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|
/// `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::syntax_bridge::ast_to_token_tree;
/// This struct contains AST for a single `macro_rules` defenition. What might
/// be very confusing is that AST has almost exactly the same shape as
/// `tt::TokenTree`, but there's a crucial difference: in macro rules, `$ident`
/// and `$()*` have special meaning (see `Var` and `Repeat` data structures)
#[derive(Debug)]
pub struct MacroRules {
pub(crate) rules: Vec<Rule>,
}
impl MacroRules {
pub fn parse(tt: &tt::Subtree) -> Option<MacroRules> {
mbe_parser::parse(tt)
}
pub fn expand(&self, tt: &tt::Subtree) -> Option<tt::Subtree> {
mbe_expander::exapnd(self, tt)
}
}
#[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>,
}
#[cfg(test)]
mod tests {
use ra_syntax::{ast, AstNode};
use super::*;
// Good first issue (although a slightly chellegning one):
//
// * Pick a random test from here
// https://github.com/intellij-rust/intellij-rust/blob/c4e9feee4ad46e7953b1948c112533360b6087bb/src/test/kotlin/org/rust/lang/core/macros/RsMacroExpansionTest.kt
// * Port the test to rust and add it to this module
// * Make it pass :-)
#[test]
fn test_convert_tt() {
let macro_definition = r#"
macro_rules! impl_froms {
($e:ident: $($v:ident),*) => {
$(
impl From<$v> for $e {
fn from(it: $v) -> $e {
$e::$v(it)
}
}
)*
}
}
"#;
let macro_invocation = r#"
impl_froms!(TokenTree: Leaf, Subtree);
"#;
let source_file = ast::SourceFile::parse(macro_definition);
let macro_definition = source_file
.syntax()
.descendants()
.find_map(ast::MacroCall::cast)
.unwrap();
let source_file = ast::SourceFile::parse(macro_invocation);
let macro_invocation = source_file
.syntax()
.descendants()
.find_map(ast::MacroCall::cast)
.unwrap();
let definition_tt = ast_to_token_tree(macro_definition.token_tree().unwrap()).unwrap();
let invocation_tt = ast_to_token_tree(macro_invocation.token_tree().unwrap()).unwrap();
let rules = crate::MacroRules::parse(&definition_tt).unwrap();
let expansion = rules.expand(&invocation_tt).unwrap();
assert_eq!(
expansion.to_string(),
"impl From < Leaf > for TokenTree {fn from (it : Leaf) -> TokenTree {TokenTree :: Leaf (it)}} \
impl From < Subtree > for TokenTree {fn from (it : Subtree) -> TokenTree {TokenTree :: Subtree (it)}}"
)
}
}
|
