1 | import baseRest from './_baseRest.js';
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2 | import createWrap from './_createWrap.js';
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3 | import getHolder from './_getHolder.js';
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4 | import replaceHolders from './_replaceHolders.js';
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5 |
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6 | /** Used to compose bitmasks for function metadata. */
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7 | var WRAP_BIND_FLAG = 1,
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8 | WRAP_BIND_KEY_FLAG = 2,
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9 | WRAP_PARTIAL_FLAG = 32;
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10 |
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11 | /**
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12 | * Creates a function that invokes the method at `object[key]` with `partials`
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13 | * prepended to the arguments it receives.
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14 | *
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15 | * This method differs from `_.bind` by allowing bound functions to reference
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16 | * methods that may be redefined or don't yet exist. See
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17 | * [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern)
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18 | * for more details.
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19 | *
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20 | * The `_.bindKey.placeholder` value, which defaults to `_` in monolithic
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21 | * builds, may be used as a placeholder for partially applied arguments.
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22 | *
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23 | * @static
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24 | * @memberOf _
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25 | * @since 0.10.0
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26 | * @category Function
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27 | * @param {Object} object The object to invoke the method on.
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28 | * @param {string} key The key of the method.
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29 | * @param {...*} [partials] The arguments to be partially applied.
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30 | * @returns {Function} Returns the new bound function.
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31 | * @example
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32 | *
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33 | * var object = {
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34 | * 'user': 'fred',
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35 | * 'greet': function(greeting, punctuation) {
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36 | * return greeting + ' ' + this.user + punctuation;
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37 | * }
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38 | * };
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39 | *
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40 | * var bound = _.bindKey(object, 'greet', 'hi');
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41 | * bound('!');
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42 | * // => 'hi fred!'
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43 | *
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44 | * object.greet = function(greeting, punctuation) {
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45 | * return greeting + 'ya ' + this.user + punctuation;
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46 | * };
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47 | *
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48 | * bound('!');
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49 | * // => 'hiya fred!'
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50 | *
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51 | * // Bound with placeholders.
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52 | * var bound = _.bindKey(object, 'greet', _, '!');
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53 | * bound('hi');
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54 | * // => 'hiya fred!'
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55 | */
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56 | var bindKey = baseRest(function(object, key, partials) {
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57 | var bitmask = WRAP_BIND_FLAG | WRAP_BIND_KEY_FLAG;
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58 | if (partials.length) {
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59 | var holders = replaceHolders(partials, getHolder(bindKey));
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60 | bitmask |= WRAP_PARTIAL_FLAG;
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61 | }
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62 | return createWrap(key, bitmask, object, partials, holders);
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63 | });
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64 |
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65 | // Assign default placeholders.
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66 | bindKey.placeholder = {};
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67 |
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68 | export default bindKey;
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