| //! The main parser interface. |
| |
| #![feature(bool_to_option)] |
| #![feature(crate_visibility_modifier)] |
| #![feature(slice_patterns)] |
| |
| use syntax::ast; |
| use syntax::print::pprust; |
| use syntax::sess::ParseSess; |
| use syntax::token::{self, Nonterminal}; |
| use syntax::tokenstream::{self, TokenStream, TokenTree}; |
| |
| use rustc_data_structures::sync::Lrc; |
| use rustc_errors::{Diagnostic, FatalError, Level, PResult}; |
| use rustc_span::{FileName, SourceFile, Span}; |
| |
| use std::borrow::Cow; |
| use std::path::Path; |
| use std::str; |
| |
| use log::info; |
| |
| pub const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments"); |
| |
| #[macro_use] |
| pub mod parser; |
| use parser::{emit_unclosed_delims, make_unclosed_delims_error, Parser}; |
| pub mod lexer; |
| pub mod validate_attr; |
| #[macro_use] |
| pub mod config; |
| |
| #[derive(Clone)] |
| pub struct Directory<'a> { |
| pub path: Cow<'a, Path>, |
| pub ownership: DirectoryOwnership, |
| } |
| |
| #[derive(Copy, Clone)] |
| pub enum DirectoryOwnership { |
| Owned { |
| // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`. |
| relative: Option<ast::Ident>, |
| }, |
| UnownedViaBlock, |
| UnownedViaMod, |
| } |
| |
| // A bunch of utility functions of the form `parse_<thing>_from_<source>` |
| // where <thing> includes crate, expr, item, stmt, tts, and one that |
| // uses a HOF to parse anything, and <source> includes file and |
| // `source_str`. |
| |
| /// A variant of 'panictry!' that works on a Vec<Diagnostic> instead of a single DiagnosticBuilder. |
| macro_rules! panictry_buffer { |
| ($handler:expr, $e:expr) => {{ |
| use rustc_errors::FatalError; |
| use std::result::Result::{Err, Ok}; |
| match $e { |
| Ok(e) => e, |
| Err(errs) => { |
| for e in errs { |
| $handler.emit_diagnostic(&e); |
| } |
| FatalError.raise() |
| } |
| } |
| }}; |
| } |
| |
| pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> { |
| let mut parser = new_parser_from_file(sess, input); |
| parser.parse_crate_mod() |
| } |
| |
| pub fn parse_crate_attrs_from_file<'a>( |
| input: &Path, |
| sess: &'a ParseSess, |
| ) -> PResult<'a, Vec<ast::Attribute>> { |
| let mut parser = new_parser_from_file(sess, input); |
| parser.parse_inner_attributes() |
| } |
| |
| pub fn parse_crate_from_source_str( |
| name: FileName, |
| source: String, |
| sess: &ParseSess, |
| ) -> PResult<'_, ast::Crate> { |
| new_parser_from_source_str(sess, name, source).parse_crate_mod() |
| } |
| |
| pub fn parse_crate_attrs_from_source_str( |
| name: FileName, |
| source: String, |
| sess: &ParseSess, |
| ) -> PResult<'_, Vec<ast::Attribute>> { |
| new_parser_from_source_str(sess, name, source).parse_inner_attributes() |
| } |
| |
| pub fn parse_stream_from_source_str( |
| name: FileName, |
| source: String, |
| sess: &ParseSess, |
| override_span: Option<Span>, |
| ) -> TokenStream { |
| let (stream, mut errors) = |
| source_file_to_stream(sess, sess.source_map().new_source_file(name, source), override_span); |
| emit_unclosed_delims(&mut errors, &sess); |
| stream |
| } |
| |
| /// Creates a new parser from a source string. |
| pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> { |
| panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source)) |
| } |
| |
| /// Creates a new parser from a source string. Returns any buffered errors from lexing the initial |
| /// token stream. |
| pub fn maybe_new_parser_from_source_str( |
| sess: &ParseSess, |
| name: FileName, |
| source: String, |
| ) -> Result<Parser<'_>, Vec<Diagnostic>> { |
| let mut parser = |
| maybe_source_file_to_parser(sess, sess.source_map().new_source_file(name, source))?; |
| parser.recurse_into_file_modules = false; |
| Ok(parser) |
| } |
| |
| /// Creates a new parser, handling errors as appropriate if the file doesn't exist. |
| pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) -> Parser<'a> { |
| source_file_to_parser(sess, file_to_source_file(sess, path, None)) |
| } |
| |
| /// Creates a new parser, returning buffered diagnostics if the file doesn't exist, |
| /// or from lexing the initial token stream. |
| pub fn maybe_new_parser_from_file<'a>( |
| sess: &'a ParseSess, |
| path: &Path, |
| ) -> Result<Parser<'a>, Vec<Diagnostic>> { |
| let file = try_file_to_source_file(sess, path, None).map_err(|db| vec![db])?; |
| maybe_source_file_to_parser(sess, file) |
| } |
| |
| /// Given a session, a crate config, a path, and a span, add |
| /// the file at the given path to the `source_map`, and returns a parser. |
| /// On an error, uses the given span as the source of the problem. |
| pub fn new_sub_parser_from_file<'a>( |
| sess: &'a ParseSess, |
| path: &Path, |
| directory_ownership: DirectoryOwnership, |
| module_name: Option<String>, |
| sp: Span, |
| ) -> Parser<'a> { |
| let mut p = source_file_to_parser(sess, file_to_source_file(sess, path, Some(sp))); |
| p.directory.ownership = directory_ownership; |
| p.root_module_name = module_name; |
| p |
| } |
| |
| /// Given a `source_file` and config, returns a parser. |
| fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> { |
| panictry_buffer!(&sess.span_diagnostic, maybe_source_file_to_parser(sess, source_file)) |
| } |
| |
| /// Given a `source_file` and config, return a parser. Returns any buffered errors from lexing the |
| /// initial token stream. |
| fn maybe_source_file_to_parser( |
| sess: &ParseSess, |
| source_file: Lrc<SourceFile>, |
| ) -> Result<Parser<'_>, Vec<Diagnostic>> { |
| let end_pos = source_file.end_pos; |
| let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?; |
| let mut parser = stream_to_parser(sess, stream, None); |
| parser.unclosed_delims = unclosed_delims; |
| if parser.token == token::Eof && parser.token.span.is_dummy() { |
| parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt()); |
| } |
| |
| Ok(parser) |
| } |
| |
| // Must preserve old name for now, because `quote!` from the *existing* |
| // compiler expands into it. |
| pub fn new_parser_from_tts(sess: &ParseSess, tts: Vec<TokenTree>) -> Parser<'_> { |
| stream_to_parser(sess, tts.into_iter().collect(), crate::MACRO_ARGUMENTS) |
| } |
| |
| // Base abstractions |
| |
| /// Given a session and a path and an optional span (for error reporting), |
| /// add the path to the session's source_map and return the new source_file or |
| /// error when a file can't be read. |
| fn try_file_to_source_file( |
| sess: &ParseSess, |
| path: &Path, |
| spanopt: Option<Span>, |
| ) -> Result<Lrc<SourceFile>, Diagnostic> { |
| sess.source_map().load_file(path).map_err(|e| { |
| let msg = format!("couldn't read {}: {}", path.display(), e); |
| let mut diag = Diagnostic::new(Level::Fatal, &msg); |
| if let Some(sp) = spanopt { |
| diag.set_span(sp); |
| } |
| diag |
| }) |
| } |
| |
| /// Given a session and a path and an optional span (for error reporting), |
| /// adds the path to the session's `source_map` and returns the new `source_file`. |
| fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>) -> Lrc<SourceFile> { |
| match try_file_to_source_file(sess, path, spanopt) { |
| Ok(source_file) => source_file, |
| Err(d) => { |
| sess.span_diagnostic.emit_diagnostic(&d); |
| FatalError.raise(); |
| } |
| } |
| } |
| |
| /// Given a `source_file`, produces a sequence of token trees. |
| pub fn source_file_to_stream( |
| sess: &ParseSess, |
| source_file: Lrc<SourceFile>, |
| override_span: Option<Span>, |
| ) -> (TokenStream, Vec<lexer::UnmatchedBrace>) { |
| panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span)) |
| } |
| |
| /// Given a source file, produces a sequence of token trees. Returns any buffered errors from |
| /// parsing the token stream. |
| pub fn maybe_file_to_stream( |
| sess: &ParseSess, |
| source_file: Lrc<SourceFile>, |
| override_span: Option<Span>, |
| ) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> { |
| let srdr = lexer::StringReader::new(sess, source_file, override_span); |
| let (token_trees, unmatched_braces) = srdr.into_token_trees(); |
| |
| match token_trees { |
| Ok(stream) => Ok((stream, unmatched_braces)), |
| Err(err) => { |
| let mut buffer = Vec::with_capacity(1); |
| err.buffer(&mut buffer); |
| // Not using `emit_unclosed_delims` to use `db.buffer` |
| for unmatched in unmatched_braces { |
| if let Some(err) = make_unclosed_delims_error(unmatched, &sess) { |
| err.buffer(&mut buffer); |
| } |
| } |
| Err(buffer) |
| } |
| } |
| } |
| |
| /// Given a stream and the `ParseSess`, produces a parser. |
| pub fn stream_to_parser<'a>( |
| sess: &'a ParseSess, |
| stream: TokenStream, |
| subparser_name: Option<&'static str>, |
| ) -> Parser<'a> { |
| Parser::new(sess, stream, None, true, false, subparser_name) |
| } |
| |
| /// Given a stream, the `ParseSess` and the base directory, produces a parser. |
| /// |
| /// Use this function when you are creating a parser from the token stream |
| /// and also care about the current working directory of the parser (e.g., |
| /// you are trying to resolve modules defined inside a macro invocation). |
| /// |
| /// # Note |
| /// |
| /// The main usage of this function is outside of rustc, for those who uses |
| /// libsyntax as a library. Please do not remove this function while refactoring |
| /// just because it is not used in rustc codebase! |
| pub fn stream_to_parser_with_base_dir<'a>( |
| sess: &'a ParseSess, |
| stream: TokenStream, |
| base_dir: Directory<'a>, |
| ) -> Parser<'a> { |
| Parser::new(sess, stream, Some(base_dir), true, false, None) |
| } |
| |
| /// Runs the given subparser `f` on the tokens of the given `attr`'s item. |
| pub fn parse_in<'a, T>( |
| sess: &'a ParseSess, |
| tts: TokenStream, |
| name: &'static str, |
| mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, |
| ) -> PResult<'a, T> { |
| let mut parser = Parser::new(sess, tts, None, false, false, Some(name)); |
| let result = f(&mut parser)?; |
| if parser.token != token::Eof { |
| parser.unexpected()?; |
| } |
| Ok(result) |
| } |
| |
| // NOTE(Centril): The following probably shouldn't be here but it acknowledges the |
| // fact that architecturally, we are using parsing (read on below to understand why). |
| |
| pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> TokenStream { |
| // A `Nonterminal` is often a parsed AST item. At this point we now |
| // need to convert the parsed AST to an actual token stream, e.g. |
| // un-parse it basically. |
| // |
| // Unfortunately there's not really a great way to do that in a |
| // guaranteed lossless fashion right now. The fallback here is to just |
| // stringify the AST node and reparse it, but this loses all span |
| // information. |
| // |
| // As a result, some AST nodes are annotated with the token stream they |
| // came from. Here we attempt to extract these lossless token streams |
| // before we fall back to the stringification. |
| let tokens = match *nt { |
| Nonterminal::NtItem(ref item) => { |
| prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span) |
| } |
| Nonterminal::NtTraitItem(ref item) | Nonterminal::NtImplItem(ref item) => { |
| prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span) |
| } |
| Nonterminal::NtIdent(ident, is_raw) => { |
| Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into()) |
| } |
| Nonterminal::NtLifetime(ident) => { |
| Some(tokenstream::TokenTree::token(token::Lifetime(ident.name), ident.span).into()) |
| } |
| Nonterminal::NtTT(ref tt) => Some(tt.clone().into()), |
| _ => None, |
| }; |
| |
| // FIXME(#43081): Avoid this pretty-print + reparse hack |
| let source = pprust::nonterminal_to_string(nt); |
| let filename = FileName::macro_expansion_source_code(&source); |
| let tokens_for_real = parse_stream_from_source_str(filename, source, sess, Some(span)); |
| |
| // During early phases of the compiler the AST could get modified |
| // directly (e.g., attributes added or removed) and the internal cache |
| // of tokens my not be invalidated or updated. Consequently if the |
| // "lossless" token stream disagrees with our actual stringification |
| // (which has historically been much more battle-tested) then we go |
| // with the lossy stream anyway (losing span information). |
| // |
| // Note that the comparison isn't `==` here to avoid comparing spans, |
| // but it *also* is a "probable" equality which is a pretty weird |
| // definition. We mostly want to catch actual changes to the AST |
| // like a `#[cfg]` being processed or some weird `macro_rules!` |
| // expansion. |
| // |
| // What we *don't* want to catch is the fact that a user-defined |
| // literal like `0xf` is stringified as `15`, causing the cached token |
| // stream to not be literal `==` token-wise (ignoring spans) to the |
| // token stream we got from stringification. |
| // |
| // Instead the "probably equal" check here is "does each token |
| // recursively have the same discriminant?" We basically don't look at |
| // the token values here and assume that such fine grained token stream |
| // modifications, including adding/removing typically non-semantic |
| // tokens such as extra braces and commas, don't happen. |
| if let Some(tokens) = tokens { |
| if tokens.probably_equal_for_proc_macro(&tokens_for_real) { |
| return tokens; |
| } |
| info!( |
| "cached tokens found, but they're not \"probably equal\", \ |
| going with stringified version" |
| ); |
| } |
| return tokens_for_real; |
| } |
| |
| fn prepend_attrs( |
| sess: &ParseSess, |
| attrs: &[ast::Attribute], |
| tokens: Option<&tokenstream::TokenStream>, |
| span: rustc_span::Span, |
| ) -> Option<tokenstream::TokenStream> { |
| let tokens = tokens?; |
| if attrs.len() == 0 { |
| return Some(tokens.clone()); |
| } |
| let mut builder = tokenstream::TokenStreamBuilder::new(); |
| for attr in attrs { |
| assert_eq!( |
| attr.style, |
| ast::AttrStyle::Outer, |
| "inner attributes should prevent cached tokens from existing" |
| ); |
| |
| let source = pprust::attribute_to_string(attr); |
| let macro_filename = FileName::macro_expansion_source_code(&source); |
| |
| let item = match attr.kind { |
| ast::AttrKind::Normal(ref item) => item, |
| ast::AttrKind::DocComment(_) => { |
| let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span)); |
| builder.push(stream); |
| continue; |
| } |
| }; |
| |
| // synthesize # [ $path $tokens ] manually here |
| let mut brackets = tokenstream::TokenStreamBuilder::new(); |
| |
| // For simple paths, push the identifier directly |
| if item.path.segments.len() == 1 && item.path.segments[0].args.is_none() { |
| let ident = item.path.segments[0].ident; |
| let token = token::Ident(ident.name, ident.as_str().starts_with("r#")); |
| brackets.push(tokenstream::TokenTree::token(token, ident.span)); |
| |
| // ... and for more complicated paths, fall back to a reparse hack that |
| // should eventually be removed. |
| } else { |
| let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span)); |
| brackets.push(stream); |
| } |
| |
| brackets.push(item.args.outer_tokens()); |
| |
| // The span we list here for `#` and for `[ ... ]` are both wrong in |
| // that it encompasses more than each token, but it hopefully is "good |
| // enough" for now at least. |
| builder.push(tokenstream::TokenTree::token(token::Pound, attr.span)); |
| let delim_span = tokenstream::DelimSpan::from_single(attr.span); |
| builder.push(tokenstream::TokenTree::Delimited( |
| delim_span, |
| token::DelimToken::Bracket, |
| brackets.build().into(), |
| )); |
| } |
| builder.push(tokens.clone()); |
| Some(builder.build()) |
| } |