43 lines
1.3 KiB
JavaScript
43 lines
1.3 KiB
JavaScript
var apply = require('./_apply'),
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createCtor = require('./_createCtor'),
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root = require('./_root');
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/** Used to compose bitmasks for function metadata. */
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var WRAP_BIND_FLAG = 1;
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/**
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* Creates a function that wraps `func` to invoke it with the `this` binding
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* of `thisArg` and `partials` prepended to the arguments it receives.
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*
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* @private
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* @param {Function} func The function to wrap.
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* @param {number} bitmask The bitmask flags. See `createWrap` for more details.
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* @param {*} thisArg The `this` binding of `func`.
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* @param {Array} partials The arguments to prepend to those provided to
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* the new function.
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* @returns {Function} Returns the new wrapped function.
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*/
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function createPartial(func, bitmask, thisArg, partials) {
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var isBind = bitmask & WRAP_BIND_FLAG,
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Ctor = createCtor(func);
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function wrapper() {
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var argsIndex = -1,
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argsLength = arguments.length,
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leftIndex = -1,
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leftLength = partials.length,
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args = Array(leftLength + argsLength),
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fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;
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while (++leftIndex < leftLength) {
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args[leftIndex] = partials[leftIndex];
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}
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while (argsLength--) {
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args[leftIndex++] = arguments[++argsIndex];
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}
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return apply(fn, isBind ? thisArg : this, args);
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}
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return wrapper;
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}
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module.exports = createPartial;
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