Class: Ruty::Parser::ArgumentLexer

Inherits:
Object
  • Object
show all
Defined in:
lib/ruty/parser.rb

Overview

class for parsing arguments. used by the parse_arguments function. It's usualy a better idea to not use this class yourself because it's pretty low level.

Constant Summary collapse

WHITESPACE_RE =

lexer constants

/\s+/m
NAME_RE =
/[a-zA-Z_][a-zA-Z0-9_]*(\.[a-zA-Z_][a-zA-Z0-9_]*)*/
PIPE_RE =
/\|/
FILTER_END_RE =
/;/
SEPARATOR_RE =
/,/
STRING_RE =
/
  (?:
    "([^"\\]*(?:\\.[^"\\]*)*)"
  |
    '([^'\\]*(?:\\.[^'\\]*)*)'
  )
/xm
NUMBER_RE =
/\d+(\.\d*)?/

Instance Method Summary collapse

Constructor Details

#initialize(string) ⇒ ArgumentLexer

create a new ArgumentLexer for the given string


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# File 'lib/ruty/parser.rb', line 131

def initialize string
  @string = string
end

Instance Method Details

#lex(&block) ⇒ Object

lex the string. For each return token this function calls the given block with the token type and value.


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# File 'lib/ruty/parser.rb', line 137

def lex &block
  s = StringScanner.new(@string)
  state = :initial

  while not s.eos?
    # supress whitespace. no matter in which state we are.
    next if s.scan(WHITESPACE_RE)

    # normal data, no filters.
    if state == :initial
      if match = s.scan(NAME_RE)
        block.call(:name, match)
      elsif s.scan(PIPE_RE)
        state = :filter
        block.call(:filter_start, nil)
      elsif s.scan(SEPARATOR_RE)
        block.call(:separator, nil)
      elsif match = s.scan(STRING_RE)
        block.call(:string, match)
      elsif match = s.scan(NUMBER_RE)
        block.call(:number, match)
      else
        # nothing matched and we are not at the end of
        # the string, raise an error
        raise TemplateSyntaxError, 'unexpected character ' \
                                   "'#{s.getch}' in block tag"
      end
    
    # filter syntax
    elsif state == :filter
      # if a second pipe occours we start a new filter
      if s.scan(PIPE_RE)
        block.call(:filter_end, nil)
        block.call(:filter_start, nil)
      # filter ends with ; -- handle that
      elsif s.scan(FILTER_END_RE)
        block.call(:filter_end, nil)
        state = :initial
      elsif s.scan(SEPARATOR_RE)
        block.call(:separator, nil)
      # variables, strings and numbers
      elsif match = s.scan(NAME_RE)
        block.call(:name, match)
      elsif match = s.scan(STRING_RE)
        block.call(:string, match)
      elsif match = s.scan(NUMBER_RE)
        block.call(:number, match)
      else
        # nothing matched and we are not at the end of
        # the string, raise an error
        raise TemplateSyntaxError, 'unexpected character ' \
                                   "'#{s.getch}' in filter def"
      end
    end
  end
  block.call(:filter_end, nil) if state == :filter
end