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Merge pull request #486 from kitcambridge/uniq

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`_.uniq()` should work with sparse arrays.
This commit is contained in:
Jeremy Ashkenas
2012-02-21 09:43:54 -08:00
parent 23931b2716 8808f7d531
commit c99cfca75e
2 changed files with 30 additions and 6 deletions
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22
test/arrays.js
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@@ -89,6 +89,28 @@ $(document).ready(function() {
var result = (function(){ return _.uniq(arguments); })(1, 2, 1, 3, 1, 4);
equal(result.join(', '), '1, 2, 3, 4', 'works on an arguments object');
var list = [];
list[2] = list[3] = null;
list[8] = 2;
list[10] = 2;
list[11] = 5;
list[14] = 5;
list[16] = 8;
list[19] = 8;
list[26] = list[29] = undefined;
list[33] = "hi";
var result = _.uniq(list, true);
if (0 in [undefined]) {
// According to the JScript ES 3 spec, section 2.1.26, JScript 5.x (IE <=
// 8) treats `undefined` elements in arrays as elisions.
deepEqual(result, [null, 2, 5, 8, undefined, "hi"], "Works with sorted sparse arrays");
equal(result.length, 6, "The resulting array should not be sparse");
} else {
deepEqual(result, [null, 2, 5, 8, "hi"], "Works with sorted sparse arrays where `undefined` elements are elided");
equal(result.length, 5, "The resulting array should not be sparse");
}
});
test("arrays: intersection", function() {

14
underscore.js
View File

@@ -372,15 +372,17 @@
// Aliased as `unique`.
_.uniq = _.unique = function(array, isSorted, iterator) {
var initial = iterator ? _.map(array, iterator) : array;
var result = [];
_.reduce(initial, function(memo, el, i) {
if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) {
memo[memo.length] = el;
result[result.length] = array[i];
var results = [];
// The `isSorted` flag is irrelevant if the array only contains two elements.
if (array.length < 3) isSorted = true;
_.reduce(initial, function (memo, value, index) {
if (isSorted ? _.last(memo) !== value || !memo.length : !_.include(memo, value)) {
memo.push(value);
results.push(array[index]);
}
return memo;
}, []);
return result;
return results;
};
// Produce an array that contains the union: each distinct element from all of