/*
 * $Id$
 *
 * Copyright (c) 1996, 2009, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.sun.javatest.finder;

import java.io.IOException;

/**
  * This class extracts all ASCII characters within two of Java's
  * comments:  traditional comments (bound by "/*" and "*\/") and
  * documentation comments (bound by "/**" and "*\/").  The comment
  * may span multiple lines.  All leading "*" characters and any
  * preceding blanks or tabs are ignored.
  *
  * @see CommentStream
  */
public class JavaCommentStream extends CommentStream
{
    public String readComment() throws IOException {
	int c;
	StringBuffer comment = new StringBuffer(0);

    commentStart:
	// start of comment is "/*".
	while (true) {
	    switch (c = cs.read()) {
	    case -1:
		return null;
	    case '/':
		switch (cs.read()) {
		case -1:
		    return null;
		case '*':
		    break commentStart;
		case '/':
 		    skipLine();
		    break;
		default:
		    break;
		}
		break;
	    case '\'':
	    case '"':
		skipString(c);
		break;
	    default:
		if ((!Character.isWhitespace((char) c)) && fastScan)
		    return null;
		break;
	    }
	}

	startLine = true;

	// end of comment is "*/".
	// take care to handle repeated stars before end of comment
	boolean starPending = false;
    commentEnd:
	while (true) {
	    switch (c = cs.read()) {
	    case -1:
		return null;
	    case '*':
		if (starPending) 
		    putc(comment, c); // flush pending *, leave * pending
		else
		    starPending = true;
		break;
	    case '/':
		if (starPending)
		    break commentEnd;  // finally got "*/"
		putc(comment, c);
		break;
	    default:
		if (starPending) {
		    putc(comment, '*');
		    starPending = false;
		}
		putc(comment, c);
		break;
	    }
	}
	return comment.toString();
    } // readComment()

    //-----internal routines----------------------------------------------------

    private void putc(StringBuffer s, int c) {
	switch (c) {
	    //case '\b':
	    //case '\f':
	    //break;
	case '\n':
	case '\r':
	    //XXX dump the newline info?
	    s.append((char) c);
	    startLine = true;
	    break;
	case ' ':
	case '\t':
	case '*':
	    if (!startLine)
		s.append((char) c);
	    break;
	default:
	    startLine = false;
	    s.append((char) c);
	    break;
	}
    } // putc()

    private void skipLine() throws IOException {
	while (true) {
	    int c = cs.read();
	    if (c == -1 || c == '\r' || c == '\n')
		return;
	}
    }

    private void skipString(int term) throws IOException {
	while (true) {
	    int c = cs.read();
	    if (c == -1 || c == term)
		return;
	    else if (c == '\\') {
		// since we are only interested in finding the end of the
		// string, we don't need to parse the escape: it is sufficient
		// to just skip the next character, in case the escape is
		// \\ or \' or \"
		c = cs.read();
	    }
	}
    }

    //----------member variables------------------------------------------------

    private boolean startLine;
}
