Add GHC Core lexer (#1377)

This commit adds a lexer for the GHC Core language.

lib/rouge/demos/ghc-core

@@ -0,0 +1,26 @@
+Rec {
+-- RHS size: {terms: 24, types: 3, coercions: 0, joins: 0/0}
+Main.fib_fib [Occ=LoopBreaker] :: Integer -> Integer
+[GblId, Arity=1, Str=<S,U>, Unf=OtherCon []]
+Main.fib_fib
+  = \ (ds_d2OU :: Integer) ->
+      case integer-gmp-1.0.2.0:GHC.Integer.Type.eqInteger#
+             ds_d2OU Main.fib1
+      of {
+        __DEFAULT ->
+          case integer-gmp-1.0.2.0:GHC.Integer.Type.eqInteger#
+                 ds_d2OU Main.fib3
+          of {
+            __DEFAULT ->
+              integer-gmp-1.0.2.0:GHC.Integer.Type.plusInteger
+                (Main.fib_fib
+                   (integer-gmp-1.0.2.0:GHC.Integer.Type.minusInteger
+                      ds_d2OU Main.fib3))
+                (Main.fib_fib
+                   (integer-gmp-1.0.2.0:GHC.Integer.Type.minusInteger
+                      ds_d2OU Main.fib2));
+            1# -> Main.fib3
+          };
+        1# -> Main.fib1
+      }
+end Rec }

lib/rouge/lexers/ghc_core.rb

@@ -0,0 +1,151 @@
+# -*- coding: utf-8 -*- #
+# frozen_string_literal: true
+
+# See http://www.cs.cmu.edu/afs/andrew/course/15/411/ghc/share/doc/ghc/ext-core/core.pdf for a description of the syntax
+# of the language and https://www.aosabook.org/en/ghc.html for a high level overview.
+module Rouge
+  module Lexers
+    class GHCCore < RegexLexer
+      title "GHC Core"
+      desc "Intermediate representation of the GHC Haskell compiler."
+      tag 'ghc-core'
+
+      filenames '*.dump-simpl', '*.dump-cse', '*.dump-ds', '*.dump-spec'
+
+      state :root do
+        # sections
+        rule %r/^=====.*=====$/, Generic::Heading
+        # timestamps
+        rule %r/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d+ UTC$/, Comment::Single
+        rule %r/^Result size of .+\s*.*}/, Comment::Multiline
+        rule %r/--.*$/, Comment::Single
+
+        rule %r/\[/, Comment::Special, :annotation
+
+        mixin :recursive_binding
+        mixin :ghc_rule
+        mixin :function
+
+        # rest is Text
+        rule %r/\s/m, Text
+        rule %r/.*/, Text
+      end
+
+      state :expression do
+        rule %r/[\n]+/, Text
+        rule %r/(?=^\S)/ do
+          pop!
+        end
+
+        rule %r/\s+/, Text, :expression_line
+      end
+
+      state :expression_line do
+        rule %r/ /, Text
+
+        mixin :common
+
+        rule %r/\n/, Text, :pop!
+      end
+
+      state :annotation do
+        rule %r/\]/, Comment::Special, :pop!
+        rule %r/\[/, Comment::Special, :annotation
+        rule %r/[^\[\]]+/, Comment::Special
+      end
+
+      state :common do
+        # array, e.g. '[]' or '[Char]'
+        rule %r/\[[^=]*\]/, Keyword::Type
+
+        rule %r/\[/, Comment::Special, :annotation
+
+        mixin :literal
+        mixin :constants
+        mixin :punctuation
+        mixin :operator
+        mixin :name
+      end
+
+      state :literal do
+        rule %r/\d+\.\d+\#{0,2}/, Literal::Number::Float
+        rule %r/\d+\#{0,2}/, Literal::Number::Integer
+        rule %r/".*"#/, Literal::String
+        rule %r/'.'#/, Literal::String::Char
+      end
+
+      state :constants do
+        rule %r/__DEFAULT/, Name::Constant
+      end
+
+      state :name do
+        rule %r/^([A-Z]\w*)(\.)/ do |m|
+          token Name::Namespace, m[0]
+          token Punctuation, m[1]
+        end
+
+        rule %r/[A-Z][^\s.,(){}]*/, Keyword::Type
+
+        # packages, e.g. 'ghc-prim-0.5.3:'
+        rule %r/(^[a-z].*?\d+\.\d+\.\d+)(:)(?=\S)/ do |m|
+          token Name::Namespace, m[1]
+          token Punctuation, m[2]
+        end
+
+        rule %r/\S*\(,\)\S*/, Name::Variable # '(,)' is a name, not punctuation
+        rule %r/\S[^\s.,(){}]*/, Name::Variable
+      end
+
+      state :punctuation do
+        rule %r/[.,(){};]/, Punctuation
+      end
+
+      state :operator do
+        rule %r/=>/, Operator
+        rule %r/->/, Operator
+        rule %r/::/, Operator
+        rule %r/=/, Operator
+        rule %r/forall/, Keyword
+        rule %r/case/, Keyword
+        rule %r/of/, Keyword
+        rule %r/letrec/, Keyword
+        rule %r/let/, Keyword
+        rule %r/join/, Keyword
+        rule %r/@/, Operator
+        rule %r/\\/, Operator
+      end
+
+      state :recursive_binding do
+        rule %r/(Rec)(\s*)({)/ do |m|
+          token Keyword, m[1]
+          token Text, m[2]
+          token Punctuation, m[3]
+        end
+
+        rule %r/^(end)(\s*)(Rec)(\s*)(})/ do |m|
+          token Keyword, m[1]
+          token Text, m[2]
+          token Keyword, m[3]
+          token Text, m[4]
+          token Punctuation, m[5]
+        end
+      end
+
+      state :ghc_rule do
+        rule %r/^(".*?")/m do |m|
+          token Name::Label, m[0]
+
+          push :expression
+        end
+      end
+
+      state :function do
+        rule %r/^(\S+)(?=.*?(=|::))/m do |m|
+          token Name::Function, m[0]
+
+          push :expression
+        end
+      end
+    end
+  end
+end