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Checks no repetition for an empty token

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This commit is contained in:
Edwin Cheng 2020-04-25 23:09:20 +08:00
parent 44e6c2cb54
commit d5eb43f246
2 changed files with 75 additions and 12 deletions
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50
crates/ra_mbe/src/lib.rs
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@ -19,6 +19,7 @@ use crate::{
#[derive(Debug, PartialEq, Eq)]
pub enum ParseError {
Expected(String),
RepetitionEmtpyTokenTree,
}
#[derive(Debug, PartialEq, Eq)]
@ -194,20 +195,46 @@ impl Rule {
}
}
fn to_parse_error(e: ExpandError) -> ParseError {
let msg = match e {
ExpandError::InvalidRepeat => "invalid repeat".to_string(),
_ => "invalid macro definition".to_string(),
};
ParseError::Expected(msg)
}
fn validate(pattern: &tt::Subtree) -> Result<(), ParseError> {
for op in parse_pattern(pattern) {
let op = match op {
Ok(it) => it,
Err(e) => {
let msg = match e {
ExpandError::InvalidRepeat => "invalid repeat".to_string(),
_ => "invalid macro definition".to_string(),
};
return Err(ParseError::Expected(msg));
}
};
let op = op.map_err(to_parse_error)?;
match op {
Op::TokenTree(tt::TokenTree::Subtree(subtree)) | Op::Repeat { subtree, .. } => {
Op::TokenTree(tt::TokenTree::Subtree(subtree)) => validate(subtree)?,
Op::Repeat { subtree, separator, .. } => {
// Checks that no repetition which could match an empty token
// https://github.com/rust-lang/rust/blob/a58b1ed44f5e06976de2bdc4d7dc81c36a96934f/src/librustc_expand/mbe/macro_rules.rs#L558
if separator.is_none() {
if parse_pattern(subtree).all(|child_op| {
match child_op.map_err(to_parse_error) {
Ok(Op::Var { kind, .. }) => {
// vis is optional
if kind.map_or(false, |it| it == "vis") {
return true;
}
}
Ok(Op::Repeat { kind, .. }) => {
return matches!(
kind,
parser::RepeatKind::ZeroOrMore | parser::RepeatKind::ZeroOrOne
)
}
_ => {}
}
false
}) {
return Err(ParseError::RepetitionEmtpyTokenTree);
}
}
validate(subtree)?
}
_ => (),
@ -216,6 +243,7 @@ fn validate(pattern: &tt::Subtree) -> Result<(), ParseError> {
Ok(())
}
#[derive(Debug)]
pub struct ExpandResult<T>(pub T, pub Option<ExpandError>);
impl<T> ExpandResult<T> {