Token t : Token.values()) {
	    if (t.name != null)
		enterKeyword(t.name, t);
	    else
		tokenName[t.ordinal()] = null;
	}

	key = new Token[maxKey+1];
	for (int i = 0; i <= maxKey; i++) key[i] = IDENTIFIER;
	for (Token t : Token.values()) {
	    if (t.name != null)
		key[tokenName[t.ordinal()].index] = t;
	}
    }


    public Token key(Name name) {
	return (name.index > maxKey) ? IDENTIFIER : key[name.index];
    }

    /**
     * Keyword array. Maps name indices to Token.
     */
    private final Token[] key;

    /**	 The number of the last entered keyword.
     */
    private int maxKey = 0;

    /** The names of all tokens.
     */
    private Name[] tokenName = new Name[Token.values().length];

    public String token2string(Token token) {
	switch (token) {
	case IDENTIFIER:
	    return log.getLocalizedString("token.identifier");
	case CHARLITERAL:
	    return log.getLocalizedString("token.character");
	case STRINGLITERAL:
	    return log.getLocalizedString("token.string");
	case INTLITERAL:
	    return log.getLocalizedString("token.integer");
	case LONGLITERAL:
	    return log.getLocalizedString("token.long-integer");
	case FLOATLITERAL:
	    return log.getLocalizedString("token.float");
	case DOUBLELITERAL:
	    return log.getLocalizedString("token.double");
	case ERROR:
	    return log.getLocalizedString("token.bad-symbol");
	case EOF:
	    return log.getLocalizedString("token.end-of-input");
	case DOT: case COMMA: case SEMI: case LPAREN: case RPAREN:
	case LBRACKET: case RBRACKET: case LBRACE: case RBRACE:
	    return "'" + token.name + "'";
	default:
	    return token.name;
	}
    }

    private void enterKeyword(String s, Token token) {
	Name n = names.fromString(s);
	tokenName[token.ordinal()] = n;
	if (n.index > maxKey) maxKey = n.index;
    }
}