Class: NexusParser::Lexer

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

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ Lexer

Returns a new instance of Lexer.



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

def initialize(input)
  @input = input
  # linefeed check the input here -
  @input.gsub!(/\x0D/,"") # get rid of possible dos carrige returns
  @next_token = nil
end

Instance Method Details

#peek(token_class) ⇒ Object

checks whether the next token is of the specified class.



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# File 'lib/nexus_parser/lexer.rb', line 13

def peek(token_class)
  token = read_next_token(token_class)
  return token.class == token_class
end

#pop(token_class) ⇒ Object

return (and delete) the next token from the input stream, or raise an exception if the next token is not of the given class.



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# File 'lib/nexus_parser/lexer.rb', line 20

def pop(token_class)
  token = read_next_token(token_class)
  @next_token = nil
  if token.class != token_class
    raise(NexusParser::ParseError,"expected #{token_class.to_s} but received #{token.class.to_s} at #{@input[0..40]}...", caller)
  else
    return token
  end
end