Chris@2: /*
Chris@2: 	Copyright (C) 2001, 2006 by Simon Dixon
Chris@2: 
Chris@2: 	This program is free software; you can redistribute it and/or modify
Chris@2: 	it under the terms of the GNU General Public License as published by
Chris@2: 	the Free Software Foundation; either version 2 of the License, or
Chris@2: 	(at your option) any later version.
Chris@2: 
Chris@2: 	This program is distributed in the hope that it will be useful,
Chris@2: 	but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@2: 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@2: 	GNU General Public License for more details.
Chris@2: 
Chris@2: 	You should have received a copy of the GNU General Public License along
Chris@2: 	with this program (the file gpl.txt); if not, download it from
Chris@2: 	http://www.gnu.org/licenses/gpl.txt or write to the
Chris@2: 	Free Software Foundation, Inc.,
Chris@2: 	51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Chris@2: */
Chris@2: 
Chris@2: package at.ofai.music.util;
Chris@2: 
Chris@2: /**	A simple parser for Prolog-type notation, but only handling the subset of
Chris@2:  *	Prolog used in "match" files.
Chris@2:  */
Chris@2: public class Matcher {
Chris@2: 
Chris@2: 	/** The unparsed part of the current line of text */
Chris@2: 	protected String s;
Chris@2: 
Chris@2: 	/** The constructor is initialised with the input line of text for parsing*/
Chris@2: 	public Matcher(String data) { s = data; }
Chris@2: 
Chris@2: 	/** Reinitialise the parser with a new line of input */
Chris@2: 	public void set(String data) { s = data; }
Chris@2: 
Chris@2: 	/** Return the unparsed part of the input line */
Chris@2: 	public String get() { return s; }
Chris@2: 
Chris@2: 	/** Returns true if there is input data remaining */
Chris@2: 	public boolean hasData() {
Chris@2: 		return (s != null) && (s.length() > 0);
Chris@2: 	} // hasData()
Chris@2: 
Chris@2: 	/** Matches a String with the unparsed input data.
Chris@2: 	 *	If the complete String occurs at the beginning of the unparsed data,
Chris@2: 	 *	the unparsed data is advanced to the end of the String; otherwise
Chris@2: 	 *	the data is left unchanged.
Chris@2: 	 *
Chris@2: 	 *	@param m	the String to match
Chris@2: 	 *	@return		true if m matches the beginning of the unparsed data
Chris@2: 	 */
Chris@2: 	public boolean matchString(String m) {
Chris@2: 		if (s.startsWith(m)) {
Chris@2: 			s = s.substring(m.length());
Chris@2: 			return true;
Chris@2: 		}
Chris@2: 		return false;
Chris@2: 	} // matchString()
Chris@2: 
Chris@2: 	/**	Skips input up to and including the next instance of a given character.
Chris@2: 	 *	It is an error for the character not to occur in the data.
Chris@2: 	 *	@param c	the character to skip to
Chris@2: 	 */
Chris@2: 	public void skip(char c) {
Chris@2: 		int index = s.indexOf(c);
Chris@2: 		if (index >= 0)
Chris@2: 			s = s.substring(index + 1);
Chris@2: 		else
Chris@2: 			throw new RuntimeException("Parse error in skip(), expecting " + c);
Chris@2: 	} // skip()
Chris@2: 
Chris@2: 	/**	Removes whitespace from the beginning and end of the line.
Chris@2: 	 */
Chris@2: 	public void trimSpace() {
Chris@2: 		s = s.trim();
Chris@2: 	} // trimSpace()
Chris@2: 
Chris@2: 	/**	Returns and consumes the next character of unparsed data. */
Chris@2: 	public char getChar() {
Chris@2: 		char c = s.charAt(0);
Chris@2: 		s = s.substring(1);
Chris@2: 		return c;
Chris@2: 	} // getChar()
Chris@2: 
Chris@2: 	/** Returns and consumes an int value from the head of the unparsed data. */
Chris@2: 	public int getInt() {
Chris@2: 		int sz = 0;
Chris@2: 		trimSpace();
Chris@2: 		while ((sz < s.length()) && (Character.isDigit(s.charAt(sz)) ||
Chris@2: 					((sz==0) && (s.charAt(sz) == '-'))))
Chris@2: 			sz++;
Chris@2: 		int val = Integer.parseInt(s.substring(0, sz));
Chris@2: 		s = s.substring(sz);
Chris@2: 		return val;
Chris@2: 	} // getInt()
Chris@2: 
Chris@2: 	/**	Returns and consumes a double value, with two limitations:
Chris@2: 	 *	1) exponents are ignored  e.g. 5.4e-3 is read as 5.4;
Chris@2: 	 *	2) a value terminated by a 2nd "." causes an Exception to be thrown
Chris@2: 	 */
Chris@2: 	public double getDouble() {
Chris@2: 		int sz = 0;
Chris@2: 		trimSpace();
Chris@2: 		while ((sz < s.length()) && (Character.isDigit(s.charAt(sz)) ||
Chris@2: 					((sz==0)&&(s.charAt(sz) == '-')) || (s.charAt(sz) == '.')))
Chris@2: 			sz++;
Chris@2: 		double val = Double.parseDouble(s.substring(0, sz));
Chris@2: 		s = s.substring(sz);
Chris@2: 		return val;
Chris@2: 	} // getDouble()
Chris@2: 
Chris@2: 	/** Returns and consumes a string terminated by the first comma,
Chris@2: 	 *	parenthesis, bracket or brace. Equivalent to getString(false).
Chris@2: 	 */
Chris@2: 	public String getString() {
Chris@2: 		return getString(false);
Chris@2: 	} // getString()
Chris@2: 
Chris@2: 	/**
Chris@2: 	 *	Returns and consumes a string terminated by various punctuation symbols.
Chris@2: 	 *	Terminators include: '(', '[', '{', ',', '}', ']' and ')'.
Chris@2: 	 *	An Exception is thrown if no terminator is found.
Chris@2: 	 *
Chris@2: 	 *	@param extraPunctuation Specifies whether '-' and '.' are terminators
Chris@2: 	 */
Chris@2: 	public String getString(boolean extraPunctuation) {
Chris@2: 		char[] stoppers = {'(','[','{',',','}',']',')','-','.'};
Chris@2: 		int index1 = s.indexOf(stoppers[0]);
Chris@2: 		for (int i = 1; i < stoppers.length - (extraPunctuation? 0:2); i++) {
Chris@2: 			int index2 = s.indexOf(stoppers[i]);
Chris@2: 			if (index1 >= 0) {
Chris@2: 				if ((index2 >= 0) && (index1 > index2))
Chris@2: 					index1 = index2;
Chris@2: 			} else
Chris@2: 				index1 = index2;
Chris@2: 		}
Chris@2: 		if (index1 < 0)
Chris@2: 			throw new RuntimeException("getString(): no terminator: " + s);
Chris@2: 		String val = s.substring(0, index1);
Chris@2: 		s = s.substring(index1);
Chris@2: 		return val;
Chris@2: 	} // getString()
Chris@2: 
Chris@2: 	/** Returns and consumes a comma-separated list of terms, surrounded by a
Chris@2: 	 *	matching set of parentheses, brackets or braces.
Chris@2: 	 *	The list may have any number of levels of recursion.
Chris@2: 	 *	@return	The return value is a linked list of the terms
Chris@2: 	 *			(which themselves may be lists or String values)
Chris@2: 	 */
Chris@2: 	public ListTerm getList() {
Chris@2: 		if ("([{".indexOf(s.charAt(0)) >= 0)
Chris@2: 			return new ListTerm(getChar());
Chris@2: 		return null;
Chris@2: 	} // getList()
Chris@2: 
Chris@2: 	/**	Returns and consumes a Prolog-style predicate, consisting of a functor
Chris@2: 	 *	followed by an optional list of arguments in parentheses.
Chris@2: 	 */
Chris@2: 	public Predicate getPredicate() {
Chris@2: 		return new Predicate();
Chris@2: 	} // getPredicate()
Chris@2: 
Chris@2: 	class Predicate {
Chris@2: 
Chris@2: 		String head;
Chris@2: 		ListTerm args;
Chris@2: 
Chris@2: 		protected Predicate() {
Chris@2: 			head = getString(true);
Chris@2: 			args = getList();
Chris@2: 		}
Chris@2: 		
Chris@2: 		public Object arg(int index) {
Chris@2: 			ListTerm t = args;
Chris@2: 			for (int i = 0; i < index; i++)
Chris@2: 				t = t.next;
Chris@2: 			return t.term;
Chris@2: 		} // arg
Chris@2: 
Chris@2: 		public String toString() {
Chris@2: 			return (args == null)? head: head + args;
Chris@2: 		}
Chris@2: 
Chris@2: 	} // inner class Predicate
Chris@2: 
Chris@2: 	class ListTerm {
Chris@2: 
Chris@2: 		Object term;
Chris@2: 		ListTerm next;
Chris@2: 		char opener, closer;
Chris@2: 
Chris@2: 		protected ListTerm(char c) {
Chris@2: 			opener = c;
Chris@2: 			term = null;
Chris@2: 			next = null;
Chris@2: 			if (hasData()) {
Chris@2: 				switch(s.charAt(0)) {
Chris@2: 					case '(':
Chris@2: 					case '[':
Chris@2: 					case '{':
Chris@2: 						term = new ListTerm(getChar());
Chris@2: 						break;
Chris@2: 					default:
Chris@2: 						term = getString();
Chris@2: 						break;
Chris@2: 				}
Chris@2: 			}
Chris@2: 			if (hasData()) {
Chris@2: 				closer = getChar();
Chris@2: 				switch(closer) {
Chris@2: 					case ')':
Chris@2: 						if (opener == '(')
Chris@2: 							return;
Chris@2: 						break;
Chris@2: 					case ']':
Chris@2: 						if (opener == '[')
Chris@2: 							return;
Chris@2: 						break;
Chris@2: 					case '}':
Chris@2: 						if (opener == '{')
Chris@2: 							return;
Chris@2: 						break;
Chris@2: 					case ',':
Chris@2: 						next = new ListTerm(opener);
Chris@2: 						return;
Chris@2: 				}
Chris@2: 			}
Chris@2: 			throw new RuntimeException("Parse error in ListTerm(): " + s);
Chris@2: 		} // constructor
Chris@2: 
Chris@2: 		public String toString() {
Chris@2: 			String s = "" + opener;
Chris@2: 			for (ListTerm ptr = this; ptr != null; ptr = ptr.next)
Chris@2: 				s += ptr.term.toString() + ptr.closer;
Chris@2: 			return s;
Chris@2: 		} // toString()
Chris@2: 
Chris@2: 	} // inner class ListTerm
Chris@2: 
Chris@2: } // class Matcher
Chris@2: