1 //! The main parser interface.
3 #![feature(crate_visibility_modifier)]
6 use syntax::print::pprust;
7 use syntax::sess::ParseSess;
8 use syntax::token::{self, Nonterminal};
9 use syntax::tokenstream::{self, TokenStream, TokenTree};
11 use errors::{PResult, FatalError, Level, Diagnostic};
12 use rustc_data_structures::sync::Lrc;
13 use syntax_pos::{Span, SourceFile, FileName};
21 pub const MACRO_ARGUMENTS: Option<&'static str> = Some("macro arguments");
25 use parser::{Parser, emit_unclosed_delims, make_unclosed_delims_error};
27 pub mod validate_attr;
31 pub struct Directory<'a> {
32 pub path: Cow<'a, Path>,
33 pub ownership: DirectoryOwnership,
36 #[derive(Copy, Clone)]
37 pub enum DirectoryOwnership {
39 // None if `mod.rs`, `Some("foo")` if we're in `foo.rs`.
40 relative: Option<ast::Ident>,
46 // A bunch of utility functions of the form `parse_<thing>_from_<source>`
47 // where <thing> includes crate, expr, item, stmt, tts, and one that
48 // uses a HOF to parse anything, and <source> includes file and
51 /// A variant of 'panictry!' that works on a Vec<Diagnostic> instead of a single DiagnosticBuilder.
52 macro_rules! panictry_buffer {
53 ($handler:expr, $e:expr) => ({
54 use std::result::Result::{Ok, Err};
55 use errors::FatalError;
60 $handler.emit_diagnostic(&e);
68 pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
69 let mut parser = new_parser_from_file(sess, input);
70 parser.parse_crate_mod()
73 pub fn parse_crate_attrs_from_file<'a>(input: &Path, sess: &'a ParseSess)
74 -> PResult<'a, Vec<ast::Attribute>> {
75 let mut parser = new_parser_from_file(sess, input);
76 parser.parse_inner_attributes()
79 pub fn parse_crate_from_source_str(name: FileName, source: String, sess: &ParseSess)
80 -> PResult<'_, ast::Crate> {
81 new_parser_from_source_str(sess, name, source).parse_crate_mod()
84 pub fn parse_crate_attrs_from_source_str(name: FileName, source: String, sess: &ParseSess)
85 -> PResult<'_, Vec<ast::Attribute>> {
86 new_parser_from_source_str(sess, name, source).parse_inner_attributes()
89 pub fn parse_stream_from_source_str(
93 override_span: Option<Span>,
95 let (stream, mut errors) = source_file_to_stream(
97 sess.source_map().new_source_file(name, source),
100 emit_unclosed_delims(&mut errors, &sess);
104 /// Creates a new parser from a source string.
105 pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
106 panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source))
109 /// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
111 pub fn maybe_new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String)
112 -> Result<Parser<'_>, Vec<Diagnostic>>
114 let mut parser = maybe_source_file_to_parser(sess,
115 sess.source_map().new_source_file(name, source))?;
116 parser.recurse_into_file_modules = false;
120 /// Creates a new parser, handling errors as appropriate if the file doesn't exist.
121 pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path) -> Parser<'a> {
122 source_file_to_parser(sess, file_to_source_file(sess, path, None))
125 /// Creates a new parser, returning buffered diagnostics if the file doesn't exist,
126 /// or from lexing the initial token stream.
127 pub fn maybe_new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path)
128 -> Result<Parser<'a>, Vec<Diagnostic>> {
129 let file = try_file_to_source_file(sess, path, None).map_err(|db| vec![db])?;
130 maybe_source_file_to_parser(sess, file)
133 /// Given a session, a crate config, a path, and a span, add
134 /// the file at the given path to the `source_map`, and returns a parser.
135 /// On an error, uses the given span as the source of the problem.
136 pub fn new_sub_parser_from_file<'a>(sess: &'a ParseSess,
138 directory_ownership: DirectoryOwnership,
139 module_name: Option<String>,
140 sp: Span) -> Parser<'a> {
141 let mut p = source_file_to_parser(sess, file_to_source_file(sess, path, Some(sp)));
142 p.directory.ownership = directory_ownership;
143 p.root_module_name = module_name;
147 /// Given a `source_file` and config, returns a parser.
148 fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> {
149 panictry_buffer!(&sess.span_diagnostic,
150 maybe_source_file_to_parser(sess, source_file))
153 /// Given a `source_file` and config, return a parser. Returns any buffered errors from lexing the
154 /// initial token stream.
155 fn maybe_source_file_to_parser(
157 source_file: Lrc<SourceFile>,
158 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
159 let end_pos = source_file.end_pos;
160 let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?;
161 let mut parser = stream_to_parser(sess, stream, None);
162 parser.unclosed_delims = unclosed_delims;
163 if parser.token == token::Eof && parser.token.span.is_dummy() {
164 parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt());
170 // Must preserve old name for now, because `quote!` from the *existing*
171 // compiler expands into it.
172 pub fn new_parser_from_tts(sess: &ParseSess, tts: Vec<TokenTree>) -> Parser<'_> {
173 stream_to_parser(sess, tts.into_iter().collect(), crate::MACRO_ARGUMENTS)
179 /// Given a session and a path and an optional span (for error reporting),
180 /// add the path to the session's source_map and return the new source_file or
181 /// error when a file can't be read.
182 fn try_file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
183 -> Result<Lrc<SourceFile>, Diagnostic> {
184 sess.source_map().load_file(path)
186 let msg = format!("couldn't read {}: {}", path.display(), e);
187 let mut diag = Diagnostic::new(Level::Fatal, &msg);
188 if let Some(sp) = spanopt {
195 /// Given a session and a path and an optional span (for error reporting),
196 /// adds the path to the session's `source_map` and returns the new `source_file`.
197 fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>)
199 match try_file_to_source_file(sess, path, spanopt) {
200 Ok(source_file) => source_file,
202 sess.span_diagnostic.emit_diagnostic(&d);
208 /// Given a `source_file`, produces a sequence of token trees.
209 pub fn source_file_to_stream(
211 source_file: Lrc<SourceFile>,
212 override_span: Option<Span>,
213 ) -> (TokenStream, Vec<lexer::UnmatchedBrace>) {
214 panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span))
217 /// Given a source file, produces a sequence of token trees. Returns any buffered errors from
218 /// parsing the token stream.
219 pub fn maybe_file_to_stream(
221 source_file: Lrc<SourceFile>,
222 override_span: Option<Span>,
223 ) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> {
224 let srdr = lexer::StringReader::new(sess, source_file, override_span);
225 let (token_trees, unmatched_braces) = srdr.into_token_trees();
228 Ok(stream) => Ok((stream, unmatched_braces)),
230 let mut buffer = Vec::with_capacity(1);
231 err.buffer(&mut buffer);
232 // Not using `emit_unclosed_delims` to use `db.buffer`
233 for unmatched in unmatched_braces {
234 if let Some(err) = make_unclosed_delims_error(unmatched, &sess) {
235 err.buffer(&mut buffer);
243 /// Given a stream and the `ParseSess`, produces a parser.
244 pub fn stream_to_parser<'a>(
247 subparser_name: Option<&'static str>,
249 Parser::new(sess, stream, None, true, false, subparser_name)
252 /// Given a stream, the `ParseSess` and the base directory, produces a parser.
254 /// Use this function when you are creating a parser from the token stream
255 /// and also care about the current working directory of the parser (e.g.,
256 /// you are trying to resolve modules defined inside a macro invocation).
260 /// The main usage of this function is outside of rustc, for those who uses
261 /// libsyntax as a library. Please do not remove this function while refactoring
262 /// just because it is not used in rustc codebase!
263 pub fn stream_to_parser_with_base_dir<'a>(
266 base_dir: Directory<'a>,
268 Parser::new(sess, stream, Some(base_dir), true, false, None)
271 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
272 pub fn parse_in_attr<'a, T>(
274 attr: &ast::Attribute,
275 mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
276 ) -> PResult<'a, T> {
277 let mut parser = Parser::new(
279 attr.get_normal_item().tokens.clone(),
285 let result = f(&mut parser)?;
286 if parser.token != token::Eof {
287 parser.unexpected()?;
292 // NOTE(Centril): The following probably shouldn't be here but it acknowledges the
293 // fact that architecturally, we are using parsing (read on below to understand why).
295 pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> TokenStream {
296 // A `Nonterminal` is often a parsed AST item. At this point we now
297 // need to convert the parsed AST to an actual token stream, e.g.
298 // un-parse it basically.
300 // Unfortunately there's not really a great way to do that in a
301 // guaranteed lossless fashion right now. The fallback here is to just
302 // stringify the AST node and reparse it, but this loses all span
305 // As a result, some AST nodes are annotated with the token stream they
306 // came from. Here we attempt to extract these lossless token streams
307 // before we fall back to the stringification.
308 let tokens = match *nt {
309 Nonterminal::NtItem(ref item) => {
310 prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
312 Nonterminal::NtTraitItem(ref item) => {
313 prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
315 Nonterminal::NtImplItem(ref item) => {
316 prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
318 Nonterminal::NtIdent(ident, is_raw) => {
319 Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into())
321 Nonterminal::NtLifetime(ident) => {
322 Some(tokenstream::TokenTree::token(token::Lifetime(ident.name), ident.span).into())
324 Nonterminal::NtTT(ref tt) => {
325 Some(tt.clone().into())
330 // FIXME(#43081): Avoid this pretty-print + reparse hack
331 let source = pprust::nonterminal_to_string(nt);
332 let filename = FileName::macro_expansion_source_code(&source);
333 let tokens_for_real = parse_stream_from_source_str(filename, source, sess, Some(span));
335 // During early phases of the compiler the AST could get modified
336 // directly (e.g., attributes added or removed) and the internal cache
337 // of tokens my not be invalidated or updated. Consequently if the
338 // "lossless" token stream disagrees with our actual stringification
339 // (which has historically been much more battle-tested) then we go
340 // with the lossy stream anyway (losing span information).
342 // Note that the comparison isn't `==` here to avoid comparing spans,
343 // but it *also* is a "probable" equality which is a pretty weird
344 // definition. We mostly want to catch actual changes to the AST
345 // like a `#[cfg]` being processed or some weird `macro_rules!`
348 // What we *don't* want to catch is the fact that a user-defined
349 // literal like `0xf` is stringified as `15`, causing the cached token
350 // stream to not be literal `==` token-wise (ignoring spans) to the
351 // token stream we got from stringification.
353 // Instead the "probably equal" check here is "does each token
354 // recursively have the same discriminant?" We basically don't look at
355 // the token values here and assume that such fine grained token stream
356 // modifications, including adding/removing typically non-semantic
357 // tokens such as extra braces and commas, don't happen.
358 if let Some(tokens) = tokens {
359 if tokens.probably_equal_for_proc_macro(&tokens_for_real) {
362 info!("cached tokens found, but they're not \"probably equal\", \
363 going with stringified version");
365 return tokens_for_real
370 attrs: &[ast::Attribute],
371 tokens: Option<&tokenstream::TokenStream>,
372 span: syntax_pos::Span
373 ) -> Option<tokenstream::TokenStream> {
374 let tokens = tokens?;
375 if attrs.len() == 0 {
376 return Some(tokens.clone())
378 let mut builder = tokenstream::TokenStreamBuilder::new();
380 assert_eq!(attr.style, ast::AttrStyle::Outer,
381 "inner attributes should prevent cached tokens from existing");
383 let source = pprust::attribute_to_string(attr);
384 let macro_filename = FileName::macro_expansion_source_code(&source);
386 let item = match attr.kind {
387 ast::AttrKind::Normal(ref item) => item,
388 ast::AttrKind::DocComment(_) => {
389 let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
390 builder.push(stream);
395 // synthesize # [ $path $tokens ] manually here
396 let mut brackets = tokenstream::TokenStreamBuilder::new();
398 // For simple paths, push the identifier directly
399 if item.path.segments.len() == 1 && item.path.segments[0].args.is_none() {
400 let ident = item.path.segments[0].ident;
401 let token = token::Ident(ident.name, ident.as_str().starts_with("r#"));
402 brackets.push(tokenstream::TokenTree::token(token, ident.span));
404 // ... and for more complicated paths, fall back to a reparse hack that
405 // should eventually be removed.
407 let stream = parse_stream_from_source_str(macro_filename, source, sess, Some(span));
408 brackets.push(stream);
411 brackets.push(item.tokens.clone());
413 // The span we list here for `#` and for `[ ... ]` are both wrong in
414 // that it encompasses more than each token, but it hopefully is "good
415 // enough" for now at least.
416 builder.push(tokenstream::TokenTree::token(token::Pound, attr.span));
417 let delim_span = tokenstream::DelimSpan::from_single(attr.span);
418 builder.push(tokenstream::TokenTree::Delimited(
419 delim_span, token::DelimToken::Bracket, brackets.build().into()));
421 builder.push(tokens.clone());
422 Some(builder.build())