| 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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