diff options
Diffstat (limited to 'src/librustc_parse/lib.rs')
| -rw-r--r-- | src/librustc_parse/lib.rs | 212 |
1 files changed, 4 insertions, 208 deletions
diff --git a/src/librustc_parse/lib.rs b/src/librustc_parse/lib.rs index 8ca3f6c5768..be86b4b7c77 100644 --- a/src/librustc_parse/lib.rs +++ b/src/librustc_parse/lib.rs @@ -7,18 +7,14 @@ #![feature(or_patterns)] use rustc_ast::ast; -use rustc_ast::token::{self, DelimToken, Nonterminal, Token, TokenKind}; -use rustc_ast::tokenstream::{self, IsJoint, TokenStream, TokenTree}; +use rustc_ast::token::{self, Nonterminal}; +use rustc_ast::tokenstream::{self, TokenStream, TokenTree}; use rustc_ast_pretty::pprust; use rustc_data_structures::sync::Lrc; use rustc_errors::{Diagnostic, FatalError, Level, PResult}; use rustc_session::parse::ParseSess; -use rustc_span::symbol::kw; -use rustc_span::{FileName, SourceFile, Span, DUMMY_SP}; +use rustc_span::{FileName, SourceFile, Span}; -use smallvec::SmallVec; - -use std::mem; use std::path::Path; use std::str; @@ -310,7 +306,7 @@ pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> Toke // modifications, including adding/removing typically non-semantic // tokens such as extra braces and commas, don't happen. if let Some(tokens) = tokens { - if tokenstream_probably_equal_for_proc_macro(&tokens, &tokens_for_real, sess) { + if tokens.probably_equal_for_proc_macro(&tokens_for_real) { return tokens; } info!( @@ -385,203 +381,3 @@ fn prepend_attrs( builder.push(tokens.clone()); Some(builder.build()) } - -// See comments in `Nonterminal::to_tokenstream` for why we care about -// *probably* equal here rather than actual equality -// -// This is otherwise the same as `eq_unspanned`, only recursing with a -// different method. -pub fn tokenstream_probably_equal_for_proc_macro( - first: &TokenStream, - other: &TokenStream, - sess: &ParseSess, -) -> bool { - // When checking for `probably_eq`, we ignore certain tokens that aren't - // preserved in the AST. Because they are not preserved, the pretty - // printer arbitrarily adds or removes them when printing as token - // streams, making a comparison between a token stream generated from an - // AST and a token stream which was parsed into an AST more reliable. - fn semantic_tree(tree: &TokenTree) -> bool { - if let TokenTree::Token(token) = tree { - if let - // The pretty printer tends to add trailing commas to - // everything, and in particular, after struct fields. - | token::Comma - // The pretty printer emits `NoDelim` as whitespace. - | token::OpenDelim(DelimToken::NoDelim) - | token::CloseDelim(DelimToken::NoDelim) - // The pretty printer collapses many semicolons into one. - | token::Semi - // The pretty printer collapses whitespace arbitrarily and can - // introduce whitespace from `NoDelim`. - | token::Whitespace - // The pretty printer can turn `$crate` into `::crate_name` - | token::ModSep = token.kind { - return false; - } - } - true - } - - // When comparing two `TokenStream`s, we ignore the `IsJoint` information. - // - // However, `rustc_parse::lexer::tokentrees::TokenStreamBuilder` will - // use `Token.glue` on adjacent tokens with the proper `IsJoint`. - // Since we are ignoreing `IsJoint`, a 'glued' token (e.g. `BinOp(Shr)`) - // and its 'split'/'unglued' compoenents (e.g. `Gt, Gt`) are equivalent - // when determining if two `TokenStream`s are 'probably equal'. - // - // Therefore, we use `break_two_token_op` to convert all tokens - // to the 'unglued' form (if it exists). This ensures that two - // `TokenStream`s which differ only in how their tokens are glued - // will be considered 'probably equal', which allows us to keep spans. - // - // This is important when the original `TokenStream` contained - // extra spaces (e.g. `f :: < Vec < _ > > ( ) ;'). These extra spaces - // will be omitted when we pretty-print, which can cause the original - // and reparsed `TokenStream`s to differ in the assignment of `IsJoint`, - // leading to some tokens being 'glued' together in one stream but not - // the other. See #68489 for more details. - fn break_tokens(tree: TokenTree) -> impl Iterator<Item = TokenTree> { - // In almost all cases, we should have either zero or one levels - // of 'unglueing'. However, in some unusual cases, we may need - // to iterate breaking tokens mutliple times. For example: - // '[BinOpEq(Shr)] => [Gt, Ge] -> [Gt, Gt, Eq]' - let mut token_trees: SmallVec<[_; 2]>; - if let TokenTree::Token(token) = &tree { - let mut out = SmallVec::<[_; 2]>::new(); - out.push(token.clone()); - // Iterate to fixpoint: - // * We start off with 'out' containing our initial token, and `temp` empty - // * If we are able to break any tokens in `out`, then `out` will have - // at least one more element than 'temp', so we will try to break tokens - // again. - // * If we cannot break any tokens in 'out', we are done - loop { - let mut temp = SmallVec::<[_; 2]>::new(); - let mut changed = false; - - for token in out.into_iter() { - if let Some((first, second)) = token.kind.break_two_token_op() { - temp.push(Token::new(first, DUMMY_SP)); - temp.push(Token::new(second, DUMMY_SP)); - changed = true; - } else { - temp.push(token); - } - } - out = temp; - if !changed { - break; - } - } - token_trees = out.into_iter().map(|t| TokenTree::Token(t)).collect(); - if token_trees.len() != 1 { - debug!("break_tokens: broke {:?} to {:?}", tree, token_trees); - } - } else { - token_trees = SmallVec::new(); - token_trees.push(tree); - } - token_trees.into_iter() - } - - let expand_nt = |tree: TokenTree| { - if let TokenTree::Token(Token { kind: TokenKind::Interpolated(nt), span }) = &tree { - nt_to_tokenstream(nt, sess, *span).into_trees() - } else { - TokenStream::new(vec![(tree, IsJoint::NonJoint)]).into_trees() - } - }; - - // Break tokens after we expand any nonterminals, so that we break tokens - // that are produced as a result of nonterminal expansion. - let mut t1 = first.trees().filter(semantic_tree).flat_map(expand_nt).flat_map(break_tokens); - let mut t2 = other.trees().filter(semantic_tree).flat_map(expand_nt).flat_map(break_tokens); - for (t1, t2) in t1.by_ref().zip(t2.by_ref()) { - if !tokentree_probably_equal_for_proc_macro(&t1, &t2, sess) { - return false; - } - } - t1.next().is_none() && t2.next().is_none() -} - -// See comments in `Nonterminal::to_tokenstream` for why we care about -// *probably* equal here rather than actual equality -crate fn token_probably_equal_for_proc_macro(first: &Token, other: &Token) -> bool { - use TokenKind::*; - - if mem::discriminant(&first.kind) != mem::discriminant(&other.kind) { - return false; - } - match (&first.kind, &other.kind) { - (&Eq, &Eq) - | (&Lt, &Lt) - | (&Le, &Le) - | (&EqEq, &EqEq) - | (&Ne, &Ne) - | (&Ge, &Ge) - | (&Gt, &Gt) - | (&AndAnd, &AndAnd) - | (&OrOr, &OrOr) - | (&Not, &Not) - | (&Tilde, &Tilde) - | (&At, &At) - | (&Dot, &Dot) - | (&DotDot, &DotDot) - | (&DotDotDot, &DotDotDot) - | (&DotDotEq, &DotDotEq) - | (&Comma, &Comma) - | (&Semi, &Semi) - | (&Colon, &Colon) - | (&ModSep, &ModSep) - | (&RArrow, &RArrow) - | (&LArrow, &LArrow) - | (&FatArrow, &FatArrow) - | (&Pound, &Pound) - | (&Dollar, &Dollar) - | (&Question, &Question) - | (&Whitespace, &Whitespace) - | (&Comment, &Comment) - | (&Eof, &Eof) => true, - - (&BinOp(a), &BinOp(b)) | (&BinOpEq(a), &BinOpEq(b)) => a == b, - - (&OpenDelim(a), &OpenDelim(b)) | (&CloseDelim(a), &CloseDelim(b)) => a == b, - - (&DocComment(a), &DocComment(b)) | (&Shebang(a), &Shebang(b)) => a == b, - - (&Literal(a), &Literal(b)) => a == b, - - (&Lifetime(a), &Lifetime(b)) => a == b, - (&Ident(a, b), &Ident(c, d)) => { - b == d && (a == c || a == kw::DollarCrate || c == kw::DollarCrate) - } - - // Expanded by `tokenstream_probably_equal_for_proc_macro` - (&Interpolated(_), &Interpolated(_)) => unreachable!(), - - _ => panic!("forgot to add a token?"), - } -} - -// See comments in `Nonterminal::to_tokenstream` for why we care about -// *probably* equal here rather than actual equality -// -// This is otherwise the same as `eq_unspanned`, only recursing with a -// different method. -pub fn tokentree_probably_equal_for_proc_macro( - first: &TokenTree, - other: &TokenTree, - sess: &ParseSess, -) -> bool { - match (first, other) { - (TokenTree::Token(token), TokenTree::Token(token2)) => { - token_probably_equal_for_proc_macro(token, token2) - } - (TokenTree::Delimited(_, delim, tts), TokenTree::Delimited(_, delim2, tts2)) => { - delim == delim2 && tokenstream_probably_equal_for_proc_macro(&tts, &tts2, sess) - } - _ => false, - } -} |