import _ from './underscore.js'; import { toString, SymbolProto } from './_setup.js'; import getByteLength from './_getByteLength.js'; import isTypedArray from './isTypedArray.js'; import isFunction from './isFunction.js'; import { hasStringTagBug } from './_stringTagBug.js'; import isDataView from './isDataView.js'; import keys from './keys.js'; import has from './_has.js'; import toBufferView from './_toBufferView.js'; // We use this string twice, so give it a name for minification. var tagDataView = '[object DataView]'; // Internal recursive comparison function for `_.isEqual`. function eq(a, b, aStack, bStack) { // Identical objects are equal. `0 === -0`, but they aren't identical. // See the [Harmony `egal` proposal](https://wiki.ecmascript.org/doku.php?id=harmony:egal). if (a === b) return a !== 0 || 1 / a === 1 / b; // `null` or `undefined` only equal to itself (strict comparison). if (a == null || b == null) return false; // `NaN`s are equivalent, but non-reflexive. if (a !== a) return b !== b; // Exhaust primitive checks var type = typeof a; if (type !== 'function' && type !== 'object' && typeof b != 'object') return false; return deepEq(a, b, aStack, bStack); } // Internal recursive comparison function for `_.isEqual`. function deepEq(a, b, aStack, bStack) { // Unwrap any wrapped objects. if (a instanceof _) a = a._wrapped; if (b instanceof _) b = b._wrapped; // Compare `[[Class]]` names. var className = toString.call(a); if (className !== toString.call(b)) return false; // Work around a bug in IE 10 - Edge 13. if (hasStringTagBug && className == '[object Object]' && isDataView(a)) { if (!isDataView(b)) return false; className = tagDataView; } switch (className) { // These types are compared by value. case '[object RegExp]': // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i') case '[object String]': // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is // equivalent to `new String("5")`. return '' + a === '' + b; case '[object Number]': // `NaN`s are equivalent, but non-reflexive. // Object(NaN) is equivalent to NaN. if (+a !== +a) return +b !== +b; // An `egal` comparison is performed for other numeric values. return +a === 0 ? 1 / +a === 1 / b : +a === +b; case '[object Date]': case '[object Boolean]': // Coerce dates and booleans to numeric primitive values. Dates are compared by their // millisecond representations. Note that invalid dates with millisecond representations // of `NaN` are not equivalent. return +a === +b; case '[object Symbol]': return SymbolProto.valueOf.call(a) === SymbolProto.valueOf.call(b); case '[object ArrayBuffer]': case tagDataView: // Coerce to typed array so we can fall through. return deepEq(toBufferView(a), toBufferView(b), aStack, bStack); } var areArrays = className === '[object Array]'; if (!areArrays && isTypedArray(a)) { var byteLength = getByteLength(a); if (byteLength !== getByteLength(b)) return false; if (a.buffer === b.buffer && a.byteOffset === b.byteOffset) return true; areArrays = true; } if (!areArrays) { if (typeof a != 'object' || typeof b != 'object') return false; // Objects with different constructors are not equivalent, but `Object`s or `Array`s // from different frames are. var aCtor = a.constructor, bCtor = b.constructor; if (aCtor !== bCtor && !(isFunction(aCtor) && aCtor instanceof aCtor && isFunction(bCtor) && bCtor instanceof bCtor) && ('constructor' in a && 'constructor' in b)) { return false; } } // Assume equality for cyclic structures. The algorithm for detecting cyclic // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`. // Initializing stack of traversed objects. // It's done here since we only need them for objects and arrays comparison. aStack = aStack || []; bStack = bStack || []; var length = aStack.length; while (length--) { // Linear search. Performance is inversely proportional to the number of // unique nested structures. if (aStack[length] === a) return bStack[length] === b; } // Add the first object to the stack of traversed objects. aStack.push(a); bStack.push(b); // Recursively compare objects and arrays. if (areArrays) { // Compare array lengths to determine if a deep comparison is necessary. length = a.length; if (length !== b.length) return false; // Deep compare the contents, ignoring non-numeric properties. while (length--) { if (!eq(a[length], b[length], aStack, bStack)) return false; } } else { // Deep compare objects. var _keys = keys(a), key; length = _keys.length; // Ensure that both objects contain the same number of properties before comparing deep equality. if (keys(b).length !== length) return false; while (length--) { // Deep compare each member key = _keys[length]; if (!(has(b, key) && eq(a[key], b[key], aStack, bStack))) return false; } } // Remove the first object from the stack of traversed objects. aStack.pop(); bStack.pop(); return true; } // Perform a deep comparison to check if two objects are equal. export default function isEqual(a, b) { return eq(a, b); }