module Rouge
  module Lexers
    class SML < RegexLexer
      desc 'Standard ML'
      tag 'sml'
      aliases 'ml'
      filenames '*.sml', '*.sig', '*.fun'

      mimetypes 'text/x-standardml', 'application/x-standardml'

      def self.keywords
        @keywords ||= Set.new %w(
          abstype and andalso as case datatype do else end exception
          fn fun handle if in infix infixr let local nonfix of op open
          orelse raise rec then type val with withtype while
          eqtype functor include sharing sig signature struct structure
          where
        )
      end

      id = /[a-z][\w']*/i
      symbol = %r([!%&$#/:<=>?@\\~`^|*+-]+)

      def self.analyze_text(text)
        return 0
      end

      state :whitespace do
        rule /\s+/m, Text
        rule /[(][*]/, Comment, :comment
      end

      state :delimiters do
        rule /[(\[{]/, Punctuation, :main
        rule /[)\]}]/, Punctuation, :pop!

        rule /\b(let|if|local)\b(?!')/, Keyword::Reserved do
          push; push
        end

        rule /\b(struct|sig|while)\b(?!')/ do
          token Keyword::Reserved
          push
        end

        rule /\b(do|else|end|in|then)\b(?!')/, Keyword::Reserved, :pop!
      end

      def token_for_id_with_dot(id)
        if self.class.keywords.include? id
          Error
        else
          Name::Namespace
        end
      end

      def token_for_final_id(id)
        if self.class.keywords.include? id or self.class.symbolic_reserved.include? id
          Error
        else
          Name
        end
      end

      def token_for_id(id)
        if self.class.keywords.include? id
          Keyword::Reserved
        elsif self.class.symbolic_reserved.include? id
          Punctuation
        else
          Name
        end
      end

      state :core do
        rule /[()\[\]{},;_]|[.][.][.]/, Punctuation
        rule /#"/, Str::Char, :char
        rule /~?0x[0-9a-fA-F]+/, Num::Hex
        rule /0wx[0-9a-fA-F]+/, Num::Hex
        rule /0w\d+/, Num::Integer
        rule /~?\d+[.]\d+[eE]~?\d+/, Num::Float
        rule /~?\d+[.]\d+/, Num::Float
        rule /~?\d+/, Num::Integer

        rule /#\s*[1-9][0-9]*/, Name::Label
        rule /#\s*#{id}/, Name::Label
        rule /#\s+#{symbol}/, Name::Label

        rule /\b(datatype|abstype)\b(?!')/, Keyword::Reserved, :dname
        rule(/(?=\bexception\b(?!'))/) { push :ename }
        rule /\b(functor|include|open|signature|structure)\b(?!')/,
          Keyword::Reserved, :sname
        rule /\b(type|eqtype)\b(?!')/, Keyword::Reserved, :tname

        rule /'#{id}/, Name::Decorator
        rule /(#{id})([.])/ do |m|
          groups(token_for_id_with_dot(m[1]), Punctuation)
          push :dotted
        end

        state :dotted do
          rule /(#{id})([.])/ do |m|
            groups(token_for_id_with_dot(m[1]), Punctuation)
          end
        end
      end

      state :root do
        rule /#!.*?\n/, Comment::Preproc
        rule(//) { push :main }
      end
    end
  end
end