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RFC 3349 precursors #120329

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merged 7 commits into from
Jan 26, 2024
Merged

RFC 3349 precursors #120329

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314dbc7
Avoid useless checking in `from_token_lit`.
nnethercote Jan 22, 2024
4b4bdb5
Fix copy/paste error.
nnethercote Jan 24, 2024
ef1e222
Use `from` instead of `into` in unescaping code.
nnethercote Jan 22, 2024
a1c0721
Rework `CStrUnit`.
nnethercote Jan 23, 2024
5e5aa6d
Rename and invert sense of `Mode` predicates.
nnethercote Jan 23, 2024
86f371e
Rename the unescaping functions.
nnethercote Jan 24, 2024
6be2e56
Use `unescape_unicode` for raw C string literals.
nnethercote Jan 24, 2024
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96 changes: 27 additions & 69 deletions compiler/rustc_ast/src/util/literal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,7 @@
use crate::ast::{self, LitKind, MetaItemLit, StrStyle};
use crate::token::{self, Token};
use rustc_lexer::unescape::{
byte_from_char, unescape_byte, unescape_c_string, unescape_char, unescape_literal, CStrUnit,
Mode,
byte_from_char, unescape_byte, unescape_char, unescape_mixed, unescape_unicode, MixedUnit, Mode,
};
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::Span;
Expand Down Expand Up @@ -48,6 +47,9 @@ impl LitKind {
return Err(LitError::InvalidSuffix);
}

// For byte/char/string literals, chars and escapes have already been
// checked in the lexer (in `cook_lexer_literal`). So we can assume all
// chars and escapes are valid here.
Ok(match kind {
token::Bool => {
assert!(symbol.is_bool_lit());
Expand All @@ -56,12 +58,12 @@ impl LitKind {
token::Byte => {
return unescape_byte(symbol.as_str())
.map(LitKind::Byte)
.map_err(|_| LitError::LexerError);
.map_err(|_| panic!("failed to unescape byte literal"));
}
token::Char => {
return unescape_char(symbol.as_str())
.map(LitKind::Char)
.map_err(|_| LitError::LexerError);
.map_err(|_| panic!("failed to unescape char literal"));
}

// There are some valid suffixes for integer and float literals,
Expand All @@ -77,113 +79,69 @@ impl LitKind {
let s = symbol.as_str();
// Vanilla strings are so common we optimize for the common case where no chars
// requiring special behaviour are present.
let symbol = if s.contains(['\\', '\r']) {
let symbol = if s.contains('\\') {
let mut buf = String::with_capacity(s.len());
let mut error = Ok(());
// Force-inlining here is aggressive but the closure is
// called on every char in the string, so it can be
// hot in programs with many long strings.
unescape_literal(
// called on every char in the string, so it can be hot in
// programs with many long strings containing escapes.
unescape_unicode(
s,
Mode::Str,
&mut #[inline(always)]
|_, unescaped_char| match unescaped_char {
|_, c| match c {
Ok(c) => buf.push(c),
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
assert!(!err.is_fatal(), "failed to unescape string literal")
}
},
);
error?;
Symbol::intern(&buf)
} else {
symbol
};
LitKind::Str(symbol, ast::StrStyle::Cooked)
}
token::StrRaw(n) => {
// Raw strings have no escapes, so we only need to check for invalid chars, and we
// can reuse the symbol on success.
let mut error = Ok(());
unescape_literal(symbol.as_str(), Mode::RawStr, &mut |_, unescaped_char| {
match unescaped_char {
Ok(_) => {}
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
}
}
});
error?;
// Raw strings have no escapes so no work is needed here.
LitKind::Str(symbol, ast::StrStyle::Raw(n))
}
token::ByteStr => {
let s = symbol.as_str();
let mut buf = Vec::with_capacity(s.len());
let mut error = Ok(());
unescape_literal(s, Mode::ByteStr, &mut |_, c| match c {
unescape_unicode(s, Mode::ByteStr, &mut |_, c| match c {
Ok(c) => buf.push(byte_from_char(c)),
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
assert!(!err.is_fatal(), "failed to unescape string literal")
}
});
error?;
LitKind::ByteStr(buf.into(), StrStyle::Cooked)
}
token::ByteStrRaw(n) => {
// Raw strings have no escapes, so we only need to check for invalid chars, and we
// can convert the symbol directly to a `Lrc<u8>` on success.
let s = symbol.as_str();
let mut error = Ok(());
unescape_literal(s, Mode::RawByteStr, &mut |_, c| match c {
Ok(_) => {}
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
}
});
LitKind::ByteStr(s.to_owned().into_bytes().into(), StrStyle::Raw(n))
// Raw strings have no escapes so we can convert the symbol
// directly to a `Lrc<u8>`.
let buf = symbol.as_str().to_owned().into_bytes();
LitKind::ByteStr(buf.into(), StrStyle::Raw(n))
}
token::CStr => {
let s = symbol.as_str();
let mut buf = Vec::with_capacity(s.len());
let mut error = Ok(());
unescape_c_string(s, Mode::CStr, &mut |_span, c| match c {
Ok(CStrUnit::Byte(b)) => buf.push(b),
Ok(CStrUnit::Char(c)) => {
unescape_mixed(s, Mode::CStr, &mut |_span, c| match c {
Ok(MixedUnit::Char(c)) => {
buf.extend_from_slice(c.encode_utf8(&mut [0; 4]).as_bytes())
}
Ok(MixedUnit::HighByte(b)) => buf.push(b),
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
assert!(!err.is_fatal(), "failed to unescape C string literal")
}
});
error?;
buf.push(0);
LitKind::CStr(buf.into(), StrStyle::Cooked)
}
token::CStrRaw(n) => {
// Raw strings have no escapes, so we only need to check for invalid chars, and we
// can convert the symbol directly to a `Lrc<u8>` on success.
let s = symbol.as_str();
let mut error = Ok(());
unescape_c_string(s, Mode::RawCStr, &mut |_, c| match c {
Ok(_) => {}
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
}
});
error?;
let mut buf = s.to_owned().into_bytes();
// Raw strings have no escapes so we can convert the symbol
// directly to a `Lrc<u8>` after appending the terminating NUL
// char.
let mut buf = symbol.as_str().to_owned().into_bytes();
buf.push(0);
LitKind::CStr(buf.into(), StrStyle::Raw(n))
}
Expand Down
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