mirror of
https://github.com/rust-lang/rust-analyzer
synced 2025-01-19 08:34:09 +00:00
8a50aecb07
I didn't follow rustc precisely, because I think it does some things wrongly (or they are FIXME), but I only allowed more code, not less. So we're all fine.
631 lines
25 KiB
Rust
631 lines
25 KiB
Rust
//! Transcriber takes a template, like `fn $ident() {}`, a set of bindings like
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//! `$ident => foo`, interpolates variables in the template, to get `fn foo() {}`
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use intern::{sym, Symbol};
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use span::{Edition, Span};
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use tt::Delimiter;
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use crate::{
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expander::{Binding, Bindings, Fragment},
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parser::{ConcatMetaVarExprElem, MetaVarKind, Op, RepeatKind, Separator},
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ExpandError, ExpandErrorKind, ExpandResult, MetaTemplate,
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};
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impl Bindings {
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fn get(&self, name: &Symbol, span: Span) -> Result<&Binding, ExpandError> {
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match self.inner.get(name) {
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Some(binding) => Ok(binding),
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None => Err(ExpandError::new(
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span,
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ExpandErrorKind::UnresolvedBinding(Box::new(Box::from(name.as_str()))),
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)),
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}
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}
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fn get_fragment(
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&self,
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name: &Symbol,
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mut span: Span,
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nesting: &mut [NestingState],
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marker: impl Fn(&mut Span),
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) -> Result<Fragment, ExpandError> {
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macro_rules! binding_err {
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($($arg:tt)*) => { ExpandError::binding_error(span, format!($($arg)*)) };
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}
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let mut b = self.get(name, span)?;
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for nesting_state in nesting.iter_mut() {
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nesting_state.hit = true;
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b = match b {
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Binding::Fragment(_) => break,
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Binding::Missing(_) => break,
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Binding::Nested(bs) => bs.get(nesting_state.idx).ok_or_else(|| {
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nesting_state.at_end = true;
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binding_err!("could not find nested binding `{name}`")
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})?,
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Binding::Empty => {
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nesting_state.at_end = true;
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return Err(binding_err!("could not find empty binding `{name}`"));
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}
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};
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}
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match b {
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Binding::Fragment(f @ (Fragment::Path(sub) | Fragment::Expr(sub))) => {
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let tt::Subtree { delimiter, token_trees } = sub;
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marker(&mut span);
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let subtree = tt::Subtree {
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delimiter: tt::Delimiter {
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// FIXME split span
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open: span,
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close: span,
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kind: delimiter.kind,
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},
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token_trees: token_trees.clone(),
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};
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Ok(match f {
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Fragment::Tokens(_) | Fragment::Empty => unreachable!(),
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Fragment::Expr(_) => Fragment::Expr,
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Fragment::Path(_) => Fragment::Path,
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}(subtree))
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}
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Binding::Fragment(it @ (Fragment::Tokens(_) | Fragment::Empty)) => Ok(it.clone()),
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// emit some reasonable default expansion for missing bindings,
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// this gives better recovery than emitting the `$fragment-name` verbatim
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Binding::Missing(it) => Ok({
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marker(&mut span);
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match it {
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MetaVarKind::Stmt => {
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Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct {
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span,
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char: ';',
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spacing: tt::Spacing::Alone,
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})))
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}
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MetaVarKind::Block => Fragment::Tokens(tt::TokenTree::Subtree(tt::Subtree {
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delimiter: tt::Delimiter {
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open: span,
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close: span,
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kind: tt::DelimiterKind::Brace,
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},
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token_trees: Box::new([]),
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})),
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// FIXME: Meta and Item should get proper defaults
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MetaVarKind::Meta | MetaVarKind::Item | MetaVarKind::Tt | MetaVarKind::Vis => {
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Fragment::Empty
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}
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MetaVarKind::Path
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| MetaVarKind::Ty
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| MetaVarKind::Pat
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| MetaVarKind::PatParam
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| MetaVarKind::Expr(_)
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| MetaVarKind::Ident => {
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Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
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sym: sym::missing.clone(),
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span,
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is_raw: tt::IdentIsRaw::No,
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})))
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}
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MetaVarKind::Lifetime => {
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Fragment::Tokens(tt::TokenTree::Subtree(tt::Subtree {
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delimiter: tt::Delimiter::invisible_spanned(span),
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token_trees: Box::new([
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tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct {
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char: '\'',
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span,
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spacing: tt::Spacing::Joint,
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})),
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tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
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sym: sym::missing.clone(),
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span,
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is_raw: tt::IdentIsRaw::No,
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})),
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]),
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}))
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}
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MetaVarKind::Literal => {
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Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
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sym: sym::missing.clone(),
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span,
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is_raw: tt::IdentIsRaw::No,
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})))
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}
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}
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}),
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Binding::Nested(_) => {
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Err(binding_err!("expected simple binding, found nested binding `{name}`"))
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}
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Binding::Empty => {
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Err(binding_err!("expected simple binding, found empty binding `{name}`"))
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}
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}
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}
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}
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pub(super) fn transcribe(
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template: &MetaTemplate,
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bindings: &Bindings,
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marker: impl Fn(&mut Span) + Copy,
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call_site: Span,
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) -> ExpandResult<tt::Subtree<Span>> {
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let mut ctx = ExpandCtx { bindings, nesting: Vec::new(), call_site };
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let mut arena: Vec<tt::TokenTree<Span>> = Vec::new();
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expand_subtree(&mut ctx, template, None, &mut arena, marker)
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}
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#[derive(Debug)]
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struct NestingState {
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idx: usize,
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/// `hit` is currently necessary to tell `expand_repeat` if it should stop
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/// because there is no variable in use by the current repetition
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hit: bool,
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/// `at_end` is currently necessary to tell `expand_repeat` if it should stop
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/// because there is no more value available for the current repetition
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at_end: bool,
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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<NestingState>,
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call_site: Span,
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}
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fn expand_subtree(
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ctx: &mut ExpandCtx<'_>,
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template: &MetaTemplate,
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delimiter: Option<Delimiter<Span>>,
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arena: &mut Vec<tt::TokenTree<Span>>,
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marker: impl Fn(&mut Span) + Copy,
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) -> ExpandResult<tt::Subtree<Span>> {
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// remember how many elements are in the arena now - when returning, we want to drain exactly how many elements we added. This way, the recursive uses of the arena get their own "view" of the arena, but will reuse the allocation
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let start_elements = arena.len();
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let mut err = None;
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'ops: for op in template.iter() {
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match op {
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Op::Literal(it) => arena.push(
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tt::Leaf::from({
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let mut it = it.clone();
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marker(&mut it.span);
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it
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})
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.into(),
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),
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Op::Ident(it) => arena.push(
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tt::Leaf::from({
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let mut it = it.clone();
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marker(&mut it.span);
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it
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})
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.into(),
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),
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Op::Punct(puncts) => {
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for punct in puncts.as_slice() {
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arena.push(
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tt::Leaf::from({
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let mut it = *punct;
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marker(&mut it.span);
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it
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})
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.into(),
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);
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}
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}
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Op::Subtree { tokens, delimiter } => {
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let mut delimiter = *delimiter;
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marker(&mut delimiter.open);
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marker(&mut delimiter.close);
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let ExpandResult { value: tt, err: e } =
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expand_subtree(ctx, tokens, Some(delimiter), arena, marker);
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err = err.or(e);
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arena.push(tt.into());
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}
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Op::Var { name, id, .. } => {
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let ExpandResult { value: fragment, err: e } = expand_var(ctx, name, *id, marker);
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err = err.or(e);
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push_fragment(ctx, arena, fragment);
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}
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Op::Repeat { tokens: subtree, kind, separator } => {
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let ExpandResult { value: fragment, err: e } =
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expand_repeat(ctx, subtree, *kind, separator.as_deref(), arena, marker);
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err = err.or(e);
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push_fragment(ctx, arena, fragment)
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}
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Op::Ignore { name, id } => {
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// Expand the variable, but ignore the result. This registers the repetition count.
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// FIXME: Any emitted errors are dropped.
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expand_var(ctx, name, *id, marker);
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}
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Op::Index { depth } => {
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let index =
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ctx.nesting.get(ctx.nesting.len() - 1 - depth).map_or(0, |nest| nest.idx);
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arena.push(
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tt::Leaf::Literal(tt::Literal {
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symbol: Symbol::integer(index),
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span: ctx.call_site,
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kind: tt::LitKind::Integer,
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suffix: None,
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})
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.into(),
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);
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}
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Op::Len { depth } => {
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let length = ctx.nesting.get(ctx.nesting.len() - 1 - depth).map_or(0, |_nest| {
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// FIXME: to be implemented
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0
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});
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arena.push(
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tt::Leaf::Literal(tt::Literal {
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symbol: Symbol::integer(length),
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span: ctx.call_site,
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kind: tt::LitKind::Integer,
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suffix: None,
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})
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.into(),
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);
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}
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Op::Count { name, depth } => {
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let mut binding = match ctx.bindings.get(name, ctx.call_site) {
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Ok(b) => b,
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Err(e) => {
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if err.is_none() {
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err = Some(e);
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}
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continue;
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}
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};
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for state in ctx.nesting.iter_mut() {
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state.hit = true;
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match binding {
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Binding::Fragment(_) | Binding::Missing(_) => {
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// `count()` will report an error.
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break;
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}
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Binding::Nested(bs) => {
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if let Some(b) = bs.get(state.idx) {
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binding = b;
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} else {
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state.at_end = true;
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continue 'ops;
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}
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}
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Binding::Empty => {
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state.at_end = true;
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// FIXME: Breaking here and proceeding to `count()` isn't the most
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// correct thing to do here. This could be a binding of some named
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// fragment which we don't know the depth of, so `count()` will just
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// return 0 for this no matter what `depth` is. See test
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// `count_interaction_with_empty_binding` for example.
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break;
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}
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}
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}
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let res = count(binding, 0, depth.unwrap_or(0));
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arena.push(
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tt::Leaf::Literal(tt::Literal {
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symbol: Symbol::integer(res),
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span: ctx.call_site,
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suffix: None,
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kind: tt::LitKind::Integer,
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})
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.into(),
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);
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}
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Op::Concat { elements, span: concat_span } => {
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let mut concatenated = String::new();
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for element in elements {
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match element {
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ConcatMetaVarExprElem::Ident(ident) => {
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concatenated.push_str(ident.sym.as_str())
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}
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ConcatMetaVarExprElem::Literal(lit) => {
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// FIXME: This isn't really correct wrt. escaping, but that's what rustc does and anyway
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// escaping is used most of the times for characters that are invalid in identifiers.
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concatenated.push_str(lit.symbol.as_str())
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}
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ConcatMetaVarExprElem::Var(var) => {
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// Handling of repetitions in `${concat}` isn't fleshed out in rustc, so we currently
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// err at it.
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// FIXME: Do what rustc does for repetitions.
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let var_value = match ctx.bindings.get_fragment(
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&var.sym,
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var.span,
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&mut ctx.nesting,
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marker,
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) {
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Ok(var) => var,
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Err(e) => {
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if err.is_none() {
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err = Some(e);
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};
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continue;
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}
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};
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let value = match &var_value {
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Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(ident))) => {
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ident.sym.as_str()
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}
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Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Literal(lit))) => {
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lit.symbol.as_str()
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}
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_ => {
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if err.is_none() {
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err = Some(ExpandError::binding_error(var.span, "metavariables of `${concat(..)}` must be of type `ident`, `literal` or `tt`"))
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}
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continue;
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}
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};
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concatenated.push_str(value);
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}
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}
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}
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// `${concat}` span comes from the macro (at least for now).
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// See https://github.com/rust-lang/rust/blob/b0af276da341/compiler/rustc_expand/src/mbe/transcribe.rs#L724-L726.
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let mut result_span = *concat_span;
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marker(&mut result_span);
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// FIXME: NFC normalize the result.
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if !rustc_lexer::is_ident(&concatenated) {
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if err.is_none() {
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err = Some(ExpandError::binding_error(
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*concat_span,
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"`${concat(..)}` is not generating a valid identifier",
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));
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}
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// Insert a dummy identifier for better parsing.
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concatenated.clear();
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concatenated.push_str("__ra_concat_dummy");
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}
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let needs_raw =
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parser::SyntaxKind::from_keyword(&concatenated, Edition::LATEST).is_some();
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let is_raw = if needs_raw { tt::IdentIsRaw::Yes } else { tt::IdentIsRaw::No };
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arena.push(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
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is_raw,
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span: result_span,
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sym: Symbol::intern(&concatenated),
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})));
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}
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}
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}
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// drain the elements added in this instance of expand_subtree
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let tts = arena.drain(start_elements..).collect();
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ExpandResult {
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value: tt::Subtree {
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delimiter: delimiter.unwrap_or_else(|| tt::Delimiter::invisible_spanned(ctx.call_site)),
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token_trees: tts,
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},
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err,
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}
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}
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fn expand_var(
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ctx: &mut ExpandCtx<'_>,
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v: &Symbol,
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id: Span,
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marker: impl Fn(&mut Span),
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) -> ExpandResult<Fragment> {
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// We already handle $crate case in mbe parser
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debug_assert!(*v != sym::crate_);
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match ctx.bindings.get_fragment(v, id, &mut ctx.nesting, marker) {
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Ok(it) => ExpandResult::ok(it),
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Err(e) if matches!(e.inner.1, ExpandErrorKind::UnresolvedBinding(_)) => {
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// Note that it is possible to have a `$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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let tt = tt::Subtree {
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delimiter: tt::Delimiter::invisible_spanned(id),
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token_trees: Box::new([
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tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone, span: id })
|
|
.into(),
|
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tt::Leaf::from(tt::Ident {
|
|
sym: v.clone(),
|
|
span: id,
|
|
is_raw: tt::IdentIsRaw::No,
|
|
})
|
|
.into(),
|
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]),
|
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}
|
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.into();
|
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ExpandResult::ok(Fragment::Tokens(tt))
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}
|
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Err(e) => ExpandResult {
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value: Fragment::Tokens(tt::TokenTree::Subtree(tt::Subtree::empty(tt::DelimSpan {
|
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open: ctx.call_site,
|
|
close: ctx.call_site,
|
|
}))),
|
|
err: Some(e),
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},
|
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}
|
|
}
|
|
|
|
fn expand_repeat(
|
|
ctx: &mut ExpandCtx<'_>,
|
|
template: &MetaTemplate,
|
|
kind: RepeatKind,
|
|
separator: Option<&Separator>,
|
|
arena: &mut Vec<tt::TokenTree<Span>>,
|
|
marker: impl Fn(&mut Span) + Copy,
|
|
) -> ExpandResult<Fragment> {
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|
let mut buf: Vec<tt::TokenTree<Span>> = Vec::new();
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ctx.nesting.push(NestingState { idx: 0, at_end: false, hit: false });
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|
// Dirty hack to make macro-expansion terminate.
|
|
// This should be replaced by a proper macro-by-example implementation
|
|
let limit = 65536;
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|
let mut has_seps = 0;
|
|
let mut counter = 0;
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|
let mut err = None;
|
|
|
|
loop {
|
|
let ExpandResult { value: mut t, err: e } =
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expand_subtree(ctx, template, None, arena, marker);
|
|
let nesting_state = ctx.nesting.last_mut().unwrap();
|
|
if nesting_state.at_end || !nesting_state.hit {
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break;
|
|
}
|
|
nesting_state.idx += 1;
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nesting_state.hit = false;
|
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|
|
counter += 1;
|
|
if counter == limit {
|
|
tracing::warn!(
|
|
"expand_tt in repeat pattern exceed limit => {:#?}\n{:#?}",
|
|
template,
|
|
ctx
|
|
);
|
|
return ExpandResult {
|
|
value: Fragment::Tokens(
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|
tt::Subtree {
|
|
delimiter: tt::Delimiter::invisible_spanned(ctx.call_site),
|
|
token_trees: Box::new([]),
|
|
}
|
|
.into(),
|
|
),
|
|
err: Some(ExpandError::new(ctx.call_site, ExpandErrorKind::LimitExceeded)),
|
|
};
|
|
}
|
|
|
|
if e.is_some() {
|
|
err = err.or(e);
|
|
continue;
|
|
}
|
|
|
|
t.delimiter.kind = tt::DelimiterKind::Invisible;
|
|
push_subtree(&mut buf, t);
|
|
|
|
if let Some(sep) = separator {
|
|
has_seps = match sep {
|
|
Separator::Ident(ident) => {
|
|
buf.push(tt::Leaf::from(ident.clone()).into());
|
|
1
|
|
}
|
|
Separator::Literal(lit) => {
|
|
buf.push(tt::Leaf::from(lit.clone()).into());
|
|
1
|
|
}
|
|
Separator::Puncts(puncts) => {
|
|
for &punct in puncts {
|
|
buf.push(tt::Leaf::from(punct).into());
|
|
}
|
|
puncts.len()
|
|
}
|
|
};
|
|
}
|
|
|
|
if RepeatKind::ZeroOrOne == kind {
|
|
break;
|
|
}
|
|
}
|
|
|
|
ctx.nesting.pop().unwrap();
|
|
for _ in 0..has_seps {
|
|
buf.pop();
|
|
}
|
|
|
|
// Check if it is a single token subtree without any delimiter
|
|
// e.g {Delimiter:None> ['>'] /Delimiter:None>}
|
|
let tt = tt::Subtree {
|
|
delimiter: tt::Delimiter::invisible_spanned(ctx.call_site),
|
|
token_trees: buf.into_boxed_slice(),
|
|
};
|
|
|
|
if RepeatKind::OneOrMore == kind && counter == 0 {
|
|
let span = tt.delimiter.open;
|
|
return ExpandResult {
|
|
value: Fragment::Tokens(tt.into()),
|
|
err: Some(ExpandError::new(span, ExpandErrorKind::UnexpectedToken)),
|
|
};
|
|
}
|
|
ExpandResult { value: Fragment::Tokens(tt.into()), err }
|
|
}
|
|
|
|
fn push_fragment(ctx: &ExpandCtx<'_>, buf: &mut Vec<tt::TokenTree<Span>>, fragment: Fragment) {
|
|
match fragment {
|
|
Fragment::Tokens(tt::TokenTree::Subtree(tt)) => push_subtree(buf, tt),
|
|
Fragment::Expr(sub) => {
|
|
push_subtree(buf, sub);
|
|
}
|
|
Fragment::Path(tt) => fix_up_and_push_path_tt(ctx, buf, tt),
|
|
Fragment::Tokens(tt) => buf.push(tt),
|
|
Fragment::Empty => (),
|
|
}
|
|
}
|
|
|
|
fn push_subtree(buf: &mut Vec<tt::TokenTree<Span>>, tt: tt::Subtree<Span>) {
|
|
match tt.delimiter.kind {
|
|
tt::DelimiterKind::Invisible => buf.extend(Vec::from(tt.token_trees)),
|
|
_ => buf.push(tt.into()),
|
|
}
|
|
}
|
|
|
|
/// Inserts the path separator `::` between an identifier and its following generic
|
|
/// argument list, and then pushes into the buffer. See [`Fragment::Path`] for why
|
|
/// we need this fixup.
|
|
fn fix_up_and_push_path_tt(
|
|
ctx: &ExpandCtx<'_>,
|
|
buf: &mut Vec<tt::TokenTree<Span>>,
|
|
subtree: tt::Subtree<Span>,
|
|
) {
|
|
stdx::always!(matches!(subtree.delimiter.kind, tt::DelimiterKind::Invisible));
|
|
let mut prev_was_ident = false;
|
|
// Note that we only need to fix up the top-level `TokenTree`s because the
|
|
// context of the paths in the descendant `Subtree`s won't be changed by the
|
|
// mbe transcription.
|
|
for tt in Vec::from(subtree.token_trees) {
|
|
if prev_was_ident {
|
|
// Pedantically, `(T) -> U` in `FnOnce(T) -> U` is treated as a generic
|
|
// argument list and thus needs `::` between it and `FnOnce`. However in
|
|
// today's Rust this type of path *semantically* cannot appear as a
|
|
// top-level expression-context path, so we can safely ignore it.
|
|
if let tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: '<', .. })) = tt {
|
|
buf.push(
|
|
tt::Leaf::Punct(tt::Punct {
|
|
char: ':',
|
|
spacing: tt::Spacing::Joint,
|
|
span: ctx.call_site,
|
|
})
|
|
.into(),
|
|
);
|
|
buf.push(
|
|
tt::Leaf::Punct(tt::Punct {
|
|
char: ':',
|
|
spacing: tt::Spacing::Alone,
|
|
span: ctx.call_site,
|
|
})
|
|
.into(),
|
|
);
|
|
}
|
|
}
|
|
prev_was_ident = matches!(tt, tt::TokenTree::Leaf(tt::Leaf::Ident(_)));
|
|
buf.push(tt);
|
|
}
|
|
}
|
|
|
|
/// Handles `${count(t, depth)}`. `our_depth` is the recursion depth and `count_depth` is the depth
|
|
/// defined by the metavar expression.
|
|
fn count(binding: &Binding, depth_curr: usize, depth_max: usize) -> usize {
|
|
match binding {
|
|
Binding::Nested(bs) => {
|
|
if depth_curr == depth_max {
|
|
bs.len()
|
|
} else {
|
|
bs.iter().map(|b| count(b, depth_curr + 1, depth_max)).sum()
|
|
}
|
|
}
|
|
Binding::Empty => 0,
|
|
Binding::Fragment(_) | Binding::Missing(_) => 1,
|
|
}
|
|
}
|