-
Notifications
You must be signed in to change notification settings - Fork 12.8k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Implement macro meta-variable expressions
- Loading branch information
Showing
17 changed files
with
900 additions
and
44 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,157 @@ | ||
| use rustc_ast::token; | ||
| use rustc_ast::tokenstream::{Cursor, TokenStream, TokenTree}; | ||
| use rustc_ast::{LitIntType, LitKind}; | ||
| use rustc_ast_pretty::pprust; | ||
| use rustc_errors::{Applicability, PResult}; | ||
| use rustc_session::parse::ParseSess; | ||
| use rustc_span::symbol::Ident; | ||
| use rustc_span::Span; | ||
|
|
||
| /// A meta-variable expression, for expansions based on properties of meta-variables. | ||
| #[derive(Debug, Clone, PartialEq, Encodable, Decodable)] | ||
| crate enum MetaVarExpr { | ||
| /// The number of repetitions of an identifier, optionally limited to a number | ||
| /// of outer-most repetition depths. If the depth limit is `None` then the depth is unlimited. | ||
| Count(Ident, Option<usize>), | ||
|
|
||
| /// Ignore a meta-variable for repetition without expansion. | ||
| Ignore(Ident), | ||
|
|
||
| /// The index of the repetition at a particular depth, where 0 is the inner-most | ||
| /// repetition. The `usize` is the depth. | ||
| Index(usize), | ||
|
|
||
| /// The length of the repetition at a particular depth, where 0 is the inner-most | ||
| /// repetition. The `usize` is the depth. | ||
| Length(usize), | ||
| } | ||
|
|
||
| impl MetaVarExpr { | ||
| /// Attempt to parse a meta-variable expression from a token stream. | ||
| crate fn parse<'sess>( | ||
| input: &TokenStream, | ||
| outer_span: Span, | ||
| sess: &'sess ParseSess, | ||
| ) -> PResult<'sess, MetaVarExpr> { | ||
| let mut tts = input.trees(); | ||
| let ident = parse_ident(&mut tts, sess, outer_span)?; | ||
| let Some(TokenTree::Delimited(_, token::Paren, args)) = tts.next() else { | ||
| let msg = "meta-variable expression parameter must be wrapped in parentheses"; | ||
| return Err(sess.span_diagnostic.struct_span_err(ident.span, msg)); | ||
| }; | ||
| check_trailing_token(&mut tts, sess)?; | ||
| let mut iter = args.trees(); | ||
| let rslt = match &*ident.as_str() { | ||
| "count" => parse_count(&mut iter, sess, ident.span)?, | ||
| "ignore" => MetaVarExpr::Ignore(parse_ident(&mut iter, sess, ident.span)?), | ||
| "index" => MetaVarExpr::Index(parse_depth(&mut iter, sess, ident.span)?), | ||
| "length" => MetaVarExpr::Length(parse_depth(&mut iter, sess, ident.span)?), | ||
| _ => { | ||
| let err_msg = "unrecognized meta-variable expression"; | ||
| let mut err = sess.span_diagnostic.struct_span_err(ident.span, err_msg); | ||
| err.span_suggestion( | ||
| ident.span, | ||
| "supported expressions are count, ignore, index and length", | ||
| String::new(), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| return Err(err); | ||
| } | ||
| }; | ||
| check_trailing_token(&mut iter, sess)?; | ||
| Ok(rslt) | ||
| } | ||
|
|
||
| crate fn ident(&self) -> Option<&Ident> { | ||
| match self { | ||
| MetaVarExpr::Count(ident, _) | MetaVarExpr::Ignore(ident) => Some(&ident), | ||
| MetaVarExpr::Index(..) | MetaVarExpr::Length(..) => None, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Checks if there are any remaining tokens. For example, `${ignore(ident ... a b c ...)}` | ||
| fn check_trailing_token<'sess>(iter: &mut Cursor, sess: &'sess ParseSess) -> PResult<'sess, ()> { | ||
| if let Some(tt) = iter.next() { | ||
| let mut diag = sess.span_diagnostic.struct_span_err( | ||
| tt.span(), | ||
| &format!("unexpected token: {}", pprust::tt_to_string(&tt)), | ||
| ); | ||
| diag.span_note(tt.span(), "meta-variable expression must not have trailing tokens"); | ||
| Err(diag) | ||
| } else { | ||
| Ok(()) | ||
| } | ||
| } | ||
|
|
||
| /// Parse a meta-variable `count` expression: `count(ident[, depth])` | ||
| fn parse_count<'sess>( | ||
| iter: &mut Cursor, | ||
| sess: &'sess ParseSess, | ||
| span: Span, | ||
| ) -> PResult<'sess, MetaVarExpr> { | ||
| let ident = parse_ident(iter, sess, span)?; | ||
| let depth = if try_eat_comma(iter) { Some(parse_depth(iter, sess, span)?) } else { None }; | ||
| Ok(MetaVarExpr::Count(ident, depth)) | ||
| } | ||
|
|
||
| /// Parses the depth used by index(depth) and length(depth). | ||
| fn parse_depth<'sess>( | ||
| iter: &mut Cursor, | ||
| sess: &'sess ParseSess, | ||
| span: Span, | ||
| ) -> PResult<'sess, usize> { | ||
| let Some(tt) = iter.next() else { return Ok(0) }; | ||
| let TokenTree::Token(token::Token { | ||
| kind: token::TokenKind::Literal(lit), .. | ||
| }) = tt else { | ||
| return Err(sess.span_diagnostic.struct_span_err( | ||
| span, | ||
| "meta-variable expression depth must be a literal" | ||
| )); | ||
| }; | ||
| if let Ok(lit_kind) = LitKind::from_lit_token(lit) | ||
| && let LitKind::Int(n_u128, LitIntType::Unsuffixed) = lit_kind | ||
| && let Ok(n_usize) = usize::try_from(n_u128) | ||
| { | ||
| Ok(n_usize) | ||
| } | ||
| else { | ||
| let msg = "only unsuffixes integer literals are supported in meta-variable expressions"; | ||
| Err(sess.span_diagnostic.struct_span_err(span, msg)) | ||
| } | ||
| } | ||
|
|
||
| /// Parses an generic ident | ||
| fn parse_ident<'sess>( | ||
| iter: &mut Cursor, | ||
| sess: &'sess ParseSess, | ||
| span: Span, | ||
| ) -> PResult<'sess, Ident> { | ||
| let err_fn = |msg| sess.span_diagnostic.struct_span_err(span, msg); | ||
| if let Some(tt) = iter.next() && let TokenTree::Token(token) = tt { | ||
| if let Some((elem, false)) = token.ident() { | ||
| return Ok(elem); | ||
| } | ||
| let token_str = pprust::token_to_string(&token); | ||
| let mut err = err_fn(&format!("expected identifier, found `{}`", &token_str)); | ||
| err.span_suggestion( | ||
| token.span, | ||
| &format!("try removing `{}`", &token_str), | ||
| String::new(), | ||
| Applicability::MaybeIncorrect, | ||
| ); | ||
| return Err(err); | ||
| } | ||
| Err(err_fn("expected identifier")) | ||
| } | ||
|
|
||
| /// Tries to move the iterator forward returning `true` if there is a comma. If not, then the | ||
| /// iterator is not modified and the result is `false`. | ||
| fn try_eat_comma(iter: &mut Cursor) -> bool { | ||
| if let Some(TokenTree::Token(token::Token { kind: token::Comma, .. })) = iter.look_ahead(0) { | ||
| let _ = iter.next(); | ||
| return true; | ||
| } | ||
| false | ||
| } |
Oops, something went wrong.