x-tools / xtools

( function ( $ ) {

	'use strict';

	var MessageParser = function ( options ) {

		this.options = $.extend( {}, $.i18n.parser.defaults, options );

		this.language = $.i18n.languages[ String.locale ] || $.i18n.languages[ 'default' ];

		this.emitter = $.i18n.parser.emitter;

	};

	MessageParser.prototype = {

		constructor: MessageParser,

		simpleParse: function ( message, parameters ) {

			return message.replace( /\$(\d+)/g, function ( str, match ) {

				var index = parseInt( match, 10 ) - 1;

				return parameters[ index ] !== undefined ? parameters[ index ] : '$' + match;

			} );

		},

		parse: function ( message, replacements ) {

			if ( message.indexOf( '{{' ) < 0 ) {

				return this.simpleParse( message, replacements );

			}

			this.emitter.language = $.i18n.languages[ $.i18n().locale ] ||

				$.i18n.languages[ 'default' ];

			return this.emitter.emit( this.ast( message ), replacements );

		},

		ast: function ( message ) {

			var pipe, colon, backslash, anyCharacter, dollar, digits, regularLiteral,

				regularLiteralWithoutBar, regularLiteralWithoutSpace, escapedOrLiteralWithoutBar,

				escapedOrRegularLiteral, templateContents, templateName, openTemplate,

				closeTemplate, expression, paramExpression, result,

				pos = 0;

			// Try parsers until one works, if none work return null

			function choice( parserSyntax ) {

				return function () {

					var i, result;

					for ( i = 0; i < parserSyntax.length; i++ ) {

						result = parserSyntax[ i ]();

						if ( result !== null ) {

							return result;

						}

					}

					return null;

				};

			}

			// Try several parserSyntax-es in a row.

			// All must succeed; otherwise, return null.

			// This is the only eager one.

			function sequence( parserSyntax ) {

				var i, res,

					originalPos = pos,

					result = [];

				for ( i = 0; i < parserSyntax.length; i++ ) {

					res = parserSyntax[ i ]();

					if ( res === null ) {

						pos = originalPos;

						return null;

					}

					result.push( res );

				}

				return result;

			}

			// Run the same parser over and over until it fails.

			// Must succeed a minimum of n times; otherwise, return null.

			function nOrMore( n, p ) {

				return function () {

					var originalPos = pos,

						result = [],

						parsed = p();

					while ( parsed !== null ) {

						result.push( parsed );

						parsed = p();

					}

					if ( result.length < n ) {

						pos = originalPos;

						return null;

					}

					return result;

				};

			}

			// Helpers -- just make parserSyntax out of simpler JS builtin types

			function makeStringParser( s ) {

				var len = s.length;

				return function () {

					var result = null;

					if ( message.slice( pos, pos + len ) === s ) {

						result = s;

						pos += len;

					}

					return result;

				};

			}

			function makeRegexParser( regex ) {

				return function () {

					var matches = message.slice( pos ).match( regex );

					if ( matches === null ) {

						return null;

					}

					pos += matches[ 0 ].length;

					return matches[ 0 ];

				};

			}

			pipe = makeStringParser( '|' );

			colon = makeStringParser( ':' );

			backslash = makeStringParser( '\\' );

			anyCharacter = makeRegexParser( /^./ );

			dollar = makeStringParser( '$' );

			digits = makeRegexParser( /^\d+/ );

			regularLiteral = makeRegexParser( /^[^{}\[\]$\\]/ );

			regularLiteralWithoutBar = makeRegexParser( /^[^{}\[\]$\\|]/ );

			regularLiteralWithoutSpace = makeRegexParser( /^[^{}\[\]$\s]/ );

			// There is a general pattern:

			// parse a thing;

			// if it worked, apply transform,

			// otherwise return null.

			// But using this as a combinator seems to cause problems

			// when combined with nOrMore().

			// May be some scoping issue.

			function transform( p, fn ) {

				return function () {

					var result = p();

					return result === null ? null : fn( result );

				};

			}

			// Used to define "literals" within template parameters. The pipe

			// character is the parameter delimeter, so by default

			// it is not a literal in the parameter

			function literalWithoutBar() {

				var result = nOrMore( 1, escapedOrLiteralWithoutBar )();

				return result === null ? null : result.join( '' );

			}

			function literal() {

				var result = nOrMore( 1, escapedOrRegularLiteral )();

				return result === null ? null : result.join( '' );

			}

			function escapedLiteral() {

				var result = sequence( [ backslash, anyCharacter ] );

				return result === null ? null : result[ 1 ];

			}

			choice( [ escapedLiteral, regularLiteralWithoutSpace ] );

			escapedOrLiteralWithoutBar = choice( [ escapedLiteral, regularLiteralWithoutBar ] );

			escapedOrRegularLiteral = choice( [ escapedLiteral, regularLiteral ] );

			function replacement() {

				var result = sequence( [ dollar, digits ] );

				if ( result === null ) {

					return null;

				}

				return [ 'REPLACE', parseInt( result[ 1 ], 10 ) - 1 ];

			}

			templateName = transform(

				// see $wgLegalTitleChars

				// not allowing : due to the need to catch "PLURAL:$1"

				makeRegexParser( /^[ !"$&'()*,.\/0-9;=?@A-Z\^_`a-z~\x80-\xFF+\-]+/ ),

				function ( result ) {

					return result.toString();

				}

			);

			function templateParam() {

				var expr,

					result = sequence( [ pipe, nOrMore( 0, paramExpression ) ] );

				if ( result === null ) {

					return null;

				}

				expr = result[ 1 ];

				// use a "CONCAT" operator if there are multiple nodes,

				// otherwise return the first node, raw.

				return expr.length > 1 ? [ 'CONCAT' ].concat( expr ) : expr[ 0 ];

			}

			function templateWithReplacement() {

				var result = sequence( [ templateName, colon, replacement ] );

				return result === null ? null : [ result[ 0 ], result[ 2 ] ];

			}

			function templateWithOutReplacement() {

				var result = sequence( [ templateName, colon, paramExpression ] );

				return result === null ? null : [ result[ 0 ], result[ 2 ] ];

			}

			templateContents = choice( [

				function () {

					var res = sequence( [

						// templates can have placeholders for dynamic

						// replacement eg: {{PLURAL:$1|one car|$1 cars}}

						// or no placeholders eg:

						// {{GRAMMAR:genitive|{{SITENAME}}}

						choice( [ templateWithReplacement, templateWithOutReplacement ] ),

						nOrMore( 0, templateParam )

					] );

					return res === null ? null : res[ 0 ].concat( res[ 1 ] );

				},

				function () {

					var res = sequence( [ templateName, nOrMore( 0, templateParam ) ] );

					if ( res === null ) {

						return null;

					}

					return [ res[ 0 ] ].concat( res[ 1 ] );

				}

			] );

			openTemplate = makeStringParser( '{{' );

			closeTemplate = makeStringParser( '}}' );

			function template() {

				var result = sequence( [ openTemplate, templateContents, closeTemplate ] );

				return result === null ? null : result[ 1 ];

			}

			expression = choice( [ template, replacement, literal ] );

			paramExpression = choice( [ template, replacement, literalWithoutBar ] );

			function start() {

				var result = nOrMore( 0, expression )();

				if ( result === null ) {

					return null;

				}

				return [ 'CONCAT' ].concat( result );

			}

			result = start();

			/*

			 * For success, the pos must have gotten to the end of the input

			 * and returned a non-null.

			 * n.b. This is part of language infrastructure, so we do not throw an internationalizable message.

			 */

			if ( result === null || pos !== message.length ) {

				throw new Error( 'Parse error at position ' + pos.toString() + ' in input: ' + message );

			}

			return result;

		}

	};

	$.extend( $.i18n.parser, new MessageParser() );

}( jQuery ) );