git.r.bdr.sh - rbdr/dotfiles/blob

   1 /* -*- Mode: js; js-indent-level: 2; -*- */
   2 /*
   3  * Copyright 2014 Mozilla Foundation and contributors
   4  * Licensed under the New BSD license. See LICENSE or:
   5  * http://opensource.org/licenses/BSD-3-Clause
   6  */
   7 if (typeof define !== 'function') {
   8     var define = require('amdefine')(module, require);
   9 }
  10 define(function (require, exports, module) {
  11
  12   var util = require('./util');
  13
  14   /**
  15    * Determine whether mappingB is after mappingA with respect to generated
  16    * position.
  17    */
  18   function generatedPositionAfter(mappingA, mappingB) {
  19     // Optimized for most common case
  20     var lineA = mappingA.generatedLine;
  21     var lineB = mappingB.generatedLine;
  22     var columnA = mappingA.generatedColumn;
  23     var columnB = mappingB.generatedColumn;
  24     return lineB > lineA || lineB == lineA && columnB >= columnA ||
  25            util.compareByGeneratedPositions(mappingA, mappingB) <= 0;
  26   }
  27
  28   /**
  29    * A data structure to provide a sorted view of accumulated mappings in a
  30    * performance conscious manner. It trades a neglibable overhead in general
  31    * case for a large speedup in case of mappings being added in order.
  32    */
  33   function MappingList() {
  34     this._array = [];
  35     this._sorted = true;
  36     // Serves as infimum
  37     this._last = {generatedLine: -1, generatedColumn: 0};
  38   }
  39
  40   /**
  41    * Iterate through internal items. This method takes the same arguments that
  42    * `Array.prototype.forEach` takes.
  43    *
  44    * NOTE: The order of the mappings is NOT guaranteed.
  45    */
  46   MappingList.prototype.unsortedForEach =
  47     function MappingList_forEach(aCallback, aThisArg) {
  48       this._array.forEach(aCallback, aThisArg);
  49     };
  50
  51   /**
  52    * Add the given source mapping.
  53    *
  54    * @param Object aMapping
  55    */
  56   MappingList.prototype.add = function MappingList_add(aMapping) {
  57     var mapping;
  58     if (generatedPositionAfter(this._last, aMapping)) {
  59       this._last = aMapping;
  60       this._array.push(aMapping);
  61     } else {
  62       this._sorted = false;
  63       this._array.push(aMapping);
  64     }
  65   };
  66
  67   /**
  68    * Returns the flat, sorted array of mappings. The mappings are sorted by
  69    * generated position.
  70    *
  71    * WARNING: This method returns internal data without copying, for
  72    * performance. The return value must NOT be mutated, and should be treated as
  73    * an immutable borrow. If you want to take ownership, you must make your own
  74    * copy.
  75    */
  76   MappingList.prototype.toArray = function MappingList_toArray() {
  77     if (!this._sorted) {
  78       this._array.sort(util.compareByGeneratedPositions);
  79       this._sorted = true;
  80     }
  81     return this._array;
  82   };
  83
  84   exports.MappingList = MappingList;
  85
  86 });