geometry-tag

Part of the boost_geometry workspace — a Rust port of Boost.Geometry. Most users should depend on the facade crate, which re-exports this one; depend on this crate directly only for a slimmer build.

Geometry kind tags and the tag-hierarchy marker traits.

Eleven empty tag types identify each OGC geometry kind, and a set of marker traits (Single, Multi, Pointlike, Linear, Polylinear, Areal, Polygonal, Volumetric) reproduce the C++ struct-inheritance hierarchy at the Rust trait-bound level. Together they let downstream crates dispatch on tag identity (one impl per tag) and tag category (one impl that covers every linear tag, every areal tag, etc.) — the Rust analogue of tag_cast<Tag, Stops...>.

References:

• boost/geometry/core/tags.hpp — tag hierarchy declarations.
• boost/geometry/core/tag.hpp — the traits::tag<G>::type metafunction.
• boost/geometry/core/tag_cast.hpp — base-tag walking, replaced here by Rust trait super-bounds.

Examples

Category dispatch — one impl covers every linear tag:

use geometry_tag::{Linear, LinestringTag, MultiLinestringTag, SegmentTag};

fn accepts_linear<T: Linear>() {}
accepts_linear::<SegmentTag>();
accepts_linear::<LinestringTag>();
accepts_linear::<MultiLinestringTag>();

License

BSL-1.0 — see LICENSE.