Start on basic heuristic approach

lib/linguist/heuristics.rb

@@ -0,0 +1,43 @@
+require 'linguist/tokenizer'
+
+module Linguist
+  # A collection of simple heuristics that can be used to better analysis languages.
+  class Heuristics
+    # Public: Given an array of String language names, a
+    # apply all heuristics against the given data and return an array
+    # of matching languages, or nil.
+    # data      - Array of tokens or String data to analyze.
+    # languages - Array of language name Strings to restrict to.
+
+    # Returns an array of language name Strings, or []
+    def self.find_by_heuristics(data, languages)
+      if languages.all? { |l| ["pod", "perl"].include?(l) }
+        disambiguate_pod(data, languages)
+      elsif languages.all? { |l| ["objective-c", "c++"].include?(l) }
+        disambiguate_h(data, languages)
+      end
+    end
+
+    # Internal: Initialize a Heuristics class
+    def initialize
+    end
+
+    # .pod extensions are ambigious between perl and pod.
+    #
+    # Returns an array of still-possible languages, or nil
+    def self.disambiguate_pod(data, languages)
+      matches = []
+      matches << Language["Perl"] if data.includes?("my $")
+      matches
+    end
+
+    # .h extensions are ambigious between C, C++, and Objective-C.
+    # We want to look for Objective-C.
+    def self.disambiguate_h(data, languages)
+      matches = []
+      matches << Language["Objective-C"] if data.includes?("NSData *") && data.includes?("@interface")
+      matches
+    end
+  end
+end
+