rust-analyzer/crates/ra_mbe/src/lib.rs

/// `mbe` (short for Macro By Example) crate contains code for handling
/// `macro_rules` macros. It uses `TokenTree` (from `ra_tt` package) as the
/// interface, although it contains some code to bridge `SyntaxNode`s and
/// `TokenTree`s as well!

macro_rules! impl_froms {
    ($e:ident: $($v:ident), *) => {
        $(
            impl From<$v> for $e {
                fn from(it: $v) -> $e {
                    $e::$v(it)
                }
            }
        )*
    }
}

mod tt_cursor;
mod mbe_parser;
mod mbe_expander;
mod syntax_bridge;

use ra_syntax::SmolStr;

pub use tt::{Delimiter, Punct};

pub use crate::{
    mbe_parser::parse,
    mbe_expander::exapnd,
    syntax_bridge::macro_call_to_tt,
};

#[derive(Debug)]
pub struct MacroRules {
    pub(crate) rules: Vec<Rule>,
}

#[derive(Debug)]
pub(crate) struct Rule {
    pub(crate) lhs: Subtree,
    pub(crate) rhs: Subtree,
}

#[derive(Debug)]
pub(crate) enum TokenTree {
    Leaf(Leaf),
    Subtree(Subtree),
    Repeat(Repeat),
}
impl_froms!(TokenTree: Leaf, Subtree, Repeat);

#[derive(Debug)]
pub(crate) enum Leaf {
    Literal(Literal),
    Punct(Punct),
    Ident(Ident),
    Var(Var),
}
impl_froms!(Leaf: Literal, Punct, Ident, Var);

#[derive(Debug)]
pub(crate) struct Subtree {
    pub(crate) delimiter: Delimiter,
    pub(crate) token_trees: Vec<TokenTree>,
}

#[derive(Debug)]
pub(crate) struct Repeat {
    pub(crate) subtree: Subtree,
    pub(crate) kind: RepeatKind,
    pub(crate) separator: Option<char>,
}

#[derive(Debug)]
pub(crate) enum RepeatKind {
    ZeroOrMore,
    OneOrMore,
    ZeroOrOne,
}

#[derive(Debug)]
pub(crate) struct Literal {
    pub(crate) text: SmolStr,
}

#[derive(Debug)]
pub(crate) struct Ident {
    pub(crate) text: SmolStr,
}

#[derive(Debug)]
pub(crate) struct Var {
    pub(crate) text: SmolStr,
    pub(crate) kind: Option<SmolStr>,
}