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Introduce
string_reader.parse_all_token_trees().
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,138 @@ | ||
| // Copyright 2016 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
|
|
||
| use print::pprust::token_to_string; | ||
| use parse::lexer::StringReader; | ||
| use parse::{token, PResult}; | ||
| use syntax_pos::Span; | ||
| use tokenstream::{Delimited, TokenTree}; | ||
|
|
||
| use std::rc::Rc; | ||
|
|
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| impl<'a> StringReader<'a> { | ||
| // Parse a stream of tokens into a list of `TokenTree`s, up to an `Eof`. | ||
| pub fn parse_all_token_trees(&mut self) -> PResult<'a, Vec<TokenTree>> { | ||
| let mut tts = Vec::new(); | ||
| while self.token != token::Eof { | ||
| tts.push(self.parse_token_tree()?); | ||
| } | ||
| Ok(tts) | ||
| } | ||
|
|
||
| // Parse a stream of tokens into a list of `TokenTree`s, up to a `CloseDelim`. | ||
| fn parse_token_trees_until_close_delim(&mut self) -> Vec<TokenTree> { | ||
| let mut tts = vec![]; | ||
| loop { | ||
| if let token::CloseDelim(..) = self.token { | ||
| return tts; | ||
| } | ||
| match self.parse_token_tree() { | ||
| Ok(tt) => tts.push(tt), | ||
| Err(mut e) => { | ||
| e.emit(); | ||
| return tts; | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn parse_token_tree(&mut self) -> PResult<'a, TokenTree> { | ||
| match self.token { | ||
| token::Eof => { | ||
| let msg = "this file contains an un-closed delimiter"; | ||
| let mut err = self.sess.span_diagnostic.struct_span_err(self.span, msg); | ||
| for &(_, sp) in &self.open_braces { | ||
| err.span_help(sp, "did you mean to close this delimiter?"); | ||
| } | ||
| Err(err) | ||
| }, | ||
| token::OpenDelim(delim) => { | ||
| // The span for beginning of the delimited section | ||
| let pre_span = self.span; | ||
|
|
||
| // Parse the open delimiter. | ||
| self.open_braces.push((delim, self.span)); | ||
| let open_span = self.span; | ||
| self.real_token(); | ||
|
|
||
| // Parse the token trees within the delimiters. | ||
| // We stop at any delimiter so we can try to recover if the user | ||
| // uses an incorrect delimiter. | ||
| let tts = self.parse_token_trees_until_close_delim(); | ||
|
|
||
| let close_span = self.span; | ||
| // Expand to cover the entire delimited token tree | ||
| let span = Span { hi: close_span.hi, ..pre_span }; | ||
|
|
||
| match self.token { | ||
| // Correct delimiter. | ||
| token::CloseDelim(d) if d == delim => { | ||
| self.open_braces.pop().unwrap(); | ||
|
|
||
| // Parse the close delimiter. | ||
| self.real_token(); | ||
| } | ||
| // Incorrect delimiter. | ||
| token::CloseDelim(other) => { | ||
| let token_str = token_to_string(&self.token); | ||
| let msg = format!("incorrect close delimiter: `{}`", token_str); | ||
| let mut err = self.sess.span_diagnostic.struct_span_err(self.span, &msg); | ||
| // This is a conservative error: only report the last unclosed delimiter. | ||
| // The previous unclosed delimiters could actually be closed! The parser | ||
| // just hasn't gotten to them yet. | ||
| if let Some(&(_, sp)) = self.open_braces.last() { | ||
| err.span_note(sp, "unclosed delimiter"); | ||
| }; | ||
| err.emit(); | ||
|
|
||
| self.open_braces.pop().unwrap(); | ||
|
|
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| // If the incorrect delimiter matches an earlier opening | ||
| // delimiter, then don't consume it (it can be used to | ||
| // close the earlier one). Otherwise, consume it. | ||
| // E.g., we try to recover from: | ||
| // fn foo() { | ||
| // bar(baz( | ||
| // } // Incorrect delimiter but matches the earlier `{` | ||
| if !self.open_braces.iter().any(|&(b, _)| b == other) { | ||
| self.real_token(); | ||
| } | ||
| } | ||
| token::Eof => { | ||
| // Silently recover, the EOF token will be seen again | ||
| // and an error emitted then. Thus we don't pop from | ||
| // self.open_braces here. | ||
| }, | ||
| _ => {} | ||
| } | ||
|
|
||
| Ok(TokenTree::Delimited(span, Rc::new(Delimited { | ||
| delim: delim, | ||
| open_span: open_span, | ||
| tts: tts, | ||
| close_span: close_span, | ||
| }))) | ||
| }, | ||
| token::CloseDelim(_) => { | ||
| // An unexpected closing delimiter (i.e., there is no | ||
| // matching opening delimiter). | ||
| let token_str = token_to_string(&self.token); | ||
| let msg = format!("unexpected close delimiter: `{}`", token_str); | ||
| let err = self.sess.span_diagnostic.struct_span_err(self.span, &msg); | ||
| Err(err) | ||
| }, | ||
| _ => { | ||
| let tt = TokenTree::Token(self.span, self.token.clone()); | ||
| self.real_token(); | ||
| Ok(tt) | ||
| } | ||
| } | ||
| } | ||
| } |
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