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use super::{StringReader, UnmatchedBrace};
use rustc_ast::token::{self, Delimiter, Token};
use rustc_ast::tokenstream::{DelimSpan, Spacing, TokenStream, TokenTree};
use rustc_ast_pretty::pprust::token_to_string;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::PResult;
use rustc_span::Span;
impl<'a> StringReader<'a> {
pub(super) fn into_token_trees(self) -> (PResult<'a, TokenStream>, Vec<UnmatchedBrace>) {
let mut tt_reader = TokenTreesReader {
string_reader: self,
token: Token::dummy(),
open_braces: Vec::new(),
unmatched_braces: Vec::new(),
matching_delim_spans: Vec::new(),
last_unclosed_found_span: None,
last_delim_empty_block_spans: FxHashMap::default(),
matching_block_spans: Vec::new(),
};
let res = tt_reader.parse_all_token_trees();
(res, tt_reader.unmatched_braces)
}
}
struct TokenTreesReader<'a> {
string_reader: StringReader<'a>,
token: Token,
open_braces: Vec<(Delimiter, Span)>,
unmatched_braces: Vec<UnmatchedBrace>,
matching_delim_spans: Vec<(Delimiter, Span, Span)>,
last_unclosed_found_span: Option<Span>,
last_delim_empty_block_spans: FxHashMap<Delimiter, Span>,
matching_block_spans: Vec<(Span, Span)>,
}
impl<'a> TokenTreesReader<'a> {
fn parse_all_token_trees(&mut self) -> PResult<'a, TokenStream> {
let mut buf = TokenStreamBuilder::default();
self.bump();
while self.token != token::Eof {
buf.push(self.parse_token_tree()?);
}
Ok(buf.into_token_stream())
}
fn parse_token_trees_until_close_delim(&mut self) -> TokenStream {
let mut buf = TokenStreamBuilder::default();
loop {
if let token::CloseDelim(..) = self.token.kind {
return buf.into_token_stream();
}
match self.parse_token_tree() {
Ok(tree) => buf.push(tree),
Err(mut e) => {
e.emit();
return buf.into_token_stream();
}
}
}
}
fn parse_token_tree(&mut self) -> PResult<'a, TokenTree> {
let sm = self.string_reader.sess.source_map();
match self.token.kind {
token::Eof => {
let msg = "this file contains an unclosed delimiter";
let mut err =
self.string_reader.sess.span_diagnostic.struct_span_err(self.token.span, msg);
for &(_, sp) in &self.open_braces {
err.span_label(sp, "unclosed delimiter");
self.unmatched_braces.push(UnmatchedBrace {
expected_delim: Delimiter::Brace,
found_delim: None,
found_span: self.token.span,
unclosed_span: Some(sp),
candidate_span: None,
});
}
if let Some((delim, _)) = self.open_braces.last() {
if let Some((_, open_sp, close_sp)) =
self.matching_delim_spans.iter().find(|(d, open_sp, close_sp)| {
if let Some(close_padding) = sm.span_to_margin(*close_sp) {
if let Some(open_padding) = sm.span_to_margin(*open_sp) {
return delim == d && close_padding != open_padding;
}
}
false
})
{
err.span_label(*open_sp, "this delimiter might not be properly closed...");
err.span_label(
*close_sp,
"...as it matches this but it has different indentation",
);
}
}
Err(err)
}
token::OpenDelim(delim) => {
let pre_span = self.token.span;
self.open_braces.push((delim, self.token.span));
self.bump();
let tts = self.parse_token_trees_until_close_delim();
let delim_span = DelimSpan::from_pair(pre_span, self.token.span);
match self.token.kind {
token::CloseDelim(d) if d == delim => {
let (open_brace, open_brace_span) = self.open_braces.pop().unwrap();
let close_brace_span = self.token.span;
if tts.is_empty() {
let empty_block_span = open_brace_span.to(close_brace_span);
if !sm.is_multiline(empty_block_span) {
self.last_delim_empty_block_spans.insert(delim, empty_block_span);
}
}
if let (Delimiter::Brace, Delimiter::Brace) = (open_brace, delim) {
self.matching_block_spans.push((open_brace_span, close_brace_span));
}
if self.open_braces.is_empty() {
self.matching_delim_spans.clear();
} else {
self.matching_delim_spans.push((
open_brace,
open_brace_span,
close_brace_span,
));
}
self.bump();
}
token::CloseDelim(other) => {
let mut unclosed_delimiter = None;
let mut candidate = None;
if self.last_unclosed_found_span != Some(self.token.span) {
self.last_unclosed_found_span = Some(self.token.span);
if let Some(&(_, sp)) = self.open_braces.last() {
unclosed_delimiter = Some(sp);
};
if let Some(current_padding) = sm.span_to_margin(self.token.span) {
for (brace, brace_span) in &self.open_braces {
if let Some(padding) = sm.span_to_margin(*brace_span) {
if current_padding == padding && brace == &other {
candidate = Some(*brace_span);
}
}
}
}
let (tok, _) = self.open_braces.pop().unwrap();
self.unmatched_braces.push(UnmatchedBrace {
expected_delim: tok,
found_delim: Some(other),
found_span: self.token.span,
unclosed_span: unclosed_delimiter,
candidate_span: candidate,
});
} else {
self.open_braces.pop();
}
if !self.open_braces.iter().any(|&(b, _)| b == other) {
self.bump();
}
}
token::Eof => {
}
_ => {}
}
Ok(TokenTree::Delimited(delim_span, delim, tts))
}
token::CloseDelim(delim) => {
let token_str = token_to_string(&self.token);
let msg = format!("unexpected closing delimiter: `{}`", token_str);
let mut err =
self.string_reader.sess.span_diagnostic.struct_span_err(self.token.span, &msg);
if let Some(parent) = self.matching_block_spans.last() {
if let Some(span) = self.last_delim_empty_block_spans.remove(&delim) {
if (parent.0.to(parent.1)).contains(span) {
err.span_label(
span,
"block is empty, you might have not meant to close it",
);
} else {
err.span_label(parent.0, "this opening brace...");
err.span_label(parent.1, "...matches this closing brace");
}
} else {
err.span_label(parent.0, "this opening brace...");
err.span_label(parent.1, "...matches this closing brace");
}
}
err.span_label(self.token.span, "unexpected closing delimiter");
Err(err)
}
_ => {
let tok = self.token.take();
let mut spacing = self.bump();
if !self.token.is_op() {
spacing = Spacing::Alone;
}
Ok(TokenTree::Token(tok, spacing))
}
}
}
fn bump(&mut self) -> Spacing {
let (spacing, token) = self.string_reader.next_token();
self.token = token;
spacing
}
}
#[derive(Default)]
struct TokenStreamBuilder {
buf: Vec<TokenTree>,
}
impl TokenStreamBuilder {
#[inline(always)]
fn push(&mut self, tree: TokenTree) {
if let Some(TokenTree::Token(prev_token, Spacing::Joint)) = self.buf.last()
&& let TokenTree::Token(token, joint) = &tree
&& let Some(glued) = prev_token.glue(token)
{
self.buf.pop();
self.buf.push(TokenTree::Token(glued, *joint));
} else {
self.buf.push(tree)
}
}
fn into_token_stream(self) -> TokenStream {
TokenStream::new(self.buf)
}
}