[[FEAT]] Implement support for object spread/rest

package.json

@@ -34,7 +34,7 @@
     "test-cli": "nodeunit tests/cli.js",
     "test-node": "npm run test-unit && npm run test-cli && npm run test-regression",
     "test-regression": "nodeunit tests/regression",
-    "test-unit": "nodeunit tests/unit",
+    "test-unit": "nodeunit tests/unit tests/unit/unstable",
     "test": "npm run test-node && npm run test-browser"
   },
   "main": "./src/jshint.js",

src/jshint.js

@@ -3344,6 +3344,13 @@ var JSHINT = (function() {
           } else if (nextVal === "set" && i && f["(metrics)"].arity !== 1) {
             warning("W077", t, i);
           }
+
+        } else if (spreadrest("spread")) {
+          if (!state.option.unstable.objspreadrest) {
+            warning("W144", state.tokens.next, "object spread property", "objspreadrest");
+          }
+
+          expression(10);
         } else {
           if (state.tokens.next.value === "*" && state.tokens.next.type === "(punctuator)") {
             if (!state.inES6()) {
@@ -3478,8 +3485,19 @@ var JSHINT = (function() {
         nextInnerDE();
       } else {
         // this id will either be the property name or the property name and the assigning identifier
-        id = identifier();
-        if (checkPunctuator(state.tokens.next, ":")) {
+        var isRest = spreadrest("rest");
+
+        if (isRest) {
+          if (!state.option.unstable.objspreadrest) {
+            warning("W144", state.tokens.next, "object rest property", "objspreadrest");
+          }
+
+          nextInnerDE();
+        } else {
+          id = identifier();
+        }
+
+        if (!isRest && checkPunctuator(state.tokens.next, ":")) {
           advance(":");
           nextInnerDE();
         } else if (id) {
@@ -3489,6 +3507,10 @@ var JSHINT = (function() {
           }
           identifiers.push({ id: id, token: state.tokens.curr });
         }
+
+        if (isRest && checkPunctuator(state.tokens.next, ",")) {
+          warning("W130", state.tokens.next);
+        }
       }
     };
 

src/messages.js

@@ -234,7 +234,8 @@ var warnings = {
   W141: "Empty {a}: this is unnecessary and can be removed.",
   W142: "Empty {a}: consider replacing with `import '{b}';`.",
   W143: "Assignment to properties of a mapped arguments object may cause " +
-    "unexpected changes to formal parameters."
+    "unexpected changes to formal parameters.",
+  W144: "'{a}' is a non-standard language feature. Enable it using the '{b}' unstable option."
 };
 
 var info = {

src/options.js

@@ -1011,7 +1011,34 @@ exports.val = {
  * the presence and behavior of these options is volatile; JSHint reserves the
  * right to remove or modify them between major version releases.
  */
-exports.unstable = {};
+exports.unstable = {
+  /**
+   * Enable parsing support for rest properties for object destructuring
+   * assignment and spread properties for object literals. From the proposal:
+   *
+   * > Rest Properties
+   * >
+   * > Rest properties collect the remaining own enumerable property keys that
+   * > are not already picked off by the destructuring pattern. Those keys and
+   * > their values are copied onto a new object.
+   * >
+   * >     let { x, y, ...z } = { x: 1, y: 2, a: 3, b: 4 };
+   * >     x; // 1
+   * >     y; // 2
+   * >     z; // { a: 3, b: 4 }
+   * >
+   * > Spread Properties
+   * >
+   * > Spread properties in object initializers copies own enumerable
+   * > properties from a provided object onto the newly created object.
+   * >
+   * >     let n = { x, y, ...z };
+   * >     n; // { x: 1, y: 2, a: 3, b: 4 }
+   *
+   * https://github.com/tc39/proposal-object-rest-spread
+   */
+  objspreadrest: true
+};
 
 // These are JSHint boolean options which are shared with JSLint
 // where the definition in JSHint is opposite JSLint