Support for files generated by Racc.

This changeset includes a sample racc file from [this auto-generated
file](44e9bf0440/lib/rjson/parser.rb)
(MIT-licensed).

[Racc](https://github.com/tenderlove/racc) Racc is an LALR(1) parser
generator. It is written in Ruby itself, and generates ruby programs.

lib/linguist/generated.rb

@@ -71,7 +71,8 @@ module Linguist
       generated_jni_header? ||
       vcr_cassette? ||
       generated_module? ||
-      generated_unity3d_meta?
+      generated_unity3d_meta? ||
+      generated_racc?
     end
 
     # Internal: Is the blob an Xcode file?
@@ -359,5 +360,18 @@ module Linguist
       return false unless lines.count > 1
       return lines[0].include?("fileFormatVersion: ")
     end
+
+    # Internal: Is this a Racc-generated file?
+    #
+    # A Racc-generated file contains:
+    # # This file is automatically generated by Racc x.y.z
+    # on the third line.
+    #
+    # Return true or false
+    def generated_racc?
+      return false unless extname == '.rb'
+      return false unless lines.count > 2
+      return lines[2].start_with?("# This file is automatically generated by Racc")
+    end
   end
 end

samples/Ruby/racc.rb

@@ -0,0 +1,267 @@
+#
+# DO NOT MODIFY!!!!
+# This file is automatically generated by Racc 1.4.7
+# from Racc grammer file "".
+#
+
+require 'racc/parser.rb'
+module RJSON
+  class Parser < Racc::Parser
+
+
+  require 'rjson/handler'
+
+  attr_reader :handler
+
+  def initialize tokenizer, handler = Handler.new
+    @tokenizer = tokenizer
+    @handler   = handler
+    super()
+  end
+
+  def next_token
+    @tokenizer.next_token
+  end
+
+  def parse
+    do_parse
+    handler
+  end
+##### State transition tables begin ###
+
+racc_action_table = [
+     9,    33,     9,    11,    13,    16,    19,    22,     9,     7,
+    23,     1,     9,    11,    13,    16,    19,    29,    30,     7,
+    21,     1,     9,    11,    13,    16,    19,    31,   nil,     7,
+    21,     1,    23,     7,   nil,     1 ]
+
+racc_action_check = [
+     6,    27,    33,    33,    33,    33,    33,     3,    31,    33,
+     6,    33,    29,    29,    29,    29,    29,    12,    22,    29,
+    12,    29,     2,     2,     2,     2,     2,    25,   nil,     2,
+     2,     2,    25,     0,   nil,     0 ]
+
+racc_action_pointer = [
+    24,   nil,    20,     7,   nil,   nil,    -2,   nil,   nil,   nil,
+   nil,   nil,    10,   nil,   nil,   nil,   nil,   nil,   nil,   nil,
+   nil,   nil,    18,   nil,   nil,    20,   nil,    -7,   nil,    10,
+   nil,     6,   nil,     0,   nil,   nil,   nil ]
+
+racc_action_default = [
+   -27,   -12,   -21,   -27,    -1,    -2,   -27,   -10,   -15,   -26,
+    -8,   -22,   -27,   -23,   -17,   -16,   -24,   -20,   -18,   -25,
+   -19,   -11,   -27,   -13,    -3,   -27,    -6,   -27,    -9,   -21,
+    37,   -27,    -4,   -21,   -14,    -5,    -7 ]
+
+racc_goto_table = [
+     8,    26,    24,    27,    10,     3,    25,     5,     4,    12,
+   nil,   nil,   nil,   nil,    28,   nil,   nil,   nil,   nil,   nil,
+   nil,    32,   nil,   nil,   nil,   nil,    35,    34,    27,   nil,
+   nil,    36 ]
+
+racc_goto_check = [
+     9,     7,     5,     8,    11,     1,     6,     3,     2,    12,
+   nil,   nil,   nil,   nil,    11,   nil,   nil,   nil,   nil,   nil,
+   nil,     5,   nil,   nil,   nil,   nil,     7,     9,     8,   nil,
+   nil,     9 ]
+
+racc_goto_pointer = [
+   nil,     5,     8,     7,   nil,    -4,     0,    -5,    -3,    -2,
+   nil,     2,     7,   nil,   nil ]
+
+racc_goto_default = [
+   nil,   nil,    14,    18,     6,   nil,   nil,   nil,    20,   nil,
+     2,   nil,   nil,    15,    17 ]
+
+racc_reduce_table = [
+  0, 0, :racc_error,
+  1, 14, :_reduce_none,
+  1, 14, :_reduce_none,
+  2, 15, :_reduce_none,
+  3, 15, :_reduce_none,
+  3, 19, :_reduce_none,
+  1, 19, :_reduce_none,
+  3, 20, :_reduce_none,
+  2, 16, :_reduce_none,
+  3, 16, :_reduce_none,
+  1, 23, :_reduce_10,
+  1, 24, :_reduce_11,
+  1, 17, :_reduce_12,
+  1, 18, :_reduce_13,
+  3, 25, :_reduce_none,
+  1, 25, :_reduce_none,
+  1, 22, :_reduce_none,
+  1, 22, :_reduce_none,
+  1, 22, :_reduce_none,
+  1, 26, :_reduce_none,
+  1, 26, :_reduce_20,
+  0, 27, :_reduce_none,
+  1, 27, :_reduce_22,
+  1, 27, :_reduce_23,
+  1, 27, :_reduce_24,
+  1, 27, :_reduce_25,
+  1, 21, :_reduce_26 ]
+
+racc_reduce_n = 27
+
+racc_shift_n = 37
+
+racc_token_table = {
+  false => 0,
+  :error => 1,
+  :STRING => 2,
+  :NUMBER => 3,
+  :TRUE => 4,
+  :FALSE => 5,
+  :NULL => 6,
+  "," => 7,
+  ":" => 8,
+  "[" => 9,
+  "]" => 10,
+  "{" => 11,
+  "}" => 12 }
+
+racc_nt_base = 13
+
+racc_use_result_var = true
+
+Racc_arg = [
+  racc_action_table,
+  racc_action_check,
+  racc_action_default,
+  racc_action_pointer,
+  racc_goto_table,
+  racc_goto_check,
+  racc_goto_default,
+  racc_goto_pointer,
+  racc_nt_base,
+  racc_reduce_table,
+  racc_token_table,
+  racc_shift_n,
+  racc_reduce_n,
+  racc_use_result_var ]
+
+Racc_token_to_s_table = [
+  "$end",
+  "error",
+  "STRING",
+  "NUMBER",
+  "TRUE",
+  "FALSE",
+  "NULL",
+  "\",\"",
+  "\":\"",
+  "\"[\"",
+  "\"]\"",
+  "\"{\"",
+  "\"}\"",
+  "$start",
+  "document",
+  "object",
+  "array",
+  "start_object",
+  "end_object",
+  "pairs",
+  "pair",
+  "string",
+  "value",
+  "start_array",
+  "end_array",
+  "values",
+  "scalar",
+  "literal" ]
+
+Racc_debug_parser = false
+
+##### State transition tables end #####
+
+# reduce 0 omitted
+
+# reduce 1 omitted
+
+# reduce 2 omitted
+
+# reduce 3 omitted
+
+# reduce 4 omitted
+
+# reduce 5 omitted
+
+# reduce 6 omitted
+
+# reduce 7 omitted
+
+# reduce 8 omitted
+
+# reduce 9 omitted
+
+def _reduce_10(val, _values, result)
+ @handler.start_array  
+    result
+end
+
+def _reduce_11(val, _values, result)
+ @handler.end_array    
+    result
+end
+
+def _reduce_12(val, _values, result)
+ @handler.start_object 
+    result
+end
+
+def _reduce_13(val, _values, result)
+ @handler.end_object   
+    result
+end
+
+# reduce 14 omitted
+
+# reduce 15 omitted
+
+# reduce 16 omitted
+
+# reduce 17 omitted
+
+# reduce 18 omitted
+
+# reduce 19 omitted
+
+def _reduce_20(val, _values, result)
+ @handler.scalar val[0] 
+    result
+end
+
+# reduce 21 omitted
+
+def _reduce_22(val, _values, result)
+ n = val[0]; result = n.count('.') > 0 ? n.to_f : n.to_i 
+    result
+end
+
+def _reduce_23(val, _values, result)
+ result = true 
+    result
+end
+
+def _reduce_24(val, _values, result)
+ result = false 
+    result
+end
+
+def _reduce_25(val, _values, result)
+ result = nil 
+    result
+end
+
+def _reduce_26(val, _values, result)
+ @handler.scalar val[0].gsub(/^"|"$/, '') 
+    result
+end
+
+def _reduce_none(val, _values, result)
+  val[0]
+end
+
+  end   # class Parser
+  end   # module RJSON

test/test_blob.rb

@@ -255,6 +255,9 @@ class TestBlob < Minitest::Test
 
     # Unity3D-generated metadata
     assert sample_blob("Unity3D Asset/Tiles.meta").generated?
+
+    # Racc-generated Ruby
+    assert sample_blob("Ruby/racc.rb").generated?
   end
 
   def test_vendored