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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
use alloc::borrow::Cow;
#[cfg(any(feature = "serde_human", feature = "datagen"))]
use alloc::string::ToString;
use icu_provider::{yoke, zerofrom};
use regex_automata::dfa::sparse::DFA;
use regex_automata::dfa::Automaton;
/// A precompiled regex
#[derive(Clone, Debug, yoke::Yokeable, zerofrom::ZeroFrom)]
#[allow(clippy::exhaustive_structs)] // not a public API
pub struct StringMatcher<'data> {
// Safety: These always represent a valid DFA (DFA::from_bytes(dfa_bytes).is_ok())
dfa_bytes: Cow<'data, [u8]>,
pattern: Option<Cow<'data, str>>,
}
impl PartialEq for StringMatcher<'_> {
fn eq(&self, other: &Self) -> bool {
self.dfa_bytes == other.dfa_bytes
}
}
#[cfg(feature = "datagen")]
impl databake::Bake for StringMatcher<'_> {
fn bake(&self, env: &databake::CrateEnv) -> databake::TokenStream {
env.insert("icu_list");
let bytes = (&&*self.dfa_bytes).bake(env);
// Safe because our own data is safe
databake::quote! {
unsafe { ::icu_list::provider::StringMatcher::from_dfa_bytes_unchecked(#bytes) }
}
}
}
#[cfg(feature = "datagen")]
impl serde::Serialize for StringMatcher<'_> {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: serde::ser::Serializer,
{
if serializer.is_human_readable() {
self.pattern
.as_ref()
.map(|pattern| pattern.serialize(serializer))
.unwrap_or_else(|| {
use serde::ser::Error;
Err(S::Error::custom(
"cannot serialize a deserialized bincode StringMatcher to JSON",
))
})
} else {
self.dfa_bytes.serialize(serializer)
}
}
}
#[cfg(feature = "serde")]
impl<'de: 'data, 'data> serde::Deserialize<'de> for StringMatcher<'data> {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: serde::de::Deserializer<'de>,
{
use icu_provider::serde::borrow_de_utils::CowBytesWrap;
#[cfg(feature = "serde_human")]
if deserializer.is_human_readable() {
use serde::de::Error;
return StringMatcher::new(<&str>::deserialize(deserializer)?)
.map_err(|e| D::Error::custom(e.to_string()));
}
if cfg!(target_endian = "big") {
// TODO: Convert LE to BE. For now we just behave like the
// accept-nothing DFA on BE systems.
return Ok(StringMatcher {
dfa_bytes: Cow::Borrowed(&[]),
pattern: None,
});
}
let dfa_bytes = <CowBytesWrap<'de>>::deserialize(deserializer)?.0;
// Verify safety invariant
DFA::from_bytes(&dfa_bytes).map_err(|e| {
use serde::de::Error;
D::Error::custom(alloc::format!("Invalid DFA bytes: {}", e))
})?;
Ok(StringMatcher {
dfa_bytes,
pattern: None,
})
}
}
impl<'data> StringMatcher<'data> {
/// Creates a `StringMatcher` from a serialized DFA. Used internally by databake.
///
/// # Safety
///
/// `dfa_bytes` has to be a valid DFA (regex_automata::dfa::sparse::DFA::from_bytes(dfa_bytes).is_ok())
pub const unsafe fn from_dfa_bytes_unchecked(dfa_bytes: &'data [u8]) -> Self {
Self {
dfa_bytes: Cow::Borrowed(dfa_bytes),
pattern: None,
}
}
/// Creates a `StringMatcher` from regex.
#[cfg(any(feature = "datagen", feature = "serde_human",))]
pub fn new(pattern: &str) -> Result<Self, icu_provider::DataError> {
use regex_automata::{
dfa::dense::{Builder, Config},
SyntaxConfig,
};
let mut builder = Builder::new();
let dfa = builder
.syntax(SyntaxConfig::new().case_insensitive(true))
.configure(Config::new().anchored(true).minimize(true))
.build(pattern)
.map_err(|_| {
icu_provider::DataError::custom("Cannot build DFA").with_display_context(&pattern)
})?
.to_sparse()
.map_err(|_| {
icu_provider::DataError::custom("Cannot sparsify DFA")
.with_display_context(&pattern)
})?;
Ok(Self {
dfa_bytes: dfa.to_bytes_little_endian().into(),
pattern: Some(pattern.to_string().into()),
})
}
#[allow(clippy::unwrap_used)] // by invariant
pub(crate) fn test(&self, string: &str) -> bool {
cfg!(target_endian = "little")
&& matches!(
// Safe due to struct invariant.
unsafe { DFA::from_bytes_unchecked(&self.dfa_bytes).unwrap().0 }
.find_earliest_fwd(string.as_bytes()),
Ok(Some(_))
)
}
}
#[cfg(all(test, feature = "datagen"))]
mod test {
use super::*;
#[test]
fn test_string_matcher() {
let matcher = StringMatcher::new("abc.*").unwrap();
assert!(!matcher.test("ab"));
assert!(matcher.test("abc"));
assert!(matcher.test("abcde"));
}
#[test]
fn test_postcard_serialization() {
let matcher = StringMatcher::new("abc*").unwrap();
let mut bytes = postcard::to_stdvec(&matcher).unwrap();
assert_eq!(
postcard::from_bytes::<StringMatcher>(&bytes).unwrap(),
matcher
);
// A corrupted byte leads to an error
bytes[17] ^= 255;
assert!(postcard::from_bytes::<StringMatcher>(&bytes).is_err());
bytes[17] ^= 255;
// An extra byte leads to an error
bytes.insert(123, 40);
assert!(postcard::from_bytes::<StringMatcher>(&bytes).is_err());
bytes.remove(123);
// Missing bytes lead to an error
assert!(postcard::from_bytes::<StringMatcher>(&bytes[0..bytes.len() - 5]).is_err());
}
#[test]
#[cfg(feature = "serde_human")]
fn test_json_serialization() {
let matcher = StringMatcher::new("abc*").unwrap();
let json = serde_json::to_string(&matcher).unwrap();
assert_eq!(
serde_json::from_str::<StringMatcher>(&json).unwrap(),
matcher
);
assert!(serde_json::from_str::<StringMatcher>(".*[").is_err());
}
#[test]
#[ignore] // https://github.com/rust-lang/rust/issues/98906
fn databake() {
databake::test_bake!(
StringMatcher,
const: unsafe {
crate::provider::StringMatcher::from_dfa_bytes_unchecked(&[49u8, 50u8, 51u8, ])
},
icu_list
);
}
}
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