mirror of
https://github.com/rust-lang/rust-analyzer
synced 2024-12-26 13:03:31 +00:00
split mbe expander code into two modules
This commit is contained in:
Aleksey Kladov
parent
ba583091e6
commit
37ef8927c3
3 changed files with 448 additions and 418 deletions
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@ -2,10 +2,11 @@
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//! `tt::TokenTree` representing an argument of macro invocation, and produces a
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//! `tt::TokenTree` for the result of the expansion.
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use ra_parser::FragmentKind::*;
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mod matcher;
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mod transcriber;
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use ra_syntax::SmolStr;
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use rustc_hash::FxHashMap;
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use tt::TokenId;
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use crate::tt_cursor::TtCursor;
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use crate::ExpandError;
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@ -19,14 +20,12 @@ pub(crate) fn expand(
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fn expand_rule(rule: &crate::Rule, input: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {
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let mut input = TtCursor::new(input);
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let bindings = match_lhs(&rule.lhs, &mut input)?;
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let bindings = matcher::match_lhs(&rule.lhs, &mut input)?;
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if !input.is_eof() {
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return Err(ExpandError::UnexpectedToken);
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}
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let mut ctx = ExpandCtx { bindings: &bindings, nesting: Vec::new(), var_expanded: false };
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expand_subtree(&rule.rhs, &mut ctx)
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let res = transcriber::transcribe(&bindings, &rule.rhs)?;
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Ok(res)
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}
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/// The actual algorithm for expansion is not too hard, but is pretty tricky.
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@ -95,403 +94,6 @@ enum Fragment {
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Ast(tt::TokenTree),
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}
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impl Bindings {
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fn push_optional(&mut self, name: &SmolStr) {
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// FIXME: Do we have a better way to represent an empty token ?
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// Insert an empty subtree for empty token
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let tt = tt::Subtree { delimiter: tt::Delimiter::None, token_trees: vec![] }.into();
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self.inner.insert(name.clone(), Binding::Fragment(Fragment::Tokens(tt)));
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}
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fn push_empty(&mut self, name: &SmolStr) {
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self.inner.insert(name.clone(), Binding::Empty);
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}
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fn contains(&self, name: &SmolStr) -> bool {
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self.inner.contains_key(name)
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}
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fn get(&self, name: &SmolStr, nesting: &[usize]) -> Result<&Fragment, ExpandError> {
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let mut b = self.inner.get(name).ok_or_else(|| {
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ExpandError::BindingError(format!("could not find binding `{}`", name))
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})?;
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for &idx in nesting.iter() {
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b = match b {
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Binding::Fragment(_) => break,
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Binding::Nested(bs) => bs.get(idx).ok_or_else(|| {
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ExpandError::BindingError(format!("could not find nested binding `{}`", name))
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})?,
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Binding::Empty => {
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return Err(ExpandError::BindingError(format!(
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"could not find empty binding `{}`",
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name
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)))
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}
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};
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}
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match b {
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Binding::Fragment(it) => Ok(it),
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Binding::Nested(_) => Err(ExpandError::BindingError(format!(
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"expected simple binding, found nested binding `{}`",
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name
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))),
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Binding::Empty => Err(ExpandError::BindingError(format!(
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"expected simple binding, found empty binding `{}`",
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name
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))),
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}
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}
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fn push_nested(&mut self, idx: usize, nested: Bindings) -> Result<(), ExpandError> {
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for (key, value) in nested.inner {
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if !self.inner.contains_key(&key) {
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self.inner.insert(key.clone(), Binding::Nested(Vec::new()));
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}
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match self.inner.get_mut(&key) {
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Some(Binding::Nested(it)) => {
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// insert empty nested bindings before this one
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while it.len() < idx {
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it.push(Binding::Nested(vec![]));
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}
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it.push(value);
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}
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_ => {
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return Err(ExpandError::BindingError(format!(
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"could not find binding `{}`",
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key
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)));
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}
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}
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}
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Ok(())
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}
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fn merge(&mut self, nested: Bindings) {
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self.inner.extend(nested.inner);
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}
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}
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fn collect_vars(subtree: &crate::Subtree) -> Vec<SmolStr> {
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let mut res = vec![];
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for tkn in subtree.token_trees.iter() {
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match tkn {
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crate::TokenTree::Leaf(crate::Leaf::Var(crate::Var { text, .. })) => {
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res.push(text.clone());
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}
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crate::TokenTree::Subtree(subtree) => {
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res.extend(collect_vars(subtree));
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}
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crate::TokenTree::Repeat(crate::Repeat { subtree, .. }) => {
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res.extend(collect_vars(subtree));
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}
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_ => {}
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}
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}
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res
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}
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fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings, ExpandError> {
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let mut res = Bindings::default();
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for pat in pattern.token_trees.iter() {
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match pat {
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crate::TokenTree::Leaf(leaf) => match leaf {
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crate::Leaf::Var(crate::Var { text, kind }) => {
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let kind = kind.as_ref().ok_or(ExpandError::UnexpectedToken)?;
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match match_meta_var(kind.as_str(), input)? {
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Some(fragment) => {
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res.inner.insert(text.clone(), Binding::Fragment(fragment));
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}
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None => res.push_optional(text),
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}
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}
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crate::Leaf::Punct(punct) => {
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if !input.eat_punct().map(|p| p.char == punct.char).unwrap_or(false) {
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return Err(ExpandError::UnexpectedToken);
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}
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}
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crate::Leaf::Ident(ident) => {
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if input.eat_ident().map(|i| &i.text) != Some(&ident.text) {
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return Err(ExpandError::UnexpectedToken);
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}
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}
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crate::Leaf::Literal(literal) => {
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if input.eat_literal().map(|i| &i.text) != Some(&literal.text) {
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return Err(ExpandError::UnexpectedToken);
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}
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}
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},
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crate::TokenTree::Repeat(crate::Repeat { subtree, kind, separator }) => {
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// Dirty hack to make macro-expansion terminate.
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// This should be replaced by a propper macro-by-example implementation
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let mut limit = 65536;
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let mut counter = 0;
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let mut memento = input.save();
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loop {
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match match_lhs(subtree, input) {
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Ok(nested) => {
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limit -= 1;
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if limit == 0 {
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log::warn!("match_lhs excced in repeat pattern exceed limit => {:#?}\n{:#?}\n{:#?}\n{:#?}", subtree, input, kind, separator);
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break;
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}
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memento = input.save();
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res.push_nested(counter, nested)?;
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counter += 1;
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if counter == 1 {
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if let crate::RepeatKind::ZeroOrOne = kind {
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break;
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}
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}
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if let Some(separator) = separator {
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if !input
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.eat_seperator()
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.map(|sep| sep == *separator)
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.unwrap_or(false)
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{
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input.rollback(memento);
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break;
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}
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}
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}
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Err(_) => {
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input.rollback(memento);
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break;
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}
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}
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}
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match kind {
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crate::RepeatKind::OneOrMore if counter == 0 => {
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return Err(ExpandError::UnexpectedToken);
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}
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_ if counter == 0 => {
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// Collect all empty variables in subtrees
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collect_vars(subtree).iter().for_each(|s| res.push_empty(s));
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}
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_ => {}
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}
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}
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crate::TokenTree::Subtree(subtree) => {
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let input_subtree =
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input.eat_subtree().map_err(|_| ExpandError::UnexpectedToken)?;
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if subtree.delimiter != input_subtree.delimiter {
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return Err(ExpandError::UnexpectedToken);
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}
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let mut input = TtCursor::new(input_subtree);
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let bindings = match_lhs(&subtree, &mut input)?;
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if !input.is_eof() {
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return Err(ExpandError::UnexpectedToken);
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}
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res.merge(bindings);
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}
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}
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}
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Ok(res)
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}
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fn match_meta_var(kind: &str, input: &mut TtCursor) -> Result<Option<Fragment>, ExpandError> {
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let fragment = match kind {
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"path" => Path,
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"expr" => Expr,
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"ty" => Type,
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"pat" => Pattern,
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"stmt" => Statement,
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"block" => Block,
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"meta" => MetaItem,
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"item" => Item,
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_ => {
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let tt = match kind {
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"ident" => {
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let ident = input.eat_ident().ok_or(ExpandError::UnexpectedToken)?.clone();
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tt::Leaf::from(ident).into()
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}
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"tt" => input.eat().ok_or(ExpandError::UnexpectedToken)?.clone(),
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"lifetime" => input.eat_lifetime().ok_or(ExpandError::UnexpectedToken)?.clone(),
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"literal" => {
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let literal = input.eat_literal().ok_or(ExpandError::UnexpectedToken)?.clone();
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tt::Leaf::from(literal).into()
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}
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// `vis` is optional
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"vis" => match input.try_eat_vis() {
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Some(vis) => vis,
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None => return Ok(None),
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},
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_ => return Err(ExpandError::UnexpectedToken),
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};
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return Ok(Some(Fragment::Tokens(tt)));
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}
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};
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let tt = input.eat_fragment(fragment).ok_or(ExpandError::UnexpectedToken)?;
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let fragment = if kind == "expr" { Fragment::Ast(tt) } else { Fragment::Tokens(tt) };
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Ok(Some(fragment))
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}
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#[derive(Debug)]
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struct ExpandCtx<'a> {
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bindings: &'a Bindings,
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nesting: Vec<usize>,
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var_expanded: bool,
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}
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fn expand_subtree(
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template: &crate::Subtree,
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ctx: &mut ExpandCtx,
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) -> Result<tt::Subtree, ExpandError> {
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let mut buf: Vec<tt::TokenTree> = Vec::new();
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for tt in template.token_trees.iter() {
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let tt = expand_tt(tt, ctx)?;
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push_fragment(&mut buf, tt);
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}
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Ok(tt::Subtree { delimiter: template.delimiter, token_trees: buf })
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}
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fn expand_tt(template: &crate::TokenTree, ctx: &mut ExpandCtx) -> Result<Fragment, ExpandError> {
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let res: tt::TokenTree = match template {
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crate::TokenTree::Subtree(subtree) => expand_subtree(subtree, ctx)?.into(),
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crate::TokenTree::Repeat(repeat) => {
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let mut buf: Vec<tt::TokenTree> = Vec::new();
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ctx.nesting.push(0);
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// Dirty hack to make macro-expansion terminate.
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// This should be replaced by a propper macro-by-example implementation
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let mut limit = 65536;
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let mut has_seps = 0;
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let mut counter = 0;
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// We store the old var expanded value, and restore it later
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// It is because before this `$repeat`,
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// it is possible some variables already expanad in the same subtree
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//
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// `some_var_expanded` keep check if the deeper subtree has expanded variables
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let mut some_var_expanded = false;
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let old_var_expanded = ctx.var_expanded;
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ctx.var_expanded = false;
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while let Ok(t) = expand_subtree(&repeat.subtree, ctx) {
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// if no var expanded in the child, we count it as a fail
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if !ctx.var_expanded {
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break;
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}
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// Reset `ctx.var_expandeded` to see if there is other expanded variable
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// in the next matching
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some_var_expanded = true;
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ctx.var_expanded = false;
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counter += 1;
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limit -= 1;
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if limit == 0 {
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log::warn!(
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"expand_tt excced in repeat pattern exceed limit => {:#?}\n{:#?}",
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template,
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ctx
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);
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break;
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}
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let idx = ctx.nesting.pop().unwrap();
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ctx.nesting.push(idx + 1);
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push_subtree(&mut buf, t);
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if let Some(ref sep) = repeat.separator {
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match sep {
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crate::Separator::Ident(ident) => {
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has_seps = 1;
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buf.push(tt::Leaf::from(ident.clone()).into());
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}
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crate::Separator::Literal(lit) => {
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has_seps = 1;
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buf.push(tt::Leaf::from(lit.clone()).into());
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}
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crate::Separator::Puncts(puncts) => {
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has_seps = puncts.len();
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for punct in puncts {
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buf.push(tt::Leaf::from(*punct).into());
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}
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}
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}
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}
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if let crate::RepeatKind::ZeroOrOne = repeat.kind {
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break;
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}
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}
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// Restore the `var_expanded` by combining old one and the new one
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ctx.var_expanded = some_var_expanded || old_var_expanded;
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ctx.nesting.pop().unwrap();
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for _ in 0..has_seps {
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buf.pop();
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}
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if crate::RepeatKind::OneOrMore == repeat.kind && counter == 0 {
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return Err(ExpandError::UnexpectedToken);
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}
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// Check if it is a single token subtree without any delimiter
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// e.g {Delimiter:None> ['>'] /Delimiter:None>}
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tt::Subtree { delimiter: tt::Delimiter::None, token_trees: buf }.into()
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}
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crate::TokenTree::Leaf(leaf) => match leaf {
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crate::Leaf::Ident(ident) => {
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tt::Leaf::from(tt::Ident { text: ident.text.clone(), id: TokenId::unspecified() })
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.into()
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}
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crate::Leaf::Punct(punct) => tt::Leaf::from(*punct).into(),
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crate::Leaf::Var(v) => {
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if v.text == "crate" {
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// FIXME: Properly handle $crate token
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tt::Leaf::from(tt::Ident { text: "$crate".into(), id: TokenId::unspecified() })
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.into()
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} else if !ctx.bindings.contains(&v.text) {
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// Note that it is possible to have a `$var` inside a macro which is not bound.
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// For example:
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// ```
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// macro_rules! foo {
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// ($a:ident, $b:ident, $c:tt) => {
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// macro_rules! bar {
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// ($bi:ident) => {
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// fn $bi() -> u8 {$c}
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// }
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// }
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// }
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// ```
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// We just treat it a normal tokens
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tt::Subtree {
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delimiter: tt::Delimiter::None,
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token_trees: vec![
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tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone })
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.into(),
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tt::Leaf::from(tt::Ident {
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text: v.text.clone(),
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id: TokenId::unspecified(),
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})
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.into(),
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],
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}
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.into()
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} else {
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let fragment = ctx.bindings.get(&v.text, &ctx.nesting)?.clone();
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ctx.var_expanded = true;
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return Ok(fragment);
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}
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}
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crate::Leaf::Literal(l) => tt::Leaf::from(tt::Literal { text: l.text.clone() }).into(),
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},
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};
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Ok(Fragment::Tokens(res))
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}
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#[cfg(test)]
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mod tests {
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use ra_syntax::{ast, AstNode};
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@ -562,17 +164,3 @@ mod tests {
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expand_rule(&rules.rules[0], &invocation_tt)
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}
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}
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fn push_fragment(buf: &mut Vec<tt::TokenTree>, fragment: Fragment) {
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match fragment {
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Fragment::Tokens(tt::TokenTree::Subtree(tt)) => push_subtree(buf, tt),
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Fragment::Tokens(tt) | Fragment::Ast(tt) => buf.push(tt),
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}
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}
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fn push_subtree(buf: &mut Vec<tt::TokenTree>, tt: tt::Subtree) {
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match tt.delimiter {
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tt::Delimiter::None => buf.extend(tt.token_trees),
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_ => buf.push(tt.into()),
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}
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}
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|
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215
crates/ra_mbe/src/mbe_expander/matcher.rs
Normal file
215
crates/ra_mbe/src/mbe_expander/matcher.rs
Normal file
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@ -0,0 +1,215 @@
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use crate::{
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mbe_expander::{Binding, Bindings, Fragment},
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tt_cursor::TtCursor,
|
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ExpandError,
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};
|
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|
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use ra_parser::FragmentKind::*;
|
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use ra_syntax::SmolStr;
|
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|
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impl Bindings {
|
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fn push_optional(&mut self, name: &SmolStr) {
|
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// FIXME: Do we have a better way to represent an empty token ?
|
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// Insert an empty subtree for empty token
|
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let tt = tt::Subtree { delimiter: tt::Delimiter::None, token_trees: vec![] }.into();
|
||||
self.inner.insert(name.clone(), Binding::Fragment(Fragment::Tokens(tt)));
|
||||
}
|
||||
|
||||
fn push_empty(&mut self, name: &SmolStr) {
|
||||
self.inner.insert(name.clone(), Binding::Empty);
|
||||
}
|
||||
|
||||
fn push_nested(&mut self, idx: usize, nested: Bindings) -> Result<(), ExpandError> {
|
||||
for (key, value) in nested.inner {
|
||||
if !self.inner.contains_key(&key) {
|
||||
self.inner.insert(key.clone(), Binding::Nested(Vec::new()));
|
||||
}
|
||||
match self.inner.get_mut(&key) {
|
||||
Some(Binding::Nested(it)) => {
|
||||
// insert empty nested bindings before this one
|
||||
while it.len() < idx {
|
||||
it.push(Binding::Nested(vec![]));
|
||||
}
|
||||
it.push(value);
|
||||
}
|
||||
_ => {
|
||||
return Err(ExpandError::BindingError(format!(
|
||||
"could not find binding `{}`",
|
||||
key
|
||||
)));
|
||||
}
|
||||
}
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
fn merge(&mut self, nested: Bindings) {
|
||||
self.inner.extend(nested.inner);
|
||||
}
|
||||
}
|
||||
|
||||
pub(super) fn match_lhs(
|
||||
pattern: &crate::Subtree,
|
||||
input: &mut TtCursor,
|
||||
) -> Result<Bindings, ExpandError> {
|
||||
let mut res = Bindings::default();
|
||||
for pat in pattern.token_trees.iter() {
|
||||
match pat {
|
||||
crate::TokenTree::Leaf(leaf) => match leaf {
|
||||
crate::Leaf::Var(crate::Var { text, kind }) => {
|
||||
let kind = kind.as_ref().ok_or(ExpandError::UnexpectedToken)?;
|
||||
match match_meta_var(kind.as_str(), input)? {
|
||||
Some(fragment) => {
|
||||
res.inner.insert(text.clone(), Binding::Fragment(fragment));
|
||||
}
|
||||
None => res.push_optional(text),
|
||||
}
|
||||
}
|
||||
crate::Leaf::Punct(punct) => {
|
||||
if !input.eat_punct().map(|p| p.char == punct.char).unwrap_or(false) {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
}
|
||||
crate::Leaf::Ident(ident) => {
|
||||
if input.eat_ident().map(|i| &i.text) != Some(&ident.text) {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
}
|
||||
crate::Leaf::Literal(literal) => {
|
||||
if input.eat_literal().map(|i| &i.text) != Some(&literal.text) {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
}
|
||||
},
|
||||
crate::TokenTree::Repeat(crate::Repeat { subtree, kind, separator }) => {
|
||||
// Dirty hack to make macro-expansion terminate.
|
||||
// This should be replaced by a propper macro-by-example implementation
|
||||
let mut limit = 65536;
|
||||
let mut counter = 0;
|
||||
|
||||
let mut memento = input.save();
|
||||
|
||||
loop {
|
||||
match match_lhs(subtree, input) {
|
||||
Ok(nested) => {
|
||||
limit -= 1;
|
||||
if limit == 0 {
|
||||
log::warn!("match_lhs excced in repeat pattern exceed limit => {:#?}\n{:#?}\n{:#?}\n{:#?}", subtree, input, kind, separator);
|
||||
break;
|
||||
}
|
||||
|
||||
memento = input.save();
|
||||
res.push_nested(counter, nested)?;
|
||||
counter += 1;
|
||||
if counter == 1 {
|
||||
if let crate::RepeatKind::ZeroOrOne = kind {
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if let Some(separator) = separator {
|
||||
if !input
|
||||
.eat_seperator()
|
||||
.map(|sep| sep == *separator)
|
||||
.unwrap_or(false)
|
||||
{
|
||||
input.rollback(memento);
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
Err(_) => {
|
||||
input.rollback(memento);
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
match kind {
|
||||
crate::RepeatKind::OneOrMore if counter == 0 => {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
_ if counter == 0 => {
|
||||
// Collect all empty variables in subtrees
|
||||
collect_vars(subtree).iter().for_each(|s| res.push_empty(s));
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
crate::TokenTree::Subtree(subtree) => {
|
||||
let input_subtree =
|
||||
input.eat_subtree().map_err(|_| ExpandError::UnexpectedToken)?;
|
||||
if subtree.delimiter != input_subtree.delimiter {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
|
||||
let mut input = TtCursor::new(input_subtree);
|
||||
let bindings = match_lhs(&subtree, &mut input)?;
|
||||
if !input.is_eof() {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
|
||||
res.merge(bindings);
|
||||
}
|
||||
}
|
||||
}
|
||||
Ok(res)
|
||||
}
|
||||
|
||||
fn match_meta_var(kind: &str, input: &mut TtCursor) -> Result<Option<Fragment>, ExpandError> {
|
||||
let fragment = match kind {
|
||||
"path" => Path,
|
||||
"expr" => Expr,
|
||||
"ty" => Type,
|
||||
"pat" => Pattern,
|
||||
"stmt" => Statement,
|
||||
"block" => Block,
|
||||
"meta" => MetaItem,
|
||||
"item" => Item,
|
||||
_ => {
|
||||
let tt = match kind {
|
||||
"ident" => {
|
||||
let ident = input.eat_ident().ok_or(ExpandError::UnexpectedToken)?.clone();
|
||||
tt::Leaf::from(ident).into()
|
||||
}
|
||||
"tt" => input.eat().ok_or(ExpandError::UnexpectedToken)?.clone(),
|
||||
"lifetime" => input.eat_lifetime().ok_or(ExpandError::UnexpectedToken)?.clone(),
|
||||
"literal" => {
|
||||
let literal = input.eat_literal().ok_or(ExpandError::UnexpectedToken)?.clone();
|
||||
tt::Leaf::from(literal).into()
|
||||
}
|
||||
// `vis` is optional
|
||||
"vis" => match input.try_eat_vis() {
|
||||
Some(vis) => vis,
|
||||
None => return Ok(None),
|
||||
},
|
||||
_ => return Err(ExpandError::UnexpectedToken),
|
||||
};
|
||||
return Ok(Some(Fragment::Tokens(tt)));
|
||||
}
|
||||
};
|
||||
let tt = input.eat_fragment(fragment).ok_or(ExpandError::UnexpectedToken)?;
|
||||
let fragment = if kind == "expr" { Fragment::Ast(tt) } else { Fragment::Tokens(tt) };
|
||||
Ok(Some(fragment))
|
||||
}
|
||||
|
||||
fn collect_vars(subtree: &crate::Subtree) -> Vec<SmolStr> {
|
||||
let mut res = Vec::new();
|
||||
|
||||
for tkn in subtree.token_trees.iter() {
|
||||
match tkn {
|
||||
crate::TokenTree::Leaf(crate::Leaf::Var(crate::Var { text, .. })) => {
|
||||
res.push(text.clone());
|
||||
}
|
||||
crate::TokenTree::Subtree(subtree) => {
|
||||
res.extend(collect_vars(subtree));
|
||||
}
|
||||
crate::TokenTree::Repeat(crate::Repeat { subtree, .. }) => {
|
||||
res.extend(collect_vars(subtree));
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
|
||||
res
|
||||
}
|
||||
227
crates/ra_mbe/src/mbe_expander/transcriber.rs
Normal file
227
crates/ra_mbe/src/mbe_expander/transcriber.rs
Normal file
|
|
@ -0,0 +1,227 @@
|
|||
use ra_syntax::SmolStr;
|
||||
|
||||
use crate::{
|
||||
mbe_expander::{Binding, Bindings, Fragment},
|
||||
ExpandError,
|
||||
};
|
||||
|
||||
impl Bindings {
|
||||
fn contains(&self, name: &SmolStr) -> bool {
|
||||
self.inner.contains_key(name)
|
||||
}
|
||||
|
||||
fn get(&self, name: &SmolStr, nesting: &[usize]) -> Result<&Fragment, ExpandError> {
|
||||
let mut b = self.inner.get(name).ok_or_else(|| {
|
||||
ExpandError::BindingError(format!("could not find binding `{}`", name))
|
||||
})?;
|
||||
for &idx in nesting.iter() {
|
||||
b = match b {
|
||||
Binding::Fragment(_) => break,
|
||||
Binding::Nested(bs) => bs.get(idx).ok_or_else(|| {
|
||||
ExpandError::BindingError(format!("could not find nested binding `{}`", name))
|
||||
})?,
|
||||
Binding::Empty => {
|
||||
return Err(ExpandError::BindingError(format!(
|
||||
"could not find empty binding `{}`",
|
||||
name
|
||||
)))
|
||||
}
|
||||
};
|
||||
}
|
||||
match b {
|
||||
Binding::Fragment(it) => Ok(it),
|
||||
Binding::Nested(_) => Err(ExpandError::BindingError(format!(
|
||||
"expected simple binding, found nested binding `{}`",
|
||||
name
|
||||
))),
|
||||
Binding::Empty => Err(ExpandError::BindingError(format!(
|
||||
"expected simple binding, found empty binding `{}`",
|
||||
name
|
||||
))),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub(super) fn transcribe(
|
||||
bindings: &Bindings,
|
||||
template: &crate::Subtree,
|
||||
) -> Result<tt::Subtree, ExpandError> {
|
||||
let mut ctx = ExpandCtx { bindings: &bindings, nesting: Vec::new(), var_expanded: false };
|
||||
expand_subtree(template, &mut ctx)
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
struct ExpandCtx<'a> {
|
||||
bindings: &'a Bindings,
|
||||
nesting: Vec<usize>,
|
||||
var_expanded: bool,
|
||||
}
|
||||
|
||||
fn expand_subtree(
|
||||
template: &crate::Subtree,
|
||||
ctx: &mut ExpandCtx,
|
||||
) -> Result<tt::Subtree, ExpandError> {
|
||||
let mut buf: Vec<tt::TokenTree> = Vec::new();
|
||||
for tt in template.token_trees.iter() {
|
||||
let tt = expand_tt(tt, ctx)?;
|
||||
push_fragment(&mut buf, tt);
|
||||
}
|
||||
|
||||
Ok(tt::Subtree { delimiter: template.delimiter, token_trees: buf })
|
||||
}
|
||||
|
||||
fn expand_tt(template: &crate::TokenTree, ctx: &mut ExpandCtx) -> Result<Fragment, ExpandError> {
|
||||
let res: tt::TokenTree = match template {
|
||||
crate::TokenTree::Subtree(subtree) => expand_subtree(subtree, ctx)?.into(),
|
||||
crate::TokenTree::Repeat(repeat) => {
|
||||
let mut buf: Vec<tt::TokenTree> = Vec::new();
|
||||
ctx.nesting.push(0);
|
||||
// Dirty hack to make macro-expansion terminate.
|
||||
// This should be replaced by a propper macro-by-example implementation
|
||||
let mut limit = 65536;
|
||||
let mut has_seps = 0;
|
||||
let mut counter = 0;
|
||||
|
||||
// We store the old var expanded value, and restore it later
|
||||
// It is because before this `$repeat`,
|
||||
// it is possible some variables already expanad in the same subtree
|
||||
//
|
||||
// `some_var_expanded` keep check if the deeper subtree has expanded variables
|
||||
let mut some_var_expanded = false;
|
||||
let old_var_expanded = ctx.var_expanded;
|
||||
ctx.var_expanded = false;
|
||||
|
||||
while let Ok(t) = expand_subtree(&repeat.subtree, ctx) {
|
||||
// if no var expanded in the child, we count it as a fail
|
||||
if !ctx.var_expanded {
|
||||
break;
|
||||
}
|
||||
|
||||
// Reset `ctx.var_expandeded` to see if there is other expanded variable
|
||||
// in the next matching
|
||||
some_var_expanded = true;
|
||||
ctx.var_expanded = false;
|
||||
|
||||
counter += 1;
|
||||
limit -= 1;
|
||||
if limit == 0 {
|
||||
log::warn!(
|
||||
"expand_tt excced in repeat pattern exceed limit => {:#?}\n{:#?}",
|
||||
template,
|
||||
ctx
|
||||
);
|
||||
break;
|
||||
}
|
||||
|
||||
let idx = ctx.nesting.pop().unwrap();
|
||||
ctx.nesting.push(idx + 1);
|
||||
push_subtree(&mut buf, t);
|
||||
|
||||
if let Some(ref sep) = repeat.separator {
|
||||
match sep {
|
||||
crate::Separator::Ident(ident) => {
|
||||
has_seps = 1;
|
||||
buf.push(tt::Leaf::from(ident.clone()).into());
|
||||
}
|
||||
crate::Separator::Literal(lit) => {
|
||||
has_seps = 1;
|
||||
buf.push(tt::Leaf::from(lit.clone()).into());
|
||||
}
|
||||
|
||||
crate::Separator::Puncts(puncts) => {
|
||||
has_seps = puncts.len();
|
||||
for punct in puncts {
|
||||
buf.push(tt::Leaf::from(*punct).into());
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if let crate::RepeatKind::ZeroOrOne = repeat.kind {
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
// Restore the `var_expanded` by combining old one and the new one
|
||||
ctx.var_expanded = some_var_expanded || old_var_expanded;
|
||||
|
||||
ctx.nesting.pop().unwrap();
|
||||
for _ in 0..has_seps {
|
||||
buf.pop();
|
||||
}
|
||||
|
||||
if crate::RepeatKind::OneOrMore == repeat.kind && counter == 0 {
|
||||
return Err(ExpandError::UnexpectedToken);
|
||||
}
|
||||
|
||||
// Check if it is a single token subtree without any delimiter
|
||||
// e.g {Delimiter:None> ['>'] /Delimiter:None>}
|
||||
tt::Subtree { delimiter: tt::Delimiter::None, token_trees: buf }.into()
|
||||
}
|
||||
crate::TokenTree::Leaf(leaf) => match leaf {
|
||||
crate::Leaf::Ident(ident) => tt::Leaf::from(tt::Ident {
|
||||
text: ident.text.clone(),
|
||||
id: tt::TokenId::unspecified(),
|
||||
})
|
||||
.into(),
|
||||
crate::Leaf::Punct(punct) => tt::Leaf::from(*punct).into(),
|
||||
crate::Leaf::Var(v) => {
|
||||
if v.text == "crate" {
|
||||
// FIXME: Properly handle $crate token
|
||||
tt::Leaf::from(tt::Ident {
|
||||
text: "$crate".into(),
|
||||
id: tt::TokenId::unspecified(),
|
||||
})
|
||||
.into()
|
||||
} else if !ctx.bindings.contains(&v.text) {
|
||||
// Note that it is possible to have a `$var` inside a macro which is not bound.
|
||||
// For example:
|
||||
// ```
|
||||
// macro_rules! foo {
|
||||
// ($a:ident, $b:ident, $c:tt) => {
|
||||
// macro_rules! bar {
|
||||
// ($bi:ident) => {
|
||||
// fn $bi() -> u8 {$c}
|
||||
// }
|
||||
// }
|
||||
// }
|
||||
// ```
|
||||
// We just treat it a normal tokens
|
||||
tt::Subtree {
|
||||
delimiter: tt::Delimiter::None,
|
||||
token_trees: vec![
|
||||
tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone })
|
||||
.into(),
|
||||
tt::Leaf::from(tt::Ident {
|
||||
text: v.text.clone(),
|
||||
id: tt::TokenId::unspecified(),
|
||||
})
|
||||
.into(),
|
||||
],
|
||||
}
|
||||
.into()
|
||||
} else {
|
||||
let fragment = ctx.bindings.get(&v.text, &ctx.nesting)?.clone();
|
||||
ctx.var_expanded = true;
|
||||
return Ok(fragment);
|
||||
}
|
||||
}
|
||||
crate::Leaf::Literal(l) => tt::Leaf::from(tt::Literal { text: l.text.clone() }).into(),
|
||||
},
|
||||
};
|
||||
Ok(Fragment::Tokens(res))
|
||||
}
|
||||
|
||||
fn push_fragment(buf: &mut Vec<tt::TokenTree>, fragment: Fragment) {
|
||||
match fragment {
|
||||
Fragment::Tokens(tt::TokenTree::Subtree(tt)) => push_subtree(buf, tt),
|
||||
Fragment::Tokens(tt) | Fragment::Ast(tt) => buf.push(tt),
|
||||
}
|
||||
}
|
||||
|
||||
fn push_subtree(buf: &mut Vec<tt::TokenTree>, tt: tt::Subtree) {
|
||||
match tt.delimiter {
|
||||
tt::Delimiter::None => buf.extend(tt.token_trees),
|
||||
_ => buf.push(tt.into()),
|
||||
}
|
||||
}
|
||||
Loading…
Reference in a new issue