Crate icu_codepointtrie_builder
source ·Expand description
icu_codepointtrie_builder
is a utility crate of the ICU4X
project.
This crate exposes functionality to build a CodePointTrie
from values provided at runtime.
Because it is normally expected for CodePointTrie
data to be pre-compiled, this crate is not
optimized for speed; it should be used during a build phase.
Under the hood, this crate uses the CodePointTrie builder code from ICU4C, UMutableCPTrie
.
For more context, see https://github.com/unicode-org/icu4x/issues/1837.
Unlike most of ICU4X, due in large part to the native dependency, this crate is not guaranteed to be panic-free.
§Build configuration
This crate has two primary modes it can be used in: "wasm"
and "icu4c"
, exposed as
Cargo features. If both are enabled, the code will internally use the wasm codepath.
The "wasm"
mode uses a Wasm module packaged into this Rust crate that contains
pre-compiled ICU4C CodePointTrie builder code. It evaluates the Wasm module using
the Wasmer runtime, which “just works”, but it requires a large number of
Rust/Cargo dependencies.
The "icu4c"
mode reduces the number of Rust dependencies, but it requires having a local copy
of ICU4C available. To configure "icu4c"
mode in Cargo, set the following environment variables:
- Set
ICU4C_LIB_PATH
to a directory full of ICU4C static or shared libraries. - Set
ICU4C_LINK_STATICALLY
to any value to use the static libraries. - Set
ICU4C_RENAME_VERSION
to the integer ICU4C version if ICU4C has renaming enabled. By default, we attempt to link non-renamed symbols.
If using dynamic linking, at runtime, you may need to set [DY]LD_LIBRARY_PATH
to the ICU4C_LIB_PATH
.
If not using Cargo, make sure to pass ICU4C_LIB_PATH
to the linker via -L
, link against
icuuc
, icui18n
and icudata
via -l
flags, and set --cfg icu4c_enable_renaming
if you need
renamed ICU4C symbols.
§Examples
use icu::collections::codepointtrie::CodePointTrie;
use icu::collections::codepointtrie::TrieType;
use icu_codepointtrie_builder::CodePointTrieBuilder;
use icu_codepointtrie_builder::CodePointTrieBuilderData;
let default_value = 1;
let error_value = 2;
let values_by_code_point = &[3, 4, 5, 6];
let cpt: CodePointTrie<u8> = CodePointTrieBuilder {
data: CodePointTrieBuilderData::ValuesByCodePoint(values_by_code_point),
default_value,
error_value,
trie_type: TrieType::Small,
}
.build();
assert_eq!(cpt.get32(0), 3);
assert_eq!(cpt.get32(1), 4);
assert_eq!(cpt.get32(2), 5);
assert_eq!(cpt.get32(3), 6);
assert_eq!(cpt.get32(4), 1); // default value
assert_eq!(cpt.get32(u32::MAX), 2); // error value
Structs§
- Settings for building a
CodePointTrie
.
Enums§
- Wrapper over the data to be encoded into a
CodePointTrie
.