Add Lustre lexer (#905)

This commit adds a lexer for the Lustre language.

lib/rouge/demos/lustre

@@ -0,0 +1,6 @@
+node count(init: int; reset, event: bool) returns (c: int);
+let
+	c = init -> if reset then init
+					else if event then pre(c)+1
+					else pre(c);
+tel;

lib/rouge/lexers/lustre.rb

@@ -0,0 +1,80 @@
+# -*- coding: utf-8 -*- #
+#
+# adapted from ocaml.rb, hence some ocaml-ism migth remains
+module Rouge
+  module Lexers
+    class Lustre < RegexLexer
+      title "Lustre"
+      desc 'The Lustre programming language (Verimag)'
+      tag 'lustre'
+      filenames '*.lus'
+      mimetypes 'text/x-lustre'
+
+      def self.keywords
+        @keywords ||= Set.new %w(
+          extern unsafe assert const current enum function
+          let node operator returns
+          step struct tel type var  model package needs
+          provides uses is body end include merge
+        )
+      end
+
+      def self.word_operators
+        @word_operators ||= Set.new %w(
+           div and xor mod or not nor if then else fby pre when with) 
+      end
+
+      def self.primitives
+        @primitives ||= Set.new %w(int real bool)
+      end
+
+      operator = %r([,!$%&*+./:<=>?@^|~#-]+)
+      id = /[a-z_][\w']*/i
+
+      state :root do
+        rule (/\s+/m), Text
+        rule (/false|true/), Keyword::Constant
+        rule %r(\-\-.*), Comment::Single
+        rule %r(/\*.*?\*/)m, Comment::Multiline
+        rule %r(\(\*.*?\*\))m, Comment::Multiline
+        rule id do |m|
+          match = m[0]
+          if self.class.keywords.include? match
+            token Keyword
+          elsif self.class.word_operators.include? match
+            token Operator::Word
+          elsif self.class.primitives.include? match
+            token Keyword::Type
+          else
+            token Name
+          end
+        end
+
+        rule (/[(){}\[\];]+/), Punctuation
+        rule operator, Operator
+
+        rule (/-?\d[\d_]*(.[\d_]*)?(e[+-]?\d[\d_]*)/i), Num::Float
+        rule (/\d[\d_]*/), Num::Integer
+
+        rule (/'(?:(\\[\\"'ntbr ])|(\\[0-9]{3})|(\\x\h{2}))'/), Str::Char
+        rule (/'[.]'/), Str::Char
+        rule (/"/), Str::Double, :string
+        rule (/[~?]#{id}/), Name::Variable
+      end
+
+      state :string do
+        rule (/[^\\"]+/), Str::Double
+        mixin :escape_sequence
+        rule (/\\\n/), Str::Double
+        rule (/"/), Str::Double, :pop!
+      end
+
+      state :escape_sequence do
+        rule (/\\[\\"'ntbr]/), Str::Escape
+        rule (/\\\d{3}/), Str::Escape
+        rule (/\\x\h{2}/), Str::Escape
+      end
+
+    end
+  end
+end

spec/lexers/lustre_spec.rb

@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*- #
+
+describe Rouge::Lexers::Lustre do
+  let(:subject) { Rouge::Lexers::Lustre.new }
+
+  describe 'guessing' do
+    include Support::Guessing
+
+    it 'guesses by filename' do
+      assert_guess :filename => 'foo.lus'
+    end
+
+    it 'guesses by mimetype' do
+      assert_guess :mimetype => 'text/x-lustre'
+    end
+  end
+end
+

spec/visual/samples/lustre

@@ -0,0 +1,49 @@
+-------------------------------------------------------------------
+
+-- Constants
+const size = 50; -- size of the sliding windows used to smooth values
+const period = 0.1;  -- in seconds
+const speed_max = 110.0;                                           -- comment with leading whitespace
+
+-- Types
+type roof_state = enum { locked, in_motion };
+
+type update_acc = {
+  i: int; 
+  j: int; 
+  v: real
+};
+
+-- Nodes
+node roof(Tick, Parked, OnOff, Done: bool) returns (Locked:bool; Roof_Speed:real);
+var 
+  pst, st : roof_state;
+  Tick_on_in_motion : bool when in_motion(st);
+let
+  pst = locked fby st;
+  st =  merge pst  
+         (locked    -> if (OnOff and Parked) when locked(pst) then in_motion else locked)
+         (in_motion -> if Done when in_motion(pst) then locked else in_motion);
+  Locked = (st=locked) ;
+  Tick_on_in_motion = Tick when in_motion(st);
+  Roof_Speed = merge st
+    (locked    -> 0.0 when locked(st))
+    (in_motion -> roof_speed(Tick_on_in_motion));
+tel
+
+node sum<<const d: int; const init:real>>(s: real) returns (res:real);
+var
+  a,pre_a: real^d; -- circular array
+  i: int; 
+let
+  i = 0 fby i + 1;
+  pre_a = (init^d) fby a;
+  a = assign<<d>>(s, i mod d, pre_a);
+  res =red<<+; d>>(0.0, a); --- / Lustre::int2real(d) ;
+tel
+
+-- Functions
+function braking_time(Speed:real) returns (res:real);
+let
+  res = Speed * Speed / k;
+tel