add support for private declarations

acorn.js

@@ -2008,7 +2008,9 @@
             return parseLabeledStatement(node, maybeName, expr);
           }
 
-          if (expr.name === "declare") {
+          if (options.ecmaVersion >= 7 && expr.name === "private" && tokType === _name) {
+            return parsePrivate(node);
+          } else if (expr.name === "declare") {
             if (tokType === _class || tokType === _name || tokType === _function || tokType === _var) {
               return parseDeclare(node);
             }
@@ -2988,6 +2990,15 @@
     }
   }
 
+  function parsePrivate(node) {
+    node.declarations = [];
+    do {
+      node.declarations.push(parseIdent());
+    } while (eat(_comma));
+    semicolon();
+    return finishNode(node, "PrivateDeclaration");
+  }
+
   // Parse a class declaration or literal (depending on the
   // `isStatement` parameter).
   
@@ -3010,15 +3021,20 @@
     expect(_braceL);
     while (!eat(_braceR)) {
       var method = startNode();
+      if (options.ecmaVersion >= 7 && tokType === _name && tokVal === "private") {
+        next();
+        classBody.body.push(parsePrivate(method));
+        continue;
+      }
       if (tokType === _name && tokVal === "static") {
         next();
         method['static'] = true;
-        } else {
+      } else {
         method['static'] = false;
-        }
+      }
       var isAsync = false;
       var isGenerator = eat(_star);
-       if (options.ecmaVersion >= 7 && !isGenerator && tokType === _name && tokVal === "async") {
+      if (options.ecmaVersion >= 7 && !isGenerator && tokType === _name && tokVal === "async") {
         var asyncId = parseIdent();
         if (tokType === _colon || tokType === _parenL) {
           method.key = asyncId;

test/tests-6to5.js

@@ -2088,3 +2088,131 @@ test('delete foo::bar;', {
 }, {
   ecmaVersion: 7
 });
+
+test("private A;", {
+  type: "Program",
+  start: 0,
+  end: 10,
+  body: [{
+    type: "PrivateDeclaration",
+    start: 0,
+    end: 10,
+    declarations: [{
+      type: "Identifier",
+      start: 8,
+      end: 9,
+      name: "A"
+    }]
+  }]
+}, {
+  ecmaVersion: 7
+});
+
+test("private A, B;", {
+  type: "Program",
+  start: 0,
+  end: 13,
+  body: [{
+    type: "PrivateDeclaration",
+    start: 0,
+    end: 13,
+    declarations: [
+      {
+        type: "Identifier",
+        start: 8,
+        end: 9,
+        name: "A"
+      },
+      {
+        type: "Identifier",
+        start: 11,
+        end: 12,
+        name: "B"
+      }
+    ]
+  }]
+}, {
+  ecmaVersion: 7
+});
+
+test("class A { private A; }", {
+  type: "Program",
+  start: 0,
+  end: 22,
+  body: [{
+    type: "ClassDeclaration",
+    start: 0,
+    end: 22,
+    id: {
+      type: "Identifier",
+      start: 6,
+      end: 7,
+      name: "A"
+    },
+    superClass: null,
+    body: {
+      type: "ClassBody",
+      start: 8,
+      end: 22,
+      body: [{
+        type: "PrivateDeclaration",
+        start: 10,
+        end: 20,
+        declarations: [
+          {
+            type: "Identifier",
+            start: 18,
+            end: 19,
+            name: "A"
+          }
+        ]
+      }]
+    }
+  }]
+}, {
+  ecmaVersion: 7
+});
+
+test("class A { private A, B; }", {
+  type: "Program",
+  start: 0,
+  end: 25,
+  body: [{
+    type: "ClassDeclaration",
+    start: 0,
+    end: 25,
+    id: {
+      type: "Identifier",
+      start: 6,
+      end: 7,
+      name: "A"
+    },
+    superClass: null,
+    body: {
+      type: "ClassBody",
+      start: 8,
+      end: 25,
+      body: [{
+        type: "PrivateDeclaration",
+        start: 10,
+        end: 23,
+        declarations: [
+          {
+            type: "Identifier",
+            start: 18,
+            end: 19,
+            name: "A"
+          },
+          {
+            type: "Identifier",
+            start: 21,
+            end: 22,
+            name: "B"
+          }
+        ]
+      }]
+    }
+  }]
+}, {
+  ecmaVersion: 7
+});