rewriter: merged remove*Terminators

Cokefile

@@ -95,6 +95,7 @@ task \build:browser
 task \bench, 'quick benchmark of compilation time', ->
   Lexer    = require \./lib/lexer
   Rewriter = require \./lib/rewriter
+  Coco     = require \./lib/coco
   co     = coreSources().map(-> slurp it).join \\n
   fmt    = -> "#{bold}#{ "   #{it}".slice -4 }#{reset} ms"
   total  = nc = 0

lib/rewriter.js

@@ -4,8 +4,7 @@ var BALANCED_PAIRS, INVERSES, EXPR_START, EXPR_END, left, rite, ARG, _i, _len, _
 exports.rewrite = rewrite;
 exports.able = able;
 function rewrite(it){
-  removeLeadingTerminators(it);
-  removeMidExpressionTerminators(it);
+  removeTerminators(it);
   closeCalls(it);
   addImplicitIndentation(it);
   tagPostfixConditionals(it);
@@ -16,40 +15,15 @@ function rewrite(it){
   expandNumbers(it);
   return it;
 }
-function detectEnd(tokens, i, ok, go){
-  var levels, token, tag;
-  levels = 0;
-  while (token = tokens[i]) {
-    if (!levels) {
-      if (ok(token, i)) {
-        return go(token, i);
-      }
-    } else if (0 > levels) {
-      return go(token, i - 1);
-    }
-    tag = token[0];
-    if (__indexOf.call(EXPR_START, tag) >= 0) {
-      ++levels;
-    } else if (__indexOf.call(EXPR_END, tag) >= 0) {
-      --levels;
-    }
-    ++i;
-  }
-}
-function removeLeadingTerminators(tokens){
-  var i, tag, _len;
-  for (i = 0, _len = tokens.length; i < _len; ++i) {
-    tag = tokens[i][0];
-    if (tag !== 'TERMINATOR') {
+function removeTerminators(tokens){
+  var i, that;
+  i = -1;
+  while (that = tokens[++i]) {
+    if (that[0] !== 'TERMINATOR') {
       break;
     }
   }
-  if (i) {
-    tokens.splice(0, i);
-  }
-}
-function removeMidExpressionTerminators(tokens){
-  var i, that;
+  i && tokens.splice(0, i);
   i = 1;
   while (that = tokens[++i]) {
     if (tokens[i - 1][0] !== 'TERMINATOR') {
@@ -397,6 +371,26 @@ function expandNumbers(tokens){
     }
   }
 }
+function detectEnd(tokens, i, ok, go){
+  var levels, token, tag;
+  levels = 0;
+  while (token = tokens[i]) {
+    if (!levels) {
+      if (ok(token, i)) {
+        return go(token, i);
+      }
+    } else if (0 > levels) {
+      return go(token, i - 1);
+    }
+    tag = token[0];
+    if (__indexOf.call(EXPR_START, tag) >= 0) {
+      ++levels;
+    } else if (__indexOf.call(EXPR_END, tag) >= 0) {
+      --levels;
+    }
+    ++i;
+  }
+}
 function able(tokens, i, call){
   var tag, _ref;
   i == null && (i = tokens.length);

src/rewriter.co

@@ -17,38 +17,24 @@ exports import {rewrite, able}
 # corrected before implicit parentheses can be wrapped around blocks of code.
 
 function rewrite ->
-  removeLeadingTerminators       it
-  removeMidExpressionTerminators it
-  closeCalls                     it
-  addImplicitIndentation         it
-  tagPostfixConditionals         it
-  addImplicitBraces              it
-  addImplicitParentheses         it
-  ensureBalance                  it
-  rewriteClosingParens           it
-  expandNumbers                  it
+  removeTerminators      it
+  closeCalls             it
+  addImplicitIndentation it
+  tagPostfixConditionals it
+  addImplicitBraces      it
+  addImplicitParentheses it
+  ensureBalance          it
+  rewriteClosingParens   it
+  expandNumbers          it
   it
 
-function detectEnd (tokens, i, ok, go) ->
-  levels = 0
-  while token = tokens[i]
-    if      not levels then return go token, i if ok token, i
-    else if 0 > levels then return go token, i-1
-    [tag] = token
-    if      tag of EXPR_START then ++levels
-    else if tag of EXPR_END   then --levels
-    ++i
-  void
-
-# Dispatch leading terminators that would introduce ambiguity in the grammar.
-function removeLeadingTerminators (tokens) ->
-  break unless tag is \TERMINATOR for [tag], i of tokens
-  tokens.splice 0, i if i
-  void
-
-# Some blocks occur in the middle of expressions--when we're expecting
-# this, remove their trailing terminators.
-function removeMidExpressionTerminators (tokens) ->
+# - Dispatch leading terminators that would introduce ambiguity in the grammar.
+# - Some blocks occur in the middle of expressions.
+#   Remove their trailing terminators here to simplify things.
+function removeTerminators (tokens) ->
+  i = -1
+  break unless that.0 is \TERMINATOR while tokens[++i]
+  i and tokens.splice 0, i
   i = 1
   while tokens[++i]
     continue unless tokens[i-1].0 is \TERMINATOR
@@ -277,6 +263,21 @@ function expandNumbers (tokens) ->
       i += ts.length - 1
   void
 
+### Helpers
+
+# Seeks `tokens` from index `i` for a token of the same level matching `ok`,
+# then calls `go`.
+function detectEnd (tokens, i, ok, go) ->
+  levels = 0
+  while token = tokens[i]
+    if      not levels then return go token, i if ok token, i
+    else if 0 > levels then return go token, i-1
+    [tag] = token
+    if      tag of EXPR_START then ++levels
+    else if tag of EXPR_END   then --levels
+    ++i
+  void
+
 # Checks whether or not the previous token is {index,`call`}able.
 function able (tokens, i = tokens.length, call) ->
   tag = tokens[i-1].0
@@ -294,7 +295,7 @@ function indexOfPair (tokens, i) ->
 
 function carp (msg, lno) -> throw SyntaxError msg + ' on line ' + -~lno
 
-#### Constants
+### Constants
 
 # List of the token pairs that must be balanced.
 BALANCED_PAIRS = [