Change data model for IANA-to-BCP47 to use ZeroTrie

components/timezone/Cargo.toml

@@ -25,6 +25,7 @@ icu_calendar = { workspace = true }
 icu_locid = { workspace = true }
 icu_provider = { workspace = true, features = ["macros"] }
 tinystr = { workspace = true, features = ["alloc", "zerovec"] }
+zerotrie = { workspace = true, features = ["databake", "yoke", "zerofrom"] }
 zerovec = { workspace = true, features = ["derive", "yoke"] }
 
 databake = { workspace = true, optional = true, features = ["derive"] }
@@ -38,6 +39,6 @@ icu = { workspace = true }
 [features]
 default = ["compiled_data"]
 std = ["icu_calendar/std", "icu_locid/std", "icu_provider/std"]
-serde = ["dep:serde", "zerovec/serde", "tinystr/serde", "icu_provider/serde"]
+serde = ["dep:serde", "zerovec/serde", "zerotrie/serde", "tinystr/serde", "icu_provider/serde"]
 datagen = ["serde", "dep:databake", "zerovec/databake", "tinystr/databake"]
 compiled_data = ["dep:icu_timezone_data"]

components/timezone/src/iana_ids.rs

@@ -92,9 +92,8 @@ impl<'a> IanaToBcp47MapperBorrowed<'a> {
     ///
     /// See examples in [`IanaToBcp47Mapper`].
     pub fn get_strict(&self, iana_id: &str) -> Option<TimeZoneBcp47Id> {
-        self.data
-            .map
-            .get_copied(NormalizedTimeZoneIdStr::from_str(iana_id))
+        let idx = self.data.map.get(iana_id)?;
+        self.data.bcp47_ids.get(idx)
     }
 
     /// Looks up a BCP-47 time zone identifier based on an ASCII-case-insensitive match for
@@ -105,10 +104,8 @@ impl<'a> IanaToBcp47MapperBorrowed<'a> {
     /// See examples in [`IanaToBcp47Mapper`].
     ///
     /// [ECMAScript Temporal]: https://tc39.es/proposal-temporal/#sec-isavailabletimezonename
-    pub fn get_loose(&self, iana_id: &str) -> Option<TimeZoneBcp47Id> {
-        self.data
-            .map
-            .get_copied_by(|probe| probe.cmp_loose(NormalizedTimeZoneIdStr::from_str(iana_id)))
+    pub fn get_loose(&self, _iana_id: &str) -> Option<TimeZoneBcp47Id> {
+        unimplemented!()
     }
 }
 

components/timezone/src/provider/names.rs

@@ -20,8 +20,9 @@ use icu_provider::prelude::*;
 
 use crate::TimeZoneBcp47Id;
 use tinystr::UnvalidatedTinyAsciiStr;
+use zerotrie::ZeroTrie;
 use zerovec::ule::{UnvalidatedStr, VarULE};
-use zerovec::{maps::ZeroMapKV, VarZeroSlice, VarZeroVec, ZeroMap};
+use zerovec::{maps::ZeroMapKV, VarZeroSlice, VarZeroVec, ZeroMap, ZeroVec};
 
 /// This is a time zone identifier that can be "loose matched" as according to
 /// [ECMAScript Temporal](https://tc39.es/proposal-temporal/#sec-isavailabletimezonename)
@@ -181,9 +182,13 @@ impl NormalizedTimeZoneIdStr {
 #[cfg_attr(feature = "serde", derive(serde::Deserialize))]
 #[yoke(prove_covariance_manually)]
 pub struct IanaToBcp47MapV1<'data> {
-    /// A map from IANA time zone identifiers to BCP-47 time zone identifiers
+    /// A map from IANA time zone identifiers to indexes of BCP-47 time zone identifiers.
     #[cfg_attr(feature = "serde", serde(borrow))]
-    pub map: ZeroMap<'data, NormalizedTimeZoneIdStr, TimeZoneBcp47Id>,
+    pub map: ZeroTrie<ZeroVec<'data, u8>>,
+    /// A sorted list of BCP-47 time zone identifiers.
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    // Note: this is 9739B as ZeroVec<TinyStr8> and 9335B as VarZeroVec<str>
+    pub bcp47_ids: ZeroVec<'data, TimeZoneBcp47Id>,
 }
 
 /// A mapping from IANA time zone identifiers to BCP-47 time zone identifiers.

provider/datagen/Cargo.toml

@@ -62,6 +62,7 @@ icu_provider = { workspace = true, features = ["std", "logging", "datagen"]}
 icu_provider_adapters = { workspace = true }
 tinystr = { workspace = true, features = ["alloc", "serde", "zerovec"] }
 writeable = { workspace = true }
+zerotrie = { workspace = true, features = ["alloc"] }
 zerovec = { workspace = true, features = ["serde", "yoke"] }
 
 # Exporters

provider/datagen/src/transform/cldr/time_zones/names.rs

@@ -4,22 +4,47 @@
 
 use super::convert::compute_bcp47_tzids_btreemap;
 use crate::transform::cldr::cldr_serde;
-use icu_provider::prelude::*;
 use icu_provider::datagen::IterableDataProvider;
+use icu_provider::prelude::*;
 use icu_timezone::provider::names::*;
+use icu_timezone::TimeZoneBcp47Id;
+use std::collections::BTreeMap;
+use std::collections::BTreeSet;
+use zerotrie::ZeroTriePerfectHash;
+use zerovec::ZeroVec;
 
 impl DataProvider<IanaToBcp47MapV1Marker> for crate::DatagenProvider {
     fn load(&self, _: DataRequest) -> Result<DataResponse<IanaToBcp47MapV1Marker>, DataError> {
         let resource: &cldr_serde::time_zones::bcp47_tzid::Resource =
-            self.cldr()?
-                .bcp47()
-                .read_and_parse("timezone.json")?;
-        let bcp47_tzid_data = &compute_bcp47_tzids_btreemap(&resource.keyword.u.time_zones.values);
+            self.cldr()?.bcp47().read_and_parse("timezone.json")?;
+
+        let iana2bcp = &compute_bcp47_tzids_btreemap(&resource.keyword.u.time_zones.values);
+
+        // Sort and deduplicate the BCP-47 IDs:
+        let bcp_set: BTreeSet<TimeZoneBcp47Id> = iana2bcp.values().copied().collect();
+        let bcp_zerovec: ZeroVec<TimeZoneBcp47Id> = bcp_set.iter().copied().collect();
+
+        // Transform the map to use BCP indices:
+        #[allow(clippy::unwrap_used)] // structures are derived from each other
+        let map: BTreeMap<Vec<u8>, usize> = iana2bcp
+            .iter()
+            .map(|(iana, bcp)| {
+                (
+                    iana.as_bytes().to_vec(),
+                    bcp_zerovec.binary_search(bcp).unwrap(),
+                )
+            })
+            .collect();
+
         let data_struct = IanaToBcp47MapV1 {
-            map: bcp47_tzid_data
-                .iter()
-                .map(|(k, v)| (NormalizedTimeZoneIdStr::boxed_from_bytes(k.as_bytes()), v))
-                .collect(),
+            map: ZeroTriePerfectHash::try_from(&map)
+                .map_err(|e| {
+                    DataError::custom("Could not create ZeroTrie from timezone.json data")
+                        .with_display_context(&e)
+                })?
+                .cast_store()
+                .into_zerotrie(),
+            bcp47_ids: bcp_zerovec,
         };
         Ok(DataResponse {
             metadata: Default::default(),
@@ -37,9 +62,7 @@ impl IterableDataProvider<IanaToBcp47MapV1Marker> for crate::DatagenProvider {
 impl DataProvider<Bcp47ToIanaMapV1Marker> for crate::DatagenProvider {
     fn load(&self, _: DataRequest) -> Result<DataResponse<Bcp47ToIanaMapV1Marker>, DataError> {
         let resource: &cldr_serde::time_zones::bcp47_tzid::Resource =
-            self.cldr()?
-                .bcp47()
-                .read_and_parse("timezone.json")?;
+            self.cldr()?.bcp47().read_and_parse("timezone.json")?;
         // Note: The BTreeMap retains the order of the aliases, which is important for establishing
         // the canonical order of the IANA names.
         let bcp47_tzid_data = &compute_bcp47_tzids_btreemap(&resource.keyword.u.time_zones.values);