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Optimize _.sortBy by adding baseCompareAscending and compareMultipleAscending.

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This commit is contained in:
John-David Dalton
2013-12-28 19:56:52 -06:00
parent 53d7c6c085
commit 95be8b2cf3
7 changed files with 283 additions and 216 deletions
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56
dist/lodash.underscore.js vendored
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@@ -113,6 +113,27 @@
/*--------------------------------------------------------------------------*/
/**
* The base implementation of `compareAscending` used to compare values and
* sort them in ascending order without guaranteeing a stable sort.
*
* @private
* @param {*} a The value to compare to `b`.
* @param {*} b The value to compare to `a`.
* @returns {number} Returns the sort order indicator for `a`.
*/
function baseCompareAscending(a, b) {
if (a !== b) {
if (a > b || typeof a == 'undefined') {
return 1;
}
if (a < b || typeof b == 'undefined') {
return -1;
}
}
return 0;
}
/**
* The base implementation of `_.indexOf` without support for binary searches
* or `fromIndex` constraints.
@@ -136,40 +157,16 @@
}
/**
* Used by `sortBy` to compare transformed `collection` elements, stable sorting
* them in ascending order.
* Used by `sortBy` to compare transformed elements of a collection and stable
* sort them in ascending order.
*
* @private
* @param {Object} a The object to compare to `b`.
* @param {Object} b The object to compare to `a`.
* @returns {number} Returns the sort order indicator of `1` or `-1`.
* @returns {number} Returns the sort order indicator for `a`.
*/
function compareAscending(a, b) {
var ac = a.criteria,
bc = b.criteria,
index = -1,
length = ac.length;
while (++index < length) {
var value = ac[index],
other = bc[index];
if (value !== other) {
if (value > other || typeof value == 'undefined') {
return 1;
}
if (value < other || typeof other == 'undefined') {
return -1;
}
}
}
// Fixes an `Array#sort` bug in the JS engine embedded in Adobe applications
// that causes it, under certain circumstances, to return the same value for
// `a` and `b`. See https://github.com/jashkenas/underscore/pull/1247
//
// This also ensures a stable sort in V8 and other engines.
// See http://code.google.com/p/v8/issues/detail?id=90
return a.index - b.index;
return baseCompareAscending(a.criteria, b.criteria) || a.index - b.index;
}
/**
@@ -2694,6 +2691,7 @@
result[index] = result[rand];
result[rand] = value;
});
return result;
}
@@ -2842,7 +2840,7 @@
callback = createCallback(callback, thisArg, 3);
forEach(collection, function(value, key, collection) {
result[++index] = {
'criteria': [callback(value, key, collection)],
'criteria': callback(value, key, collection),
'index': index,
'value': value
};