Macro ecmascript::build_ast

macro_rules! build_ast {
    ([$($many:tt)+]) => { ... };
    (regex_lit /{$pattern:expr}/{$flags:expr}) => { ... };
    (regex_lit /{$pattern:expr}/) => { ... };
    (this) => { ... };
    (id $id:expr) => { ... };
    (null) => { ... };
    (true) => { ... };
    (false) => { ... };
    (num $lit:expr) => { ... };
    (str $lit:expr) => { ... };
    (array [$($elements:tt),*]) => { ... };
    (obj [$($properties:tt),+]) => { ... };
    ([$($key:tt)+]: [$($value:tt)+]) => { ... };
    (function [$($params:tt),+] {$body:expr}) => { ... };
    (...[$($expression:tt)+]) => { ... };
    (call [$($id:tt)+] [$($args:tt)+]) => { ... };
    (yield) => { ... };
    (<$id:ident />) => { ... };
}

This macro makes constructing complicated syntax trees very easy. This can be useful for re-writing parts of the AST, or deriving a a syntax tree from other trees (eg. concatenating syntax trees).

Example

let my_wrapper_func = build_ast! {
  function [id "my_wrapper".to_string()] ( ) {
    var [id "foo".to_string()] = [obj []];
  }
};

Conventions

• we use [] to represent recursive calls to the macro
• we use {} to accept a rust expression eg: call [id "my_func".to_string()] [ [id "a".to_string()] [true] [null] ] recursively expands to

build_ast!(call build_ast!(...) [ build_ast!(...), build_ast!(...), build_ast!(...) ])