[d565449] | 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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