1 use super::{StringReader, UnmatchedBrace};
3 use rustc_ast_pretty::pprust::token_to_string;
4 use rustc_data_structures::fx::FxHashMap;
5 use rustc_errors::PResult;
7 use syntax::token::{self, Token};
8 use syntax::tokenstream::{
11 TokenStream, TokenTree, TreeAndJoint,
14 impl<'a> StringReader<'a> {
15 crate fn into_token_trees(self) -> (PResult<'a, TokenStream>, Vec<UnmatchedBrace>) {
16 let mut tt_reader = TokenTreesReader {
18 token: Token::dummy(),
20 open_braces: Vec::new(),
21 unmatched_braces: Vec::new(),
22 matching_delim_spans: Vec::new(),
23 last_unclosed_found_span: None,
24 last_delim_empty_block_spans: FxHashMap::default(),
26 let res = tt_reader.parse_all_token_trees();
27 (res, tt_reader.unmatched_braces)
31 struct TokenTreesReader<'a> {
32 string_reader: StringReader<'a>,
34 joint_to_prev: IsJoint,
35 /// Stack of open delimiters and their spans. Used for error message.
36 open_braces: Vec<(token::DelimToken, Span)>,
37 unmatched_braces: Vec<UnmatchedBrace>,
38 /// The type and spans for all braces
40 /// Used only for error recovery when arriving to EOF with mismatched braces.
41 matching_delim_spans: Vec<(token::DelimToken, Span, Span)>,
42 last_unclosed_found_span: Option<Span>,
43 last_delim_empty_block_spans: FxHashMap<token::DelimToken, Span>,
46 impl<'a> TokenTreesReader<'a> {
47 // Parse a stream of tokens into a list of `TokenTree`s, up to an `Eof`.
48 fn parse_all_token_trees(&mut self) -> PResult<'a, TokenStream> {
49 let mut buf = TokenStreamBuilder::default();
52 while self.token != token::Eof {
53 buf.push(self.parse_token_tree()?);
56 Ok(buf.into_token_stream())
59 // Parse a stream of tokens into a list of `TokenTree`s, up to a `CloseDelim`.
60 fn parse_token_trees_until_close_delim(&mut self) -> TokenStream {
61 let mut buf = TokenStreamBuilder::default();
63 if let token::CloseDelim(..) = self.token.kind {
64 return buf.into_token_stream();
67 match self.parse_token_tree() {
68 Ok(tree) => buf.push(tree),
71 return buf.into_token_stream();
77 fn parse_token_tree(&mut self) -> PResult<'a, TreeAndJoint> {
78 let sm = self.string_reader.sess.source_map();
79 match self.token.kind {
81 let msg = "this file contains an unclosed delimiter";
83 self.string_reader.sess.span_diagnostic.struct_span_err(self.token.span, msg);
84 for &(_, sp) in &self.open_braces {
85 err.span_label(sp, "unclosed delimiter");
86 self.unmatched_braces.push(UnmatchedBrace {
87 expected_delim: token::DelimToken::Brace,
89 found_span: self.token.span,
90 unclosed_span: Some(sp),
95 if let Some((delim, _)) = self.open_braces.last() {
96 if let Some((_, open_sp, close_sp)) =
97 self.matching_delim_spans.iter().find(|(d, open_sp, close_sp)| {
98 if let Some(close_padding) = sm.span_to_margin(*close_sp) {
99 if let Some(open_padding) = sm.span_to_margin(*open_sp) {
100 return delim == d && close_padding != open_padding;
105 // these are in reverse order as they get inserted on close, but
107 // we want the last open/first close
108 err.span_label(*open_sp, "this delimiter might not be properly closed...");
111 "...as it matches this but it has different indentation",
117 token::OpenDelim(delim) => {
118 // The span for beginning of the delimited section
119 let pre_span = self.token.span;
121 // Parse the open delimiter.
122 self.open_braces.push((delim, self.token.span));
125 // Parse the token trees within the delimiters.
126 // We stop at any delimiter so we can try to recover if the user
127 // uses an incorrect delimiter.
128 let tts = self.parse_token_trees_until_close_delim();
130 // Expand to cover the entire delimited token tree
131 let delim_span = DelimSpan::from_pair(pre_span, self.token.span);
133 match self.token.kind {
134 // Correct delimiter.
135 token::CloseDelim(d) if d == delim => {
136 let (open_brace, open_brace_span) = self.open_braces.pop().unwrap();
137 let close_brace_span = self.token.span;
140 let empty_block_span = open_brace_span.to(close_brace_span);
141 self.last_delim_empty_block_spans.insert(delim, empty_block_span);
144 if self.open_braces.len() == 0 {
145 // Clear up these spans to avoid suggesting them as we've found
146 // properly matched delimiters so far for an entire block.
147 self.matching_delim_spans.clear();
149 self.matching_delim_spans.push((
155 // Parse the closing delimiter.
158 // Incorrect delimiter.
159 token::CloseDelim(other) => {
160 let mut unclosed_delimiter = None;
161 let mut candidate = None;
162 if self.last_unclosed_found_span != Some(self.token.span) {
163 // do not complain about the same unclosed delimiter multiple times
164 self.last_unclosed_found_span = Some(self.token.span);
165 // This is a conservative error: only report the last unclosed
166 // delimiter. The previous unclosed delimiters could actually be
167 // closed! The parser just hasn't gotten to them yet.
168 if let Some(&(_, sp)) = self.open_braces.last() {
169 unclosed_delimiter = Some(sp);
171 if let Some(current_padding) = sm.span_to_margin(self.token.span) {
172 for (brace, brace_span) in &self.open_braces {
173 if let Some(padding) = sm.span_to_margin(*brace_span) {
174 // high likelihood of these two corresponding
175 if current_padding == padding && brace == &other {
176 candidate = Some(*brace_span);
181 let (tok, _) = self.open_braces.pop().unwrap();
182 self.unmatched_braces.push(UnmatchedBrace {
184 found_delim: Some(other),
185 found_span: self.token.span,
186 unclosed_span: unclosed_delimiter,
187 candidate_span: candidate,
190 self.open_braces.pop();
193 // If the incorrect delimiter matches an earlier opening
194 // delimiter, then don't consume it (it can be used to
195 // close the earlier one). Otherwise, consume it.
196 // E.g., we try to recover from:
199 // } // Incorrect delimiter but matches the earlier `{`
200 if !self.open_braces.iter().any(|&(b, _)| b == other) {
205 // Silently recover, the EOF token will be seen again
206 // and an error emitted then. Thus we don't pop from
207 // self.open_braces here.
212 Ok(TokenTree::Delimited(delim_span, delim, tts.into()).into())
214 token::CloseDelim(delim) => {
215 // An unexpected closing delimiter (i.e., there is no
216 // matching opening delimiter).
217 let token_str = token_to_string(&self.token);
218 let msg = format!("unexpected closing delimiter: `{}`", token_str);
220 self.string_reader.sess.span_diagnostic.struct_span_err(self.token.span, &msg);
222 if let Some(span) = self.last_delim_empty_block_spans.remove(&delim) {
225 "this block is empty, you might have not meant to close it",
228 err.span_label(self.token.span, "unexpected closing delimiter");
232 let tt = TokenTree::Token(self.token.take());
234 let is_joint = self.joint_to_prev == Joint && self.token.is_op();
235 Ok((tt, if is_joint { Joint } else { NonJoint }))
240 fn real_token(&mut self) {
241 self.joint_to_prev = Joint;
243 let token = self.string_reader.next_token();
245 token::Whitespace | token::Comment | token::Shebang(_) | token::Unknown(_) => {
246 self.joint_to_prev = NonJoint;
258 struct TokenStreamBuilder {
259 buf: Vec<TreeAndJoint>,
262 impl TokenStreamBuilder {
263 fn push(&mut self, (tree, joint): TreeAndJoint) {
264 if let Some((TokenTree::Token(prev_token), Joint)) = self.buf.last() {
265 if let TokenTree::Token(token) = &tree {
266 if let Some(glued) = prev_token.glue(token) {
268 self.buf.push((TokenTree::Token(glued), joint));
273 self.buf.push((tree, joint))
276 fn into_token_stream(self) -> TokenStream {
277 TokenStream::new(self.buf)