--- /dev/null
+'use strict';
+
+var eq = require('./eq')
+ , isPlainObject = require('./is-plain-object')
+ , value = require('./valid-value')
+
+ , isArray = Array.isArray, keys = Object.keys
+ , propertyIsEnumerable = Object.prototype.propertyIsEnumerable
+
+ , eqArr, eqVal, eqObj;
+
+eqArr = function (a, b, recMap) {
+ var i, l = a.length;
+ if (l !== b.length) return false;
+ for (i = 0; i < l; ++i) {
+ if (a.hasOwnProperty(i) !== b.hasOwnProperty(i)) return false;
+ if (!eqVal(a[i], b[i], recMap)) return false;
+ }
+ return true;
+};
+
+eqObj = function (a, b, recMap) {
+ var k1 = keys(a), k2 = keys(b);
+ if (k1.length !== k2.length) return false;
+ return k1.every(function (key) {
+ if (!propertyIsEnumerable.call(b, key)) return false;
+ return eqVal(a[key], b[key], recMap);
+ });
+};
+
+eqVal = function (a, b, recMap) {
+ var i, eqX, c1, c2;
+ if (eq(a, b)) return true;
+ if (isPlainObject(a)) {
+ if (!isPlainObject(b)) return false;
+ eqX = eqObj;
+ } else if (isArray(a) && isArray(b)) {
+ eqX = eqArr;
+ } else {
+ return false;
+ }
+ c1 = recMap[0];
+ c2 = recMap[1];
+ i = c1.indexOf(a);
+ if (i !== -1) {
+ if (c2[i].indexOf(b) !== -1) return true;
+ } else {
+ i = c1.push(a) - 1;
+ c2[i] = [];
+ }
+ c2[i].push(b);
+ return eqX(a, b, recMap);
+};
+
+module.exports = function (a, b) {
+ if (eq(value(a), value(b))) return true;
+ return eqVal(Object(a), Object(b), [[], []]);
+};