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Diffstat (limited to 'src/librustc_parse/lib.rs')
| -rw-r--r-- | src/librustc_parse/lib.rs | 423 |
1 files changed, 423 insertions, 0 deletions
diff --git a/src/librustc_parse/lib.rs b/src/librustc_parse/lib.rs new file mode 100644 index 00000000000..9f507d5319e --- /dev/null +++ b/src/librustc_parse/lib.rs @@ -0,0 +1,423 @@ +//! The main parser interface. + +#![feature(crate_visibility_modifier)] + +use syntax::ast; +use syntax::print::pprust; +use syntax::sess::ParseSess; +use syntax::token::{self, Nonterminal}; +use syntax::tokenstream::{self, TokenStream, TokenTree}; + +use errors::{PResult, FatalError, Level, Diagnostic}; +use rustc_data_structures::sync::Lrc; +use syntax_pos::{Span, SourceFile, FileName}; + +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::{Parser, emit_unclosed_delims, make_unclosed_delims_error}; +pub mod lexer; +pub mod validate_attr; +pub mod error_codes; + +#[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 std::result::Result::{Ok, Err}; + use errors::FatalError; + 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_attr<'a, T>( + sess: &'a ParseSess, + attr: &ast::Attribute, + mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>, +) -> PResult<'a, T> { + let mut parser = Parser::new( + sess, + attr.get_normal_item().tokens.clone(), + None, + false, + false, + Some("attribute"), + ); + 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) => { + prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span) + } + 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: syntax_pos::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.tokens.clone()); + + // 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()) +} |