Class: Rgviz::Lexer

Inherits:
StringScanner
  • Object
show all
Defined in:
lib/rgviz/lexer.rb

Direct Known Subclasses

Parser

Instance Method Summary collapse

Constructor Details

#initialize(str) ⇒ Lexer

Returns a new instance of Lexer.



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# File 'lib/rgviz/lexer.rb', line 5

def initialize(str)
  super
  @token = Token.new
end

Instance Method Details

#next_token ⇒ Object 



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# File 'lib/rgviz/lexer.rb', line 10

def next_token
  @token.start = pos
  @token.string = nil
  @token.value = nil

  skip /\s*/

  if eos?
    @token.value = Token::EOF
  elsif scan /"([^"]*)"/
    @token.value = Token::STRING
    @token.string = self[1]
  elsif scan /'([^']*)'/
    @token.value = Token::STRING
    @token.string = self[1]
  elsif scan /`([^`]*)`/
    @token.value = Token::ID
    @token.string = self[1]
  elsif scan /\d+\.\d*/ or scan /\.\d+/
    @token.value = Token::DECIMAL
    @token.number = matched.to_f
  elsif scan /\d+/
    @token.value = Token::INTEGER
    @token.number = matched.to_i
  else
    @token.value = if scan /\+/ then Token::PLUS
      elsif scan /\-/ then Token::MINUS
      elsif scan /\*/ then Token::STAR
      elsif scan /\// then Token::SLASH
      elsif scan /\,/ then Token::COMMA
      elsif scan /\(/ then Token::LPAREN
      elsif scan /\)/ then Token::RPAREN
      elsif scan /\=/ then Token::EQ
      elsif scan /\!\=/ or scan /\<\>/ then Token::NEQ
      elsif scan /\>\=/ then Token::GTE
      elsif scan /\>/ then Token::GT
      elsif scan /\<\=/ then Token::LTE
      elsif scan /\</ then Token::LT
      elsif scan /and\b/i then Token::And
      elsif scan /asc\b/i then Token::Asc
      elsif scan /avg\b/i then Token::Avg
      elsif scan /by\b/i then Token::By
      elsif scan /concat\b/i then Token::Concat
      elsif scan /contains\b/i then Token::Contains
      elsif scan /count\b/i then Token::Count
      elsif scan /date\b/i then Token::Date
      elsif scan /datediff\b/i then Token::DateDiff
      elsif scan /datetime\b/i then Token::DateTime
      elsif scan /day\b/i then Token::Day
      elsif scan /dayofweek\b/i then Token::DayOfWeek
      elsif scan /desc\b/i then Token::Desc
      elsif scan /ends\b/i then Token::Ends
      elsif scan /false\b/i then Token::False
      elsif scan /floor\b/i then Token::Floor
      elsif scan /format\b/i then Token::Format
      elsif scan /group\b/i then Token::Group
      elsif scan /hour\b/i then Token::Hour
      elsif scan /is\b/i then Token::Is
      elsif scan /label\b/i then Token::Label
      elsif scan /like\b/i then Token::Like
      elsif scan /limit\b/i then Token::Limit
      elsif scan /lower\b/i then Token::Lower
      elsif scan /matches\b/i then Token::Matches
      elsif scan /max\b/i then Token::Max
      elsif scan /millisecond\b/i then Token::Millisecond
      elsif scan /min\b/i then Token::Min
      elsif scan /minute\b/i then Token::Minute
      elsif scan /month\b/i then Token::Month
      elsif scan /not\b/i then Token::Not
      elsif scan /now\b/i then Token::Now
      elsif scan /no_format\b/i then Token::NoFormat
      elsif scan /no_values\b/i then Token::NoValues
      elsif scan /null\b/i then Token::Null
      elsif scan /offset\b/i then Token::Offset
      elsif scan /options\b/i then Token::Options
      elsif scan /or\b/i then Token::Or
      elsif scan /order\b/i then Token::Order
      elsif scan /pivot\b/i then Token::Pivot
      elsif scan /quarter\b/i then Token::Quarter
      elsif scan /round\b/i then Token::Round
      elsif scan /second\b/i then Token::Second
      elsif scan /select\b/i then Token::Select
      elsif scan /starts\b/i then Token::Starts
      elsif scan /sum\b/i then Token::Sum
      elsif scan /timeofday\b/i then Token::TimeOfDay
      elsif scan /timestamp\b/i then Token::Timestamp
      elsif scan /todate\b/i then Token::ToDate
      elsif scan /true\b/i then Token::True
      elsif scan /upper\b/i then Token::Upper
      elsif scan /where\b/i then Token::Where
      elsif scan /with\b/i then Token::With
      elsif scan /year\b/i then Token::Year
      elsif scan /[a-zA-Z_]\w*\b/ then Token::ID
    end

    if @token.value
      @token.string = matched
    else
      raise ParseException.new("Unexpected character #{string[pos].chr}")
    end
  end

  return @token
end