0001-Search-backwards-rather-than-forwards.patch

From e69827d6fbfa919387fbc0dbb15ba5079d2ea947 Mon Sep 17 00:00:00 2001
From: Matthew Draper <[email protected]>
Date: Tue, 25 Jan 2011 10:47:02 +1030
Subject: [PATCH] Search backwards rather than forwards.

Most of the time, we're looking at values around the end of what we've
parsed.
---
 lib/parslet/source.rb |   19 ++++++++++---------
 1 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/lib/parslet/source.rb b/lib/parslet/source.rb
index 564e07e..70bd6d0 100644
--- a/lib/parslet/source.rb
+++ b/lib/parslet/source.rb
@@ -55,18 +55,19 @@ class Parslet::Source
   
   def line_and_column(position=nil)
     pos = (position || self.pos)
-    eol_idx = @line_ends.index { |o| o>pos }
     
-    if eol_idx
-      # eol_idx points to the offset that ends the current line.
-      # Let's try to find the offset that starts it: 
-      offset = eol_idx>0 && @line_ends[eol_idx-1] || 0
-      return [eol_idx+1, pos-offset+1]
+    if @line_ends.size > 0 && @line_ends.last > pos
+      if bol_idx = @line_ends.rindex { |o| o<=pos }
+        offset = @line_ends[bol_idx]
+        return [bol_idx+2, pos-offset+1]
+      else
+        return [1, pos+1]
+      end
     else
-      # eol_idx is nil, that means that we're beyond the last line end that
-      # we know about. Pretend for now that we're just on the last line.
+      # We're beyond the last line end that we know about. Pretend for
+      # now that we're just on the last line.
       offset = @line_ends.last || 0
       return [@line_ends.size+1, pos-offset+1]
     end
   end
-end
\ No newline at end of file
+end
-- 
1.7.2.3