1 | var apply = require('./_apply'),
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2 | arrayMap = require('./_arrayMap'),
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3 | baseIteratee = require('./_baseIteratee'),
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4 | baseRest = require('./_baseRest');
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5 |
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6 | /** Error message constants. */
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7 | var FUNC_ERROR_TEXT = 'Expected a function';
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8 |
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9 | /**
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10 | * Creates a function that iterates over `pairs` and invokes the corresponding
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11 | * function of the first predicate to return truthy. The predicate-function
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12 | * pairs are invoked with the `this` binding and arguments of the created
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13 | * function.
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14 | *
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15 | * @static
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16 | * @memberOf _
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17 | * @since 4.0.0
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18 | * @category Util
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19 | * @param {Array} pairs The predicate-function pairs.
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20 | * @returns {Function} Returns the new composite function.
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21 | * @example
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22 | *
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23 | * var func = _.cond([
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24 | * [_.matches({ 'a': 1 }), _.constant('matches A')],
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25 | * [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
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26 | * [_.stubTrue, _.constant('no match')]
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27 | * ]);
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28 | *
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29 | * func({ 'a': 1, 'b': 2 });
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30 | * // => 'matches A'
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31 | *
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32 | * func({ 'a': 0, 'b': 1 });
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33 | * // => 'matches B'
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34 | *
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35 | * func({ 'a': '1', 'b': '2' });
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36 | * // => 'no match'
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37 | */
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38 | function cond(pairs) {
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39 | var length = pairs == null ? 0 : pairs.length,
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40 | toIteratee = baseIteratee;
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41 |
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42 | pairs = !length ? [] : arrayMap(pairs, function(pair) {
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43 | if (typeof pair[1] != 'function') {
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44 | throw new TypeError(FUNC_ERROR_TEXT);
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45 | }
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46 | return [toIteratee(pair[0]), pair[1]];
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47 | });
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48 |
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49 | return baseRest(function(args) {
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50 | var index = -1;
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51 | while (++index < length) {
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52 | var pair = pairs[index];
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53 | if (apply(pair[0], this, args)) {
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54 | return apply(pair[1], this, args);
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55 | }
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56 | }
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57 | });
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58 | }
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59 |
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60 | module.exports = cond;
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