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var bindCallback = require('./bindCallback'),
isIterateeCall = require('./isIterateeCall'),
restParam = require('../function/restParam');
/**
* Creates a function that assigns properties of source object(s) to a given
* destination object.
*
* **Note:** This function is used to create `_.assign`, `_.defaults`, and `_.merge`.
*
* @private
* @param {Function} assigner The function to assign values.
* @returns {Function} Returns the new assigner function.
*/
function createAssigner(assigner) {
return restParam(function(object, sources) {
var index = -1,
length = object == null ? 0 : sources.length,
customizer = length > 2 && sources[length - 2],
guard = length > 2 && sources[2],
thisArg = length > 1 && sources[length - 1];
if (typeof customizer == 'function') {
customizer = bindCallback(customizer, thisArg, 5);
length -= 2;
} else {
customizer = typeof thisArg == 'function' ? thisArg : null;
length -= (customizer ? 1 : 0);
}
if (guard && isIterateeCall(sources[0], sources[1], guard)) {
customizer = length < 3 ? null : customizer;
length = 1;
}
while (++index < length) {
var source = sources[index];
if (source) {
assigner(object, source, customizer);
}
}
return object;
});
}
module.exports = createAssigner;
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