From a3227c2c27f9a3b76ebae727c3eb2386e3aa3582 Mon Sep 17 00:00:00 2001
From: Arfon Smith <arfon.smith@gmail.com>
Date: Tue, 13 Sep 2016 11:09:05 -0700
Subject: [PATCH] Adding basic find_by_id functionality to Language

---
 lib/linguist/language.rb | 24 ++++++++++++++++++++----
 test/test_language.rb    |  6 ++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/lib/linguist/language.rb b/lib/linguist/language.rb
index 44c08401..7ae48b17 100644
--- a/lib/linguist/language.rb
+++ b/lib/linguist/language.rb
@@ -20,10 +20,11 @@ module Linguist
   #
   # Languages are defined in `lib/linguist/languages.yml`.
   class Language
-    @languages       = []
-    @index           = {}
-    @name_index      = {}
-    @alias_index     = {}
+    @languages          = []
+    @index              = {}
+    @name_index         = {}
+    @alias_index        = {}
+    @language_id_index  = {}
 
     @extension_index          = Hash.new { |h,k| h[k] = [] }
     @interpreter_index        = Hash.new { |h,k| h[k] = [] }
@@ -84,6 +85,8 @@ module Linguist
         @filename_index[filename] << language
       end
 
+      @language_id_index[language.language_id] = language
+
       language
     end
 
@@ -193,6 +196,19 @@ module Linguist
       @interpreter_index[interpreter]
     end
 
+    # Public: Look up Languages by its language_id.
+    #
+    # language_id - Integer of language_id
+    #
+    # Examples
+    #
+    #   Language.find_by_id(100)
+    #   # => [#<Language name="Elixir">]
+    #
+    # Returns the matching Language
+    def self.find_by_id(language_id)
+      @language_id_index[language_id.to_i]
+    end
 
     # Public: Look up Language by its name.
     #
diff --git a/test/test_language.rb b/test/test_language.rb
index 3db33b54..58430455 100644
--- a/test/test_language.rb
+++ b/test/test_language.rb
@@ -77,6 +77,12 @@ class TestLanguage < Minitest::Test
     assert_equal 421, Language['xBase'].language_id
   end
 
+  def test_find_by_id
+    assert_equal Language['Elixir'], Language.find_by_id(100)
+    assert_equal Language['Ruby'], Language.find_by_id(326)
+    assert_equal Language['xBase'], Language.find_by_id(421)
+  end
+
   def test_groups
     # Test a couple identity cases
     assert_equal Language['Perl'], Language['Perl'].group