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							109 lines
						
					
					
						
							2.9 KiB
						
					
					
				//! stable.js 0.1.8, https://github.com/Two-Screen/stable | 
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//! © 2018 Angry Bytes and contributors. MIT licensed. | 
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 | 
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(function (global, factory) { | 
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  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() : | 
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  typeof define === 'function' && define.amd ? define(factory) : | 
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  (global.stable = factory()); | 
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}(this, (function () { 'use strict'; | 
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 | 
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  // A stable array sort, because `Array#sort()` is not guaranteed stable. | 
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  // This is an implementation of merge sort, without recursion. | 
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 | 
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  var stable = function (arr, comp) { | 
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    return exec(arr.slice(), comp) | 
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  }; | 
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 | 
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  stable.inplace = function (arr, comp) { | 
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    var result = exec(arr, comp); | 
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 | 
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    // This simply copies back if the result isn't in the original array, | 
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    // which happens on an odd number of passes. | 
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    if (result !== arr) { | 
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      pass(result, null, arr.length, arr); | 
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    } | 
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 | 
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    return arr | 
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  }; | 
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 | 
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  // Execute the sort using the input array and a second buffer as work space. | 
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  // Returns one of those two, containing the final result. | 
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  function exec(arr, comp) { | 
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    if (typeof(comp) !== 'function') { | 
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      comp = function (a, b) { | 
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        return String(a).localeCompare(b) | 
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      }; | 
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    } | 
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 | 
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    // Short-circuit when there's nothing to sort. | 
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    var len = arr.length; | 
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    if (len <= 1) { | 
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      return arr | 
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    } | 
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 | 
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    // Rather than dividing input, simply iterate chunks of 1, 2, 4, 8, etc. | 
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    // Chunks are the size of the left or right hand in merge sort. | 
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    // Stop when the left-hand covers all of the array. | 
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    var buffer = new Array(len); | 
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    for (var chk = 1; chk < len; chk *= 2) { | 
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      pass(arr, comp, chk, buffer); | 
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 | 
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      var tmp = arr; | 
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      arr = buffer; | 
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      buffer = tmp; | 
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    } | 
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 | 
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    return arr | 
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  } | 
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 | 
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  // Run a single pass with the given chunk size. | 
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  var pass = function (arr, comp, chk, result) { | 
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    var len = arr.length; | 
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    var i = 0; | 
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    // Step size / double chunk size. | 
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    var dbl = chk * 2; | 
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    // Bounds of the left and right chunks. | 
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    var l, r, e; | 
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    // Iterators over the left and right chunk. | 
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    var li, ri; | 
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 | 
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    // Iterate over pairs of chunks. | 
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    for (l = 0; l < len; l += dbl) { | 
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      r = l + chk; | 
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      e = r + chk; | 
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      if (r > len) r = len; | 
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      if (e > len) e = len; | 
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 | 
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      // Iterate both chunks in parallel. | 
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      li = l; | 
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      ri = r; | 
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      while (true) { | 
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        // Compare the chunks. | 
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        if (li < r && ri < e) { | 
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          // This works for a regular `sort()` compatible comparator, | 
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          // but also for a simple comparator like: `a > b` | 
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          if (comp(arr[li], arr[ri]) <= 0) { | 
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            result[i++] = arr[li++]; | 
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          } | 
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          else { | 
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            result[i++] = arr[ri++]; | 
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          } | 
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        } | 
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        // Nothing to compare, just flush what's left. | 
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        else if (li < r) { | 
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          result[i++] = arr[li++]; | 
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        } | 
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        else if (ri < e) { | 
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          result[i++] = arr[ri++]; | 
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        } | 
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        // Both iterators are at the chunk ends. | 
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        else { | 
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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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 | 
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  return stable; | 
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 | 
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})));
 | 
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 |