Merge pull request #2041 from github/emacs-vim-mode-lines

Emacs vim modelines

lib/linguist/language.rb

@@ -11,6 +11,7 @@ require 'linguist/samples'
 require 'linguist/file_blob'
 require 'linguist/blob_helper'
 require 'linguist/strategy/filename'
+require 'linguist/strategy/modeline'
 require 'linguist/shebang'
 
 module Linguist
@@ -94,6 +95,7 @@ module Linguist
     end
 
     STRATEGIES = [
+      Linguist::Strategy::Modeline,
       Linguist::Strategy::Filename,
       Linguist::Shebang,
       Linguist::Heuristics,

lib/linguist/strategy/modeline.rb

@@ -0,0 +1,30 @@
+module Linguist
+  module Strategy
+    class Modeline
+      EmacsModeline = /-\*-\s*(?:mode:)?\s*(\w+);?\s*-\*-/
+      VimModeline = /\/\*\s*vim:\s*set\s*(?:ft|filetype)=(\w+):\s*\*\//
+
+      # Public: Detects language based on Vim and Emacs modelines
+      #
+      # blob               - An object that quacks like a blob.
+      #
+      # Examples
+      #
+      #   Modeline.call(FileBlob.new("path/to/file"))
+      #
+      # Returns an Array with one Language if the blob has a Vim or Emacs modeline
+      # that matches a Language name or alias. Returns an empty array if no match.
+      def self.call(blob, _ = nil)
+        Array(Language.find_by_alias(modeline(blob.data)))
+      end
+
+      # Public: Get the modeline from the first n-lines of the file
+      #
+      # Returns a String or nil
+      def self.modeline(data)
+        match = data.match(EmacsModeline) || data.match(VimModeline)
+        match[1] if match
+      end
+    end
+  end
+end