RBNF
RBNF is an Extended Backus-Naur Form implementation for Ruby.
Installation
gem install rbnfUsage
form = RBNF[?a] / ?b / ?c #=> '"a" | "b" | "c"'
form2 = RBNF[?a].cat('b').alt('c') #=> '( "a" , "b" ) | "c"'RBNF objects can be used to perform regex-like matches on strings. The first form will match the same strings as /[abc]/ :
form =~ 'a' #=> true
form =~ 'b' #=> true
form =~ 'd' #=> false
form =~ 'ab' #=> falseRBNFs can also accomplish matches that regexes can't:
RBNF.define :parens do
RBNF[?(] + RBNF.parens.opt + ?)
end
RBNF.parens =~ '()' #=> true
RBNF.parens =~ '(())' #=> true
RBNF.parens =~ '(()))' #=> falseRBNF objects memoize matches, but otherwise make no attempt at optimizing for performance.