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Refactor and rename

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This commit is contained in:
Edwin Cheng 2019-11-05 01:01:05 +08:00
parent 42661a3b27
commit 188a1412b9
1 changed files with 20 additions and 21 deletions
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41
crates/ra_mbe/src/lib.rs
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@ -52,23 +52,21 @@ pub(crate) struct Rule {
pub(crate) rhs: tt::Subtree,
}
/// Find the "shift" (the highest id of the TokenId) inside a subtree
fn find_subtree_shift(tt: &tt::Subtree, mut cur: u32) -> u32 {
use std::cmp::max;
for t in &tt.token_trees {
cur = match t {
tt::TokenTree::Leaf(leaf) => match leaf {
tt::Leaf::Ident(ident) if ident.id != tt::TokenId::unspecified() => {
max(cur, ident.id.0)
}
_ => cur,
},
tt::TokenTree::Subtree(tt) => find_subtree_shift(tt, cur),
}
}
cur
// Find the max token id inside a subtree
fn max_id(subtree: &tt::Subtree) -> Option<u32> {
subtree
.token_trees
.iter()
.filter_map(|tt| match tt {
tt::TokenTree::Subtree(subtree) => max_id(subtree),
tt::TokenTree::Leaf(tt::Leaf::Ident(ident))
if ident.id != tt::TokenId::unspecified() =>
{
Some(ident.id.0)
}
_ => None,
})
.max()
}
/// Shift given TokenTree token id
@ -77,9 +75,7 @@ fn shift_subtree(tt: &mut tt::Subtree, shift: u32) {
match t {
tt::TokenTree::Leaf(leaf) => match leaf {
tt::Leaf::Ident(ident) if ident.id != tt::TokenId::unspecified() => {
// Note that TokenId is started from zero,
// We have to add 1 to prevent duplication.
ident.id.0 += shift + 1;
ident.id.0 += shift;
}
_ => (),
},
@ -110,7 +106,10 @@ pub fn parse(tt: &tt::Subtree) -> Result<MacroRules, ParseError> {
validate(&rule.lhs)?;
}
Ok(MacroRules { rules, shift: find_subtree_shift(tt, 0) })
// Note that TokenId is started from zero,
// We have to add 1 to prevent duplication.
let shift = max_id(tt).unwrap_or(0) + 1;
Ok(MacroRules { rules, shift })
}
pub fn expand(&self, tt: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {