var arrayPush = require('./_arrayPush'),
isFlattenable = require('./_isFlattenable');
/**
* The base implementation of `_.flatten` with support for restricting flattening.
*
* @private
* @param {Array} array The array to flatten.
* @param {number} depth The maximum recursion depth.
* @param {boolean} [predicate=isFlattenable] The function invoked per iteration.
* @param {boolean} [isStrict] Restrict to values that pass `predicate` checks.
* @param {Array} [result=[]] The initial result value.
* @returns {Array} Returns the new flattened array.
*/
function baseFlatten(array, depth, predicate, isStrict, result) {
var index = -1,
length = array.length;
predicate || (predicate = isFlattenable);
result || (result = []);
while (++index < length) {
var value = array[index];
if (depth > 0 && predicate(value)) {
if (depth > 1) {
// Recursively flatten arrays (susceptible to call stack limits).
baseFlatten(value, depth - 1, predicate, isStrict, result);
} else {
arrayPush(result, value);
}
} else if (!isStrict) {
result[result.length] = value;
}
}
return result;
}
module.exports = baseFlatten;