332dffb1f9
A `TokenStream` contains a `Lrc<Vec<(TokenTree, Spacing)>>`. But this is
not quite right. `Spacing` makes sense for `TokenTree::Token`, but does
not make sense for `TokenTree::Delimited`, because a
`TokenTree::Delimited` cannot be joined with another `TokenTree`.
This commit fixes this problem, by adding `Spacing` to `TokenTree::Token`,
changing `TokenStream` to contain a `Lrc<Vec<TokenTree>>`, and removing the
`TreeAndSpacing` typedef.
The commit removes these two impls:
- `impl From<TokenTree> for TokenStream`
- `impl From<TokenTree> for TreeAndSpacing`
These were useful, but also resulted in code with many `.into()` calls
that was hard to read, particularly for anyone not highly familiar with
the relevant types. This commit makes some other changes to compensate:
- `TokenTree::token()` becomes `TokenTree::token_{alone,joint}()`.
- `TokenStream::token_{alone,joint}()` are added.
- `TokenStream::delimited` is added.
This results in things like this:
```rust
TokenTree::token(token::Semi, stmt.span).into()
```
changing to this:
```rust
TokenStream::token_alone(token::Semi, stmt.span)
```
This makes the type of the result, and its spacing, clearer.
These changes also simplifies `Cursor` and `CursorRef`, because they no longer
need to distinguish between `next` and `next_with_spacing`.
30 lines
831 B
Rust
30 lines
831 B
Rust
use rustc_ast::tokenstream::{TokenStream, TokenTree};
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use rustc_expand::base::{self, ExtCtxt};
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use rustc_span::symbol::kw;
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use rustc_span::Span;
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pub fn expand_trace_macros(
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cx: &mut ExtCtxt<'_>,
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sp: Span,
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tt: TokenStream,
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) -> Box<dyn base::MacResult + 'static> {
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let mut cursor = tt.into_trees();
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let mut err = false;
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let value = match &cursor.next() {
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Some(TokenTree::Token(token, _)) if token.is_keyword(kw::True) => true,
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Some(TokenTree::Token(token, _)) if token.is_keyword(kw::False) => false,
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_ => {
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err = true;
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false
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}
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};
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err |= cursor.next().is_some();
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if err {
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cx.span_err(sp, "trace_macros! accepts only `true` or `false`")
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} else {
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cx.set_trace_macros(value);
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}
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base::DummyResult::any_valid(sp)
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}
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