/**
 * Supported keybindings:
 *
 *   Motion:
 *   h, j, k, l
 *   e, E, w, W, b, B, ge, gE
 *   f<character>, F<character>, t<character>, T<character>
 *   $, ^, 0
 *   gg, G
 *   %
 *   '<character>, `<character>
 *
 *   Operator:
 *   d, y, c
 *   dd, yy, cc
 *   g~, g~g~
 *   >, <, >>, <<
 *
 *   Operator-Motion:
 *   x, X, D, Y, C, ~
 *
 *   Action:
 *   a, i, s, A, I, S, o, O
 *   J
 *   u, Ctrl-r
 *   m<character>
 *   r<character>
 *
 *   Modes:
 *   ESC - leave insert mode, visual mode, and clear input state.
 *   Ctrl-[, Ctrl-c - same as ESC.
 *
 * Registers: unamed, -, a-z, A-Z, 0-9
 *   (Does not respect the special case for number registers when delete
 *    operator is made with these commands: %, (, ),  , /, ?, n, N, {, } )
 *   TODO: Implement the remaining registers.
 * Marks: a-z, A-Z, and 0-9
 *   TODO: Implement the remaining special marks. They have more complex
 *       behavior.
 *
 * Code structure:
 *  1. Default keymap
 *  2. Variable declarations and short basic helpers
 *  3. Instance (External API) implementation
 *  4. Internal state tracking objects (input state, counter) implementation
 *     and instanstiation
 *  5. Key handler (the main command dispatcher) implementation
 *  6. Motion, operator, and action implementations
 *  7. Helper functions for the key handler, motions, operators, and actions
 *  8. Set up Vim to work as a keymap for CodeMirror.
 */

(function() {
  'use strict';

  var defaultKeymap = [
    // Key to key mapping. This goes first to make it possible to override
    // existing mappings.
    { keys: ['Left'], type: 'keyToKey', toKeys: ['h'] },
    { keys: ['Right'], type: 'keyToKey', toKeys: ['l'] },
    { keys: ['Up'], type: 'keyToKey', toKeys: ['k'] },
    { keys: ['Down'], type: 'keyToKey', toKeys: ['j'] },
    { keys: ['Space'], type: 'keyToKey', toKeys: ['l'] },
    { keys: ['Backspace'], type: 'keyToKey', toKeys: ['h'] },
    { keys: ['Ctrl-Space'], type: 'keyToKey', toKeys: ['W'] },
    { keys: ['Ctrl-Backspace'], type: 'keyToKey', toKeys: ['B'] },
    { keys: ['Shift-Space'], type: 'keyToKey', toKeys: ['w'] },
    { keys: ['Shift-Backspace'], type: 'keyToKey', toKeys: ['b'] },
    { keys: ['Ctrl-n'], type: 'keyToKey', toKeys: ['j'] },
    { keys: ['Ctrl-p'], type: 'keyToKey', toKeys: ['k'] },
    { keys: ['Ctrl-['], type: 'keyToKey', toKeys: ['Esc'] },
    { keys: ['Ctrl-c'], type: 'keyToKey', toKeys: ['Esc'] },
    { keys: ['s'], type: 'keyToKey', toKeys: ['c', 'l'] },
    { keys: ['S'], type: 'keyToKey', toKeys: ['c', 'c'] },
    { keys: ['Home'], type: 'keyToKey', toKeys: ['0'] },
    { keys: ['End'], type: 'keyToKey', toKeys: ['$'] },
    { keys: ['PageUp'], type: 'keyToKey', toKeys: ['Ctrl-b'] },
    { keys: ['PageDown'], type: 'keyToKey', toKeys: ['Ctrl-f'] },
    // Motions
    { keys: ['h'], type: 'motion',
        motion: 'moveByCharacters',
        motionArgs: { forward: false }},
    { keys: ['l'], type: 'motion',
        motion: 'moveByCharacters',
        motionArgs: { forward: true }},
    { keys: ['j'], type: 'motion',
        motion: 'moveByLines',
        motionArgs: { forward: true, linewise: true }},
    { keys: ['k'], type: 'motion',
        motion: 'moveByLines',
        motionArgs: { forward: false, linewise: true }},
    { keys: ['w'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: true, wordEnd: false }},
    { keys: ['W'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: true, wordEnd: false, bigWord: true }},
    { keys: ['e'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: true, wordEnd: true, inclusive: true }},
    { keys: ['E'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: true, wordEnd: true, bigWord: true,
            inclusive: true }},
    { keys: ['b'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: false, wordEnd: false }},
    { keys: ['B'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: false, wordEnd: false, bigWord: true }},
    { keys: ['g', 'e'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: false, wordEnd: true, inclusive: true }},
    { keys: ['g', 'E'], type: 'motion',
        motion: 'moveByWords',
        motionArgs: { forward: false, wordEnd: true, bigWord: true,
            inclusive: true }},
    { keys: ['Ctrl-f'], type: 'motion',
        motion: 'moveByPage', motionArgs: { forward: true }},
    { keys: ['Ctrl-b'], type: 'motion',
        motion: 'moveByPage', motionArgs: { forward: false }},
    { keys: ['g', 'g'], type: 'motion',
        motion: 'moveToLineOrEdgeOfDocument',
        motionArgs: { forward: false, explicitRepeat: true, linewise: true }},
    { keys: ['G'], type: 'motion',
        motion: 'moveToLineOrEdgeOfDocument',
        motionArgs: { forward: true, explicitRepeat: true, linewise: true }},
    { keys: ['0'], type: 'motion', motion: 'moveToStartOfLine' },
    { keys: ['^'], type: 'motion',
        motion: 'moveToFirstNonWhiteSpaceCharacter' },
    { keys: ['$'], type: 'motion',
        motion: 'moveToEol',
        motionArgs: { inclusive: true }},
    { keys: ['%'], type: 'motion',
        motion: 'moveToMatchedSymbol',
        motionArgs: { inclusive: true }},
    { keys: ['f', 'character'], type: 'motion',
        motion: 'moveToCharacter',
        motionArgs: { forward: true , inclusive: true }},
    { keys: ['F', 'character'], type: 'motion',
        motion: 'moveToCharacter',
        motionArgs: { forward: false }},
    { keys: ['t', 'character'], type: 'motion',
        motion: 'moveTillCharacter',
        motionArgs: { forward: true, inclusive: true }},
    { keys: ['T', 'character'], type: 'motion',
        motion: 'moveTillCharacter',
        motionArgs: { forward: false }},
    { keys: ['\'', 'character'], type: 'motion', motion: 'goToMark' },
    { keys: ['`', 'character'], type: 'motion', motion: 'goToMark' },
    { keys: ['|'], type: 'motion',
        motion: 'moveToColumn',
        motionArgs: { }},
    // Operators
    { keys: ['d'], type: 'operator', operator: 'delete' },
    { keys: ['y'], type: 'operator', operator: 'yank' },
    { keys: ['c'], type: 'operator', operator: 'change',
        operatorArgs: { enterInsertMode: true } },
    { keys: ['>'], type: 'operator', operator: 'indent',
        operatorArgs: { indentRight: true }},
    { keys: ['<'], type: 'operator', operator: 'indent',
        operatorArgs: { indentRight: false }},
    { keys: ['g', '~'], type: 'operator', operator: 'swapcase' },
    { keys: ['n'], type: 'motion', motion: 'findNext' },
    { keys: ['N'], type: 'motion', motion: 'findPrev' },
    // Operator-Motion dual commands
    { keys: ['x'], type: 'operatorMotion', operator: 'delete',
        motion: 'moveByCharacters', motionArgs: { forward: true },
        operatorMotionArgs: { visualLine: false }},
    { keys: ['X'], type: 'operatorMotion', operator: 'delete',
        motion: 'moveByCharacters', motionArgs: { forward: false },
        operatorMotionArgs: { visualLine: true }},
    { keys: ['D'], type: 'operatorMotion', operator: 'delete',
      motion: 'moveToEol', motionArgs: { inclusive: true },
        operatorMotionArgs: { visualLine: true }},
    { keys: ['Y'], type: 'operatorMotion', operator: 'yank',
        motion: 'moveToEol', motionArgs: { inclusive: true },
        operatorMotionArgs: { visualLine: true }},
    { keys: ['C'], type: 'operatorMotion',
        operator: 'change', operatorArgs: { enterInsertMode: true },
        motion: 'moveToEol', motionArgs: { inclusive: true },
        operatorMotionArgs: { visualLine: true }},
    { keys: ['~'], type: 'operatorMotion', operator: 'swapcase',
        motion: 'moveByCharacters', motionArgs: { forward: true }},
    // Actions
    { keys: ['a'], type: 'action', action: 'enterInsertMode',
        actionArgs: { insertAt: 'charAfter' }},
    { keys: ['A'], type: 'action', action: 'enterInsertMode',
        actionArgs: { insertAt: 'eol' }},
    { keys: ['i'], type: 'action', action: 'enterInsertMode' },
    { keys: ['I'], type: 'action', action: 'enterInsertMode',
        motion: 'moveToFirstNonWhiteSpaceCharacter' },
    { keys: ['o'], type: 'action', action: 'newLineAndEnterInsertMode',
        actionArgs: { after: true }},
    { keys: ['O'], type: 'action', action: 'newLineAndEnterInsertMode',
        actionArgs: { after: false }},
    { keys: ['v'], type: 'action', action: 'toggleVisualMode' },
    { keys: ['V'], type: 'action', action: 'toggleVisualMode',
        actionArgs: { linewise: true }},
    { keys: ['J'], type: 'action', action: 'joinLines' },
    { keys: ['p'], type: 'action', action: 'paste',
        actionArgs: { after: true }},
    { keys: ['P'], type: 'action', action: 'paste',
        actionArgs: { after: false }},
    { keys: ['r', 'character'], type: 'action', action: 'replace' },
    { keys: ['u'], type: 'action', action: 'undo' },
    { keys: ['Ctrl-r'], type: 'action', action: 'redo' },
    { keys: ['m', 'character'], type: 'action', action: 'setMark' },
    { keys: ['\"', 'character'], type: 'action', action: 'setRegister' },
    { keys: [',', '/'], type: 'action', action: 'clearSearchHighlight' },
    // Text object motions
    { keys: ['a', 'character'], type: 'motion',
        motion: 'textObjectManipulation' },
    { keys: ['i', 'character'], type: 'motion',
        motion: 'textObjectManipulation',
        motionArgs: { textObjectInner: true }},
    // Search
    { keys: ['/'], type: 'search',
        searchArgs: { forward: true, querySrc: 'prompt' }},
    { keys: ['?'], type: 'search',
        searchArgs: { forward: false, querySrc: 'prompt' }},
    { keys: ['*'], type: 'search',
        searchArgs: { forward: true, querySrc: 'wordUnderCursor' }},
    { keys: ['#'], type: 'search',
        searchArgs: { forward: false, querySrc: 'wordUnderCursor' }},
    // Ex command
    { keys: [':'], type: 'ex' }
  ];

  var Vim = function() {
    var alphabetRegex = /[A-Za-z]/;
    var numberRegex = /[\d]/;
    var whiteSpaceRegex = /\s/;
    var wordRegexp = [(/\w/), (/[^\w\s]/)], bigWordRegexp = [(/\S/)];
    function makeKeyRange(start, size) {
      var keys = [];
      for (var i = start; i < start + size; i++) {
        keys.push(String.fromCharCode(i));
      }
      return keys;
    }
    var upperCaseAlphabet = makeKeyRange(65, 26);
    var lowerCaseAlphabet = makeKeyRange(97, 26);
    var numbers = makeKeyRange(48, 10);
    var SPECIAL_SYMBOLS = '~`!@#$%^&*()_-+=[{}]\\|/?.,<>:;\"\'';
    var specialSymbols = SPECIAL_SYMBOLS.split('');
    var specialKeys = ['Left', 'Right', 'Up', 'Down', 'Space', 'Backspace',
        'Esc', 'Home', 'End', 'PageUp', 'PageDown'];
    var validMarks = upperCaseAlphabet.concat(lowerCaseAlphabet).concat(
        numbers);
    var validRegisters = upperCaseAlphabet.concat(lowerCaseAlphabet).concat(
        numbers).concat('-\"'.split(''));

    function isAlphabet(k) {
      return alphabetRegex.test(k);
    }
    function isLine(cm, line) {
      return line >= 0 && line < cm.lineCount();
    }
    function isLowerCase(k) {
      return (/^[a-z]$/).test(k);
    }
    function isMatchableSymbol(k) {
      return '()[]{}'.indexOf(k) != -1;
    }
    function isNumber(k) {
      return numberRegex.test(k);
    }
    function isUpperCase(k) {
      return (/^[A-Z]$/).test(k);
    }
    function isAlphanumeric(k) {
      return (/^[\w]$/).test(k);
    }
    function isWhiteSpace(k) {
      return whiteSpaceRegex.test(k);
    }
    function isWhiteSpaceString(k) {
      return (/^\s*$/).test(k);
    }
    function inRangeInclusive(x, start, end) {
      return x >= start && x <= end;
    }
    function inArray(val, arr) {
      for (var i = 0; i < arr.length; i++) {
        if (arr[i] == val) {
          return true;
        }
      }
      return false;
    }

    // Global Vim state. Call getVimGlobalState to get and initialize.
    var vimGlobalState;
    function getVimGlobalState() {
      if (!vimGlobalState) {
        vimGlobalState = {
          // The current search query.
          searchQuery: null,
          // Whether we are searching backwards.
          searchIsReversed: false,
          registerController: new RegisterController({})
        };
      }
      return vimGlobalState;
    }
    function getVimState(cm) {
      if (!cm.vimState) {
        // Store instance state in the CodeMirror object.
        cm.vimState = {
          inputState: new InputState(),
          // When using jk for navigation, if you move from a longer line to a
          // shorter line, the cursor may clip to the end of the shorter line.
          // If j is pressed again and cursor goes to the next line, the
          // cursor should go back to its horizontal position on the longer
          // line if it can. This is to keep track of the horizontal position.
          lastHPos: -1,
          // The last motion command run. Cleared if a non-motion command gets
          // executed in between.
          lastMotion: null,
          marks: {},
          visualMode: false,
          // If we are in visual line mode. No effect if visualMode is false.
          visualLine: false
        };
      }
      return cm.vimState;
    }

    var vimApi= {
      buildKeyMap: function() {
        // TODO: Convert keymap into dictionary format for fast lookup.
      },
      // Testing hook, though it might be useful to expose the register
      // controller anyways.
      getRegisterController: function() {
        return getVimGlobalState().registerController;
      },
      // Testing hook.
      clearVimGlobalState_: function() {
        vimGlobalState = null;
      },
      map: function(lhs, rhs) {
        // Add user defined key bindings.
        exCommandDispatcher.map(lhs, rhs);
      },
      // Initializes vim state variable on the CodeMirror object. Should only be
      // called lazily by handleKey or for testing.
      maybeInitState: function(cm) {
        getVimState(cm);
      },
      // This is the outermost function called by CodeMirror, after keys have
      // been mapped to their Vim equivalents.
      handleKey: function(cm, key) {
        var command;
        var vim = getVimState(cm);
        if (key == 'Esc') {
          // Clear input state and get back to normal mode.
          vim.inputState.reset();
          if (vim.visualMode) {
            exitVisualMode(cm, vim);
          }
          return;
        }
        if (vim.visualMode &&
            cursorEqual(cm.getCursor('head'), cm.getCursor('anchor'))) {
          // The selection was cleared. Exit visual mode.
          exitVisualMode(cm, vim);
        }
        if (!vim.visualMode &&
            !cursorEqual(cm.getCursor('head'), cm.getCursor('anchor'))) {
          vim.visualMode = true;
          vim.visualLine = false;
        }
        if (key != '0' || (key == '0' && vim.inputState.getRepeat() === 0)) {
          // Have to special case 0 since it's both a motion and a number.
          command = commandDispatcher.matchCommand(key, defaultKeymap, vim);
        }
        if (!command) {
          if (isNumber(key)) {
            // Increment count unless count is 0 and key is 0.
            vim.inputState.pushRepeatDigit(key);
          }
          return;
        }
        if (command.type == 'keyToKey') {
          // TODO: prevent infinite recursion.
          for (var i = 0; i < command.toKeys.length; i++) {
            this.handleKey(cm, command.toKeys[i]);
          }
        } else {
          commandDispatcher.processCommand(cm, vim, command);
        }
      }
    };

    // Represents the current input state.
    function InputState() {
      this.reset();
    }
    InputState.prototype.reset = function() {
      this.prefixRepeat = [];
      this.motionRepeat = [];

      this.operator = null;
      this.operatorArgs = null;
      this.motion = null;
      this.motionArgs = null;
      this.keyBuffer = []; // For matching multi-key commands.
      this.registerName = null; // Defaults to the unamed register.
    };
    InputState.prototype.pushRepeatDigit = function(n) {
      if (!this.operator) {
        this.prefixRepeat = this.prefixRepeat.concat(n);
      } else {
        this.motionRepeat = this.motionRepeat.concat(n);
      }
    };
    InputState.prototype.getRepeat = function() {
      var repeat = 0;
      if (this.prefixRepeat.length > 0 || this.motionRepeat.length > 0) {
        repeat = 1;
        if (this.prefixRepeat.length > 0) {
          repeat *= parseInt(this.prefixRepeat.join(''), 10);
        }
        if (this.motionRepeat.length > 0) {
          repeat *= parseInt(this.motionRepeat.join(''), 10);
        }
      }
      return repeat;
    };

    /*
     * Register stores information about copy and paste registers.  Besides
     * text, a register must store whether it is linewise (i.e., when it is
     * pasted, should it insert itself into a new line, or should the text be
     * inserted at the cursor position.)
     */
    function Register(text, linewise) {
      this.clear();
      if (text) {
        this.set(text, linewise);
      }
    }
    Register.prototype = {
      set: function(text, linewise) {
        this.text = text;
        this.linewise = !!linewise;
      },
      append: function(text, linewise) {
        // if this register has ever been set to linewise, use linewise.
        if (linewise || this.linewise) {
          this.text += '\n' + text;
          this.linewise = true;
        } else {
          this.text += text;
        }
      },
      clear: function() {
        this.text = '';
        this.linewise = false;
      },
      toString: function() { return this.text; }
    };

    /*
     * vim registers allow you to keep many independent copy and paste buffers.
     * See http://usevim.com/2012/04/13/registers/ for an introduction.
     *
     * RegisterController keeps the state of all the registers.  An initial
     * state may be passed in.  The unnamed register '"' will always be
     * overridden.
     */
    function RegisterController(registers) {
      this.registers = registers;
      this.unamedRegister = registers['\"'] = new Register();
    }
    RegisterController.prototype = {
      pushText: function(registerName, operator, text, linewise) {
        // Lowercase and uppercase registers refer to the same register.
        // Uppercase just means append.
        var register = this.isValidRegister(registerName) ?
            this.getRegister(registerName) : null;
        // if no register/an invalid register was specified, things go to the
        // default registers
        if (!register) {
          switch (operator) {
            case 'yank':
              // The 0 register contains the text from the most recent yank.
              this.registers['0'] = new Register(text, linewise);
              break;
            case 'delete':
            case 'change':
              if (text.indexOf('\n') == -1) {
                // Delete less than 1 line. Update the small delete register.
                this.registers['-'] = new Register(text, linewise);
              } else {
                // Shift down the contents of the numbered registers and put the
                // deleted text into register 1.
                this.shiftNumericRegisters_();
                this.registers['1'] = new Register(text, linewise);
              }
              break;
          }
          // Make sure the unnamed register is set to what just happened
          this.unamedRegister.set(text, linewise);
          return;
        }

        // If we've gotten to this point, we've actually specified a register
        var append = isUpperCase(registerName);
        if (append) {
          register.append(text, linewise);
          // The unamed register always has the same value as the last used
          // register.
          this.unamedRegister.append(text, linewise);
        } else {
          register.set(text, linewise);
          this.unamedRegister.set(text, linewise);
        }
      },
      // Gets the register named @name.  If one of @name doesn't already exist,
      // create it.  If @name is invalid, return the unamedRegister.
      getRegister: function(name) {
        if (!this.isValidRegister(name)) {
          return this.unamedRegister;
        }
        name = name.toLowerCase();
        if (!this.registers[name]) {
          this.registers[name] = new Register();
        }
        return this.registers[name];
      },
      isValidRegister: function(name) {
        return name && inArray(name, validRegisters);
      },
      shiftNumericRegisters_: function() {
        for (var i = 9; i >= 2; i--) {
          this.registers[i] = this.getRegister('' + (i - 1));
        }
      }
    };

    var commandDispatcher = {
      matchCommand: function(key, keyMap, vim) {
        var inputState = vim.inputState;
        var keys = inputState.keyBuffer.concat(key);
        for (var i = 0; i < keyMap.length; i++) {
          var command = keyMap[i];
          if (matchKeysPartial(keys, command.keys)) {
            if (keys.length < command.keys.length) {
              // Matches part of a multi-key command. Buffer and wait for next
              // stroke.
              inputState.keyBuffer.push(key);
              return null;
            } else {
              if (inputState.operator && command.type == 'action') {
                // Ignore matched action commands after an operator. Operators
                // only operate on motions. This check is really for text
                // objects since aW, a[ etcs conflicts with a.
                continue;
              }
              // Matches whole comand. Return the command.
              if (command.keys[keys.length - 1] == 'character') {
                inputState.selectedCharacter = keys[keys.length - 1];
              }
              inputState.keyBuffer = [];
              return command;
            }
          }
        }
        // Clear the buffer since there are no partial matches.
        inputState.keyBuffer = [];
        return null;
      },
      processCommand: function(cm, vim, command) {
        switch (command.type) {
          case 'motion':
            this.processMotion(cm, vim, command);
            break;
          case 'operator':
            this.processOperator(cm, vim, command);
            break;
          case 'operatorMotion':
            this.processOperatorMotion(cm, vim, command);
            break;
          case 'action':
            this.processAction(cm, vim, command);
            break;
          case 'search':
            this.processSearch(cm, vim, command);
            break;
          case 'ex':
          case 'keyToEx':
            this.processEx(cm, vim, command);
            break;
          default:
            break;
        }
      },
      processMotion: function(cm, vim, command) {
        vim.inputState.motion = command.motion;
        vim.inputState.motionArgs = copyArgs(command.motionArgs);
        this.evalInput(cm, vim);
      },
      processOperator: function(cm, vim, command) {
        var inputState = vim.inputState;
        if (inputState.operator) {
          if (inputState.operator == command.operator) {
            // Typing an operator twice like 'dd' makes the operator operate
            // linewise
            inputState.motion = 'expandToLine';
            inputState.motionArgs = { linewise: true };
            this.evalInput(cm, vim);
            return;
          } else {
            // 2 different operators in a row doesn't make sense.
            inputState.reset();
          }
        }
        inputState.operator = command.operator;
        inputState.operatorArgs = copyArgs(command.operatorArgs);
        if (vim.visualMode) {
          // Operating on a selection in visual mode. We don't need a motion.
          this.evalInput(cm, vim);
        }
      },
      processOperatorMotion: function(cm, vim, command) {
        var visualMode = vim.visualMode;
        var operatorMotionArgs = copyArgs(command.operatorMotionArgs);
        if (operatorMotionArgs) {
          // Operator motions may have special behavior in visual mode.
          if (visualMode && operatorMotionArgs.visualLine) {
            vim.visualLine = true;
          }
        }
        this.processOperator(cm, vim, command);
        if (!visualMode) {
          this.processMotion(cm, vim, command);
        }
      },
      processAction: function(cm, vim, command) {
        var inputState = vim.inputState;
        var repeat = inputState.getRepeat();
        var repeatIsExplicit = !!repeat;
        var actionArgs = copyArgs(command.actionArgs) || {};
        if (inputState.selectedCharacter) {
          actionArgs.selectedCharacter = inputState.selectedCharacter;
        }
        // Actions may or may not have motions and operators. Do these first.
        if (command.operator) {
          this.processOperator(cm, vim, command);
        }
        if (command.motion) {
          this.processMotion(cm, vim, command);
        }
        if (command.motion || command.operator) {
          this.evalInput(cm, vim);
        }
        actionArgs.repeat = repeat || 1;
        actionArgs.repeatIsExplicit = repeatIsExplicit;
        actionArgs.registerName = inputState.registerName;
        inputState.reset();
        vim.lastMotion = null,
        actions[command.action](cm, actionArgs, vim);
      },
      processSearch: function(cm, vim, command) {
        if (!cm.getSearchCursor) {
          // Search depends on SearchCursor.
          return;
        }
        var forward = command.searchArgs.forward;
        getSearchState(cm).setReversed(!forward);
        var promptPrefix = (forward) ? '/' : '?';
        function handleQuery(query, ignoreCase, smartCase) {
          updateSearchQuery(cm, query, ignoreCase, smartCase);
          commandDispatcher.processMotion(cm, vim, {
            type: 'motion',
            motion: 'findNext'
          });
        }
        function onPromptClose(query) {
          handleQuery(query, true /** ignoreCase */, true /** smartCase */);
        }
        switch (command.searchArgs.querySrc) {
          case 'prompt':
            showPrompt(cm, onPromptClose, promptPrefix, searchPromptDesc);
            break;
          case 'wordUnderCursor':
            var word = expandWordUnderCursor(cm, false /** inclusive */,
                true /** forward */, false /** bigWord */,
                true /** noSymbol */);
            var isKeyword = true;
            if (!word) {
              word = expandWordUnderCursor(cm, false /** inclusive */,
                  true /** forward */, false /** bigWord */,
                  false /** noSymbol */);
              isKeyword = false;
            }
            if (!word) {
              return;
            }
            var query = cm.getLine(word.start.line).substring(word.start.ch,
                word.end.ch + 1);
            if (isKeyword) {
              query = '\\b' + query + '\\b';
            } else {
              query = escapeRegex(query);
            }
            cm.setCursor(word.start);
            handleQuery(query, true /** ignoreCase */, false /** smartCase */);
            break;
        }
      },
      processEx: function(cm, vim, command) {
        function onPromptClose(input) {
          exCommandDispatcher.processCommand(cm, input);
        }
        if (command.type == 'keyToEx') {
          // Handle user defined Ex to Ex mappings
          exCommandDispatcher.processCommand(cm, command.exArgs.input);
        } else {
          showPrompt(cm, onPromptClose, ':');
        }
      },
      evalInput: function(cm, vim) {
        // If the motion comand is set, execute both the operator and motion.
        // Otherwise return.
        var inputState = vim.inputState;
        var motion = inputState.motion;
        var motionArgs = inputState.motionArgs || {};
        var operator = inputState.operator;
        var operatorArgs = inputState.operatorArgs || {};
        var registerName = inputState.registerName;
        var selectionEnd = cm.getCursor('head');
        var selectionStart = cm.getCursor('anchor');
        // The difference between cur and selection cursors are that cur is
        // being operated on and ignores that there is a selection.
        var curStart = copyCursor(selectionEnd);
        var curOriginal = copyCursor(curStart);
        var curEnd;
        var repeat;
        if (motionArgs.repeat !== undefined) {
          // If motionArgs specifies a repeat, that takes precedence over the
          // input state's repeat. Used by Ex mode and can be user defined.
          repeat = inputState.motionArgs.repeat;
        } else {
          repeat = inputState.getRepeat();
        }
        if (repeat > 0 && motionArgs.explicitRepeat) {
          motionArgs.repeatIsExplicit = true;
        } else if (motionArgs.noRepeat ||
            (!motionArgs.explicitRepeat && repeat === 0)) {
          repeat = 1;
          motionArgs.repeatIsExplicit = false;
        }
        if (inputState.selectedCharacter) {
          // If there is a character input, stick it in all of the arg arrays.
          motionArgs.selectedCharacter = operatorArgs.selectedCharacter =
              inputState.selectedCharacter;
        }
        motionArgs.repeat = repeat;
        inputState.reset();
        if (motion) {
          var motionResult = motions[motion](cm, motionArgs, vim);
          vim.lastMotion = motions[motion];
          if (!motionResult) {
            return;
          }
          if (motionResult instanceof Array) {
            curStart = motionResult[0];
            curEnd = motionResult[1];
          } else {
            curEnd = motionResult;
          }
          // TODO: Handle null returns from motion commands better.
          if (!curEnd) {
            curEnd = { ch: curStart.ch, line: curStart.line };
          }
          if (vim.visualMode) {
            // Check if the selection crossed over itself. Will need to shift
            // the start point if that happened.
            if (cursorIsBefore(selectionStart, selectionEnd) &&
                (cursorEqual(selectionStart, curEnd) ||
                    cursorIsBefore(curEnd, selectionStart))) {
              // The end of the selection has moved from after the start to
              // before the start. We will shift the start right by 1.
              selectionStart.ch += 1;
            } else if (cursorIsBefore(selectionEnd, selectionStart) &&
                (cursorEqual(selectionStart, curEnd) ||
                    cursorIsBefore(selectionStart, curEnd))) {
              // The opposite happened. We will shift the start left by 1.
              selectionStart.ch -= 1;
            }
            selectionEnd = curEnd;
            if (vim.visualLine) {
              if (cursorIsBefore(selectionStart, selectionEnd)) {
                selectionStart.ch = 0;
                selectionEnd.ch = lineLength(cm, selectionEnd.line);
              } else {
                selectionEnd.ch = 0;
                selectionStart.ch = lineLength(cm, selectionStart.line);
              }
            }
            // Need to set the cursor to clear the selection. Otherwise,
            // CodeMirror can't figure out that we changed directions...
            cm.setCursor(selectionStart);
            cm.setSelection(selectionStart, selectionEnd);
          } else if (!operator) {
            curEnd = clipCursorToContent(cm, curEnd);
            cm.setCursor(curEnd.line, curEnd.ch);
          }
        }

        if (operator) {
          var inverted = false;
          vim.lastMotion = null;
          operatorArgs.repeat = repeat; // Indent in visual mode needs this.
          if (vim.visualMode) {
            curStart = selectionStart;
            curEnd = selectionEnd;
            motionArgs.inclusive = true;
          }
          // Swap start and end if motion was backward.
          if (cursorIsBefore(curEnd, curStart)) {
            var tmp = curStart;
            curStart = curEnd;
            curEnd = tmp;
            inverted = true;
          }
          if (motionArgs.inclusive && !(vim.visualMode && inverted)) {
            // Move the selection end one to the right to include the last
            // character.
            curEnd.ch++;
          }
          var linewise = motionArgs.linewise ||
              (vim.visualMode && vim.visualLine);
          if (linewise) {
            // Expand selection to entire line.
            expandSelectionToLine(cm, curStart, curEnd);
          } else if (motionArgs.forward) {
            // Clip to trailing newlines only if we the motion goes forward.
            clipToLine(cm, curStart, curEnd);
          }
          operatorArgs.registerName = registerName;
          // Keep track of linewise as it affects how paste and change behave.
          operatorArgs.linewise = linewise;
          operators[operator](cm, operatorArgs, vim, curStart,
              curEnd, curOriginal);
          if (vim.visualMode) {
            exitVisualMode(cm, vim);
          }
          if (operatorArgs.enterInsertMode) {
            actions.enterInsertMode(cm);
          }
        }
      }
    };

    /**
     * typedef {Object{line:number,ch:number}} Cursor An object containing the
     *     position of the cursor.
     */
    // All of the functions below return Cursor objects.
    var motions = {
      expandToLine: function(cm, motionArgs) {
        // Expands forward to end of line, and then to next line if repeat is
        // >1. Does not handle backward motion!
        var cur = cm.getCursor();
        return { line: cur.line + motionArgs.repeat - 1, ch: Infinity };
      },
      findNext: function(cm, motionArgs, vim) {
        return findNext(cm, false /** prev */, motionArgs.repeat);
      },
      findPrev: function(cm, motionArgs, vim) {
        return findNext(cm, true /** prev */, motionArgs.repeat);
      },
      goToMark: function(cm, motionArgs, vim) {
        var mark = vim.marks[motionArgs.selectedCharacter];
        if (mark) {
          return mark.find();
        }
        return null;
      },
      moveByCharacters: function(cm, motionArgs) {
        var cur = cm.getCursor();
        var repeat = motionArgs.repeat;
        var ch = motionArgs.forward ? cur.ch + repeat : cur.ch - repeat;
        return { line: cur.line, ch: ch };
      },
      moveByLines: function(cm, motionArgs, vim) {
        var endCh = cm.getCursor().ch;
        // Depending what our last motion was, we may want to do different
        // things. If our last motion was moving vertically, we want to
        // preserve the HPos from our last horizontal move.  If our last motion
        // was going to the end of a line, moving vertically we should go to
        // the end of the line, etc.
        switch (vim.lastMotion) {
          case this.moveByLines:
          case this.moveToColumn:
          case this.moveToEol:
            endCh = vim.lastHPos;
            break;
          default:
            vim.lastHPos = endCh;
        }
        var cur = cm.getCursor();
        var repeat = motionArgs.repeat;
        var line = motionArgs.forward ? cur.line + repeat : cur.line - repeat;
        if (line < 0 || line > cm.lineCount() - 1) {
          return null;
        }
        return { line: line, ch: endCh };
      },
      moveByPage: function(cm, motionArgs) {
        // CodeMirror only exposes functions that move the cursor page down, so
        // doing this bad hack to move the cursor and move it back. evalInput
        // will move the cursor to where it should be in the end.
        var curStart = cm.getCursor();
        var repeat = motionArgs.repeat;
        cm.moveV((motionArgs.forward ? repeat : -repeat), 'page');
        var curEnd = cm.getCursor();
        cm.setCursor(curStart);
        return curEnd;
      },
      moveByWords: function(cm, motionArgs) {
        return moveToWord(cm, motionArgs.repeat, !!motionArgs.forward,
            !!motionArgs.wordEnd, !!motionArgs.bigWord);
      },
      moveTillCharacter: function(cm, motionArgs) {
        var repeat = motionArgs.repeat;
        var curEnd = moveToCharacter(cm, repeat, motionArgs.forward,
            motionArgs.selectedCharacter);
        var increment = motionArgs.forward ? -1 : 1;
        curEnd.ch += increment;
        return curEnd;
      },
      moveToCharacter: function(cm, motionArgs) {
        var repeat = motionArgs.repeat;
        return moveToCharacter(cm, repeat, motionArgs.forward,
            motionArgs.selectedCharacter);
      },
      moveToColumn: function(cm, motionArgs, vim) {
        var repeat = motionArgs.repeat;
        // repeat is equivalent to which column we want to move to!
        vim.lastHPos = repeat - 1;
        return moveToColumn(cm, repeat);
      },
      moveToEol: function(cm, motionArgs, vim) {
        var cur = cm.getCursor();
        vim.lastHPos = Infinity;
        return { line: cur.line + motionArgs.repeat - 1, ch: Infinity };
      },
      moveToFirstNonWhiteSpaceCharacter: function(cm) {
        // Go to the start of the line where the text begins, or the end for
        // whitespace-only lines
        var cursor = cm.getCursor();
        var line = cm.getLine(cursor.line);
        return { line: cursor.line,
            ch: findFirstNonWhiteSpaceCharacter(cm.getLine(cursor.line)) };
      },
      moveToMatchedSymbol: function(cm, motionArgs) {
        var cursor = cm.getCursor();
        var symbol = cm.getLine(cursor.line).charAt(cursor.ch);
        if (isMatchableSymbol(symbol)) {
          return findMatchedSymbol(cm, cm.getCursor(), motionArgs.symbol);
        } else {
          return cursor;
        }
      },
      moveToStartOfLine: function(cm) {
        var cursor = cm.getCursor();
        return { line: cursor.line, ch: 0 };
      },
      moveToLineOrEdgeOfDocument: function(cm, motionArgs) {
        var lineNum = motionArgs.forward ? cm.lineCount() - 1 : 0;
        if (motionArgs.repeatIsExplicit) {
          lineNum = motionArgs.repeat - 1;
        }
        return { line: lineNum,
            ch: findFirstNonWhiteSpaceCharacter(cm.getLine(lineNum)) };
      },
      textObjectManipulation: function(cm, motionArgs) {
        var character = motionArgs.selectedCharacter;
        // Inclusive is the difference between a and i
        // TODO: Instead of using the additional text object map to perform text
        //     object operations, merge the map into the defaultKeyMap and use
        //     motionArgs to define behavior. Define separate entries for 'aw',
        //     'iw', 'a[', 'i[', etc.
        var inclusive = !motionArgs.textObjectInner;
        if (!textObjects[character]) {
          // No text object defined for this, don't move.
          return null;
        }
        var tmp = textObjects[character](cm, inclusive);
        var start = tmp.start;
        var end = tmp.end;
        return [start, end];
      }
    };

    var operators = {
      change: function(cm, operatorArgs, vim, curStart, curEnd) {
        getVimGlobalState().registerController.pushText(
            operatorArgs.registerName, 'change', cm.getRange(curStart, curEnd),
            operatorArgs.linewise);
        if (operatorArgs.linewise) {
          // Delete starting at the first nonwhitespace character of the first
          // line, instead of from the start of the first line. This way we get
          // an indent when we get into insert mode. This behavior isn't quite
          // correct because we should treat this as a completely new line, and
          // indent should be whatever codemirror thinks is the right indent.
          // But cm.indentLine doesn't seem work on empty lines.
          // TODO: Fix the above.
          curStart.ch =
              findFirstNonWhiteSpaceCharacter(cm.getLine(curStart.line));
          // Insert an additional newline so that insert mode can start there.
          // curEnd should be on the first character of the new line.
          cm.replaceRange('\n', curStart, curEnd);
        } else {
          cm.replaceRange('', curStart, curEnd);
        }
        cm.setCursor(curStart);
      },
      // delete is a javascript keyword.
      'delete': function(cm, operatorArgs, vim, curStart, curEnd) {
        getVimGlobalState().registerController.pushText(
            operatorArgs.registerName, 'delete', cm.getRange(curStart, curEnd),
            operatorArgs.linewise);
        cm.replaceRange('', curStart, curEnd);
        if (operatorArgs.linewise) {
          cm.setCursor(motions.moveToFirstNonWhiteSpaceCharacter(cm));
        } else {
          cm.setCursor(curStart);
        }
      },
      indent: function(cm, operatorArgs, vim, curStart, curEnd) {
        var startLine = curStart.line;
        var endLine = curEnd.line;
        // In visual mode, n> shifts the selection right n times, instead of
        // shifting n lines right once.
        var repeat = (vim.visualMode) ? operatorArgs.repeat : 1;
        if (operatorArgs.linewise) {
          // The only way to delete a newline is to delete until the start of
          // the next line, so in linewise mode evalInput will include the next
          // line. We don't want this in indent, so we go back a line.
          endLine--;
        }
        for (var i = startLine; i <= endLine; i++) {
          for (var j = 0; j < repeat; j++) {
            cm.indentLine(i, operatorArgs.indentRight);
          }
        }
        cm.setCursor(curStart);
        cm.setCursor(motions.moveToFirstNonWhiteSpaceCharacter(cm));
      },
      swapcase: function(cm, operatorArgs, vim, curStart, curEnd, curOriginal) {
        var toSwap = cm.getRange(curStart, curEnd);
        var swapped = '';
        for (var i = 0; i < toSwap.length; i++) {
          var character = toSwap.charAt(i);
          swapped += isUpperCase(character) ? character.toLowerCase() :
              character.toUpperCase();
        }
        cm.replaceRange(swapped, curStart, curEnd);
        cm.setCursor(curOriginal);
      },
      yank: function(cm, operatorArgs, vim, curStart, curEnd, curOriginal) {
        getVimGlobalState().registerController.pushText(
            operatorArgs.registerName, 'yank',
            cm.getRange(curStart, curEnd), operatorArgs.linewise);
        cm.setCursor(curOriginal);
      }
    };

    var actions = {
      clearSearchHighlight: clearSearchHighlight,
      enterInsertMode: function(cm, actionArgs) {
        var insertAt = (actionArgs) ? actionArgs.insertAt : null;
        if (insertAt == 'eol') {
          var cursor = cm.getCursor();
          cursor = { line: cursor.line, ch: lineLength(cm, cursor.line) };
          cm.setCursor(cursor);
        } else if (insertAt == 'charAfter') {
          cm.setCursor(offsetCursor(cm.getCursor(), 0, 1));
        }
        cm.setOption('keyMap', 'vim-insert');
      },
      toggleVisualMode: function(cm, actionArgs, vim) {
        var repeat = actionArgs.repeat;
        var curStart = cm.getCursor();
        var curEnd;
        // TODO: The repeat should actually select number of characters/lines
        //     equal to the repeat times the size of the previous visual
        //     operation.
        if (!vim.visualMode) {
          vim.visualMode = true;
          vim.visualLine = !!actionArgs.linewise;
          if (vim.visualLine) {
            curStart.ch = 0;
            curEnd = clipCursorToContent(cm, {
              line: curStart.line + repeat - 1,
              ch: lineLength(cm, curStart.line)
            }, true /** includeLineBreak */);
          } else {
            curEnd = clipCursorToContent(cm, {
              line: curStart.line,
              ch: curStart.ch + repeat
            }, true /** includeLineBreak */);
          }
          // Make the initial selection.
          if (!actionArgs.repeatIsExplicit && !vim.visualLine) {
            // This is a strange case. Here the implicit repeat is 1. The
            // following commands lets the cursor hover over the 1 character
            // selection.
            cm.setCursor(curEnd);
            cm.setSelection(curEnd, curStart);
          } else {
            cm.setSelection(curStart, curEnd);
          }
        } else {
          if (!vim.visualLine && actionArgs.linewise) {
            // Shift-V pressed in characterwise visual mode. Switch to linewise
            // visual mode instead of exiting visual mode.
            vim.visualLine = true;
            curStart = cm.getCursor('anchor');
            curEnd = cm.getCursor('head');
            curStart.ch = cursorIsBefore(curStart, curEnd) ? 0 :
                lineLength(cm, curStart.line);
            curEnd.ch = cursorIsBefore(curStart, curEnd) ?
                lineLength(cm, curEnd.line) : 0;
            cm.setSelection(curStart, curEnd);
          } else {
            exitVisualMode(cm, vim);
          }
        }
      },
      joinLines: function(cm, actionArgs, vim) {
        var curStart, curEnd;
        if (vim.visualMode) {
          curStart = cm.getCursor('anchor');
          curEnd = cm.getCursor('head');
          curEnd.ch = lineLength(cm, curEnd.line) - 1;
        } else {
          // Repeat is the number of lines to join. Minimum 2 lines.
          var repeat = Math.max(actionArgs.repeat, 2);
          curStart = cm.getCursor();
          curEnd = clipCursorToContent(cm, { line: curStart.line + repeat - 1,
              ch: Infinity });
        }
        var finalCh = 0;
        cm.operation(function() {
          for (var i = curStart.line; i < curEnd.line; i++) {
            finalCh = lineLength(cm, curStart.line);
            var tmp = { line: curStart.line + 1,
                ch: lineLength(cm, curStart.line + 1) };
            var text = cm.getRange(curStart, tmp);
            text = text.replace(/\n\s*/g, ' ');
            cm.replaceRange(text, curStart, tmp);
          }
          var curFinalPos = { line: curStart.line, ch: finalCh };
          cm.setCursor(curFinalPos);
        });
      },
      newLineAndEnterInsertMode: function(cm, actionArgs) {
        var insertAt = cm.getCursor();
        if (insertAt.line === 0 && !actionArgs.after) {
          // Special case for inserting newline before start of document.
          cm.replaceRange('\n', { line: 0, ch: 0 });
          cm.setCursor(0, 0);
        } else {
          insertAt.line = (actionArgs.after) ? insertAt.line :
              insertAt.line - 1;
          insertAt.ch = lineLength(cm, insertAt.line);
          cm.setCursor(insertAt);
          var newlineFn = CodeMirror.commands.newlineAndIndentContinueComment ||
              CodeMirror.commands.newlineAndIndent;
          newlineFn(cm);
        }
        this.enterInsertMode(cm);
      },
      paste: function(cm, actionArgs, vim) {
        var cur = cm.getCursor();
        var register = getVimGlobalState().registerController.getRegister(
            actionArgs.registerName);
        if (!register.text) {
          return;
        }
        for (var text = '', i = 0; i < actionArgs.repeat; i++) {
          text += register.text;
        }
        var linewise = register.linewise;
        if (linewise) {
          if (actionArgs.after) {
            // Move the newline at the end to the start instead, and paste just
            // before the newline character of the line we are on right now.
            text = '\n' + text.slice(0, text.length - 1);
            cur.ch = lineLength(cm, cur.line);
          } else {
            cur.ch = 0;
          }
        } else {
          cur.ch += actionArgs.after ? 1 : 0;
        }
        cm.replaceRange(text, cur);
        // Now fine tune the cursor to where we want it.
        var curPosFinal;
        var idx;
        if (linewise && actionArgs.after) {
          curPosFinal = { line: cur.line + 1,
              ch: findFirstNonWhiteSpaceCharacter(cm.getLine(cur.line + 1)) };
        } else if (linewise && !actionArgs.after) {
          curPosFinal = { line: cur.line,
              ch: findFirstNonWhiteSpaceCharacter(cm.getLine(cur.line)) };
        } else if (!linewise && actionArgs.after) {
          idx = cm.indexFromPos(cur);
          curPosFinal = cm.posFromIndex(idx + text.length - 1);
        } else {
          idx = cm.indexFromPos(cur);
          curPosFinal = cm.posFromIndex(idx + text.length);
        }
        cm.setCursor(curPosFinal);
      },
      undo: function(cm, actionArgs) {
        repeatFn(cm, CodeMirror.commands.undo, actionArgs.repeat)();
      },
      redo: function(cm, actionArgs) {
        repeatFn(cm, CodeMirror.commands.redo, actionArgs.repeat)();
      },
      setRegister: function(cm, actionArgs, vim) {
        vim.inputState.registerName = actionArgs.selectedCharacter;
      },
      setMark: function(cm, actionArgs, vim) {
        var markName = actionArgs.selectedCharacter;
        if (!inArray(markName, validMarks)) {
          return;
        }
        if (vim.marks[markName]) {
          vim.marks[markName].clear();
        }
        vim.marks[markName] = cm.setBookmark(cm.getCursor());
      },
      replace: function(cm, actionArgs) {
        var replaceWith = actionArgs.selectedCharacter;
        var curStart = cm.getCursor();
        var line = cm.getLine(curStart.line);
        var replaceTo = curStart.ch + actionArgs.repeat;
        if (replaceTo > line.length) {
          return;
        }
        var curEnd = { line: curStart.line, ch: replaceTo };
        var replaceWithStr = '';
        for (var i = 0; i < curEnd.ch - curStart.ch; i++) {
          replaceWithStr += replaceWith;
        }
        cm.replaceRange(replaceWithStr, curStart, curEnd);
        cm.setCursor(offsetCursor(curEnd, 0, -1));
      }
    };

    var textObjects = {
      // TODO: lots of possible exceptions that can be thrown here. Try da(
      //     outside of a () block.
      // TODO: implement text objects for the reverse like }. Should just be
      //     an additional mapping after moving to the defaultKeyMap.
      'w': function(cm, inclusive) {
        return expandWordUnderCursor(cm, inclusive, true /** forward */,
            false /** bigWord */);
      },
      'W': function(cm, inclusive) {
        return expandWordUnderCursor(cm, inclusive,
            true /** forward */, true /** bigWord */);
      },
      '{': function(cm, inclusive) {
        return selectCompanionObject(cm, '}', inclusive);
      },
      '(': function(cm, inclusive) {
        return selectCompanionObject(cm, ')', inclusive);
      },
      '[': function(cm, inclusive) {
        return selectCompanionObject(cm, ']', inclusive);
      },
      '\'': function(cm, inclusive) {
        return findBeginningAndEnd(cm, "'", inclusive);
      },
      '\"': function(cm, inclusive) {
        return findBeginningAndEnd(cm, '"', inclusive);
      }
    };

    /*
     * Below are miscellaneous utility functions used by vim.js
     */

    /**
     * Clips cursor to ensure that:
     *   0 <= cur.ch < lineLength
     *       AND
     *   0 <= cur.line < lineCount
     * If includeLineBreak is true, then allow cur.ch == lineLength.
     */
    function clipCursorToContent(cm, cur, includeLineBreak) {
      var line = Math.min(Math.max(0, cur.line), cm.lineCount() - 1);
      var maxCh = lineLength(cm, line) - 1;
      maxCh = (includeLineBreak) ? maxCh + 1 : maxCh;
      var ch = Math.min(Math.max(0, cur.ch), maxCh);
      return { line: line, ch: ch };
    }
    // Merge arguments in place, for overriding arguments.
    function mergeArgs(to, from) {
      for (var prop in from) {
        if (from.hasOwnProperty(prop)) {
          to[prop] = from[prop];
        }
      }
    }
    function copyArgs(args) {
      var ret = {};
      for (var prop in args) {
        if (args.hasOwnProperty(prop)) {
          ret[prop] = args[prop];
        }
      }
      return ret;
    }
    function offsetCursor(cur, offsetLine, offsetCh) {
      return { line: cur.line + offsetLine, ch: cur.ch + offsetCh };
    }
    function arrayEq(a1, a2) {
      if (a1.length != a2.length) {
        return false;
      }
      for (var i = 0; i < a1.length; i++) {
        if (a1[i] != a2[i]) {
          return false;
        }
      }
      return true;
    }
    function matchKeysPartial(pressed, mapped) {
      for (var i = 0; i < pressed.length; i++) {
        // 'character' means any character. For mark, register commads, etc.
        if (pressed[i] != mapped[i] && mapped[i] != 'character') {
          return false;
        }
      }
      return true;
    }
    function arrayIsSubsetFromBeginning(small, big) {
      for (var i = 0; i < small.length; i++) {
        if (small[i] != big[i]) {
          return false;
        }
      }
      return true;
    }
    function repeatFn(cm, fn, repeat) {
      return function() {
        for (var i = 0; i < repeat; i++) {
          fn(cm);
        }
      };
    }
    function copyCursor(cur) {
      return { line: cur.line, ch: cur.ch };
    }
    function cursorEqual(cur1, cur2) {
      return cur1.ch == cur2.ch && cur1.line == cur2.line;
    }
    function cursorIsBefore(cur1, cur2) {
      if (cur1.line < cur2.line) {
        return true;
      } else if (cur1.line == cur2.line && cur1.ch < cur2.ch) {
        return true;
      }
      return false;
    }
    function lineLength(cm, lineNum) {
      return cm.getLine(lineNum).length;
    }
    function reverse(s){
      return s.split("").reverse().join("");
    }
    function trim(s) {
      if (s.trim) {
        return s.trim();
      } else {
        return s.replace(/^\s+|\s+$/g, '');
      }
    }
    function escapeRegex(s) {
      return s.replace(/([.?*+$\[\]\/\\(){}|\-])/g, "\\$1");
    }

    function exitVisualMode(cm, vim) {
      vim.visualMode = false;
      vim.visualLine = false;
      var selectionStart = cm.getCursor('anchor');
      var selectionEnd = cm.getCursor('head');
      if (!cursorEqual(selectionStart, selectionEnd)) {
        // Clear the selection and set the cursor only if the selection has not
        // already been cleared. Otherwise we risk moving the cursor somewhere
        // it's not supposed to be.
        cm.setCursor(clipCursorToContent(cm, selectionEnd));
      }
    }

    // Remove any trailing newlines from the selection. For
    // example, with the caret at the start of the last word on the line,
    // 'dw' should word, but not the newline, while 'w' should advance the
    // caret to the first character of the next line.
    function clipToLine(cm, curStart, curEnd) {
      var selection = cm.getRange(curStart, curEnd);
      var lines = selection.split('\n');
      if (lines.length > 1 && isWhiteSpaceString(lines.pop())) {
        curEnd.line--;
        curEnd.ch = lineLength(cm, curEnd.line);
      }
    }

    // Expand the selection to line ends.
    function expandSelectionToLine(cm, curStart, curEnd) {
      curStart.ch = 0;
      curEnd.ch = 0;
      curEnd.line++;
    }

    function findFirstNonWhiteSpaceCharacter(text) {
      if (!text) {
        return 0;
      }
      var firstNonWS = text.search(/\S/);
      return firstNonWS == -1 ? text.length : firstNonWS;
    }

    function expandWordUnderCursor(cm, inclusive, forward, bigWord, noSymbol) {
      var cur = cm.getCursor();
      var line = cm.getLine(cur.line);
      var idx = cur.ch;

      // Seek to first word or non-whitespace character, depending on if
      // noSymbol is true.
      var textAfterIdx = line.substring(idx);
      var firstMatchedChar;
      if (noSymbol) {
        firstMatchedChar = textAfterIdx.search(/\w/);
      } else {
        firstMatchedChar = textAfterIdx.search(/\S/);
      }
      if (firstMatchedChar == -1) {
        return null;
      }
      idx += firstMatchedChar;
      textAfterIdx = line.substring(idx);
      var textBeforeIdx = line.substring(0, idx);

      var matchRegex;
      // Greedy matchers for the "word" we are trying to expand.
      if (bigWord) {
        matchRegex = /^\S+/;
      } else {
        if ((/\w/).test(line.charAt(idx))) {
          matchRegex = /^\w+/;
        } else {
          matchRegex = /^[^\w\s]+/;
        }
      }

      var wordAfterRegex = matchRegex.exec(textAfterIdx);
      var wordStart = idx;
      var wordEnd = idx + wordAfterRegex[0].length - 1;
      // TODO: Find a better way to do this. It will be slow on very long lines.
      var wordBeforeRegex = matchRegex.exec(reverse(textBeforeIdx));
      if (wordBeforeRegex) {
        wordStart -= wordBeforeRegex[0].length;
      }

      if (inclusive) {
        wordEnd++;
      }

      return { start: { line: cur.line, ch: wordStart },
        end: { line: cur.line, ch: wordEnd }};
    }

    /*
     * Returns the boundaries of the next word. If the cursor in the middle of
     * the word, then returns the boundaries of the current word, starting at
     * the cursor. If the cursor is at the start/end of a word, and we are going
     * forward/backward, respectively, find the boundaries of the next word.
     *
     * @param {CodeMirror} cm CodeMirror object.
     * @param {Cursor} cur The cursor position.
     * @param {boolean} forward True to search forward. False to search
     *     backward.
     * @param {boolean} bigWord True if punctuation count as part of the word.
     *     False if only [a-zA-Z0-9] characters count as part of the word.
     * @return {Object{from:number, to:number, line: number}} The boundaries of
     *     the word, or null if there are no more words.
     */
    // TODO: Treat empty lines (with no whitespace) as words.
    function findWord(cm, cur, forward, bigWord) {
      var lineNum = cur.line;
      var pos = cur.ch;
      var line = cm.getLine(lineNum);
      var dir = forward ? 1 : -1;
      var regexps = bigWord ? bigWordRegexp : wordRegexp;

      while (true) {
        var stop = (dir > 0) ? line.length : -1;
        var wordStart = stop, wordEnd = stop;
        // Find bounds of next word.
        while (pos != stop) {
          var foundWord = false;
          for (var i = 0; i < regexps.length && !foundWord; ++i) {
            if (regexps[i].test(line.charAt(pos))) {
              wordStart = pos;
              // Advance to end of word.
              while (pos != stop && regexps[i].test(line.charAt(pos))) {
                pos += dir;
              }
              wordEnd = pos;
              foundWord = wordStart != wordEnd;
              if (wordStart == cur.ch && lineNum == cur.line &&
                  wordEnd == wordStart + dir) {
                // We started at the end of a word. Find the next one.
                continue;
              } else {
                return {
                  from: Math.min(wordStart, wordEnd + 1),
                  to: Math.max(wordStart, wordEnd),
                  line: lineNum };
              }
            }
          }
          if (!foundWord) {
            pos += dir;
          }
        }
        // Advance to next/prev line.
        lineNum += dir;
        if (!isLine(cm, lineNum)) {
          return null;
        }
        line = cm.getLine(lineNum);
        pos = (dir > 0) ? 0 : line.length;
      }
      // Should never get here.
      throw 'The impossible happened.';
    }

    /**
     * @param {CodeMirror} cm CodeMirror object.
     * @param {int} repeat Number of words to move past.
     * @param {boolean} forward True to search forward. False to search
     *     backward.
     * @param {boolean} wordEnd True to move to end of word. False to move to
     *     beginning of word.
     * @param {boolean} bigWord True if punctuation count as part of the word.
     *     False if only alphabet characters count as part of the word.
     * @return {Cursor} The position the cursor should move to.
     */
    function moveToWord(cm, repeat, forward, wordEnd, bigWord) {
      var cur = cm.getCursor();
      for (var i = 0; i < repeat; i++) {
        var startCh = cur.ch, startLine = cur.line, word;
        var movedToNextWord = false;
        while (!movedToNextWord) {
          // Search and advance.
          word = findWord(cm, cur, forward, bigWord);
          movedToNextWord = true;
          if (word) {
            // Move to the word we just found. If by moving to the word we end
            // up in the same spot, then move an extra character and search
            // again.
            cur.line = word.line;
            if (forward && wordEnd) {
              // 'e'
              cur.ch = word.to - 1;
            } else if (forward && !wordEnd) {
              // 'w'
              if (inRangeInclusive(cur.ch, word.from, word.to) &&
                  word.line == startLine) {
                // Still on the same word. Go to the next one.
                movedToNextWord = false;
                cur.ch = word.to - 1;
              } else {
                cur.ch = word.from;
              }
            } else if (!forward && wordEnd) {
              // 'ge'
              if (inRangeInclusive(cur.ch, word.from, word.to) &&
                  word.line == startLine) {
                // still on the same word. Go to the next one.
                movedToNextWord = false;
                cur.ch = word.from;
              } else {
                cur.ch = word.to;
              }
            } else if (!forward && !wordEnd) {
              // 'b'
              cur.ch = word.from;
            }
          } else {
            // No more words to be found. Move to the end.
            if (forward) {
              return { line: cur.line, ch: lineLength(cm, cur.line) };
            } else {
              return { line: cur.line, ch: 0 };
            }
          }
        }
      }
      return cur;
    }

    function moveToCharacter(cm, repeat, forward, character) {
      var cur = cm.getCursor();
      var start = cur.ch;
      var idx;
      for (var i = 0; i < repeat; i ++) {
        var line = cm.getLine(cur.line);
        idx = charIdxInLine(start, line, character, forward, true);
        if (idx == -1) {
          return cur;
        }
        start = idx;
      }
      return { line: cm.getCursor().line, ch: idx };
    }

    function moveToColumn(cm, repeat) {
      // repeat is always >= 1, so repeat - 1 always corresponds
      // to the column we want to go to.
      var line = cm.getCursor().line;
      return clipCursorToContent(cm, { line: line, ch: repeat - 1 });
    }

    function charIdxInLine(start, line, character, forward, includeChar) {
      // Search for char in line.
      // motion_options: {forward, includeChar}
      // If includeChar = true, include it too.
      // If forward = true, search forward, else search backwards.
      // If char is not found on this line, do nothing
      var idx;
      if (forward) {
        idx = line.indexOf(character, start + 1);
        if (idx != -1 && !includeChar) {
          idx -= 1;
        }
      } else {
        idx = line.lastIndexOf(character, start - 1);
        if (idx != -1 && !includeChar) {
          idx += 1;
        }
      }
      return idx;
    }

    function findMatchedSymbol(cm, cur, symb) {
      var line = cur.line;
      symb = symb ? symb : cm.getLine(line).charAt(cur.ch);

      // Are we at the opening or closing char
      var forwards = inArray(symb, ['(', '[', '{']);

      var reverseSymb = ({
        '(': ')', ')': '(',
        '[': ']', ']': '[',
        '{': '}', '}': '{'})[symb];

      // Couldn't find a matching symbol, abort
      if (!reverseSymb) {
        return cur;
      }

      // set our increment to move forward (+1) or backwards (-1)
      // depending on which bracket we're matching
      var increment = ({'(': 1, '{': 1, '[': 1})[symb] || -1;
      var depth = 1, nextCh = symb, index = cur.ch, lineText = cm.getLine(line);
      // Simple search for closing paren--just count openings and closings till
      // we find our match
      // TODO: use info from CodeMirror to ignore closing brackets in comments
      // and quotes, etc.
      while (nextCh && depth > 0) {
        index += increment;
        nextCh = lineText.charAt(index);
        if (!nextCh) {
          line += increment;
          index = 0;
          lineText = cm.getLine(line) || '';
          nextCh = lineText.charAt(index);
        }
        if (nextCh === symb) {
          depth++;
        } else if (nextCh === reverseSymb) {
          depth--;
        }
      }

      if (nextCh) {
        return { line: line, ch: index };
      }
      return cur;
    }

    function selectCompanionObject(cm, revSymb, inclusive) {
      var cur = cm.getCursor();

      var end = findMatchedSymbol(cm, cur, revSymb);
      var start = findMatchedSymbol(cm, end);
      start.ch += inclusive ? 1 : 0;
      end.ch += inclusive ? 0 : 1;

      return { start: start, end: end };
    }

    function regexLastIndexOf(string, pattern, startIndex) {
      for (var i = !startIndex ? string.length : startIndex;
          i >= 0; --i) {
        if (pattern.test(string.charAt(i))) {
          return i;
        }
      }
      return -1;
    }

    // Takes in a symbol and a cursor and tries to simulate text objects that
    // have identical opening and closing symbols
    // TODO support across multiple lines
    function findBeginningAndEnd(cm, symb, inclusive) {
      var cur = cm.getCursor();
      var line = cm.getLine(cur.line);
      var chars = line.split('');
      var start, end, i, len;
      var firstIndex = chars.indexOf(symb);

      // the decision tree is to always look backwards for the beginning first,
      // but if the cursor is in front of the first instance of the symb,
      // then move the cursor forward
      if (cur.ch < firstIndex) {
        cur.ch = firstIndex;
        // Why is this line even here???
        // cm.setCursor(cur.line, firstIndex+1);
      }
      // otherwise if the cursor is currently on the closing symbol
      else if (firstIndex < cur.ch && chars[cur.ch] == symb) {
        end = cur.ch; // assign end to the current cursor
        --cur.ch; // make sure to look backwards
      }

      // if we're currently on the symbol, we've got a start
      if (chars[cur.ch] == symb && !end) {
        start = cur.ch + 1; // assign start to ahead of the cursor
      } else {
        // go backwards to find the start
        for (i = cur.ch; i > -1 && !start; i--) {
          if (chars[i] == symb) {
            start = i + 1;
          }
        }
      }

      // look forwards for the end symbol
      if (start && !end) {
        for (i = start, len = chars.length; i < len && !end; i++) {
          if (chars[i] == symb) {
            end = i;
          }
        }
      }

      // nothing found
      if (!start || !end) {
        return { start: cur, end: cur };
      }

      // include the symbols
      if (inclusive) {
        --start; ++end;
      }

      return {
        start: { line: cur.line, ch: start },
        end: { line: cur.line, ch: end }
      };
    }

    // Search functions
    function SearchState() {
      // Highlighted text that match the query.
      this.marked = null;
    }
    SearchState.prototype = {
      getQuery: function() {
        return getVimGlobalState().query;
      },
      setQuery: function(query) {
        getVimGlobalState().query = query;
      },
      getMarked: function() {
        return this.marked;
      },
      setMarked: function(marked) {
        this.marked = marked;
      },
      isReversed: function() {
        return getVimGlobalState().isReversed;
      },
      setReversed: function(reversed) {
        getVimGlobalState().isReversed = reversed;
      }
    };
    function getSearchState(cm) {
      var vim = getVimState(cm);
      return vim.searchState_ || (vim.searchState_ = new SearchState());
    }
    function dialog(cm, text, shortText, callback) {
      if (cm.openDialog) {
        cm.openDialog(text, callback, {bottom: true});
      }
      else {
        callback(prompt(shortText, ""));
      }
    }
    function findUnescapedSlashes(str) {
      var escapeNextChar = false;
      var slashes = [];
      for (var i = 0; i < str.length; i++) {
        var c = str.charAt(i);
        if (!escapeNextChar && c == '/') {
          slashes.push(i);
        }
        escapeNextChar = (c == '\\');
      }
      return slashes;
    }
    /**
     * Extract the regular expression from the query and return a Regexp object.
     * Returns null if the query is blank.
     * If ignoreCase is passed in, the Regexp object will have the 'i' flag set.
     * If smartCase is passed in, and the query contains upper case letters,
     *   then ignoreCase is overridden, and the 'i' flag will not be set.
     * If the query contains the /i in the flag part of the regular expression,
     *   then both ignoreCase and smartCase are ignored, and 'i' will be passed
     *   through to the Regex object.
     */
    function parseQuery(cm, query, ignoreCase, smartCase) {
      // First try to extract regex + flags from the input. If no flags found,
      // extract just the regex. IE does not accept flags directly defined in
      // the regex string in the form /regex/flags
      var slashes = findUnescapedSlashes(query);
      var regexPart;
      var forceIgnoreCase;
      if (!slashes.length) {
        // Query looks like 'regexp'
        regexPart = query;
      } else {
        // Query looks like 'regexp/...'
        regexPart = query.substring(0, slashes[0]);
        var flagsPart = query.substring(slashes[0]);
        forceIgnoreCase = (flagsPart.indexOf('i') != -1);
      }
      if (!regexPart) {
        return null;
      }
      if (smartCase) {
        ignoreCase = (/^[^A-Z]*$/).test(regexPart);
      }
      try {
        var regexp = new RegExp(regexPart,
            (ignoreCase || forceIgnoreCase) ? 'i' : undefined);
        return regexp;
      } catch (e) {
        showConfirm(cm, 'Invalid regex: ' + regexPart);
      }
    }
    function showConfirm(cm, text) {
      if (cm.openConfirm) {
        cm.openConfirm('<span style="color: red">' + text +
            '</span> <button type="button">OK</button>', function() {},
            {bottom: true});
      } else {
        alert(text);
      }
    }
    function makePrompt(prefix, desc) {
      var raw = '';
      if (prefix) {
        raw += '<span style="font-family: monospace">' + prefix + '</span>';
      }
      raw += '<input type="text"/> ' +
          '<span style="color: #888">';
      if (desc) {
        raw += '<span style="color: #888">';
        raw += desc;
        raw += '</span>';
      }
      return raw;
    }
    var searchPromptDesc = '(Javascript regexp)';
    function showPrompt(cm, onPromptClose, prefix, desc) {
      var shortText = (prefix || '') + ' ' + (desc || '');
      dialog(cm, makePrompt(prefix, desc), shortText, onPromptClose);
    }
    function regexEqual(r1, r2) {
      if (r1 instanceof RegExp && r2 instanceof RegExp) {
          var props = ["global", "multiline", "ignoreCase", "source"];
          for (var i = 0; i < props.length; i++) {
              var prop = props[i];
              if (r1[prop] !== r2[prop]) {
                  return(false);
              }
          }
          return(true);
      }
      return(false);
    }
    function updateSearchQuery(cm, rawQuery, ignoreCase, smartCase) {
      cm.operation(function() {
        var state = getSearchState(cm);
        if (!rawQuery) {
          return;
        }
        var query = parseQuery(cm, rawQuery, !!ignoreCase, !!smartCase);
        if (!query) {
          return;
        }
        if (regexEqual(query, state.getQuery())) {
          return;
        }
        clearSearchHighlight(cm);
        highlightSearchMatches(cm, query);
        state.setQuery(query);
      });
    }
    function highlightSearchMatches(cm, query) {
      // TODO: Highlight only text inside the viewport. Highlighting everything
      // is inefficient and expensive.
      if (cm.lineCount() < 2000) { // This is too expensive on big documents.
        var marked = [];
        for (var cursor = cm.getSearchCursor(query);
            cursor.findNext();) {
          marked.push(cm.markText(cursor.from(), cursor.to(),
              { className: 'CodeMirror-searching' }));
        }
        getSearchState(cm).setMarked(marked);
      }
    }
    function findNext(cm, prev, repeat) {
      return cm.operation(function() {
        var state = getSearchState(cm);
        var query = state.getQuery();
        if (!query) {
          return;
        }
        if (!state.getMarked()) {
          highlightSearchMatches(cm, query);
        }
        var pos = cm.getCursor();
        // If search is initiated with ? instead of /, negate direction.
        prev = (state.isReversed()) ? !prev : prev;
        if (!prev) {
          pos.ch += 1;
        }
        var cursor = cm.getSearchCursor(query, pos);
        for (var i = 0; i < repeat; i++) {
          if (!cursor.find(prev)) {
            // SearchCursor may have returned null because it hit EOF, wrap
            // around and try again.
            cursor = cm.getSearchCursor(query,
                (prev) ? { line: cm.lineCount() - 1} : {line: 0, ch: 0} );
            if (!cursor.find(prev)) {
              return;
            }
          }
        }
        return cursor.from();
      });}
    function clearSearchHighlight(cm) {
      cm.operation(function() {
        var state = getSearchState(cm);
        if (!state.getQuery()) {
          return;
        }
        var marked = state.getMarked();
        if (!marked) {
          return;
        }
        for (var i = 0; i < marked.length; ++i) {
          marked[i].clear();
        }
        state.setMarked(null);
      });}

    // Ex command handling
    // Care must be taken when adding to the default Ex command map. For any
    // pair of commands that have a shared prefix, at least one of their
    // shortNames must not match the prefix of the other command.
    var defaultExCommandMap = [
      { name: 'map', type: 'builtIn' },
      { name: 'write', shortName: 'w', type: 'builtIn' },
      { name: 'undo', shortName: 'u', type: 'builtIn' },
      { name: 'redo', shortName: 'red', type: 'builtIn' }
    ];
    var ExCommandDispatcher = function() {
      this.buildCommandMap_();
    };
    ExCommandDispatcher.prototype = {
      processCommand: function(cm, input) {
        var params = this.parseInput_(input);
        var commandName;
        if (!params.commandName) {
          // If only a line range is defined, move to the line.
          if (params.line !== undefined) {
            commandName = 'move';
          }
        } else {
          var command = this.matchCommand_(params.commandName);
          if (command) {
            commandName = command.name;
            if (command.type == 'exToKey') {
              // Handle Ex to Key mapping.
              for (var i = 0; i < command.toKeys.length; i++) {
                vim.handleKey(cm, command.toKeys[i]);
              }
              return;
            } else if (command.type == 'exToEx') {
              // Handle Ex to Ex mapping.
              this.processCommand(cm, command.toInput);
              return;
            }
          }
        }
        if (!commandName) {
          showConfirm(cm, 'Not an editor command ":' + input + '"');
          return;
        }
        exCommands[commandName](cm, params);
      },
      parseInput_: function(input) {
        var result = {};
        result.input = input;
        var idx = 0;
        // Trim preceding ':'.
        var colons = (/^:+/).exec(input);
        if (colons) {
          idx += colons[0].length;
        }

        // Parse range.
        var numberMatch = (/^(\d+)/).exec(input.substring(idx));
        if (numberMatch) {
          result.line = parseInt(numberMatch[1], 10);
          idx += numberMatch[0].length;
        }

        // Parse command name.
        var commandMatch = (/^(\w+)/).exec(input.substring(idx));
        if (commandMatch) {
          result.commandName = commandMatch[1];
          idx += commandMatch[1].length;
        }

        // Parse command-line arguments
        var args = trim(input.substring(idx)).split(/\s+/);
        if (args.length && args[0]) {
          result.commandArgs = args;
        }

        return result;
      },
      matchCommand_: function(commandName) {
        // Return the command in the command map that matches the shortest
        // prefix of the passed in command name. The match is guaranteed to be
        // unambiguous if the defaultExCommandMap's shortNames are set up
        // correctly. (see @code{defaultExCommandMap}).
        for (var i = commandName.length; i > 0; i--) {
          var prefix = commandName.substring(0, i);
          if (this.commandMap_[prefix]) {
            var command = this.commandMap_[prefix];
            if (command.name.indexOf(commandName) === 0) {
              return command;
            }
          }
        }
        return null;
      },
      buildCommandMap_: function() {
        this.commandMap_ = {};
        for (var i = 0; i < defaultExCommandMap.length; i++) {
          var command = defaultExCommandMap[i];
          var key = command.shortName || command.name;
          this.commandMap_[key] = command;
        }
      },
      map: function(lhs, rhs) {
        if (lhs.charAt(0) == ':') {
          var commandName = lhs.substring(1);
          if (rhs.charAt(0) == ':') {
            // Ex to Ex mapping
            this.commandMap_[commandName] = {
              name: commandName,
              type: 'exToEx',
              toInput: rhs.substring(1)
            };
          } else {
            // Ex to key mapping
            this.commandMap_[commandName] = {
              name: commandName,
              type: 'exToKey',
              toKeys: parseKeyString(rhs)
            };
          }
        } else {
          if (rhs.charAt(0) == ':') {
            // Key to Ex mapping.
            defaultKeymap.unshift({
              keys: parseKeyString(lhs),
              type: 'keyToEx',
              exArgs: { input: rhs.substring(1) }});
          } else {
            // Key to key mapping
            defaultKeymap.unshift({
              keys: parseKeyString(lhs),
              type: 'keyToKey',
              toKeys: parseKeyString(rhs)
            });
          }
        }
      }
    };

    // Converts a key string sequence of the form a<C-w>bd<Left> into Vim's
    // keymap representation.
    function parseKeyString(str) {
      var idx = 0;
      var keys = [];
      while (idx < str.length) {
        if (str.charAt(idx) != '<') {
          keys.push(str.charAt(idx));
          idx++;
          continue;
        }
        // Vim key notation here means desktop Vim key-notation.
        // See :help key-notation in desktop Vim.
        var vimKeyNotationStart = ++idx;
        while (str.charAt(idx++) != '>') {}
        var vimKeyNotation = str.substring(vimKeyNotationStart, idx - 1);
        var match = (/^C-(.+)$/).exec(vimKeyNotation);
        if (match) {
          var key;
          switch (match[1]) {
            case 'BS':
              key = 'Backspace';
              break;
            case 'CR':
              key = 'Enter';
              break;
            case 'Del':
              key = 'Delete';
              break;
            default:
              key = match[1];
              break;
          }
          keys.push('Ctrl-' + key);
        }
      }
      return keys;
    }

    var exCommands = {
      map: function(cm, params) {
        var mapArgs = params.commandArgs;
        if (!mapArgs || mapArgs.length < 2) {
          if (cm) {
            showConfirm(cm, 'Invalid mapping: ' + params.input);
          }
          return;
        }
        exCommandDispatcher.map(mapArgs[0], mapArgs[1], cm);
      },
      move: function(cm, params) {
        commandDispatcher.processMotion(cm, getVimState(cm), {
            motion: 'moveToLineOrEdgeOfDocument',
            motionArgs: { forward: false, explicitRepeat: true,
              linewise: true, repeat: params.line }});
      },
      redo: CodeMirror.commands.redo,
      undo: CodeMirror.commands.undo,
      write: function(cm) {
        if (CodeMirror.commands.save) {
          // If a save command is defined, call it.
          CodeMirror.commands.save(cm);
        } else {
          // Saves to text area if no save command is defined.
          cm.save();
        }
      }
    };

    var exCommandDispatcher = new ExCommandDispatcher();

    // Register Vim with CodeMirror
    function buildVimKeyMap() {
      /**
       * Handle the raw key event from CodeMirror. Translate the
       * Shift + key modifier to the resulting letter, while preserving other
       * modifers.
       */
      // TODO: Figure out a way to catch capslock.
      function handleKeyEvent_(cm, key, modifier) {
        if (isUpperCase(key)) {
          // Convert to lower case if shift is not the modifier since the key
          // we get from CodeMirror is always upper case.
          if (modifier == 'Shift') {
            modifier = null;
          }
          else {
            key = key.toLowerCase();
          }
        }
        if (modifier) {
          // Vim will parse modifier+key combination as a single key.
          key = modifier + '-' + key;
        }
        vim.handleKey(cm, key);
      }

      // Closure to bind CodeMirror, key, modifier.
      function keyMapper(key, modifier) {
        return function(cm) {
          handleKeyEvent_(cm, key, modifier);
        };
      }

      var modifiers = ['Shift', 'Ctrl'];
      var keyMap = {
        'nofallthrough': true,
        'style': 'fat-cursor'
      };
      function bindKeys(keys, modifier) {
        for (var i = 0; i < keys.length; i++) {
          var key = keys[i];
          if (!modifier && inArray(key, specialSymbols)) {
            // Wrap special symbols with '' because that's how CodeMirror binds
            // them.
            key = "'" + key + "'";
          }
          if (modifier) {
            keyMap[modifier + '-' + key] = keyMapper(keys[i], modifier);
          } else {
            keyMap[key] = keyMapper(keys[i]);
          }
        }
      }
      bindKeys(upperCaseAlphabet);
      bindKeys(upperCaseAlphabet, 'Shift');
      bindKeys(upperCaseAlphabet, 'Ctrl');
      bindKeys(specialSymbols);
      bindKeys(specialSymbols, 'Ctrl');
      bindKeys(numbers);
      bindKeys(numbers, 'Ctrl');
      bindKeys(specialKeys);
      bindKeys(specialKeys, 'Ctrl');
      return keyMap;
    }
    CodeMirror.keyMap.vim = buildVimKeyMap();

    function exitInsertMode(cm) {
      cm.setCursor(cm.getCursor().line, cm.getCursor().ch-1, true);
      cm.setOption('keyMap', 'vim');
    }

    CodeMirror.keyMap['vim-insert'] = {
      // TODO: override navigation keys so that Esc will cancel automatic
      // indentation from o, O, i_<CR>
      'Esc': exitInsertMode,
      'Ctrl-[': exitInsertMode,
      'Ctrl-C': exitInsertMode,
      'Ctrl-N': 'autocomplete',
      'Ctrl-P': 'autocomplete',
      'Enter': function(cm) {
        var fn = CodeMirror.commands.newlineAndIndentContinueComment ||
            CodeMirror.commands.newlineAndIndent;
        fn(cm);
      },
      fallthrough: ['default']
    };

    return vimApi;
  };
  // Initialize Vim and make it available as an API.
  var vim = Vim();
  CodeMirror.Vim = vim;
}
)();
