109 lines
2.6 KiB
JavaScript
109 lines
2.6 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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function ignoreFunction() {}
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function createReturningFunction(value) {
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return function() {
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return value;
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};
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}
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function Parser(states) {
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this.states = this.compileStates(states);
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}
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Parser.prototype.compileStates = function(states) {
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var result = {};
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Object.keys(states).forEach(function(name) {
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result[name] = this.compileState(states[name], states);
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}, this);
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return result;
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};
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Parser.prototype.compileState = function(state, states) {
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var regExps = [];
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function iterator(str, value) {
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regExps.push({
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groups: Parser.getGroupCount(str),
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regExp: str,
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value: value
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});
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}
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function processState(statePart) {
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if(Array.isArray(statePart)) {
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statePart.forEach(processState);
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} else if(typeof statePart === "object") {
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Object.keys(statePart).forEach(function(key) {
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iterator(key, statePart[key]);
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});
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} else if(typeof statePart === "string") {
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processState(states[statePart]);
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} else {
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throw new Error("Unexpected 'state' format");
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}
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}
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processState(state);
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var total = regExps.map(function(r) {
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return "(" + r.regExp + ")";
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}).join("|");
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var actions = [];
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var pos = 1;
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regExps.forEach(function(r) {
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var fn;
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if(typeof r.value === "function") {
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fn = r.value;
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} else if(typeof r.value === "string") {
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fn = createReturningFunction(r.value);
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} else {
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fn = ignoreFunction;
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}
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actions.push({
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name: r.regExp,
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fn: fn,
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pos: pos,
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pos2: pos + r.groups + 1
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});
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pos += r.groups + 1;
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});
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return {
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regExp: new RegExp(total, "g"),
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actions: actions
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};
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};
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Parser.getGroupCount = function(regExpStr) {
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return new RegExp("(" + regExpStr + ")|^$").exec("").length - 2;
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};
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Parser.prototype.parse = function(initialState, string, context) {
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context = context || {};
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var currentState = initialState;
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var currentIndex = 0;
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for(;;) {
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var state = this.states[currentState];
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var regExp = state.regExp;
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regExp.lastIndex = currentIndex;
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var match = regExp.exec(string);
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if(!match) return context;
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var actions = state.actions;
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currentIndex = state.regExp.lastIndex;
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for(var i = 0; i < actions.length; i++) {
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var action = actions[i];
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if(match[action.pos]) {
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var ret = action.fn.apply(context, Array.prototype.slice.call(match, action.pos, action.pos2).concat([state.regExp.lastIndex - match[0].length, match[0].length]));
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if(ret) {
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if(!(ret in this.states))
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throw new Error("State '" + ret + "' doesn't exist");
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currentState = ret;
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}
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break;
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}
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}
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}
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};
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module.exports = Parser;
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