getting there with the rewriter

lib/coffee_script/rewriter.js

@@ -53,7 +53,7 @@
     this.remove_mid_expression_newlines();
     this.move_commas_outside_outdents();
     this.close_open_calls_and_indexes();
-    // this.add_implicit_parentheses()
+    this.add_implicit_parentheses();
     this.add_implicit_indentation();
     // this.ensure_balance(BALANCED_PAIRS)
     // this.rewrite_closing_parens()
@@ -182,6 +182,44 @@
       });
     })(this));
   };
+  // Methods may be optionally called without parentheses, for simple cases.
+  // Insert the implicit parentheses here, so that the parser doesn't have to
+  // deal with them.
+  re.prototype.add_implicit_parentheses = function add_implicit_parentheses() {
+    var stack;
+    stack = [0];
+    return this.scan_tokens((function(__this) {
+      var __func = function(prev, token, post, i) {
+        var __i, __j, __k, __l, idx, last, size, tmp;
+        if (token[0] === 'INDENT') {
+          stack.push(0);
+        }
+        if (token[0] === 'OUTDENT') {
+          last = stack.pop();
+          stack[stack.length - 1] += last;
+        }
+        if (stack[stack.length - 1] > 0 && (IMPLICIT_END.indexOf(token[0]) >= 0 || !(typeof post !== "undefined" && post !== null))) {
+          idx = token[0] === 'OUTDENT' ? i + 1 : i;
+          __k = 0; __l = stack[stack.length - 1];
+          for (__j=0, tmp=__k; (__k <= __l ? tmp < __l : tmp > __l); (__k <= __l ? tmp += 1 : tmp -= 1), __j++) {
+            this.tokens.splice(idx, 0, ['CALL_END', ')']);
+          }
+          size = stack[stack.length - 1] + 1;
+          stack[stack.length - 1] = 0;
+          return size;
+        }
+        if (!(prev && IMPLICIT_FUNC.indexOf(prev[0]) >= 0 && IMPLICIT_CALL.indexOf(token[0]) >= 0)) {
+          return 1;
+        }
+        this.tokens.splice(i, 0, ['CALL_START', '(']);
+        stack[stack.length - 1] += 1;
+        return 2;
+      };
+      return (function() {
+        return __func.apply(__this, arguments);
+      });
+    })(this));
+  };
   // Because our grammar is LALR(1), it can't handle some single-line
   // expressions that lack ending delimiters. Use the lexer to add the implicit
   // blocks, so it doesn't need to.

src/rewriter.coffee

@@ -45,7 +45,7 @@ re::rewrite: (tokens) ->
   this.remove_mid_expression_newlines()
   this.move_commas_outside_outdents()
   this.close_open_calls_and_indexes()
-  # this.add_implicit_parentheses()
+  this.add_implicit_parentheses()
   this.add_implicit_indentation()
   # this.ensure_balance(BALANCED_PAIRS)
   # this.rewrite_closing_parens()
@@ -132,6 +132,28 @@ re::close_open_calls_and_indexes: ->
           brackets[brackets.length - 1] -= 1
     return 1
 
+# Methods may be optionally called without parentheses, for simple cases.
+# Insert the implicit parentheses here, so that the parser doesn't have to
+# deal with them.
+re::add_implicit_parentheses: ->
+  stack: [0]
+  this.scan_tokens (prev, token, post, i) =>
+    stack.push(0) if token[0] is 'INDENT'
+    if token[0] is 'OUTDENT'
+      last: stack.pop()
+      stack[stack.length - 1] += last
+    if stack[stack.length - 1] > 0 and (IMPLICIT_END.indexOf(token[0]) >= 0 or !post?)
+      idx: if token[0] is 'OUTDENT' then i + 1 else i
+      for tmp in [0...stack[stack.length - 1]]
+        this.tokens.splice(idx, 0, ['CALL_END', ')'])
+      size: stack[stack.length - 1] + 1
+      stack[stack.length - 1]: 0
+      return size
+    return 1 unless prev and IMPLICIT_FUNC.indexOf(prev[0]) >= 0 and IMPLICIT_CALL.indexOf(token[0]) >= 0
+    this.tokens.splice(i, 0, ['CALL_START', '('])
+    stack[stack.length - 1] += 1
+    return 2
+
 # Because our grammar is LALR(1), it can't handle some single-line
 # expressions that lack ending delimiters. Use the lexer to add the implicit
 # blocks, so it doesn't need to.