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
020package org.crsh.lang.script;
021
022import org.crsh.command.SyntaxException;
023
024public 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}