/*
* $RCSfile: AbstractParser.java,v $
*
* Portions Copyright 2000-2009 Sun Microsystems, Inc. All Rights
* Reserved. Use is subject to license terms.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
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/*****************************************************************************
* Copyright (C) The Apache Software Foundation. All rights reserved. *
* ------------------------------------------------------------------------- *
* This software is published under the terms of the Apache Software License *
* version 1.1, a copy of which has been included with this distribution in *
* the LICENSE file. *
*****************************************************************************/
package com.sun.perseus.parser;
/**
* <code>AbstractParser</code> is the base class for parsers found
* in this package. <br />
* All parsers work on a <code>String</code> and the <code>AbstractParser</code>
* keeps a reference to that string along with the current position
* (@see #currentPos) and current character (@see current). <br />
* The key methods for this class are <code>read</code> which reads the next
* character in the parsed string, <code>setString</code> which sets the string
* to be parsed, and the utility methods <code>skipCommaSpaces</code>,
* <code>skipSpaces</code> and <code>skipSpacesCommaSpaces</code> which can
* be used by descendants to skip common separators.
* <br />
* For an implementation example, see {@link TransformListParser}.
*
* @version $Id: AbstractParser.java,v 1.2 2006/04/21 06:40:21 st125089 Exp $
*/
public abstract class AbstractParser {
/**
* The current position in the string
*/
protected int currentPos;
/**
* The String being parsed
*/
protected String s;
protected int length;
/**
* The current character being parsed
* This is accessible by sub-classes
*/
protected int current;
/**
* @return the next character. Returns -1 when the
* end of the String has been reached.
*/
protected final int read() {
return (currentPos < length)? s.charAt(currentPos++): -1;
}
/**
* Sets this parser's String. This also resets the
* current position to 0
*
* @param str the string this parser should parse. Should
* not be null.
*/
protected final void setString(final String str) {
if (str == null) {
throw new IllegalArgumentException();
}
this.s = str;
this.length = str.length();
this.currentPos = 0;
this.current = -1;
}
/**
* Skips the whitespaces in the current reader.
*/
protected final void skipSpaces() {
for (;;) {
switch (current) {
default:
return;
case 0x20:
case 0x09:
case 0x0D:
case 0x0A:
}
current = (currentPos < length)? s.charAt(currentPos++): -1;
}
}
/**
* Skips the whitespaces and an optional comma.
*/
protected final void skipCommaSpaces() {
skipSepSpaces(',');
}
/**
* Skips the whitespaces and an optional comma.
*
* @param sep seperator to skip in addition to spaces.
*/
protected final void skipSepSpaces(final char sep) {
wsp1: for (;;) {
switch (current) {
default:
break wsp1;
case 0x20:
case 0x9:
case 0xD:
case 0xA:
}
current = (currentPos < length)? s.charAt(currentPos++): -1;
}
if (current == sep) {
wsp2: for (;;) {
current = (currentPos < length)? s.charAt(currentPos++): -1;
switch (current) {
default:
break wsp2;
case 0x20:
case 0x9:
case 0xD:
case 0xA:
}
}
}
}
/**
* Skips wsp*,wsp* and throws an IllegalArgumentException
* if no comma is found.
*/
protected final void skipSpacesCommaSpaces() {
skipSpaces();
if (current != ',') {
throw new IllegalArgumentException();
}
current = (currentPos < length)? s.charAt(currentPos++): -1;
skipSpaces();
}
/**
* Tests if the current substring (i.e. the substring beginning at the
* current position) starts with the specified prefix. If the current
* substring starts with the specified prefix, the current character will
* be updated to point to the character immediately following the last
* character in the prefix; otherwise, the <code>currentPos</code> will
* not be affected. For example, if the string being parsed is
* "timingAttr", and the current character is 'A':
* <pre>
* currentStartsWith("Att") returns true, current == 'r'
* currentStartsWith("Attr") returns true, current == -1
* currentStartsWith("Attx") returns false, current == 'A'
* </pre>
*
* @param str the prefix to be tested
* @return <code>true</code> if the current substring starts with the
* specified prefix. The result is <code>false</code> if
* <code>currentPos</code> is non-positive, or if the current substring
* does not start with the specified prefix.
*/
protected final boolean currentStartsWith(final String str) {
if (currentPos <= 0) {
return false;
}
if (s.startsWith(str, currentPos - 1)) {
currentPos += str.length() - 1;
current = (currentPos < length)? s.charAt(currentPos++): -1;
return true;
}
return false;
}
}