add pretzel maps

acorn.js

@@ -2615,11 +2615,30 @@
     case _lt:
       return parseXJSElement();
 
+    case _colon:
+      return parsePretzelMap();
+
     default:
       unexpected();
     }
   }
 
+  function parsePretzelMap() {
+    var node = startNode();
+    next();
+
+    var start = storeCurrentPos();
+    node.callee = parseSubscripts(parseExprAtom(), start, true);
+
+    if (eat(_parenL)) {
+      node.arguments = parseExprList(_parenR, false);
+    } else {
+      node.arguments = [];
+    }
+
+    return finishNode(node, "PretzelMapExpression");
+  }
+
   // New's precedence is slightly tricky. It must allow its argument
   // to be a `[]` or dot subscript expression, but not a call — at
   // least, not without wrapping it in parentheses. Thus, it uses the

package.json

@@ -2,7 +2,7 @@
   "name": "acorn-6to5",
   "description": "Acorn fork used by 6to5",
   "main": "acorn.js",
-  "version": "0.9.1-8",
+  "version": "0.9.1-9",
   "maintainers": [
     {
       "name": "Marijn Haverbeke",

test/tests-6to5-playground.js

@@ -4,6 +4,110 @@ if (typeof exports != "undefined") {
   var testAssert = require("./driver.js").testAssert;
 }
 
+// Pretzel map
+
+test("arr.map(:toUpperCase)", {
+  type: "Program",
+  start: 0,
+  end: 21,
+  body: [{
+    type: "ExpressionStatement",
+    start: 0,
+    end: 21,
+    expression: {
+      type: "CallExpression",
+      start: 0,
+      end: 21,
+      callee: {
+        type: "MemberExpression",
+        start: 0,
+        end: 7,
+        object: {
+          type: "Identifier",
+          start: 0,
+          end: 3,
+          name: "arr"
+        },
+        property: {
+          type: "Identifier",
+          start: 4,
+          end: 7,
+          name: "map"
+        },
+        computed: false
+      },
+      arguments: [{
+        type: "PretzelMapExpression",
+        start: 8,
+        end: 20,
+        callee: {
+          type: "Identifier",
+          start: 9,
+          end: 20,
+          name: "toUpperCase"
+        },
+        arguments: []
+      }]
+    }
+  }]
+}, {
+  playground: true
+});
+
+test("arr.map(:toFixed(2))", {
+  type: "Program",
+  start: 0,
+  end: 20,
+  body: [{
+    type: "ExpressionStatement",
+    start: 0,
+    end: 20,
+    expression: {
+      type: "CallExpression",
+      start: 0,
+      end: 20,
+      callee: {
+        type: "MemberExpression",
+        start: 0,
+        end: 7,
+        object: {
+          type: "Identifier",
+          start: 0,
+          end: 3,
+          name: "arr"
+        },
+        property: {
+          type: "Identifier",
+          start: 4,
+          end: 7,
+          name: "map"
+        },
+        computed: false
+      },
+      arguments: [{
+        type: "PretzelMapExpression",
+        start: 8,
+        end: 19,
+        callee: {
+          type: "Identifier",
+          start: 9,
+          end: 16,
+          name: "toFixed"
+        },
+        arguments: [{
+          type: "Literal",
+          start: 17,
+          end: 18,
+          value: 2,
+          raw: "2"
+        }]
+      }]
+    }
+  }]
+}, {
+  playground: true
+});
+
 // Memoization assignment operator
 
 testFail("obj ?= 2;", "You can only use member expressions in memoization assignment (1:0)");