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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 ).
#[cfg(feature = "databake")]
mod databake;
#[cfg(feature = "serde")]
pub(crate) mod serde;
use crate::common::*;
#[cfg(feature = "alloc")]
use crate::Error;
#[cfg(feature = "alloc")]
use crate::Parser;
#[cfg(feature = "alloc")]
use crate::ParserOptions;
#[cfg(feature = "alloc")]
use alloc::{borrow::ToOwned, boxed::Box, str::FromStr, string::String};
use core::{convert::Infallible, fmt, marker::PhantomData};
use writeable::{adapters::TryWriteableInfallibleAsWriteable, PartsWrite, TryWriteable, Writeable};
/// A string pattern with placeholders.
///
/// There are 2 generic parameters: `Backend` and `Store`.
///
/// # Backend
///
/// This determines the nature of placeholders and serialized encoding of the pattern.
///
/// The following backends are available:
///
/// - [`SinglePlaceholder`] for patterns with up to one placeholder: `"{0} days ago"`
/// - [`DoublePlaceholder`] for patterns with up to two placeholders: `"{0} days, {1} hours ago"`
/// - [`MultiNamedPlaceholder`] for patterns with named placeholders: `"{name} sent you a message"`
///
/// # Format to Parts
///
/// [`Pattern`] propagates [`Part`]s from inner writeables. In addition, it supports annotating
/// [`Part`]s for individual literals or placeholders via the [`PlaceholderValueProvider`] trait.
///
/// # Examples
///
/// Interpolating a [`SinglePlaceholder`] pattern:
///
/// ```
/// use core::str::FromStr;
/// use icu_pattern::Pattern;
/// use icu_pattern::SinglePlaceholder;
/// use writeable::assert_writeable_eq;
///
/// let pattern = Pattern::<SinglePlaceholder>::try_from_str(
/// "Hello, {0}!",
/// Default::default(),
/// )
/// .unwrap();
///
/// assert_writeable_eq!(
/// pattern.interpolate(["Alice"]),
/// "Hello, Alice!"
/// );
/// ```
///
/// [`SinglePlaceholder`]: crate::SinglePlaceholder
/// [`DoublePlaceholder`]: crate::DoublePlaceholder
/// [`MultiNamedPlaceholder`]: crate::MultiNamedPlaceholder
/// [`Part`]: writeable::Part
#[cfg_attr(feature = "yoke", derive(yoke::Yokeable))]
#[repr(transparent)]
pub struct Pattern<B: PatternBackend> {
_backend: PhantomData<B>,
/// The encoded storage
pub store: B::Store,
}
impl<B: PatternBackend> PartialEq for Pattern<B> {
fn eq(&self, other: &Self) -> bool {
self.store == other.store
}
}
impl<B: PatternBackend> core::fmt::Debug for Pattern<B> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Pattern")
.field("_backend", &self._backend)
.field("store", &&self.store)
.finish()
}
}
impl<B: PatternBackend> Default for &'static Pattern<B> {
fn default() -> Self {
Pattern::from_ref_store_unchecked(B::empty())
}
}
#[cfg(feature = "alloc")]
impl<B: PatternBackend> Default for Box<Pattern<B>>
where
Box<B::Store>: From<&'static B::Store>,
{
fn default() -> Self {
Pattern::from_boxed_store_unchecked(Box::from(B::empty()))
}
}
#[test]
fn test_defaults() {
assert_eq!(
Box::<Pattern::<crate::SinglePlaceholder>>::default(),
Pattern::try_from_items(core::iter::empty()).unwrap()
);
assert_eq!(
Box::<Pattern::<crate::DoublePlaceholder>>::default(),
Pattern::try_from_items(core::iter::empty()).unwrap()
);
assert_eq!(
Box::<Pattern::<crate::MultiNamedPlaceholder>>::default(),
Pattern::try_from_items(core::iter::empty()).unwrap()
);
}
#[cfg(feature = "alloc")]
impl<B: PatternBackend> ToOwned for Pattern<B>
where
Box<B::Store>: for<'a> From<&'a B::Store>,
{
type Owned = Box<Pattern<B>>;
fn to_owned(&self) -> Self::Owned {
Self::from_boxed_store_unchecked(Box::from(&self.store))
}
}
#[cfg(feature = "alloc")]
impl<B: PatternBackend> Clone for Box<Pattern<B>>
where
Box<B::Store>: for<'a> From<&'a B::Store>,
{
fn clone(&self) -> Self {
Pattern::from_boxed_store_unchecked(Box::from(&self.store))
}
}
impl<B: PatternBackend> Pattern<B> {
#[cfg(feature = "alloc")]
pub(crate) const fn from_boxed_store_unchecked(store: Box<B::Store>) -> Box<Self> {
// Safety: Pattern's layout is the same as B::Store's
unsafe { core::mem::transmute(store) }
}
#[doc(hidden)] // databake
pub const fn from_ref_store_unchecked(store: &B::Store) -> &Self {
// Safety: Pattern's layout is the same as B::Store's
unsafe { &*(store as *const B::Store as *const Self) }
}
}
#[cfg(feature = "alloc")]
impl<B> Pattern<B>
where
B: PatternBackend,
{
/// Creates a pattern from an iterator of pattern items.
///
/// ✨ *Enabled with the `alloc` Cargo feature.*
///
/// # Examples
///
/// ```
/// use icu_pattern::Pattern;
/// use icu_pattern::PatternItemCow;
/// use icu_pattern::SinglePlaceholder;
/// use icu_pattern::SinglePlaceholderKey;
/// use std::borrow::Cow;
///
/// Pattern::<SinglePlaceholder>::try_from_items(
/// [
/// PatternItemCow::Placeholder(SinglePlaceholderKey::Singleton),
/// PatternItemCow::Literal(Cow::Borrowed(" days")),
/// ]
/// .into_iter(),
/// )
/// .expect("valid pattern items");
/// ```
pub fn try_from_items<'a, I>(items: I) -> Result<Box<Self>, Error>
where
I: Iterator<Item = PatternItemCow<'a, B::PlaceholderKeyCow<'a>>>,
{
let store = B::try_from_items(items.map(Ok))?;
#[cfg(debug_assertions)]
match B::validate_store(core::borrow::Borrow::borrow(&store)) {
Ok(()) => (),
Err(e) => {
debug_assert!(false, "{:?}", e);
}
};
Ok(Self::from_boxed_store_unchecked(store))
}
}
#[cfg(feature = "alloc")]
impl<'a, B> Pattern<B>
where
B: PatternBackend,
B::PlaceholderKeyCow<'a>: FromStr,
<B::PlaceholderKeyCow<'a> as FromStr>::Err: fmt::Debug,
{
/// Creates a pattern by parsing a syntax string.
///
/// ✨ *Enabled with the `alloc` Cargo feature.*
///
/// # Examples
///
/// ```
/// use icu_pattern::Pattern;
/// use icu_pattern::SinglePlaceholder;
///
/// // Create a pattern from a valid string:
/// Pattern::<SinglePlaceholder>::try_from_str("{0} days", Default::default())
/// .expect("valid pattern");
///
/// // Error on an invalid pattern:
/// Pattern::<SinglePlaceholder>::try_from_str("{0 days", Default::default())
/// .expect_err("mismatched braces");
/// ```
pub fn try_from_str(pattern: &str, options: ParserOptions) -> Result<Box<Self>, Error> {
let parser = Parser::new(pattern, options);
let store = B::try_from_items(parser)?;
#[cfg(debug_assertions)]
match B::validate_store(core::borrow::Borrow::borrow(&store)) {
Ok(()) => (),
Err(e) => {
debug_assert!(false, "{:?} for pattern {:?}", e, pattern);
}
};
Ok(Self::from_boxed_store_unchecked(store))
}
}
impl<B> Pattern<B>
where
B: PatternBackend,
{
/// Returns an iterator over the [`PatternItem`]s in this pattern.
pub fn iter(&self) -> impl Iterator<Item = PatternItem<B::PlaceholderKey<'_>>> + '_ {
B::iter_items(&self.store)
}
/// Returns a [`TryWriteable`] that interpolates items from the given replacement provider
/// into this pattern string.
pub fn try_interpolate<'a, P>(
&'a self,
value_provider: P,
) -> impl TryWriteable<Error = B::Error<'a>> + fmt::Display + 'a
where
P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,
{
WriteablePattern::<B, P> {
store: &self.store,
value_provider,
}
}
#[cfg(feature = "alloc")]
/// Interpolates the pattern directly to a string, returning the string or an error.
///
/// In addition to the error, the lossy fallback string is returned in the failure case.
///
/// ✨ *Enabled with the `alloc` Cargo feature.*
pub fn try_interpolate_to_string<'a, P>(
&'a self,
value_provider: P,
) -> Result<String, (B::Error<'a>, String)>
where
P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,
{
self.try_interpolate(value_provider)
.try_write_to_string()
.map(|s| s.into_owned())
.map_err(|(e, s)| (e, s.into_owned()))
}
}
impl<B> Pattern<B>
where
for<'b> B: PatternBackend<Error<'b> = Infallible>,
{
/// Returns a [`Writeable`] that interpolates items from the given replacement provider
/// into this pattern string.
pub fn interpolate<'a, P>(&'a self, value_provider: P) -> impl Writeable + fmt::Display + 'a
where
P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,
{
TryWriteableInfallibleAsWriteable(WriteablePattern::<B, P> {
store: &self.store,
value_provider,
})
}
#[cfg(feature = "alloc")]
/// Interpolates the pattern directly to a string.
///
/// ✨ *Enabled with the `alloc` Cargo feature.*
pub fn interpolate_to_string<'a, P>(&'a self, value_provider: P) -> String
where
P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,
{
self.interpolate(value_provider)
.write_to_string()
.into_owned()
}
}
struct WriteablePattern<'a, B: PatternBackend, P> {
store: &'a B::Store,
value_provider: P,
}
impl<'a, B, P> TryWriteable for WriteablePattern<'a, B, P>
where
B: PatternBackend,
P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>>,
{
type Error = B::Error<'a>;
fn try_write_to_parts<S: PartsWrite + ?Sized>(
&self,
sink: &mut S,
) -> Result<Result<(), Self::Error>, fmt::Error> {
let mut error = None;
let it = B::iter_items(self.store);
#[cfg(debug_assertions)]
let (size_hint, mut actual_len) = (it.size_hint(), 0);
for item in it {
match item {
PatternItem::Literal(s) => {
self.value_provider.map_literal(s).write_to_parts(sink)?;
}
PatternItem::Placeholder(key) => {
let element_writeable = self.value_provider.value_for(key);
if let Err(e) = element_writeable.try_write_to_parts(sink)? {
// Keep the first error if there was one
error.get_or_insert(e);
}
}
}
#[cfg(debug_assertions)]
{
actual_len += 1;
}
}
#[cfg(debug_assertions)]
{
debug_assert!(actual_len >= size_hint.0);
if let Some(max_len) = size_hint.1 {
debug_assert!(actual_len <= max_len);
}
}
if let Some(e) = error {
Ok(Err(e))
} else {
Ok(Ok(()))
}
}
}
impl<'a, B, P> fmt::Display for WriteablePattern<'a, B, P>
where
B: PatternBackend,
P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>>,
{
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Discard the TryWriteable error (lossy mode)
self.try_write_to(f).map(|_| ())
}
}
#[test]
fn test_try_from_str_inference() {
use crate::SinglePlaceholder;
let _: Box<Pattern<SinglePlaceholder>> =
Pattern::try_from_str("{0} days", Default::default()).unwrap();
let _ = Pattern::<SinglePlaceholder>::try_from_str("{0} days", Default::default()).unwrap();
}