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use std::cmp::max;
use oxc_str::{JSStr, JSStrBuilder};
use crate::{config::LexerConfig as Config, diagnostics};
use super::{
Kind, Lexer, Span, Token, cold_branch,
search::{SafeByteMatchTable, byte_search, safe_byte_match_table},
};
const MIN_ESCAPED_STR_LEN: usize = 16;
static DOUBLE_QUOTE_STRING_END_TABLE: SafeByteMatchTable =
safe_byte_match_table!(|b| matches!(b, b'"' | b'\r' | b'\n' | b'\\'));
static SINGLE_QUOTE_STRING_END_TABLE: SafeByteMatchTable =
safe_byte_match_table!(|b| matches!(b, b'\'' | b'\r' | b'\n' | b'\\'));
/// Macro to handle a string literal.
///
/// # SAFETY
/// `$delimiter` must be an ASCII byte.
/// Next char in `lexer.source` must be ASCII.
/// `$table` must be a `SafeByteMatchTable`.
/// `$table` must only match `$delimiter`, '\', '\r' or '\n'.
macro_rules! handle_string_literal {
($lexer:ident, $delimiter:literal, $table:ident) => {{
debug_assert!($delimiter.is_ascii());
// Skip opening quote.
// SAFETY: Caller guarantees next byte is ASCII, so safe to advance past it.
let after_opening_quote = $lexer.source.position().add(1);
// Consume bytes which are part of string
let next_byte = byte_search! {
lexer: $lexer,
table: $table,
start: after_opening_quote,
handle_eof: {
// Unterminated string is invalid JS, so a cold path. Building the diagnostic
// out-of-line keeps the `OxcDiagnostic` return buffer out of this handler's
// stack frame (matching the sibling `\\` and line-break arms below).
return cold_branch(|| {
$lexer.error(diagnostics::unterminated_string($lexer.unterminated_range()));
Kind::Undetermined
});
},
};
// Found a matching byte.
// Either end of string found, or a line break, or `\` escape.
match next_byte {
$delimiter => {
// SAFETY: Macro user guarantees delimiter is ASCII, so consuming it cannot move
// `lexer.source` off a UTF-8 character boundary.
$lexer.source.next_byte_unchecked();
Kind::Str
}
b'\\' => cold_branch(|| {
handle_string_literal_escape!($lexer, $delimiter, $table, after_opening_quote)
}),
_ => {
// Line break. This is impossible in valid JS, so cold path.
cold_branch(|| {
debug_assert!(matches!(next_byte, b'\r' | b'\n'));
$lexer.consume_char();
$lexer.error(diagnostics::unterminated_string($lexer.unterminated_range()));
Kind::Undetermined
})
}
}
}};
}
macro_rules! handle_string_literal_escape {
($lexer:ident, $delimiter:literal, $table:ident, $after_opening_quote:ident) => {{
// Create arena string to hold unescaped string.
// We don't know how long string will end up being. Take a guess that total length
// will be double what we've seen so far, or `MIN_ESCAPED_STR_LEN` minimum.
let so_far = $lexer.source.str_from_pos_to_current($after_opening_quote);
let capacity = max(so_far.len() * 2, MIN_ESCAPED_STR_LEN);
let mut str = JSStrBuilder::with_capacity_in(capacity, &$lexer.allocator);
// Push chunk before `\` into `str`.
str.push_str(so_far);
'outer: loop {
// Consume `\`
let escape_start_offset = $lexer.offset();
$lexer.consume_char();
// Consume escape sequence and add char to `str`
let mut is_valid_escape_sequence = true;
$lexer.read_string_escape_sequence(&mut str, false, &mut is_valid_escape_sequence);
if !is_valid_escape_sequence {
let range = Span::new(escape_start_offset, $lexer.offset());
$lexer.error(diagnostics::invalid_escape_sequence(range));
}
// Consume bytes until reach end of string, line break, or another escape
let chunk_start = $lexer.source.position();
while let Some(b) = $lexer.peek_byte() {
match b {
b if !$table.matches(b) => {
// SAFETY: A byte is available, as we just peeked it.
// This may put `source`'s position on a UTF-8 continuation byte, which violates
// `Source`'s invariant temporarily, but the guarantees of `SafeByteMatchTable`
// mean `!table.matches(b)` on this branch prevents exiting this loop until
// `source` is positioned on a UTF-8 character boundary again.
$lexer.source.next_byte_unchecked();
}
b if b == $delimiter => {
// End of string found. Push last chunk to `str`.
let chunk = $lexer.source.str_from_pos_to_current(chunk_start);
str.push_str(chunk);
// Consume closing quote.
// SAFETY: Caller guarantees delimiter is ASCII, so consuming it cannot move
// `lexer.source` off a UTF-8 character boundary
$lexer.source.next_byte_unchecked();
break 'outer;
}
b'\\' => {
// Another escape found. Push last chunk to `str`, and loop back to handle escape.
let chunk = $lexer.source.str_from_pos_to_current(chunk_start);
str.push_str(chunk);
continue 'outer;
}
_ => {
// Line break. This is impossible in valid JS, so cold path.
return cold_branch(|| {
debug_assert!(matches!(b, b'\r' | b'\n'));
$lexer.consume_char();
$lexer.error(diagnostics::unterminated_string($lexer.unterminated_range()));
Kind::Undetermined
});
}
}
}
// EOF
$lexer.error(diagnostics::unterminated_string($lexer.unterminated_range()));
return Kind::Undetermined;
}
$lexer.save_js_string(str.into_js_str());
Kind::Str
}};
}
/// 12.9.4 String Literals
impl<'a, C: Config> Lexer<'a, C> {
/// Read string literal delimited with `"`.
/// # SAFETY
/// Next character must be `"`.
pub(super) unsafe fn read_string_literal_double_quote(&mut self) -> Kind {
// SAFETY: Caller guarantees next char is `"`, which is ASCII.
// b'"' is an ASCII byte. `DOUBLE_QUOTE_STRING_END_TABLE` is a `SafeByteMatchTable`.
unsafe { handle_string_literal!(self, b'"', DOUBLE_QUOTE_STRING_END_TABLE) }
}
/// Read string literal delimited with `'`.
/// # SAFETY
/// Next character must be `'`.
pub(super) unsafe fn read_string_literal_single_quote(&mut self) -> Kind {
// SAFETY: Caller guarantees next char is `'`, which is ASCII.
// b'\'' is an ASCII byte. `SINGLE_QUOTE_STRING_END_TABLE` is a `SafeByteMatchTable`.
unsafe { handle_string_literal!(self, b'\'', SINGLE_QUOTE_STRING_END_TABLE) }
}
fn save_js_string(&mut self, value: JSStr<'a>) {
self.escaped_strings.insert(self.token.start(), value);
self.token.set_escaped(true);
}
pub(crate) fn get_js_string(&self, token: Token) -> JSStr<'a> {
if token.escaped() {
self.escaped_strings[&token.start()]
} else {
JSStr::from(self.get_string(token))
}
}
/// Save the string if it is escaped
/// This reduces the overall memory consumption while keeping the `Token` size small
/// Strings without escaped values can be retrieved as is from the token span
pub(super) fn save_string(&mut self, has_escape: bool, s: &'a str) {
if has_escape {
self.save_escaped_string(s);
}
}
#[cold]
fn save_escaped_string(&mut self, s: &'a str) {
self.escaped_strings.insert(self.token.start(), s.into());
self.token.set_escaped(true);
}
pub(crate) fn get_string(&self, token: Token) -> &'a str {
if token.escaped() {
// Identifiers only save validated Unicode scalar values.
// Decoded string literals and templates use `get_js_string` instead.
return self.escaped_strings[&token.start()]
.as_str()
.expect("identifier escape must be valid UTF-8");
}
let source_text = self.source.whole();
let mut start = token.start() as usize;
let mut end = token.end() as usize;
match token.kind() {
Kind::Str => {
// Omit surrounding quotes
start += 1;
end -= 1;
}
Kind::PrivateIdentifier => {
// Omit leading `#`
start += 1;
}
_ => {}
}
&source_text[start..end]
}
}