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use grep_matcher::LineTerminator;
use regex_syntax::hir::{self, Hir, HirKind};
use error::{Error, ErrorKind};
/// Return an HIR that is guaranteed to never match the given line terminator,
/// if possible.
///
/// If the transformation isn't possible, then an error is returned.
///
/// In general, if a literal line terminator occurs anywhere in the HIR, then
/// this will return an error. However, if the line terminator occurs within
/// a character class with at least one other character (that isn't also a line
/// terminator), then the line terminator is simply stripped from that class.
///
/// If the given line terminator is not ASCII, then this function returns an
/// error.
pub fn strip_from_match(
expr: Hir,
line_term: LineTerminator,
) -> Result<Hir, Error> {
if line_term.is_crlf() {
let expr1 = strip_from_match_ascii(expr, b'\r')?;
strip_from_match_ascii(expr1, b'\n')
} else {
let b = line_term.as_byte();
if b > 0x7F {
return Err(Error::new(ErrorKind::InvalidLineTerminator(b)));
}
strip_from_match_ascii(expr, b)
}
}
/// The implementation of strip_from_match. The given byte must be ASCII. This
/// function panics otherwise.
fn strip_from_match_ascii(
expr: Hir,
byte: u8,
) -> Result<Hir, Error> {
assert!(byte <= 0x7F);
let chr = byte as char;
assert_eq!(chr.len_utf8(), 1);
let invalid = || Err(Error::new(ErrorKind::NotAllowed(chr.to_string())));
Ok(match expr.into_kind() {
HirKind::Empty => Hir::empty(),
HirKind::Literal(hir::Literal::Unicode(c)) => {
if c == chr {
return invalid();
}
Hir::literal(hir::Literal::Unicode(c))
}
HirKind::Literal(hir::Literal::Byte(b)) => {
if b as char == chr {
return invalid();
}
Hir::literal(hir::Literal::Byte(b))
}
HirKind::Class(hir::Class::Unicode(mut cls)) => {
let remove = hir::ClassUnicode::new(Some(
hir::ClassUnicodeRange::new(chr, chr),
));
cls.difference(&remove);
if cls.ranges().is_empty() {
return invalid();
}
Hir::class(hir::Class::Unicode(cls))
}
HirKind::Class(hir::Class::Bytes(mut cls)) => {
let remove = hir::ClassBytes::new(Some(
hir::ClassBytesRange::new(byte, byte),
));
cls.difference(&remove);
if cls.ranges().is_empty() {
return invalid();
}
Hir::class(hir::Class::Bytes(cls))
}
HirKind::Anchor(x) => Hir::anchor(x),
HirKind::WordBoundary(x) => Hir::word_boundary(x),
HirKind::Repetition(mut x) => {
x.hir = Box::new(strip_from_match_ascii(*x.hir, byte)?);
Hir::repetition(x)
}
HirKind::Group(mut x) => {
x.hir = Box::new(strip_from_match_ascii(*x.hir, byte)?);
Hir::group(x)
}
HirKind::Concat(xs) => {
let xs = xs.into_iter()
.map(|e| strip_from_match_ascii(e, byte))
.collect::<Result<Vec<Hir>, Error>>()?;
Hir::concat(xs)
}
HirKind::Alternation(xs) => {
let xs = xs.into_iter()
.map(|e| strip_from_match_ascii(e, byte))
.collect::<Result<Vec<Hir>, Error>>()?;
Hir::alternation(xs)
}
})
}
#[cfg(test)]
mod tests {
use regex_syntax::Parser;
use error::Error;
use super::{LineTerminator, strip_from_match};
fn roundtrip(pattern: &str, byte: u8) -> String {
roundtrip_line_term(pattern, LineTerminator::byte(byte)).unwrap()
}
fn roundtrip_crlf(pattern: &str) -> String {
roundtrip_line_term(pattern, LineTerminator::crlf()).unwrap()
}
fn roundtrip_err(pattern: &str, byte: u8) -> Result<String, Error> {
roundtrip_line_term(pattern, LineTerminator::byte(byte))
}
fn roundtrip_line_term(
pattern: &str,
line_term: LineTerminator,
) -> Result<String, Error> {
let expr1 = Parser::new().parse(pattern).unwrap();
let expr2 = strip_from_match(expr1, line_term)?;
Ok(expr2.to_string())
}
#[test]
fn various() {
assert_eq!(roundtrip(r"[a\n]", b'\n'), "[a]");
assert_eq!(roundtrip(r"[a\n]", b'a'), "[\n]");
assert_eq!(roundtrip_crlf(r"[a\n]"), "[a]");
assert_eq!(roundtrip_crlf(r"[a\r]"), "[a]");
assert_eq!(roundtrip_crlf(r"[a\r\n]"), "[a]");
assert_eq!(roundtrip(r"(?-u)\s", b'a'), r"(?-u:[\x09-\x0D\x20])");
assert_eq!(roundtrip(r"(?-u)\s", b'\n'), r"(?-u:[\x09\x0B-\x0D\x20])");
assert!(roundtrip_err(r"\n", b'\n').is_err());
assert!(roundtrip_err(r"abc\n", b'\n').is_err());
assert!(roundtrip_err(r"\nabc", b'\n').is_err());
assert!(roundtrip_err(r"abc\nxyz", b'\n').is_err());
assert!(roundtrip_err(r"\x0A", b'\n').is_err());
assert!(roundtrip_err(r"\u000A", b'\n').is_err());
assert!(roundtrip_err(r"\U0000000A", b'\n').is_err());
assert!(roundtrip_err(r"\u{A}", b'\n').is_err());
assert!(roundtrip_err("\n", b'\n').is_err());
}
}
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