icucodepointtriebuilder

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.

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

```rust use icu::collections::codepointtrie::CodePointTrie; use icu::collections::codepointtrie::TrieType; use icucodepointtriebuilder::CodePointTrieBuilder; use icucodepointtriebuilder::CodePointTrieBuilderData;

let defaultvalue = 1; let errorvalue = 2; let valuesbycode_point = &[3, 4, 5, 6];

let cpt: CodePointTrie = CodePointTrieBuilder { data: CodePointTrieBuilderData::ValuesByCodePoint(valuesbycodepoint), defaultvalue, errorvalue, trietype: TrieType::Small, } .build();

asserteq!(cpt.get32(0), 3); asserteq!(cpt.get32(1), 4); asserteq!(cpt.get32(2), 5); asserteq!(cpt.get32(3), 6); asserteq!(cpt.get32(4), 1); // default value asserteq!(cpt.get32(u32::MAX), 2); // error value ```

More Information

For more information on development, authorship, contributing etc. please visit ICU4X home page.