Struct Pattern

#[repr(transparent)]
pub struct Pattern<B: PatternBackend> {
    pub store: B::Store,
    /* private fields */
}

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 Parts from inner writeables. In addition, it supports annotating Parts 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!");

Fields

store: B::Store

The encoded storage

Implementations

impl<B> Pattern<B>

where B: PatternBackend,

pub fn try_from_items<'a, I>(items: I) -> Result<Box<Self>, Error>

where I: Iterator<Item = PatternItemCow<'a, B::PlaceholderKeyCow<'a>>>,

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");

impl<'a, B> Pattern<B>

where B: PatternBackend, B::PlaceholderKeyCow<'a>: FromStr, <B::PlaceholderKeyCow<'a> as FromStr>::Err: Debug,

pub fn try_from_str( pattern: &str, options: ParserOptions, ) -> Result<Box<Self>, Error>

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");

impl<B> Pattern<B>

where B: PatternBackend,

pub fn iter( &self, ) -> impl Iterator<Item = PatternItem<'_, B::PlaceholderKey<'_>>> + '_

Returns an iterator over the PatternItems in this pattern.

pub fn try_interpolate<'a, P>( &'a self, value_provider: P, ) -> impl TryWriteable<Error = B::Error<'a>> + Display + 'a

where P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,

Returns a TryWriteable that interpolates items from the given replacement provider into this pattern string.

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,

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.

impl<B> Pattern<B>

where for<'b> B: PatternBackend<Error<'b> = Infallible>,

pub fn interpolate<'a, P>( &'a self, value_provider: P, ) -> impl Writeable + Display + 'a

where P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,

Returns a Writeable that interpolates items from the given replacement provider into this pattern string.

pub fn interpolate_to_string<'a, P>(&'a self, value_provider: P) -> String

where P: PlaceholderValueProvider<B::PlaceholderKey<'a>, Error = B::Error<'a>> + 'a,

Interpolates the pattern directly to a string.

✨ Enabled with the alloc Cargo feature.

Trait Implementations

impl<B: PatternBackend> Clone for Box<Pattern<B>>

where Box<B::Store>: for<'a> From<&'a B::Store>,

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<B: PatternBackend> Debug for Pattern<B>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<B: PatternBackend> Default for &'static Pattern<B>

fn default() -> Self

Returns the “default value” for a type.

impl<B: PatternBackend> Default for Box<Pattern<B>>

where Box<B::Store>: From<&'static B::Store>,

fn default() -> Self

Returns the “default value” for a type.

impl<'de, 'data, B: PatternBackend> Deserialize<'de> for &'data Pattern<B>

where &'data B::Store: Deserialize<'de>, 'de: 'data,

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, 'data, B> Deserialize<'de> for Box<Pattern<B>>

where B: PatternBackend<Store = str>, B::PlaceholderKeyCow<'data>: Deserialize<'de>, 'de: 'data,

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<B: PatternBackend> PartialEq for Pattern<B>

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<B: PatternBackend> Serialize for Pattern<B>

where B::Store: Serialize, for<'a> B::PlaceholderKeyCow<'a>: Serialize + From<B::PlaceholderKey<'a>>,

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<B: PatternBackend> ToOwned for Pattern<B>

where Box<B::Store>: for<'a> From<&'a B::Store>,

type Owned = Box<Pattern<B>>

The resulting type after obtaining ownership.

fn to_owned(&self) -> Self::Owned

Creates owned data from borrowed data, usually by cloning.

fn clone_into(&self, target: &mut Self::Owned)

Uses borrowed data to replace owned data, usually by cloning.

impl<B, S: ?Sized + VarULE> VarULE for Pattern<B>

where B: PatternBackend<Store = S>,

Implement VarULE for Pattern<SinglePlaceholder, str>.

Safety

Safety checklist for ULE:

1. Pattern<B> does not include any uninitialized or padding bytes.
2. Pattern<B> is aligned to 1 byte.
3. The implementation of validate_bytes() returns an error if any byte is not valid.
4. The implementation of validate_bytes() returns an error if the slice cannot be used to build a Pattern<B> in its entirety.
5. The implementation of from_bytes_unchecked() returns a reference to the same data.
6. parse_bytes() is equivalent to validate_bytes() followed by from_bytes_unchecked().
7. Pattern<B> byte equality is semantic equality.

fn validate_bytes(bytes: &[u8]) -> Result<(), UleError>

Validates a byte slice, &[u8].

unsafe fn from_bytes_unchecked(bytes: &[u8]) -> &Self

Takes a byte slice, &[u8], and return it as &Self with the same lifetime, assuming that this byte slice has previously been run through Self::parse_bytes() with success.

fn parse_bytes(bytes: &[u8]) -> Result<&Self, UleError>

Parses a byte slice, &[u8], and return it as &Self with the same lifetime.

fn as_bytes(&self) -> &[u8]

Given &Self, returns a &[u8] with the same lifetime.

fn to_boxed(&self) -> Box<Self>

Allocate on the heap as a Box<T>

impl<'a, B: PatternBackend> ZeroMapKV<'a> for Pattern<B>

where Pattern<B>: VarULE,

type Container = VarZeroVec<'a, Pattern<B>>

The container that can be used with this type: ZeroVec or VarZeroVec.

type Slice = VarZeroSlice<Pattern<B>>

type GetType = Pattern<B>

The type produced by Container::get()

type OwnedType = Box<Pattern<B>>

The type produced by Container::replace() and Container::remove(), also used during deserialization. If Self is human readable serialized, deserializing to Self::OwnedType should produce the same value once passed through Self::owned_as_self()