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matkladmatklad
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refactor lexer to use idiomatic borrowing
1 parent 40ab9d2 commit b75021b

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1 file changed

+104
-121
lines changed
  • src/libsyntax/parse/lexer

1 file changed

+104
-121
lines changed

‎src/libsyntax/parse/lexer/mod.rs‎

Lines changed: 104 additions & 121 deletions
Original file line numberDiff line numberDiff line change
@@ -321,33 +321,29 @@ impl<'a> StringReader<'a> {
321321
(pos - self.source_file.start_pos).to_usize()
322322
}
323323

324-
/// Calls `f` with a string slice of the source text spanning from `start`
325-
/// up to but excluding `self.pos`, meaning the slice does not include
326-
/// the character `self.ch`.
327-
fn with_str_from<T, F>(&self, start: BytePos, f: F) -> T
328-
where F: FnOnce(&str) -> T
324+
/// Slice of the source text from `start` up to but excluding `self.pos`,
325+
/// meaning the slice does not include the character `self.ch`.
326+
fn str_from(&self, start: BytePos) -> &str
329327
{
330-
self.with_str_from_to(start, self.pos, f)
328+
self.str_from_to(start, self.pos)
331329
}
332330

333331
/// Creates a Name from a given offset to the current offset.
334332
fn name_from(&self, start: BytePos) -> ast::Name {
335333
debug!("taking an ident from {:?} to {:?}", start, self.pos);
336-
self.with_str_from(start, Symbol::intern)
334+
Symbol::intern(self.str_from(start))
337335
}
338336

339337
/// As name_from, with an explicit endpoint.
340338
fn name_from_to(&self, start: BytePos, end: BytePos) -> ast::Name {
341339
debug!("taking an ident from {:?} to {:?}", start, end);
342-
self.with_str_from_to(start, end, Symbol::intern)
340+
Symbol::intern(self.str_from_to(start, end))
343341
}
344342

345-
/// Calls `f` with a string slice of the source text spanning from `start`
346-
/// up to but excluding `end`.
347-
fn with_str_from_to<T, F>(&self, start: BytePos, end: BytePos, f: F) -> T
348-
where F: FnOnce(&str) -> T
343+
/// Slice of the source text spanning from `start` up to but excluding `end`.
344+
fn str_from_to(&self, start: BytePos, end: BytePos) -> &str
349345
{
350-
f(&self.src[self.src_index(start)..self.src_index(end)])
346+
&self.src[self.src_index(start)..self.src_index(end)]
351347
}
352348

353349
/// Converts CRLF to LF in the given string, raising an error on bare CR.
@@ -456,8 +452,8 @@ impl<'a> StringReader<'a> {
456452
self.bump();
457453
}
458454

459-
self.with_str_from(start, |string| {
460-
if string == "_" {
455+
match self.str_from(start) {
456+
"_" => {
461457
self.sess.span_diagnostic
462458
.struct_span_warn(self.mk_sp(start, self.pos),
463459
"underscore literal suffix is not allowed")
@@ -468,10 +464,9 @@ impl<'a> StringReader<'a> {
468464
<https://github.com/rust-lang/rust/issues/42326>")
469465
.emit();
470466
None
471-
} else {
472-
Some(Symbol::intern(string))
473467
}
474-
})
468+
name => Some(Symbol::intern(name))
469+
}
475470
}
476471

477472
/// PRECONDITION: self.ch is not whitespace
@@ -513,9 +508,7 @@ impl<'a> StringReader<'a> {
513508
}
514509

515510
let kind = if doc_comment {
516-
self.with_str_from(start_bpos, |string| {
517-
token::DocComment(Symbol::intern(string))
518-
})
511+
token::DocComment(self.name_from(start_bpos))
519512
} else {
520513
token::Comment
521514
};
@@ -615,23 +608,22 @@ impl<'a> StringReader<'a> {
615608
self.bump();
616609
}
617610

618-
self.with_str_from(start_bpos, |string| {
619-
// but comments with only "*"s between two "/"s are not
620-
let kind = if is_block_doc_comment(string) {
621-
let string = if has_cr {
622-
self.translate_crlf(start_bpos,
623-
string,
624-
"bare CR not allowed in block doc-comment")
625-
} else {
626-
string.into()
627-
};
628-
token::DocComment(Symbol::intern(&string[..]))
611+
let string = self.str_from(start_bpos);
612+
// but comments with only "*"s between two "/"s are not
613+
let kind = if is_block_doc_comment(string) {
614+
let string = if has_cr {
615+
self.translate_crlf(start_bpos,
616+
string,
617+
"bare CR not allowed in block doc-comment")
629618
} else {
630-
token::Comment
619+
string.into()
631620
};
621+
token::DocComment(Symbol::intern(&string[..]))
622+
} else {
623+
token::Comment
624+
};
632625

633-
Some(Token::new(kind, self.mk_sp(start_bpos, self.pos)))
634-
})
626+
Some(Token::new(kind, self.mk_sp(start_bpos, self.pos)))
635627
}
636628

637629
/// Scan through any digits (base `scan_radix`) or underscores,
@@ -838,20 +830,17 @@ impl<'a> StringReader<'a> {
838830
self.bump();
839831
}
840832

841-
return Ok(self.with_str_from(start, |string| {
842-
// FIXME: perform NFKC normalization here. (Issue #2253)
843-
let name = ast::Name::intern(string);
844-
845-
if is_raw_ident {
846-
let span = self.mk_sp(raw_start, self.pos);
847-
if !name.can_be_raw() {
848-
self.err_span(span, &format!("`{}` cannot be a raw identifier", name));
849-
}
850-
self.sess.raw_identifier_spans.borrow_mut().push(span);
833+
// FIXME: perform NFKC normalization here. (Issue #2253)
834+
let name = self.name_from(start);
835+
if is_raw_ident {
836+
let span = self.mk_sp(raw_start, self.pos);
837+
if !name.can_be_raw() {
838+
self.err_span(span, &format!("`{}` cannot be a raw identifier", name));
851839
}
840+
self.sess.raw_identifier_spans.borrow_mut().push(span);
841+
}
852842

853-
token::Ident(name, is_raw_ident)
854-
}));
843+
return Ok(token::Ident(name, is_raw_ident));
855844
}
856845
}
857846

@@ -1300,101 +1289,95 @@ impl<'a> StringReader<'a> {
13001289
}
13011290

13021291
fn validate_char_escape(&self, start_with_quote: BytePos) {
1303-
self.with_str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1), |lit| {
1304-
if let Err((off, err)) = unescape::unescape_char(lit) {
1292+
let lit = self.str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1));
1293+
if let Err((off, err)) = unescape::unescape_char(lit) {
1294+
emit_unescape_error(
1295+
&self.sess.span_diagnostic,
1296+
lit,
1297+
self.mk_sp(start_with_quote, self.pos),
1298+
unescape::Mode::Char,
1299+
0..off,
1300+
err,
1301+
)
1302+
}
1303+
}
1304+
1305+
fn validate_byte_escape(&self, start_with_quote: BytePos) {
1306+
let lit = self.str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1));
1307+
if let Err((off, err)) = unescape::unescape_byte(lit) {
1308+
emit_unescape_error(
1309+
&self.sess.span_diagnostic,
1310+
lit,
1311+
self.mk_sp(start_with_quote, self.pos),
1312+
unescape::Mode::Byte,
1313+
0..off,
1314+
err,
1315+
)
1316+
}
1317+
}
1318+
1319+
fn validate_str_escape(&self, start_with_quote: BytePos) {
1320+
let lit = self.str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1));
1321+
unescape::unescape_str(lit, &mut |range, c| {
1322+
if let Err(err) = c {
13051323
emit_unescape_error(
13061324
&self.sess.span_diagnostic,
13071325
lit,
13081326
self.mk_sp(start_with_quote, self.pos),
1309-
unescape::Mode::Char,
1310-
0..off,
1327+
unescape::Mode::Str,
1328+
range,
13111329
err,
13121330
)
13131331
}
1314-
});
1332+
})
13151333
}
13161334

1317-
fn validate_byte_escape(&self, start_with_quote: BytePos) {
1318-
self.with_str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1), |lit| {
1319-
if let Err((off, err)) = unescape::unescape_byte(lit) {
1335+
fn validate_raw_str_escape(&self, content_start: BytePos, content_end: BytePos) {
1336+
let lit = self.str_from_to(content_start, content_end);
1337+
unescape::unescape_raw_str(lit, &mut |range, c| {
1338+
if let Err(err) = c {
13201339
emit_unescape_error(
13211340
&self.sess.span_diagnostic,
13221341
lit,
1323-
self.mk_sp(start_with_quote, self.pos),
1324-
unescape::Mode::Byte,
1325-
0..off,
1342+
self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
1343+
unescape::Mode::Str,
1344+
range,
13261345
err,
13271346
)
13281347
}
1329-
});
1330-
}
1331-
1332-
fn validate_str_escape(&self, start_with_quote: BytePos) {
1333-
self.with_str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1), |lit| {
1334-
unescape::unescape_str(lit, &mut |range, c| {
1335-
if let Err(err) = c {
1336-
emit_unescape_error(
1337-
&self.sess.span_diagnostic,
1338-
lit,
1339-
self.mk_sp(start_with_quote, self.pos),
1340-
unescape::Mode::Str,
1341-
range,
1342-
err,
1343-
)
1344-
}
1345-
})
1346-
});
1347-
}
1348-
1349-
fn validate_raw_str_escape(&self, content_start: BytePos, content_end: BytePos) {
1350-
self.with_str_from_to(content_start, content_end, |lit: &str| {
1351-
unescape::unescape_raw_str(lit, &mut |range, c| {
1352-
if let Err(err) = c {
1353-
emit_unescape_error(
1354-
&self.sess.span_diagnostic,
1355-
lit,
1356-
self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
1357-
unescape::Mode::Str,
1358-
range,
1359-
err,
1360-
)
1361-
}
1362-
})
1363-
});
1348+
})
13641349
}
13651350

13661351
fn validate_raw_byte_str_escape(&self, content_start: BytePos, content_end: BytePos) {
1367-
self.with_str_from_to(content_start, content_end, |lit: &str| {
1368-
unescape::unescape_raw_byte_str(lit, &mut |range, c| {
1369-
if let Err(err) = c {
1370-
emit_unescape_error(
1371-
&self.sess.span_diagnostic,
1372-
lit,
1373-
self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
1374-
unescape::Mode::ByteStr,
1375-
range,
1376-
err,
1377-
)
1378-
}
1379-
})
1380-
});
1352+
let lit = self.str_from_to(content_start, content_end);
1353+
unescape::unescape_raw_byte_str(lit, &mut |range, c| {
1354+
if let Err(err) = c {
1355+
emit_unescape_error(
1356+
&self.sess.span_diagnostic,
1357+
lit,
1358+
self.mk_sp(content_start - BytePos(1), content_end + BytePos(1)),
1359+
unescape::Mode::ByteStr,
1360+
range,
1361+
err,
1362+
)
1363+
}
1364+
})
13811365
}
13821366

13831367
fn validate_byte_str_escape(&self, start_with_quote: BytePos) {
1384-
self.with_str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1), |lit| {
1385-
unescape::unescape_byte_str(lit, &mut |range, c| {
1386-
if let Err(err) = c {
1387-
emit_unescape_error(
1388-
&self.sess.span_diagnostic,
1389-
lit,
1390-
self.mk_sp(start_with_quote, self.pos),
1391-
unescape::Mode::ByteStr,
1392-
range,
1393-
err,
1394-
)
1395-
}
1396-
})
1397-
});
1368+
let lit = self.str_from_to(start_with_quote + BytePos(1), self.pos - BytePos(1));
1369+
unescape::unescape_byte_str(lit, &mut |range, c| {
1370+
if let Err(err) = c {
1371+
emit_unescape_error(
1372+
&self.sess.span_diagnostic,
1373+
lit,
1374+
self.mk_sp(start_with_quote, self.pos),
1375+
unescape::Mode::ByteStr,
1376+
range,
1377+
err,
1378+
)
1379+
}
1380+
})
13981381
}
13991382
}
14001383

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