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|
use ra_syntax::SmolStr;
use crate::macros::tt;
#[derive(Debug)]
pub(crate) struct MacroRules {
rules: Vec<Rule>,
}
#[derive(Debug)]
struct Rule {
lhs: Subtree,
rhs: Subtree,
}
#[derive(Debug)]
enum TokenTree {
Leaf(Leaf),
Subtree(Subtree),
Repeat(Repeat),
}
#[derive(Debug)]
enum Leaf {
Literal(Literal),
Punct(Punct),
Ident(Ident),
Var(Var),
}
#[derive(Debug)]
struct Subtree {
delimiter: Delimiter,
token_trees: Vec<TokenTree>,
}
#[derive(Debug)]
enum Delimiter {
Parenthesis,
Brace,
Bracket,
None,
}
#[derive(Debug)]
struct Repeat {
subtree: Subtree,
kind: RepeatKind,
}
#[derive(Debug)]
enum RepeatKind {
ZeroOrMore,
OneOrMore,
ZeroOrOne,
}
#[derive(Debug)]
struct Literal {
text: SmolStr,
}
#[derive(Debug)]
struct Punct {
char: char,
}
#[derive(Debug)]
struct Ident {
text: SmolStr,
}
#[derive(Debug)]
struct Var {
text: SmolStr,
}
pub(crate) fn parse(tt: &tt::Subtree) -> Option<MacroRules> {
let mut parser = RulesParser::new(tt);
let mut rules = Vec::new();
while !parser.is_eof() {
rules.push(parse_rule(&mut parser)?)
}
Some(MacroRules { rules })
}
fn parse_rule(p: &mut RulesParser) -> Option<Rule> {
let lhs = parse_subtree(p.eat_subtree()?)?;
p.eat_punct('=')?;
p.eat_punct('>')?;
let rhs = parse_subtree(p.eat_subtree()?)?;
Some(Rule { lhs, rhs })
}
fn parse_subtree(tt: &tt::Subtree) -> Option<Subtree> {
Some(Subtree {
token_trees: Vec::new(),
delimiter: Delimiter::None,
})
}
struct RulesParser<'a> {
subtree: &'a tt::Subtree,
pos: usize,
}
impl<'a> RulesParser<'a> {
fn new(subtree: &'a tt::Subtree) -> RulesParser<'a> {
RulesParser { subtree, pos: 0 }
}
fn is_eof(&self) -> bool {
self.pos == self.subtree.token_trees.len()
}
fn current(&self) -> Option<&'a tt::TokenTree> {
self.subtree.token_trees.get(self.pos)
}
fn bump(&mut self) {
self.pos += 1;
}
fn eat_subtree(&mut self) -> Option<&'a tt::Subtree> {
match self.current()? {
tt::TokenTree::Subtree(sub) => {
self.bump();
Some(sub)
}
_ => return None,
}
}
fn eat_punct(&mut self, char: char) -> Option<()> {
match self.current()? {
tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: c })) if *c == char => {
self.bump();
Some(())
}
_ => None,
}
}
}
|
