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    }