the rewriter is done

lib/coffee_script/rewriter.js

@@ -1,5 +1,6 @@
 (function(){
   var BALANCED_PAIRS, EXPRESSION_CLOSE, EXPRESSION_START, EXPRESSION_TAIL, IMPLICIT_CALL, IMPLICIT_END, IMPLICIT_FUNC, INVERSES, SINGLE_CLOSERS, SINGLE_LINERS, __a, __b, __c, __d, __e, __f, __g, __h, pair, re;
+  var __hasProp = Object.prototype.hasOwnProperty;
   // In order to keep the grammar simple, the stream of tokens that the Lexer
   // emits is rewritten by the Rewriter, smoothing out ambiguities, mis-nested
   // indentation, and single-line flavors of expressions.
@@ -55,8 +56,8 @@
     this.close_open_calls_and_indexes();
     this.add_implicit_parentheses();
     this.add_implicit_indentation();
-    // this.ensure_balance(BALANCED_PAIRS)
-    // this.rewrite_closing_parens()
+    this.ensure_balance(BALANCED_PAIRS);
+    this.rewrite_closing_parens();
     return this.tokens;
   };
   // Rewrite the token stream, looking one token ahead and behind.
@@ -157,12 +158,12 @@
         } else if (token[0] === 'INDEX_START') {
           brackets.push(0);
         } else if (token[0] === '(') {
-          parens[-1] += 1;
+          parens[parens.length - 1] += 1;
         } else if (token[0] === '[') {
-          brackets[-1] += 1;
+          brackets[brackets.length - 1] += 1;
         } else if (token[0] === ')') {
           if (parens[parens.length - 1] === 0) {
-            parens.pop;
+            parens.pop();
             token[0] = 'CALL_END';
           } else {
             parens[parens.length - 1] -= 1;
@@ -261,4 +262,116 @@
       });
     })(this));
   };
+  // Ensure that all listed pairs of tokens are correctly balanced throughout
+  // the course of the token stream.
+  re.prototype.ensure_balance = function ensure_balance(pairs) {
+    var __i, __j, key, levels, unclosed, value;
+    levels = {
+    };
+    this.scan_tokens((function(__this) {
+      var __func = function(prev, token, post, i) {
+        var __i, __j, __k, close, open;
+        __i = pairs;
+        for (__j = 0; __j < __i.length; __j++) {
+          pair = __i[__j];
+          __k = pair;
+          open = __k[0];
+          close = __k[1];
+          levels[open] = levels[open] || 0;
+          if (token[0] === open) {
+            levels[open] += 1;
+          }
+          if (token[0] === close) {
+            levels[open] -= 1;
+          }
+          if (levels[open] < 0) {
+            throw "too many " + token[1];
+          }
+        }
+        return 1;
+      };
+      return (function() {
+        return __func.apply(__this, arguments);
+      });
+    })(this));
+    unclosed = (function() {
+      __i = []; __j = levels;
+      for (key in __j) {
+        value = __j[key];
+        if (__hasProp.call(__j, key)) {
+          if (value > 0) {
+            __i.push(key);
+          }
+        }
+      }
+      return __i;
+    }).call(this);
+    if (unclosed.length) {
+      throw "unclosed " + unclosed[0];
+    }
+  };
+  // We'd like to support syntax like this:
+  //    el.click((event) ->
+  //      el.hide())
+  // In order to accomplish this, move outdents that follow closing parens
+  // inwards, safely. The steps to accomplish this are:
+  //
+  // 1. Check that all paired tokens are balanced and in order.
+  // 2. Rewrite the stream with a stack: if you see an '(' or INDENT, add it
+  //    to the stack. If you see an ')' or OUTDENT, pop the stack and replace
+  //    it with the inverse of what we've just popped.
+  // 3. Keep track of "debt" for tokens that we fake, to make sure we end
+  //    up balanced in the end.
+  re.prototype.rewrite_closing_parens = function rewrite_closing_parens() {
+    var __i, debt, key, stack, val;
+    stack = [];
+    debt = {
+    };
+    __i = INVERSES;
+    for (key in __i) {
+      val = __i[key];
+      if (__hasProp.call(__i, key)) {
+        ((debt[key] = 0));
+      }
+    }
+    return this.scan_tokens((function(__this) {
+      var __func = function(prev, token, post, i) {
+        var inv, match, mtag, tag;
+        tag = token[0];
+        inv = INVERSES[token[0]];
+        // Push openers onto the stack.
+        if (EXPRESSION_START.indexOf(tag) >= 0) {
+          stack.push(token);
+          return 1;
+          // The end of an expression, check stack and debt for a pair.
+        } else if (EXPRESSION_TAIL.indexOf(tag) >= 0) {
+          // If the tag is already in our debt, swallow it.
+          if (debt[inv] > 0) {
+            debt[inv] -= 1;
+            this.tokens.splice(i, 1);
+            return 0;
+          } else {
+            // Pop the stack of open delimiters.
+            match = stack.pop();
+            mtag = match[0];
+            // Continue onwards if it's the expected tag.
+            if (tag === INVERSES[mtag]) {
+              return 1;
+            } else {
+              // Unexpected close, insert correct close, adding to the debt.
+              debt[mtag] += 1;
+              val = mtag === 'INDENT' ? match[1] : INVERSES[mtag];
+              this.tokens.splice(i, 0, [INVERSES[mtag], val]);
+              return 1;
+            }
+          }
+        } else {
+          return 1;
+        }
+      };
+      return (function() {
+        return __func.apply(__this, arguments);
+      });
+    })(this));
+  };
 })();