From 431a44bc74de4b038f8573e63725688998aef9fd Mon Sep 17 00:00:00 2001
From: Ingvar Stepanyan <me@rreverser.com>
Date: Sun, 4 Jan 2015 12:15:24 +0200
Subject: [PATCH] Add support for destructuring defaults (not for shorthand
 props yet).

Related to #181.
---
 acorn.js              |  9 +++++
 test/tests-harmony.js | 78 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)

diff --git a/acorn.js b/acorn.js
index 1d33a45194..aa9b60664e 100644
--- a/acorn.js
+++ b/acorn.js
@@ -1412,6 +1412,14 @@
           }
           break;
 
+        case "AssignmentExpression":
+          if (node.operator === "=") {
+            node.type = "AssignmentPattern";
+          } else {
+            unexpected(node.left.end);
+          }
+          break;
+
         default:
           if (checkType) unexpected(node.start);
       }
@@ -1508,6 +1516,7 @@
         }
         break;
 
+      case "AssignmentPattern":
       case "SpreadElement":
         break;
 
diff --git a/test/tests-harmony.js b/test/tests-harmony.js
index c7cd8ea072..f59838c0d3 100644
--- a/test/tests-harmony.js
+++ b/test/tests-harmony.js
@@ -14373,3 +14373,81 @@ test('var {get} = obj;', {
     kind: "var"
   }]
 }, {ecmaVersion: 6});
+
+// Destructuring defaults (https://github.com/marijnh/acorn/issues/181)
+
+test("var {propName: localVar = defaultValue} = obj", {
+  type: "Program",
+  body: [{
+    type: "VariableDeclaration",
+    declarations: [{
+      type: "VariableDeclarator",
+      id: {
+        type: "ObjectPattern",
+        properties: [{
+          type: "Property",
+          method: false,
+          shorthand: false,
+          computed: false,
+          key: {
+            type: "Identifier",
+            name: "propName"
+          },
+          value: {
+            type: "AssignmentPattern",
+            operator: "=",
+            left: {
+              type: "Identifier",
+              name: "localVar"
+            },
+            right: {
+              type: "Identifier",
+              name: "defaultValue"
+            }
+          },
+          kind: "init"
+        }]
+      },
+      init: {
+        type: "Identifier",
+        name: "obj"
+      }
+    }],
+    kind: "var"
+  }]
+}, {ecmaVersion: 6});
+
+test("var [a = 1, b = 2] = arr", {
+  type: "Program",
+  body: [{
+    type: "VariableDeclaration",
+    declarations: [{
+      type: "VariableDeclarator",
+      id: {
+        type: "ArrayPattern",
+        elements: [
+          {
+            type: "AssignmentPattern",
+            operator: "=",
+            left: {type: "Identifier", name: "a"},
+            right: {
+              type: "Literal",
+              value: 1
+            }
+          },
+          {
+            type: "AssignmentPattern",
+            operator: "=",
+            left: {type: "Identifier", name: "b"},
+            right: {
+              type: "Literal",
+              value: 2
+            }
+          }
+        ]
+      },
+      init: {type: "Identifier", name: "arr"}
+    }],
+    kind: "var"
+  }]
+}, {ecmaVersion: 6});