// $Id: RTSParser.js,v 1.6 2005/12/05 23:09:25 vnagarjuna Exp $ -->

// Copyright 2005 Nagarjuna Venna <vnagarjuna@yahoo.com>
// See http://lekhini.org/scripts/padma-license.txt

// See http://lekhini.org/license.txt

//Parser for RTS Text - returns syllables

function RTSParser(input) {
	this.index = 0;
	this.length = input.length;
	this.text = input;
}

function RTSParser_updateSymbolType(type) {
	if (this.state != Parser.state_CONSNT)
		return type;
	switch (type) {
		case Padma.type_accu:
			return Padma.type_gunintam;

		case Padma.type_hallu:
			return Padma.type_vattu;

		default:
			return type;
	}
}

function RTSParser_getNextMatch(length, index) {
	var result = { key: null, value: null }, key, value;
	var remaining = length - index, maxLookupLen = remaining > RTS.maxLookupLen ? RTS.maxLookupLen : remaining;
		
	for(var i = maxLookupLen; i > 0; i--) {
		key = this.text.substring(index, index + i);
		value = RTS.lookup(key);
		if (value == null)
			continue;
		//found a match
		if (value == Padma.syllbreak || RTS.isPossibleAnusvara(key)) {
			//if there is more text then if syllable break, see if it should be converted to pollu
			//or if is a possible anusvara see if it is one of the consonants that makes the n/m an anusvara
			if (length - index - i > 0) {
				var next = this.getNextMatch(length, index + i);
				if (value == Padma.syllbreak) {
					if (next.value == null || Padma.getType(next.value) != Padma.type_hallu)
						value = Padma.pollu;
				}
				else if (next.value != null && RTS.isAnusvara(value, next.value)) {
					result.key = key;
					result.value = Padma.anusvara;
					return result;
				}
			}
			else if (value == Padma.syllbreak)
				value = Padma.pollu;
		}
		break;
	}
	result.key = key;
	result.value = value;
	return result;
}

function RTSParser_next() {
	var response = new Syllable(), done = false;

	var remaining = this.length - this.index;
	for(; remaining > 0; remaining = this.length - this.index) {
		if (this.cache.key == null) {
			var result = this.getNextMatch(this.length, this.index);
			this.handleInput(result.value, result.key, response);
		}
		else {
			var key = this.cache.key, value = this.cache.value;
			this.cache.key = this.cache.value = null;
			this.handleInput(value, key, response);
		}

		if (this.state == Parser.state_START)
			return response.getSyllable();
	}

	if (response.length != 0) {
		this.handleConsonantTermination(response);
		return response.getSyllable();
	}
	return null;
}

function RTSParser_handleConsonantTermination(current) {
	if (current.body == Padma.consnt_MA) {
		current.body = Padma.anusvara;
	}
	else current.body += Padma.pollu;
}

//This doesn't seem to work in extension mode, add any mods to relationships.js too
RTSParser.prototype = new Parser("");
RTSParser.prototype.next = RTSParser_next;
RTSParser.prototype.updateSymbolType = RTSParser_updateSymbolType;
RTSParser.prototype.handleConsonantTermination = RTSParser_handleConsonantTermination;
RTSParser.prototype.getNextMatch = RTSParser_getNextMatch;