In my scheme packrat parser generator I define everything with macros. Its somewhat simpler in that I don't have to do extra parsing and I get the benefit of using macro technology to process the Peg.
The generator: https://github.com/kazzmir/Pegs/blob/master/peg.rkt An example usage: https://github.com/kazzmir/Pegs/blob/master/peg-tests/calculator.ss On 11/15/2010 07:32 AM, Alan Post wrote: > I'm implementing a packrat parser in Scheme. I'm at the point of > writing a bootstrap parser in Scheme for PEG, and my bootstrap > parser is basically working. > > I haven't yet decided on the syntax for embedding code in the > parser. My only example for doing this is peg/leg: > > http://piumarta.com/software/peg/peg.1.html > > which encloses code in {} brackets and permits references to parts > of the parse tree with <>: > > { action } > Curly braces surround actions. The action is arbitray C source > code to be executed at the end of matching. Any braces within > the action must be properly nested. Any input text that was > matched before the action and delimited by angle brackets (see > below) is made available within the action as the contents of > the character array yytext. The length of (number of characters > in) yytext is available in the variable yyleng. (These variable > names are historical; see lex(1).) > > < An opening angle bracket always matches (consuming no input) and > causes the parser to begin accumulating matched text. This text > will be made available to actions in the variable yytext. > > > A closing angle bracket always matches (consuming no input) and > causes the parser to stop accumulating text for yytext. > > What else is out there? Is this something reasonably standard or does > every tool do something different? > > -Alan _______________________________________________ PEG mailing list PEG@lists.csail.mit.edu https://lists.csail.mit.edu/mailman/listinfo/peg
