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/// Quoted string tokenization — single-quoted and double-quoted scalars.
///
/// Included into the `lexer` module from `mod.rs` via `include!("strings.rs")`.
impl<'a> Lexer<'a> {
/// Scan a single-quoted scalar
fn scan_single_quoted(&mut self) -> Result<Token, crate::error::YamlError> {
self.source.next(); // consume opening quote
let mut content = String::new();
loop {
match self.source.current() {
Some(CHAR_SINGLE_QUOTE) => {
self.source.next();
if self.source.current() == Some(CHAR_SINGLE_QUOTE) {
// Escaped quote
content.push(CHAR_SINGLE_QUOTE);
self.source.next();
} else {
// End of quoted string
// SU5Z: A comment character '#' immediately after a
// closing quoted scalar without any separating
// whitespace is invalid. Detect this here so that we
// can report a clear syntax error instead of
// silently treating it as a valid comment.
if let Some(CHAR_HASH) = self.source.current() {
return Err(crate::parser::errors::comment_errors::CommentErrors::comment_must_be_separated_from_quoted_scalar_by_whitespace(
self.source,
));
}
break;
}
}
Some(CHAR_NEWLINE) | Some(CHAR_CARRIAGE_RETURN) => {
let ch = self.source.current().unwrap();
content.push(CHAR_NEWLINE);
self.source.next();
if ch == CHAR_CARRIAGE_RETURN && self.source.current() == Some(CHAR_NEWLINE) {
self.source.next();
}
// RXY3: A document-start (---) or document-end (...) marker at the
// beginning of a line inside a single-quoted scalar terminates the
// document context, making the scalar unterminated. YAML spec §7.3.3
// and §9.2: stream directives intercept these markers even in flow
// scalars. Same rule as for double-quoted scalars (9MQT).
let c0 = self.source.current();
if c0 == Some('-') || c0 == Some('.') {
let marker = c0.unwrap();
if self.peek_ahead(1) == Some(marker) && self.peek_ahead(2) == Some(marker)
{
let c3 = self.peek_ahead(3);
let is_doc_marker = c3.map_or(true, |c| {
c == CHAR_SPACE
|| c == CHAR_TAB
|| c == CHAR_NEWLINE
|| c == CHAR_CARRIAGE_RETURN
});
if is_doc_marker {
return Err(
crate::parser::errors::token_errors::document_marker_in_single_quoted(
self.source,
),
);
}
}
}
}
Some(ch) => {
content.push(ch);
self.source.next();
}
None => {
lexer_debug!("Unterminated single-quoted string: reached EOF");
return Err(
crate::parser::errors::token_errors::unterminated_single_quoted_eof(
self.source,
),
);
}
}
}
Ok(Token::SingleQuoted(content))
}
/// Scan a double-quoted scalar
fn scan_double_quoted(&mut self) -> Result<Token, crate::error::YamlError> {
self.source.next(); // consume opening quote
let mut content = String::new();
// Track whether the quoted string literally crosses a newline in the source
// (as opposed to an escape sequence like \n). Multiline double-quoted strings
// cannot be used as implicit block mapping keys (YAML spec §8.1.1 / 7LBH).
let mut crossed_newline = false;
// Minimum count of leading SPACE characters on any continuation line
// (tabs never count as spaces per §6.1). usize::MAX = no line crossing.
let mut min_cont_spaces: usize = usize::MAX;
loop {
match self.source.current() {
Some('\\') => {
self.source.next();
match self.source.current() {
// Line folding: backslash followed by a line break (CR, LF, or CRLF)
// YAML allows escaping a line break in double-quoted scalars; the newline
// and any following indentation are suppressed (no characters added).
Some(c) if c == CHAR_NEWLINE || c == CHAR_CARRIAGE_RETURN => {
// Consume CR and optional LF
if c == CHAR_CARRIAGE_RETURN {
self.source.next();
if self.source.current() == Some(CHAR_NEWLINE) {
self.source.next();
}
} else {
// LF
self.source.next();
}
// Suppress any following indentation (spaces or tabs)
while let Some(ws) = self.source.current() {
if ws == CHAR_SPACE || ws == CHAR_TAB {
self.source.next();
} else {
break;
}
}
// Do not push any character; continue scanning content
continue;
}
Some('0') => {
content.push('\0');
self.source.next();
}
Some('a') => {
content.push('\x07');
self.source.next();
}
Some('b') => {
content.push('\x08');
self.source.next();
}
Some('t') | Some('\t') => {
content.push('\t');
self.source.next();
}
Some('n') => {
content.push('\n');
self.source.next();
}
Some('v') => {
content.push('\x0B');
self.source.next();
}
Some('f') => {
content.push('\x0C');
self.source.next();
}
Some('r') => {
content.push('\r');
self.source.next();
}
Some('e') => {
content.push('\x1B');
self.source.next();
}
Some(' ') => {
content.push(' ');
self.source.next();
}
Some('"') => {
content.push('"');
self.source.next();
}
Some('/') => {
content.push('/');
self.source.next();
}
Some('\\') => {
content.push('\\');
self.source.next();
}
Some('N') => {
content.push('\u{0085}');
self.source.next();
}
Some('_') => {
content.push('\u{00A0}');
self.source.next();
}
Some('L') => {
content.push('\u{2028}');
self.source.next();
}
Some('P') => {
content.push('\u{2029}');
self.source.next();
}
Some('x') => {
// \xXX - 2 hex digits
self.source.next();
let mut hex = String::new();
for _ in 0..2 {
match self.source.current() {
Some(c) if c.is_ascii_hexdigit() => {
hex.push(c);
self.source.next();
}
_ => {
return Err(
crate::parser::errors::token_errors::invalid_escape_x_expected_2_hex(
self.source,
),
);
}
}
}
let code = u8::from_str_radix(&hex, 16).unwrap();
content.push(code as char);
}
Some('u') => {
// \uXXXX - 4 hex digits
self.source.next();
let mut hex = String::new();
for _ in 0..4 {
match self.source.current() {
Some(c) if c.is_ascii_hexdigit() => {
hex.push(c);
self.source.next();
}
_ => {
return Err(
crate::parser::errors::token_errors::invalid_escape_u_expected_4_hex(
self.source,
),
);
}
}
}
let code = u32::from_str_radix(&hex, 16).unwrap();
match char::from_u32(code) {
Some(ch) => content.push(ch),
None => {
return Err(
crate::parser::errors::token_errors::invalid_unicode_codepoint_u4(
self.source,
code,
),
);
}
}
}
Some('U') => {
// \UXXXXXXXX - 8 hex digits
self.source.next();
let mut hex = String::new();
for _ in 0..8 {
match self.source.current() {
Some(c) if c.is_ascii_hexdigit() => {
hex.push(c);
self.source.next();
}
_ => {
return Err(
crate::parser::errors::token_errors::invalid_escape_u_expected_8_hex(
self.source,
),
);
}
}
}
let code = u32::from_str_radix(&hex, 16).unwrap();
match char::from_u32(code) {
Some(ch) => content.push(ch),
None => {
return Err(
crate::parser::errors::token_errors::invalid_unicode_codepoint_u8(
self.source,
code,
),
);
}
}
}
// Invalid escape sequences - reject per YAML 1.2 spec
Some(c) => {
return Err(
crate::parser::errors::token_errors::invalid_escape_generic(
self.source,
c,
),
);
}
None => {
lexer_debug!(
"Unterminated double-quoted string: reached EOF after escape"
);
return Err(
crate::parser::errors::token_errors::unterminated_double_quoted_eof_after_escape(
self.source,
),
);
}
}
}
Some(CHAR_DOUBLE_QUOTE) => {
self.source.next();
// SU5Z: A comment character '#' immediately after a
// closing quoted scalar without any separating
// whitespace is invalid. Detect this here so that we
// can report a clear syntax error instead of
// silently treating it as a valid comment.
if let Some(CHAR_HASH) = self.source.current() {
return Err(crate::parser::errors::comment_errors::CommentErrors::comment_must_be_separated_from_quoted_scalar_by_whitespace(
self.source,
));
}
break;
}
Some(CHAR_NEWLINE) | Some(CHAR_CARRIAGE_RETURN) => {
let ch = self.source.current().unwrap();
// Normalise CR / CRLF → LF in content
content.push(CHAR_NEWLINE);
// Mark that this double-quoted string spans multiple source lines.
crossed_newline = true;
self.source.next();
if ch == CHAR_CARRIAGE_RETURN && self.source.current() == Some(CHAR_NEWLINE) {
self.source.next();
}
// YAML 1.2: a document-start (---) or document-end (...) marker
// at the beginning of a new line inside a flow scalar terminates
// the document context, making the double-quoted string unterminated.
let c0 = self.source.current();
if c0 == Some('-') || c0 == Some('.') {
let marker = c0.unwrap();
if self.peek_ahead(1) == Some(marker) && self.peek_ahead(2) == Some(marker)
{
let c3 = self.peek_ahead(3);
let is_doc_marker = c3.map_or(true, |c| {
c == CHAR_SPACE
|| c == CHAR_TAB
|| c == CHAR_NEWLINE
|| c == CHAR_CARRIAGE_RETURN
});
if is_doc_marker {
return Err(
crate::parser::errors::token_errors::document_marker_in_double_quoted(
self.source,
),
);
}
}
}
// Count leading SPACE characters on the continuation line
// (tabs do NOT count as spaces for indentation purposes per YAML §6.1).
// Track the minimum across all continuation lines so the parser can
// validate that the continuation is more indented than the enclosing
// block context. Skip empty lines (next char is \r, \n, or EOF);
// only non-empty continuation lines count for the indentation check.
{
let mut sp = 0usize;
let mut peek_pos = 0;
loop {
match self.peek_ahead(peek_pos) {
Some(CHAR_SPACE) => {
sp += 1;
peek_pos += 1;
}
_ => break,
}
}
let next_after = self.peek_ahead(peek_pos);
let is_empty_line = matches!(
next_after,
None | Some(CHAR_NEWLINE) | Some(CHAR_CARRIAGE_RETURN)
);
if !is_empty_line && sp < min_cont_spaces {
min_cont_spaces = sp;
}
}
}
Some(ch) => {
content.push(ch);
self.source.next();
}
None => {
lexer_debug!("Unterminated double-quoted string: reached EOF");
return Err(
crate::parser::errors::token_errors::unterminated_double_quoted_eof(
self.source,
),
);
}
}
}
Ok(Token::DoubleQuoted(
content,
crossed_newline,
min_cont_spaces,
))
}
}