AuthorEmailRule.java

/*******************************************************************************
 * Copyright (c) 2007, 2009 Red Hat, Inc.
 * 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:
 *    Red Hat - initial API and implementation
 *******************************************************************************/

package org.eclipse.linuxtools.internal.rpm.ui.editor.rules;

import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.jface.text.rules.IPredicateRule;
import org.eclipse.jface.text.rules.IToken;
import org.eclipse.jface.text.rules.Token;

public class AuthorEmailRule implements IPredicateRule {

    /** Buffer used for pattern detection */
    private StringBuilder fBuffer = new StringBuilder();

    /** The success token */
    private IToken token;

    protected static final char START_CHAR = '<';

    protected static final char END_CHAR = '>';

    protected static final char[] INTER_CHARS = { '@', '.' };

    protected static final int STATE_START = 0;

    protected static final int STATE_OPENED = 1;

    protected static final int STATE_AT = 2;

    protected static final int STATE_PERIOD = 3;

    protected static final int STATE_DONE = 4;

    public AuthorEmailRule(IToken token) {
        this.token = token;
    }

    @Override
    public IToken getSuccessToken() {
        return token;
    }

    @Override
    public IToken evaluate(ICharacterScanner scanner, boolean resume) {
        /*
         * whether we think we're reading the ending sequence, i.e. the next
         * section heading
         */
        int state = STATE_START;
        fBuffer.setLength(0);
        int c;

        do {
            c = scanner.read();
            fBuffer.append((char) c);

            // we have reached the end of file or line prematurely, this is not
            // considered success
            if (c == ICharacterScanner.EOF || (char) c == '\n') {
                unreadBuffer(scanner, fBuffer);
                return Token.UNDEFINED;
            }

            // we encountered the opening character at the beginning
            if (state == STATE_START && (char) c == START_CHAR) {
                state++;
            } else if (state == STATE_OPENED) {
                // we encountered the first neccessary intermediary char
                if ((char) c == INTER_CHARS[0]) {
                    state++;
                }

                // check if we have a valid char
                if (! (Character.isLetterOrDigit((char) c) || c == '.' || c == '_' || c == '-' || c == '@')){
                    unreadBuffer(scanner, fBuffer);
                    return Token.UNDEFINED;
                }

                // we just keep reading

            } else if (state == STATE_AT) {
                // we encountered the second neccessary intermediary char
                if ((char) c == INTER_CHARS[1]) {
                    state++;
                }

                // check if we have a valid char
                if (! (Character.isLetterOrDigit((char) c) || c == '.' || c == '_' || c == '-')){
                    unreadBuffer(scanner, fBuffer);
                    return Token.UNDEFINED;
                }
                // we just keep reading
            } else if (state == STATE_PERIOD) {
                // the last char before the ending char cannot be a '.'
                if ((char) c == END_CHAR && fBuffer.charAt(fBuffer.length() - 1) != '.') {
                    state++;
                } else if ((char) c == END_CHAR){
                    unreadBuffer(scanner, fBuffer);
                    return Token.UNDEFINED;
                }
            } else {
                unreadBuffer(scanner, fBuffer);
                return Token.UNDEFINED;
            }

        } while (state != STATE_DONE);

        // we've gone through all states until we've reached STATE_DONE, success
        return token;
    }

    @Override
    public IToken evaluate(ICharacterScanner scanner) {
        return evaluate(scanner, false);
    }

    /**
     * Returns the characters in the buffer to the scanner.
     *
     * @param scanner
     *            the scanner to be used
     */
    protected void unreadBuffer(ICharacterScanner scanner, StringBuilder buffer) {
        for (int i = buffer.length() - 1; i >= 0; i--) {
            scanner.unread();
        }
    }

}