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node_modules/core-js/internals/flatten-into-array.js

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+'use strict';
+var isArray = require('../internals/is-array');
+var lengthOfArrayLike = require('../internals/length-of-array-like');
+var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer');
+var bind = require('../internals/function-bind-context');
+
+// `FlattenIntoArray` abstract operation
+// https://tc39.github.io/proposal-flatMap/#sec-FlattenIntoArray
+var flattenIntoArray = function (target, original, source, sourceLen, start, depth, mapper, thisArg) {
+  var targetIndex = start;
+  var sourceIndex = 0;
+  var mapFn = mapper ? bind(mapper, thisArg) : false;
+  var element, elementLen;
+
+  while (sourceIndex < sourceLen) {
+    if (sourceIndex in source) {
+      element = mapFn ? mapFn(source[sourceIndex], sourceIndex, original) : source[sourceIndex];
+
+      if (depth > 0 && isArray(element)) {
+        elementLen = lengthOfArrayLike(element);
+        targetIndex = flattenIntoArray(target, original, element, elementLen, targetIndex, depth - 1) - 1;
+      } else {
+        doesNotExceedSafeInteger(targetIndex + 1);
+        target[targetIndex] = element;
+      }
+
+      targetIndex++;
+    }
+    sourceIndex++;
+  }
+  return targetIndex;
+};
+
+module.exports = flattenIntoArray;