Add Meson Lexer (#1732)

* Add Meson lexer

* Fixed Meson sample

* Removed unused builtins

* Removed unneeded escape

* Removed unneeded operator

* Fixed builtins

* Added 'meson_options.txt' to filenames

Co-authored-by: Tan Le <tan.le@hey.com>

* Added URL to desc

Co-authored-by: Tan Le <tan.le@hey.com>

Co-authored-by: Tan Le <tan.le@hey.com>

lib/rouge/demos/meson

@@ -0,0 +1,10 @@
+project('tutorial', 'c', version: '0.2.3')
+executable('demo', 'main.c')
+
+version_array = meson.project_version().split('.')
+api_version = '@0@.@1@'.format(version_array[0], version_array[1])
+
+d = dependency('foo', required : get_option('myfeature'))
+if d.found()
+  app = executable('app', 'app.c', dependencies : [d])
+endif

lib/rouge/lexers/meson.rb

@@ -0,0 +1,158 @@
+# -*- coding: utf-8 -*- #
+# frozen_string_literal: true
+
+module Rouge
+  module Lexers
+    class Meson < RegexLexer
+      title "Meson"
+      desc "Meson's specification language (mesonbuild.com)"
+      tag 'meson'
+      filenames 'meson.build', 'meson_options.txt'
+
+      def self.keywords
+        @keywords ||= %w(
+          continue break elif else endif
+          if true false foreach endforeach
+        )
+      end
+
+      def self.builtin_variables
+        @builtin_variables ||= %w(
+          meson host_machine build_machine target_machine
+        )
+      end
+
+      def self.builtin_functions
+        @builtin_functions ||= %w(
+          add_global_arguments add_project_arguments
+          add_global_link_arguments add_project_link_arguments add_test_setup add_languages
+          alias_target assert benchmark both_libraries build_target configuration_data configure_file
+          custom_target declare_dependency dependency disabler environment error executable
+          generator gettext get_option get_variable files find_library find_program
+          include_directories import install_data install_headers install_man install_subdir
+          is_disabler is_variable jar join_paths library message option project
+          run_target run_command set_variable subdir subdir_done
+          subproject summary shared_library shared_module static_library test vcs_tag warning
+        )
+      end
+
+      identifier =        /[[:alpha:]_][[:alnum:]_]*/
+      dotted_identifier = /[[:alpha:]_.][[:alnum:]_.]*/
+
+      def current_string
+        @string_register ||= StringRegister.new
+      end
+
+      state :root do
+        rule %r/\n+/m, Text
+
+        rule %r/[^\S\n]+/, Text
+        rule %r(#(.*)?\n?), Comment::Single
+        rule %r/[\[\]{}:(),;.]/, Punctuation
+        rule %r/\\\n/, Text
+        rule %r/\\/, Text
+
+        rule %r/(in|and|or|not)\b/, Operator::Word
+        rule %r/[-+\/*%=<>]=?|!=/, Operator
+
+        rule %r/([f]?)('''|['])/i do |m|
+          groups Str::Affix, Str
+          current_string.register type: m[1].downcase, delim: m[2]
+          push :generic_string
+        end
+
+        rule %r/(?<!\.)#{identifier}\b\s*(?=\()/ do  |m|
+          if self.class.builtin_functions.include? m[0]
+            token Name::Builtin
+          else
+            token Name
+          end
+        end
+
+        rule %r/(?<!\.)#{identifier}(?!\s*?:)/ do |m|
+          if self.class.builtin_variables.include? m[0]
+            token Name::Builtin
+          elsif self.class.keywords.include? m[0]
+            token Keyword
+          else
+            token Name
+          end
+        end
+
+        rule identifier, Name
+
+        rule %r/0b(_?[0-1])+/i, Num::Bin
+        rule %r/0o(_?[0-7])+/i, Num::Oct
+        rule %r/0x(_?[a-f0-9])+/i, Num::Hex
+        rule %r/([1-9](_?[0-9])*|0(_?0)*)/, Num::Integer
+      end
+
+      state :generic_string do
+        rule %r/[^'\\\@]+/, Str
+
+        rule %r/'''|[']/ do |m|
+          token Str
+          if current_string.delim? m[0]
+            current_string.remove
+            pop!
+          end
+        end
+
+        rule %r/(?=\\)/, Str, :generic_escape
+
+        rule %r/\@/ do |m|
+          if current_string.type? "f"
+            token Str::Interpol
+            push :generic_interpol
+          else
+            token Str
+          end
+        end
+      end
+
+      state :generic_escape do
+        rule %r(\\
+          ( [\\abfnrtv']
+          | N{[a-zA-Z][a-zA-Z ]+[a-zA-Z]}
+          | u[a-fA-F0-9]{4}
+          | U[a-fA-F0-9]{8}
+          | x[a-fA-F0-9]{2}
+          | [0-7]{1,3}
+          )
+        )x do
+          token(Str::Escape)
+          pop!
+        end
+
+        rule %r/\\./, Str, :pop!
+      end
+
+      state :generic_interpol do
+        rule %r/[^\@]+/ do |m|
+          recurse m[0]
+        end
+        rule %r/\@/, Str::Interpol, :pop!
+      end
+
+      class StringRegister < Array
+        def delim?(delim)
+          self.last[1] == delim
+        end
+
+        def register(type: "u", delim: "'")
+          self.push [type, delim]
+        end
+
+        def remove
+          self.pop
+        end
+
+        def type?(type)
+          self.last[0].include? type
+        end
+      end
+
+      private_constant :StringRegister
+    end
+  end
+end

spec/visual/samples/meson

@@ -0,0 +1,10 @@
+project('tutorial', 'c', version: '0.2.3')
+executable('demo', 'main.c')
+
+version_array = meson.project_version().split('.')
+api_version = '@0@.@1@'.format(version_array[0], version_array[1])
+
+d = dependency('foo', required : get_option('myfeature'))
+if d.found()
+  app = executable('app', 'app.c', dependencies : [d])
+endif