Enum icu::pattern::SinglePlaceholder

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pub enum SinglePlaceholder {}
Expand description

Backend for patterns containing zero or one placeholder.

This empty type is not constructible.

§Placeholder Keys

The placeholder is always SinglePlaceholderKey::Singleton.

In Pattern::interpolate(), pass a single-element array or tuple.

§Encoding Details

The first code point of the string is 1 plus the byte offset of the placeholder counting from after that initial code point. If zero, there is no placeholder.

§Examples

Parsing a pattern into the encoding:

use core::str::FromStr;
use icu_pattern::Pattern;
use icu_pattern::SinglePlaceholder;

// Parse the string syntax and check the resulting data store:
let pattern = Pattern::<SinglePlaceholder>::try_from_str("Hello, {0}!", Default::default())
    .unwrap();

assert_eq!("\u{8}Hello, !", &pattern.store);

Example patterns supported by this backend:

use core::str::FromStr;
use icu_pattern::Pattern;
use icu_pattern::SinglePlaceholder;
use icu_pattern::QuoteMode;

// Single numeric placeholder:
assert_eq!(
    Pattern::<SinglePlaceholder>::try_from_str("{0} days ago", Default::default())
        .unwrap()
        .interpolate_to_string([5]),
    "5 days ago",
);

// Single named placeholder:
assert_eq!(
    Pattern::<SinglePlaceholder>::try_from_str("{name}", Default::default())
        .unwrap()
        .interpolate_to_string(["Alice"]),
    "Alice",
);

// No placeholder (note, the placeholder value is never accessed):
assert_eq!(
    Pattern::<SinglePlaceholder>::try_from_str("yesterday", Default::default())
        .unwrap()
        .interpolate_to_string(["hi"]),
    "yesterday",
);

// Escaped placeholder and a real placeholder:
assert_eq!(
    Pattern::<SinglePlaceholder>::try_from_str("'{0}' {1}", QuoteMode::QuotingSupported.into())
        .unwrap()
        .interpolate_to_string(("hi",)),
    "{0} hi",
);

Trait Implementations§

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impl Clone for SinglePlaceholder

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fn clone(&self) -> SinglePlaceholder

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for SinglePlaceholder

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

Formats the value using the given formatter. Read more
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impl PartialEq for SinglePlaceholder

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

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

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

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type PlaceholderKey<'a> = SinglePlaceholderKey

The type to be used as the placeholder key in code.
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type PlaceholderKeyCow<'a> = SinglePlaceholderKey

Cowable version of the type to be used as the placeholder key in code.
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type Error<'a> = Infallible

The type of error that the TryWriteable for this backend can return.
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impl Copy for SinglePlaceholder

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impl Eq for SinglePlaceholder

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impl StructuralPartialEq for SinglePlaceholder

Auto Trait Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> GetField<T> for T
where T: Copy,

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fn get_field(&self) -> T

Returns the value of this trait’s field T.
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> ErasedDestructor for T
where T: 'static,

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impl<T> MaybeSendSync for T
where T: Send + Sync,