001 /*
002 * Copyright (C) 2012 eXo Platform SAS.
003 *
004 * This is free software; you can redistribute it and/or modify it
005 * under the terms of the GNU Lesser General Public License as
006 * published by the Free Software Foundation; either version 2.1 of
007 * the License, or (at your option) any later version.
008 *
009 * This software is distributed in the hope that it will be useful,
010 * but WITHOUT ANY WARRANTY; without even the implied warranty of
011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 * Lesser General Public License for more details.
013 *
014 * You should have received a copy of the GNU Lesser General Public
015 * License along with this software; if not, write to the Free
016 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
017 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
018 */
019
020 package org.crsh.shell.impl.command;
021
022 import org.crsh.command.SyntaxException;
023
024 public class PipeLineParser {
025
026 /** . */
027 private Tokenizer tokenizer;
028
029 /** . */
030 private Token token;
031
032 public PipeLineParser(CharSequence s) {
033 this.tokenizer = new Tokenizer(s);
034 this.token = tokenizer.nextToken();
035 }
036
037 public PipeLineFactory parse() {
038 if (token == Token.EOF) {
039 return null;
040 } else {
041 return parseExpr();
042 }
043 }
044
045 private PipeLineFactory parseExpr() {
046 if (token instanceof Token.Command) {
047 Token.Command command = (Token.Command)token;
048 token = tokenizer.nextToken();
049 PipeLineFactory next;
050 if (token == Token.EOF) {
051 next = null;
052 } else if (token == Token.PIPE) {
053 token = tokenizer.nextToken();
054 next = parseExpr();
055 } else {
056 throw new SyntaxException("Syntax error");
057 }
058 return new PipeLineFactory(command.line, next);
059 } else {
060 throw new SyntaxException("Syntax error");
061 }
062 }
063 }