Add EitherWriteable and use it for DoublePlaceholder in currency format

Cargo.toml

@@ -196,6 +196,7 @@ zerovec-derive = { version = "0.10.1", path = "utils/zerovec/derive", default-fe
 
 # External deps from crates.io
 criterion = { version = "0.5" }
+either = { version = "1", default-features = false }
 
 # Tools
 icu_benchmark_macros = { path = "tools/benchmark/macros" }

components/datetime/Cargo.toml

@@ -21,7 +21,7 @@ all-features = true
 
 [dependencies]
 displaydoc = { version = "0.2.3", default-features = false }
-either = { version = "1.6.1", default-features = false }
+either = { workspace = true }
 fixed_decimal = { workspace = true }
 icu_calendar = { workspace = true }
 icu_decimal = { workspace = true }

components/experimental/src/dimension/currency/format.rs

@@ -56,17 +56,9 @@ impl<'l> Writeable for FormattedCurrency<'l> {
         }
         .ok_or(core::fmt::Error)?;
 
-        // TODO: rewrite this so it does not allocate
-        sink.write_str(
-            pattern
-                .interpolate([
-                    &self.value.write_to_string(), // placeholder 0 (currency value)
-                    currency_sign_value,           // placeholder 1 (currency sign value)
-                ])
-                .write_to_string()
-                .into_owned()
-                .as_str(),
-        )?;
+        pattern
+            .interpolate((self.value, currency_sign_value))
+            .write_to(sink)?;
 
         Ok(())
     }

provider/datagen/Cargo.toml

@@ -72,6 +72,7 @@ proc-macro2 = {version = "1", optional = true }
 
 # Other external dependencies
 displaydoc = { version = "0.2.3", default-features = false }
+either = { workspace = true }
 elsa = "1.10"
 itertools = "0.10"
 log = "0.4"
@@ -93,7 +94,6 @@ ureq = { version = "2", optional = true }
 clap = { version = "4", optional = true, features = ["derive"] }
 eyre = { version = "0.6", optional = true }
 simple_logger = { version = "4.1.0", default-features = false, optional = true }
-either = "1.9.0"
 
 [dev-dependencies]
 crlify = { path = "../../utils/crlify" }

utils/pattern/Cargo.toml

@@ -21,8 +21,9 @@ independent = true
 all-features = true
 
 [dependencies]
+either = { workspace = true }
 displaydoc = { version = "0.2.3", default-features = false }
-writeable = { workspace = true }
+writeable = { workspace = true, features = ["either"] }
 databake = { workspace = true, features = ["derive"], optional = true }
 serde = { version = "1.0", features = ["derive"], optional = true }
 yoke = { workspace = true, features = ["derive"], optional = true }

utils/pattern/src/double.rs

@@ -5,6 +5,7 @@
 //! Code for the [`DoublePlaceholder`] pattern backend.
 
 use core::{cmp::Ordering, str::FromStr};
+use either::Either;
 use writeable::Writeable;
 
 use crate::common::*;
@@ -62,16 +63,17 @@ impl FromStr for DoublePlaceholderKey {
     }
 }
 
-impl<W> PlaceholderValueProvider<DoublePlaceholderKey> for (W, W)
+impl<W0, W1> PlaceholderValueProvider<DoublePlaceholderKey> for (W0, W1)
 where
-    W: Writeable,
+    W0: Writeable,
+    W1: Writeable,
 {
-    type W<'a> = &'a W where W: 'a;
+    type W<'a> = Either<&'a W0, &'a W1> where W0: 'a, W1: 'a;
     #[inline]
     fn value_for(&self, key: DoublePlaceholderKey) -> Self::W<'_> {
         match key {
-            DoublePlaceholderKey::Place0 => &self.0,
-            DoublePlaceholderKey::Place1 => &self.1,
+            DoublePlaceholderKey::Place0 => Either::Left(&self.0),
+            DoublePlaceholderKey::Place1 => Either::Right(&self.1),
         }
     }
 }
@@ -84,7 +86,10 @@ where
     #[inline]
     fn value_for(&self, key: DoublePlaceholderKey) -> Self::W<'_> {
         let [item0, item1] = self;
-        (item0, item1).value_for(key)
+        match key {
+            DoublePlaceholderKey::Place0 => item0,
+            DoublePlaceholderKey::Place1 => item1,
+        }
     }
 }
 
@@ -230,8 +235,8 @@ impl DoublePlaceholderInfo {
 /// assert_eq!(
 ///     Pattern::<DoublePlaceholder, _>::try_from_str("{1}{0}")
 ///         .unwrap()
-///         .interpolate_to_string((1, 2)),
-///     "21",
+///         .interpolate_to_string((1, "A")),
+///     "A1",
 /// );
 /// ```
 ///

utils/writeable/Cargo.toml

@@ -20,6 +20,9 @@ independent = true
 [package.metadata.docs.rs]
 all-features = true
 
+[dependencies]
+either = { workspace = true, optional = true }
+
 [dev-dependencies]
 icu_benchmark_macros = { path = "../../tools/benchmark/macros" }
 rand = { version = "0.8", features = ["small_rng"] }
@@ -29,6 +32,7 @@ criterion = { workspace = true }
 
 [features]
 bench = []
+either = ["dep:either"]
 
 [package.metadata.cargo-all-features]
 # Bench feature gets tested separately and is only relevant for CI

utils/writeable/src/either.rs

@@ -0,0 +1,48 @@
+// 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 crate::*;
+use ::either::Either;
+
+/// A [`Writeable`] impl that delegates to one type or another type.
+impl<W0, W1> Writeable for Either<W0, W1>
+where
+    W0: Writeable,
+    W1: Writeable,
+{
+    fn write_to<W: fmt::Write + ?Sized>(&self, sink: &mut W) -> fmt::Result {
+        match self {
+            Either::Left(w) => w.write_to(sink),
+            Either::Right(w) => w.write_to(sink),
+        }
+    }
+
+    fn write_to_parts<S: PartsWrite + ?Sized>(&self, sink: &mut S) -> fmt::Result {
+        match self {
+            Either::Left(w) => w.write_to_parts(sink),
+            Either::Right(w) => w.write_to_parts(sink),
+        }
+    }
+
+    fn writeable_length_hint(&self) -> LengthHint {
+        match self {
+            Either::Left(w) => w.writeable_length_hint(),
+            Either::Right(w) => w.writeable_length_hint(),
+        }
+    }
+
+    fn write_to_string(&self) -> Cow<str> {
+        match self {
+            Either::Left(w) => w.write_to_string(),
+            Either::Right(w) => w.write_to_string(),
+        }
+    }
+
+    fn write_cmp_bytes(&self, other: &[u8]) -> core::cmp::Ordering {
+        match self {
+            Either::Left(w) => w.write_cmp_bytes(other),
+            Either::Right(w) => w.write_cmp_bytes(other),
+        }
+    }
+}

utils/writeable/src/lib.rs

@@ -67,6 +67,8 @@
 extern crate alloc;
 
 mod cmp;
+#[cfg(feature = "either")]
+mod either;
 mod impls;
 mod ops;