44 lines
1.5 KiB
JavaScript
44 lines
1.5 KiB
JavaScript
var createCtorWrapper = require('./createCtorWrapper');
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/** Used to compose bitmasks for wrapper metadata. */
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var BIND_FLAG = 1;
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/**
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* Creates a function that wraps `func` and invokes it with the optional `this`
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* binding of `thisArg` and the `partials` prepended to those provided to
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* the wrapper.
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*
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* @private
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* @param {Function} func The function to partially apply arguments to.
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* @param {number} bitmask The bitmask of flags. See `createWrapper` 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 the new function.
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* @returns {Function} Returns the new bound function.
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*/
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function createPartialWrapper(func, bitmask, thisArg, partials) {
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var isBind = bitmask & BIND_FLAG,
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Ctor = createCtorWrapper(func);
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function wrapper() {
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// Avoid `arguments` object use disqualifying optimizations by
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// converting it to an array before providing it `func`.
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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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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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var fn = (this && this !== global && this instanceof wrapper) ? Ctor : func;
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return fn.apply(isBind ? thisArg : this, args);
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}
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return wrapper;
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}
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module.exports = createPartialWrapper;
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