`Prism Parser`

A PEG parsing library built for the Prism programming language

## About This crate provides a PEG parser with the following features: * Support for left recursion * Adaptation: The grammar can be changed dynamically during parsing This crate is under heavy development and not yet ready to be used in production code. ## Example This defines the grammar of a simple arithmetic language, and support to adapt the language: ``` rule start = block; rule block { b <- "grammar" "{" g:grammar(prule_action) "}" ";" b:#adapt(g, block); s :: b <- s:stmt ";" b:block; [] <- ""; } rule stmt { Let(e) <- "let" e:expr; Do() <- "do"; } rule expr { group additive { Add(x, y) <- x:#next "+" y:#this; } group multiplicative { Mul(x, y) <- x:#next "*" y:#this; } group base { Block(b) <- "(" b:block ")"; UnaryMinus(v) <- "-" v:#this; Num(n) <- n:#str([0-9]*); } } rule layout = [' ' | '\n']; ``` Example programs in this language: ``` 1 * 2 + -3 ``` ``` grammar { rule expr { group additive { 1 + (-2) <- x:#next "-" y:#this; } } }; 1 - 2 ```