xapian-rs

xapian-rs provides a set of low-level, mostly-ergonomic Rust bindings for the Xapian search library.

The bindings are provided by a mix of auto-generation (via autocxx) and manual generation (via cxx). When necessary, small C++ shims are implemented to work around incompatibilities between these tools and the Xapian codebase.

Status / Stability

xapian-rs is currently immature, untested and incomplete. During the 0.x version series, no stability guarantees are provided for the API, and it may change or break at any time. A small, limited real-world use case has been implemented in pantry, which exercises an interesting but small subset of the capabilities of Xapian:

• Indexing
• Searching
• Faceting

Some functionality is not provided at this time, including (but not limited to):

• KeyMaker
• Custom RangeProcessor implementations

Design

Where possible, xapian-rs tries to provide simple and ergonomic interactions with idiomatic Rust code. However, Xapian is a C++ codebase which uses C++ idioms, and this does have some consequences on the current design (as do limitations of the autocxx and cxx):

• Xapian primarily uses exceptions for error handling. autocxx does not currently support catching exceptions (though cxx does). In the current version, any Xapian exception will trigger a panic in Rust code. This will improve as the library evolves.
• Xapian uses C++ strings very heavily. C++ strings provide no encoding guarantees, while Rust strings are guaranteed to be valid UTF-8. These bindings currently handle this in a way that is inconsistent (though at times convenient). This will become more well-defined as the library evolves.
• Several Xapian types are exposed in a way that allows implementation via Rust traits. At present, these traits are generally implemented via &self references, and therefore interior mutability is often needed to implement interesting functionality.
• Some of these traits intentionally leak memory when passed to FFI today. This will improve as the library evolves.

Examples

Several examples are provided in the examples directory. The tests directory's integration tests are also useful.