Class: RDParser::Scanner

Inherits:
Object
  • Object
show all
Defined in:
lib/rdparser/scanner.rb

Overview

Scanner is basically a proxy class for StringScanner that adds some convenience features. Could probably be a subclass actually, but this was a quick, scrappy job so I could get onto the fun stuff in RDParser!

Instance Method Summary collapse

Constructor Details

#initialize(string, options = {}) ⇒ Scanner

Returns a new instance of Scanner.



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# File 'lib/rdparser/scanner.rb', line 8

def initialize(string, options = {})
  @options = options
  @scanner = StringScanner.new(string.dup)
  @rollback_pointers = []
end

Instance Method Details

#eos? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rdparser/scanner.rb', line 18

def eos?
  @scanner.eos?
end

#lookahead ⇒ Object 



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# File 'lib/rdparser/scanner.rb', line 26

def lookahead
  @scanner.peek(10)
end

#position ⇒ Object 



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# File 'lib/rdparser/scanner.rb', line 14

def position
  @scanner.pos
end

#rollback ⇒ Object 



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# File 'lib/rdparser/scanner.rb', line 43

def rollback
  begin
    (@scanner.pos = @rollback_pointers.pop) && true
  rescue
    nil
  end
end

#rollback_position ⇒ Object 



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# File 'lib/rdparser/scanner.rb', line 22

def rollback_position
  @rollback_pointers.last
end

#rollback_to(posi) ⇒ Object 



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# File 'lib/rdparser/scanner.rb', line 51

def rollback_to(posi)
  @scanner.pos = posi
  @rollback_pointers.delete_if { |p| p >= posi }
end

#scan(regexp) ⇒ Object 



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# File 'lib/rdparser/scanner.rb', line 30

def scan(regexp)
  space = @options[:slurp_whitespace] && @options[:slurp_whitespace] == true ? /\s*/ : //
    if regexp.class == String
      regexp = Regexp.new(regexp.gsub(/\(|\)|\+|\|/) { |a| '\\' + a })
    end
  if match = @scanner.scan(/(#{space}(#{regexp}))/)
    @rollback_pointers << (@scanner.pos - match.length)
    @options[:slurp_whitespace] && @options[:slurp_whitespace] == true ? match.sub(/^\s*/, '') : match
  else
    nil
  end
end