Merge commit 'be3e8236086165e5e45a5a10783823874b3f3ebd' as 'lib/vscode'

lib/vscode/extensions/json-language-features/client/src/utils/hash.ts

@@ -0,0 +1,58 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+/**
+ * Return a hash value for an object.
+ */
+export function hash(obj: any, hashVal = 0): number {
+	switch (typeof obj) {
+		case 'object':
+			if (obj === null) {
+				return numberHash(349, hashVal);
+			} else if (Array.isArray(obj)) {
+				return arrayHash(obj, hashVal);
+			}
+			return objectHash(obj, hashVal);
+		case 'string':
+			return stringHash(obj, hashVal);
+		case 'boolean':
+			return booleanHash(obj, hashVal);
+		case 'number':
+			return numberHash(obj, hashVal);
+		case 'undefined':
+			return 937 * 31;
+		default:
+			return numberHash(obj, 617);
+	}
+}
+
+function numberHash(val: number, initialHashVal: number): number {
+	return (((initialHashVal << 5) - initialHashVal) + val) | 0;  // hashVal * 31 + ch, keep as int32
+}
+
+function booleanHash(b: boolean, initialHashVal: number): number {
+	return numberHash(b ? 433 : 863, initialHashVal);
+}
+
+function stringHash(s: string, hashVal: number) {
+	hashVal = numberHash(149417, hashVal);
+	for (let i = 0, length = s.length; i < length; i++) {
+		hashVal = numberHash(s.charCodeAt(i), hashVal);
+	}
+	return hashVal;
+}
+
+function arrayHash(arr: any[], initialHashVal: number): number {
+	initialHashVal = numberHash(104579, initialHashVal);
+	return arr.reduce((hashVal, item) => hash(item, hashVal), initialHashVal);
+}
+
+function objectHash(obj: any, initialHashVal: number): number {
+	initialHashVal = numberHash(181387, initialHashVal);
+	return Object.keys(obj).sort().reduce((hashVal, key) => {
+		hashVal = stringHash(key, hashVal);
+		return hash(obj[key], hashVal);
+	}, initialHashVal);
+}