1 //! The main parser interface.
3 #![feature(array_windows)]
4 #![feature(box_patterns)]
5 #![feature(if_let_guard)]
6 #![feature(let_chains)]
7 #![feature(never_type)]
8 #![feature(rustc_attrs)]
9 #![recursion_limit = "256"]
16 use rustc_ast::tokenstream::TokenStream;
17 use rustc_ast::Attribute;
18 use rustc_ast::{AttrItem, MetaItem};
19 use rustc_ast_pretty::pprust;
20 use rustc_data_structures::sync::Lrc;
21 use rustc_errors::{Applicability, Diagnostic, FatalError, Level, PResult};
22 use rustc_session::parse::ParseSess;
23 use rustc_span::{FileName, SourceFile, Span};
27 pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");
31 use parser::{emit_unclosed_delims, make_unclosed_delims_error, Parser};
33 pub mod validate_attr;
37 // A bunch of utility functions of the form `parse_<thing>_from_<source>`
38 // where <thing> includes crate, expr, item, stmt, tts, and one that
39 // uses a HOF to parse anything, and <source> includes file and
42 /// A variant of 'panictry!' that works on a Vec<Diagnostic> instead of a single DiagnosticBuilder.
43 macro_rules! panictry_buffer {
44 ($handler:expr, $e:expr) => {{
45 use rustc_errors::FatalError;
46 use std::result::Result::{Err, Ok};
51 $handler.emit_diagnostic(&mut e);
59 pub fn parse_crate_from_file<'a>(input: &Path, sess: &'a ParseSess) -> PResult<'a, ast::Crate> {
60 let mut parser = new_parser_from_file(sess, input, None);
61 parser.parse_crate_mod()
64 pub fn parse_crate_attrs_from_file<'a>(
67 ) -> PResult<'a, ast::AttrVec> {
68 let mut parser = new_parser_from_file(sess, input, None);
69 parser.parse_inner_attributes()
72 pub fn parse_crate_from_source_str(
76 ) -> PResult<'_, ast::Crate> {
77 new_parser_from_source_str(sess, name, source).parse_crate_mod()
80 pub fn parse_crate_attrs_from_source_str(
84 ) -> PResult<'_, ast::AttrVec> {
85 new_parser_from_source_str(sess, name, source).parse_inner_attributes()
88 pub fn parse_stream_from_source_str(
92 override_span: Option<Span>,
94 let (stream, mut errors) =
95 source_file_to_stream(sess, sess.source_map().new_source_file(name, source), override_span);
96 emit_unclosed_delims(&mut errors, &sess);
100 /// Creates a new parser from a source string.
101 pub fn new_parser_from_source_str(sess: &ParseSess, name: FileName, source: String) -> Parser<'_> {
102 panictry_buffer!(&sess.span_diagnostic, maybe_new_parser_from_source_str(sess, name, source))
105 /// Creates a new parser from a source string. Returns any buffered errors from lexing the initial
107 pub fn maybe_new_parser_from_source_str(
111 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
112 maybe_source_file_to_parser(sess, sess.source_map().new_source_file(name, source))
115 /// Creates a new parser, handling errors as appropriate if the file doesn't exist.
116 /// If a span is given, that is used on an error as the source of the problem.
117 pub fn new_parser_from_file<'a>(sess: &'a ParseSess, path: &Path, sp: Option<Span>) -> Parser<'a> {
118 source_file_to_parser(sess, file_to_source_file(sess, path, sp))
121 /// Given a session and a `source_file`, returns a parser.
122 fn source_file_to_parser(sess: &ParseSess, source_file: Lrc<SourceFile>) -> Parser<'_> {
123 panictry_buffer!(&sess.span_diagnostic, maybe_source_file_to_parser(sess, source_file))
126 /// Given a session and a `source_file`, return a parser. Returns any buffered errors from lexing the
127 /// initial token stream.
128 fn maybe_source_file_to_parser(
130 source_file: Lrc<SourceFile>,
131 ) -> Result<Parser<'_>, Vec<Diagnostic>> {
132 let end_pos = source_file.end_pos;
133 let (stream, unclosed_delims) = maybe_file_to_stream(sess, source_file, None)?;
134 let mut parser = stream_to_parser(sess, stream, None);
135 parser.unclosed_delims = unclosed_delims;
136 if parser.token == token::Eof {
137 parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt(), None);
145 /// Given a session and a path and an optional span (for error reporting),
146 /// add the path to the session's source_map and return the new source_file or
147 /// error when a file can't be read.
148 fn try_file_to_source_file(
151 spanopt: Option<Span>,
152 ) -> Result<Lrc<SourceFile>, Diagnostic> {
153 sess.source_map().load_file(path).map_err(|e| {
154 let msg = format!("couldn't read {}: {}", path.display(), e);
155 let mut diag = Diagnostic::new(Level::Fatal, &msg);
156 if let Some(sp) = spanopt {
163 /// Given a session and a path and an optional span (for error reporting),
164 /// adds the path to the session's `source_map` and returns the new `source_file`.
165 fn file_to_source_file(sess: &ParseSess, path: &Path, spanopt: Option<Span>) -> Lrc<SourceFile> {
166 match try_file_to_source_file(sess, path, spanopt) {
167 Ok(source_file) => source_file,
169 sess.span_diagnostic.emit_diagnostic(&mut d);
175 /// Given a `source_file`, produces a sequence of token trees.
176 pub fn source_file_to_stream(
178 source_file: Lrc<SourceFile>,
179 override_span: Option<Span>,
180 ) -> (TokenStream, Vec<lexer::UnmatchedBrace>) {
181 panictry_buffer!(&sess.span_diagnostic, maybe_file_to_stream(sess, source_file, override_span))
184 /// Given a source file, produces a sequence of token trees. Returns any buffered errors from
185 /// parsing the token stream.
186 pub fn maybe_file_to_stream(
188 source_file: Lrc<SourceFile>,
189 override_span: Option<Span>,
190 ) -> Result<(TokenStream, Vec<lexer::UnmatchedBrace>), Vec<Diagnostic>> {
191 let src = source_file.src.as_ref().unwrap_or_else(|| {
192 sess.span_diagnostic.bug(&format!(
193 "cannot lex `source_file` without source: {}",
194 sess.source_map().filename_for_diagnostics(&source_file.name)
198 let (token_trees, unmatched_braces) =
199 lexer::parse_token_trees(sess, src.as_str(), source_file.start_pos, override_span);
202 Ok(stream) => Ok((stream, unmatched_braces)),
204 let mut buffer = Vec::with_capacity(1);
205 err.buffer(&mut buffer);
206 // Not using `emit_unclosed_delims` to use `db.buffer`
207 for unmatched in unmatched_braces {
208 if let Some(err) = make_unclosed_delims_error(unmatched, &sess) {
209 err.buffer(&mut buffer);
217 /// Given a stream and the `ParseSess`, produces a parser.
218 pub fn stream_to_parser<'a>(
221 subparser_name: Option<&'static str>,
223 Parser::new(sess, stream, false, subparser_name)
226 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
227 pub fn parse_in<'a, T>(
231 mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
232 ) -> PResult<'a, T> {
233 let mut parser = Parser::new(sess, tts, false, Some(name));
234 let result = f(&mut parser)?;
235 if parser.token != token::Eof {
236 parser.unexpected()?;
241 pub fn fake_token_stream_for_item(sess: &ParseSess, item: &ast::Item) -> TokenStream {
242 let source = pprust::item_to_string(item);
243 let filename = FileName::macro_expansion_source_code(&source);
244 parse_stream_from_source_str(filename, source, sess, Some(item.span))
247 pub fn fake_token_stream_for_crate(sess: &ParseSess, krate: &ast::Crate) -> TokenStream {
248 let source = pprust::crate_to_string_for_macros(krate);
249 let filename = FileName::macro_expansion_source_code(&source);
250 parse_stream_from_source_str(filename, source, sess, Some(krate.spans.inner_span))
253 pub fn parse_cfg_attr(
255 parse_sess: &ParseSess,
256 ) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
257 match attr.get_normal_item().args {
258 ast::MacArgs::Delimited(dspan, delim, ref tts) if !tts.is_empty() => {
259 let msg = "wrong `cfg_attr` delimiters";
260 crate::validate_attr::check_meta_bad_delim(parse_sess, dspan, delim, msg);
261 match parse_in(parse_sess, tts.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
262 Ok(r) => return Some(r),
264 e.help(&format!("the valid syntax is `{}`", CFG_ATTR_GRAMMAR_HELP))
265 .note(CFG_ATTR_NOTE_REF)
270 _ => error_malformed_cfg_attr_missing(attr.span, parse_sess),
275 const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
276 const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
277 <https://doc.rust-lang.org/reference/conditional-compilation.html\
278 #the-cfg_attr-attribute>";
280 fn error_malformed_cfg_attr_missing(span: Span, parse_sess: &ParseSess) {
283 .struct_span_err(span, "malformed `cfg_attr` attribute input")
286 "missing condition and attribute",
287 CFG_ATTR_GRAMMAR_HELP,
288 Applicability::HasPlaceholders,
290 .note(CFG_ATTR_NOTE_REF)