module CodeRay
module Scanners

  # Scanner for C++.
  # 
  # Aliases: cs, csharp
  class CSharp < Scanner

    register_for :csharp
    file_extension 'cs'
    title 'C#'
    
    #-- http://www.cppreference.com/wiki/keywords/start
    KEYWORDS = [
      'as', 'break', 'case', 'catch', 'class', 'const', 'continue', 'default', 
      'delegate', 'do', 'else', 'enum', 'event', 'finally', 'get', 'for', 'foreach',
      'goto', 'if', 'in', 'interface', 'is', 'lock', 'namespace', 'new', 
      'operator', 'out', 'params', 'readonly', 'ref', 'return', 'set', 'sizeof',
      'stackalloc', 'struct', 'switch', 'throw', 'try', 'typeof', 'using', 'var',
      'while', 'yield'
    ]  # :nodoc:
    
    PREDEFINED_TYPES = [
      'bool', 'byte', 'char', 'decimal', 'double', 'float', 'int', 'long',
      'object', 'sbyte', 'short', 'string', 'uint', 'ulong', 'ushort'
    ]  # :nodoc:
    PREDEFINED_CONSTANTS = [
      'false', 'null', 'true'
    ]  # :nodoc:
    PREDEFINED_VARIABLES = [
      'base', 'this'
    ]  # :nodoc:
    DIRECTIVES = [
      'abstract', 'checked', 'explicit', 'extern', 'fixed', 'implicit', 'internal',
      'override', 'private', 'protected', 'public', 'sealed', 'static', 'unchecked',
      'unsafe', 'virtual', 'void', 'volatile'
    ]  # :nodoc:
    
    IDENT_KIND = WordList.new(:ident).
      add(KEYWORDS, :keyword).
      add(PREDEFINED_TYPES, :predefined_type).
      add(PREDEFINED_VARIABLES, :local_variable).
      add(DIRECTIVES, :directive).
      add(PREDEFINED_CONSTANTS, :predefined_constant)  # :nodoc:

    ESCAPE = / [rbfntv\n\\'"] | x[a-fA-F0-9]{1,2} | [0-7]{1,3} /x  # :nodoc:
    UNICODE_ESCAPE =  / u[a-fA-F0-9]{4} | U[a-fA-F0-9]{8} /x  # :nodoc:
    
  protected
    
    def scan_tokens encoder, options

      state = :initial
      label_expected = true
      case_expected = false
      label_expected_before_preproc_line = nil
      in_preproc_line = false

      until eos?

        case state

        when :initial

          if match = scan(/ \s+ | \\\n /x)
            if in_preproc_line && match != "\\\n" && match.index(?\n)
              in_preproc_line = false
              label_expected = label_expected_before_preproc_line
            end
            encoder.text_token match, :space

          elsif match = scan(%r! // [^\n\\]* (?: \\. [^\n\\]* )* | /\* (?: .*? \*/ | .* ) !mx)
            encoder.text_token match, :comment

          elsif match = scan(/ \# \s* if \s* 0 /x)
            match << scan_until(/ ^\# (?:elif|else|endif) .*? $ | \z /xm) unless eos?
            encoder.text_token match, :comment

          elsif match = scan(/ [-+*=<>?:;,!&^|()\[\]{}~%]+ | \/=? | \.(?!\d) /x)
            label_expected = match =~ /[;\{\}]/
            if case_expected
              label_expected = true if match == ':'
              case_expected = false
            end
            encoder.text_token match, :operator

          elsif match = scan(/ [A-Za-z_][A-Za-z_0-9]* /x)
            kind = IDENT_KIND[match]
            if kind == :ident && label_expected && !in_preproc_line && scan(/:(?!:)/)
              kind = :label
              match << matched
            else
              label_expected = false
              if kind == :keyword
                case match
                when 'class', 'interface', 'struct'
                  state = :class_name_expected
                when 'case', 'default'
                  case_expected = true
                end
              end
            end
            encoder.text_token match, kind

          elsif match = scan(/\$/)
            encoder.text_token match, :ident
          
          elsif match = scan(/@?"/)
            encoder.begin_group :string
            state = :string
            encoder.text_token match, :delimiter

          elsif match = scan(/'/)
            encoder.begin_group :char
            state = :char
            encoder.text_token match, :delimiter

          elsif match = scan(/#[ \t]*(\w*)/)
            encoder.text_token match, :preprocessor
            in_preproc_line = true
            label_expected_before_preproc_line = label_expected

          elsif match = scan(/\d+[dDfFmM]|\d*\.\d+(?:[eE][+-]?\d+)?[dDfFmM]?|\d+[eE][+-]?\d+[dDfFmM]?/)
            label_expected = false
            encoder.text_token match, :float

          elsif match = scan(/0[xX][0-9A-Fa-f]+|[0-9]+(([uU][lL])|[lL])?/)
            label_expected = false
            encoder.text_token match, :integer

          else
            encoder.text_token getch, :error

          end

        when :string
          if match = scan(/[^\\"]+/)
            encoder.text_token match, :content
          elsif match = scan(/"/)
            encoder.text_token match, :delimiter
            encoder.end_group :string
            state = :initial
            label_expected = false
          elsif match = scan(/ \\ (?: #{ESCAPE} | #{UNICODE_ESCAPE} ) /mox)
            encoder.text_token match, :char
          elsif match = scan(/ \\ | $ /x)
            encoder.end_group :string
            encoder.text_token match, :error
            state = :initial
            label_expected = false
          else
            raise_inspect "else case \" reached; %p not handled." % peek(1), encoder
          end

        when :char
          if match = scan(/[^\\'']+/)
            encoder.text_token match, :content
          elsif match = scan(/'/)
            encoder.text_token match, :delimiter
            encoder.end_group :char
            state = :initial
            label_expected = false
          elsif match = scan(/ \\ (?: #{ESCAPE} | #{UNICODE_ESCAPE} ) /mox)
            encoder.text_token match, :char
          elsif match = scan(/ \\ | $ /x)
            encoder.end_group :char
            encoder.text_token match, :error
            state = :initial
            label_expected = false
          else
            raise_inspect "else case \" reached; %p not handled." % peek(1), encoder
          end

        when :class_name_expected
          if match = scan(/ [A-Za-z_][A-Za-z_0-9]* /x)
            encoder.text_token match, :class
            state = :initial

          elsif match = scan(/\s+/)
            encoder.text_token match, :space

          else
            encoder.text_token getch, :error
            state = :initial

          end
          
        else
          raise_inspect 'Unknown state', encoder

        end

      end

      if state == :string
        encoder.end_group :string
      end

      encoder
    end

  end

end
end