From 413c881af8e2a9f000e55398a4a73c912958282c Mon Sep 17 00:00:00 2001
From: Charlie Somerville <charlie@charliesomerville.com>
Date: Wed, 16 Oct 2013 11:41:19 -0400
Subject: [PATCH] add @primary_extension_index to ensure we don't have duped
 primary exts

---
 lib/linguist/language.rb | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/linguist/language.rb b/lib/linguist/language.rb
index 0a8d3d54..e18e8ab7 100644
--- a/lib/linguist/language.rb
+++ b/lib/linguist/language.rb
@@ -15,8 +15,10 @@ module Linguist
     @index           = {}
     @name_index      = {}
     @alias_index     = {}
-    @extension_index = Hash.new { |h,k| h[k] = [] }
-    @filename_index  = Hash.new { |h,k| h[k] = [] }
+
+    @extension_index          = Hash.new { |h,k| h[k] = [] }
+    @filename_index           = Hash.new { |h,k| h[k] = [] }
+    @primary_extension_index  = {}
 
     # Valid Languages types
     TYPES = [:data, :markup, :programming]
@@ -63,6 +65,12 @@ module Linguist
         @extension_index[extension] << language
       end
 
+      if @primary_extension_index.key?(language.primary_extension)
+        raise ArgumentError, "Duplicate primary extension: #{language.primary_extension}"
+      end
+
+      @primary_extension_index[language.primary_extension] = language
+
       language.filenames.each do |filename|
         @filename_index[filename] << language
       end