_createPartial.js•1.38 kB
var apply = require('./_apply'),
createCtor = require('./_createCtor'),
root = require('./_root');
/** Used to compose bitmasks for function metadata. */
var WRAP_BIND_FLAG = 1;
/**
* Creates a function that wraps `func` to invoke it with the `this` binding
* of `thisArg` and `partials` prepended to the arguments it receives.
*
* @private
* @param {Function} func The function to wrap.
* @param {number} bitmask The bitmask flags. See `createWrap` for more details.
* @param {*} thisArg The `this` binding of `func`.
* @param {Array} partials The arguments to prepend to those provided to
* the new function.
* @returns {Function} Returns the new wrapped function.
*/
function createPartial(func, bitmask, thisArg, partials) {
var isBind = bitmask & WRAP_BIND_FLAG,
Ctor = createCtor(func);
function wrapper() {
var argsIndex = -1,
argsLength = arguments.length,
leftIndex = -1,
leftLength = partials.length,
args = Array(leftLength + argsLength),
fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;
while (++leftIndex < leftLength) {
args[leftIndex] = partials[leftIndex];
}
while (argsLength--) {
args[leftIndex++] = arguments[++argsIndex];
}
return apply(fn, isBind ? thisArg : this, args);
}
return wrapper;
}
module.exports = createPartial;