1 | /** Error message constants. */
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2 | var FUNC_ERROR_TEXT = 'Expected a function';
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3 |
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4 | /**
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5 | * Creates a function that negates the result of the predicate `func`. The
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6 | * `func` predicate is invoked with the `this` binding and arguments of the
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7 | * created function.
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8 | *
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9 | * @static
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10 | * @memberOf _
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11 | * @since 3.0.0
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12 | * @category Function
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13 | * @param {Function} predicate The predicate to negate.
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14 | * @returns {Function} Returns the new negated function.
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15 | * @example
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16 | *
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17 | * function isEven(n) {
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18 | * return n % 2 == 0;
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19 | * }
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20 | *
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21 | * _.filter([1, 2, 3, 4, 5, 6], _.negate(isEven));
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22 | * // => [1, 3, 5]
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23 | */
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24 | function negate(predicate) {
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25 | if (typeof predicate != 'function') {
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26 | throw new TypeError(FUNC_ERROR_TEXT);
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27 | }
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28 | return function() {
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29 | var args = arguments;
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30 | switch (args.length) {
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31 | case 0: return !predicate.call(this);
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32 | case 1: return !predicate.call(this, args[0]);
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33 | case 2: return !predicate.call(this, args[0], args[1]);
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34 | case 3: return !predicate.call(this, args[0], args[1], args[2]);
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35 | }
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36 | return !predicate.apply(this, args);
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37 | };
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38 | }
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39 |
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40 | module.exports = negate;
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