CodeMirror for Tweets

editor.js

/*jslint latedef:false*/
'use strict';

var CodeMirror = require('codemirror');
var twitterText = require('twitter-text');

CodeMirror.defineSimpleMode = function(name, states) {
  CodeMirror.defineMode(name, function(config) {
    return CodeMirror.simpleMode(config, states);
  });
};

CodeMirror.simpleMode = function(config, states) {
  ensureState(states, 'start');
  var states_ = {}, meta = states.meta || {};
  for (var state in states) if (state !== meta && states.hasOwnProperty(state)) {
    var list = states_[state] = [], orig = states[state];
    for (var i = 0; i < orig.length; i++) {
      var data = orig[i];
      list.push(new Rule(data, states));
    }
  }
  var mode = {
    startState: function() {
      return {state: 'start', pending: null,
              local: null, localState: null};
    },
    copyState: function(state) {
      var s = {state: state.state, pending: state.pending,
               local: state.local, localState: null};
      if (state.localState)
        s.localState = CodeMirror.copyState(state.local.mode, state.localState);
      if (state.stack)
        s.stack = state.stack.slice(0);
      for (var pers = state.persistentStates; pers; pers = pers.next)
        s.persistentStates = {mode: pers.mode,
                              spec: pers.spec,
                              state: pers.state === state.localState ? s.localState : CodeMirror.copyState(pers.mode, pers.state),
                              next: s.persistentStates};
      return s;
    },
    token: tokenFunction(states_, config),
    innerMode: function(state) { return state.local && {mode: state.local.mode, state: state.localState}; }
  };
  if (meta) for (var prop in meta) if (meta.hasOwnProperty(prop))
    mode[prop] = meta[prop];
  return mode;
};

function ensureState(states, name) {
  if (!states.hasOwnProperty(name))
    throw new Error('Undefined state ' + name + 'in simple mode');
}

function toRegex(val, caret) {
  if (!val) return /(?:)/;
  var flags = '';
  if (val instanceof RegExp) {
    if (val.ignoreCase) flags = 'i';
    val = val.source;
  } else {
    val = String(val);
  }
  return new RegExp((caret === false ? '' : '^') + '(?:' + val + ')', flags);
}

function Rule(data, states) {
  if (data.next || data.push) ensureState(states, data.next || data.push);
  this.regex = toRegex(data.regex);
  this.token = data.token;
  this.data = data;
}

function tokenFunction(states, config) {
  return function(stream, state) {
    if (state.pending) {
      var pend = state.pending.shift();
      if (state.pending.length === 0) state.pending = null;
      stream.pos += pend.text.length;
      return pend.token;
    }

    if (state.local) {
      var tok;
      if (state.local.end && stream.match(state.local.end)) {
        tok = state.local.endToken || null;
        state.local = state.localState = null;
        return tok;
      } else {
        var m;
        tok = state.local.mode.token(stream, state.localState);
        if (state.local.endScan && (m = state.local.endScan.exec(stream.current())))
          stream.pos = stream.start + m.index;
        return tok;
      }
    }

    var curState = states[state.state];
    for (var i = 0; i < curState.length; i++) {
      var rule = curState[i];
      var matches = stream.match(rule.regex);
      if (matches) {
        return rule.token;
      }
    }
    stream.next();
    return null;
  };
}

CodeMirror.defineSimpleMode('twitter', {
  start: [
    {regex: twitterText.regexen.validMentionOrList, token: 'keyword'},
    {regex: twitterText.regexen.extractUrl, token: 'keyword'},
    {regex: twitterText.regexen.validHashtag, token: 'keyword'},
    {regex: twitterText.regexen.validCashtag, token: 'keyword'}
  ]
});

module.exports = CodeMirror;