Oniguruma Bindings

Java bindings for the Oniguruma regular expression library. This repository publishes a JNI backend backed by the onig Rust crate and an FFM backend backed by the upstream C library. Both modules are primarily designed to support syntax highlighting in IntelliJ-based IDEs through the textmate-core library.

Modules

oniguruma-jni

A JNI wrapper implemented in Rust using the onig crate.

• Maven coordinate: me.zolotov.oniguruma:oniguruma-jni
• Java package: me.zolotov.oniguruma.jni
• JPMS module: me.zolotov.oniguruma.jni
• Documentation: oniguruma-jni/README.md

oniguruma-ffm

A Java Foreign Function & Memory wrapper backed by the upstream C library.

• Maven coordinate: me.zolotov.oniguruma:oniguruma-ffm
• Java package: me.zolotov.oniguruma.ffm
• JPMS module: me.zolotov.oniguruma.ffm
• Documentation: oniguruma-ffm/README.md

Performance

Both modules run the same JMH suite against shared inputs; the results are published continuously to the benchmark dashboard. The FFM binding is consistently ahead on operations dominated by per-call binding overhead. Where the time comes from:

• Cheaper native calls. FFM downcall handles compile to specialized stubs that are close to a plain native call. A JNI native method pays for argument marshalling and the JNI transition on every crossing, and the Rust side adds a catch_unwind wrapper per call.
• Results are read, not marshalled. After a match, FFM reads the offsets straight out of the native OnigRegion struct and writes one Java int[]. The JNI binding has to build the array through JNI functions (NewIntArray + SetIntArrayRegion), each itself a JNI crossing.
• One copy per string, no pinning. createString in FFM is a malloc and one copy into native memory. The JNI path enters a GC-critical section to pin the Java array, copies into the Rust heap, and boxes the result.
• Cheaper error paths. A failed FFM compile builds one Java exception with the oniguruma diagnostic. The JNI path constructs a Rust error, formats it, and re-throws it across the boundary through the JNI exception machinery.
• Per-call allocations are reused. Both bindings reuse a per-thread match region instead of calling onig_region_new/onig_region_free around every search; FFM also compiles patterns through a reused per-thread scratch block, so a small createRegex performs no allocation besides the returned handle wrapper.

Building

Build all modules:

./gradlew build

Build a single module:

./gradlew :oniguruma-jni:build
./gradlew :oniguruma-ffm:build

Run module benchmarks:

./gradlew :oniguruma-jni:jmh
./gradlew :oniguruma-ffm:jmh

The repository also contains an internal benchmarks project with shared JMH inputs and state.

Contributing

Contributions are welcome! Please feel free to submit pull requests.

Acknowledgments

• Oniguruma – the regular expression library both backends build on, written and maintained by K.Kosako.
• rust-onig – the onig crate the JNI backend is implemented with, maintained by Will Speak, Ivan Ivashchenko and Vincent Prouillet.

Note

This library is primarily intended for use with the textmate-core library in IntelliJ-based IDEs. While it can be used independently, the API is designed with this specific use case in mind.