Add geo-traits crate

.github/workflows/test.yml

@@ -118,6 +118,32 @@ jobs:
       # we don't want to test `proj-network` because it only enables the `proj` feature
       - run: cargo test --features "use-proj use-serde"
 
+  geo_traits:
+    name: geo-traits
+    runs-on: ubuntu-latest
+    if: "!contains(github.event.head_commit.message, '[skip ci]')"
+    defaults:
+      run:
+        working-directory: geo-traits
+    strategy:
+      matrix:
+        container_image:
+          # We aim to support rust-stable plus (at least) the prior 3 releases,
+          # giving us about 6 months of coverage.
+          #
+          # Minimum supported rust version (MSRV)
+          - "ghcr.io/georust/geo-ci:proj-9.4.0-rust-1.75"
+          # Two most recent releases - we omit older ones for expedient CI
+          - "ghcr.io/georust/geo-ci:proj-9.4.0-rust-1.78"
+          - "ghcr.io/georust/geo-ci:proj-9.4.0-rust-1.79"
+    container:
+      image: ${{ matrix.container_image }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - run: cargo check --all-targets
+      - run: cargo test
+
   geo_postgis:
     name: geo-postgis
     runs-on: ubuntu-latest
@@ -184,4 +210,3 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
       - run: RUSTDOCFLAGS="-D warnings" cargo doc --all-features --no-deps
-

Cargo.toml

@@ -2,11 +2,12 @@
 resolver = "2"
 members = [
   "geo",
-  "geo-types",
+  "geo-bool-ops-benches",
   "geo-postgis",
   "geo-test-fixtures",
+  "geo-traits",
+  "geo-types",
   "jts-test-runner",
-  "geo-bool-ops-benches",
 ]
 
 [patch.crates-io]

geo-traits/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "geo-traits"
+version = "0.1.0"
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/georust/geo"
+documentation = "https://docs.rs/geo-traits/"
+readme = "../README.md"
+keywords = ["gis", "geo", "geography", "geospatial"]
+description = "Geospatial traits"
+rust-version = "1.65"
+edition = "2021"
+
+[dependencies]
+geo-types = "0.7"
+
+[dev-dependencies]

geo-traits/src/coord.rs

@@ -0,0 +1,141 @@
+use std::marker::PhantomData;
+
+use geo_types::{Coord, CoordNum};
+
+use crate::Dimensions;
+
+/// A trait for accessing data from a generic Coord.
+///
+/// Refer to [geo_types::Coord] for information about semantics and validity.
+pub trait CoordTrait {
+    /// The coordinate type of this geometry
+    type T: CoordNum;
+
+    /// Dimensions of the coordinate tuple
+    fn dim(&self) -> Dimensions;
+
+    /// Access the n'th (0-based) element of the CoordinateTuple.
+    /// Returns `None` if `n >= DIMENSION`.
+    /// See also [`nth_unchecked()`](Self::nth_unchecked).
+    fn nth(&self, n: usize) -> Option<Self::T> {
+        if n < self.dim().size() {
+            Some(self.nth_unchecked(n))
+        } else {
+            None
+        }
+    }
+
+    /// x component of this coord.
+    fn x(&self) -> Self::T;
+
+    /// y component of this coord.
+    fn y(&self) -> Self::T;
+
+    /// Returns a tuple that contains the x/horizontal & y/vertical component of the coord.
+    fn x_y(&self) -> (Self::T, Self::T) {
+        (self.x(), self.y())
+    }
+
+    /// Access the n'th (0-based) element of the CoordinateTuple.
+    /// May panic if n >= DIMENSION.
+    /// See also [`nth()`](Self::nth).
+    fn nth_unchecked(&self, n: usize) -> Self::T;
+}
+
+impl<T: CoordNum> CoordTrait for Coord<T> {
+    type T = T;
+
+    fn nth_unchecked(&self, n: usize) -> Self::T {
+        match n {
+            0 => self.x(),
+            1 => self.y(),
+            _ => panic!("Coord only supports 2 dimensions"),
+        }
+    }
+
+    fn dim(&self) -> Dimensions {
+        Dimensions::Xy
+    }
+
+    fn x(&self) -> Self::T {
+        self.x
+    }
+
+    fn y(&self) -> Self::T {
+        self.y
+    }
+}
+
+impl<T: CoordNum> CoordTrait for &Coord<T> {
+    type T = T;
+
+    fn nth_unchecked(&self, n: usize) -> Self::T {
+        match n {
+            0 => self.x(),
+            1 => self.y(),
+            _ => panic!("Coord only supports 2 dimensions"),
+        }
+    }
+
+    fn dim(&self) -> Dimensions {
+        Dimensions::Xy
+    }
+
+    fn x(&self) -> Self::T {
+        self.x
+    }
+
+    fn y(&self) -> Self::T {
+        self.y
+    }
+}
+
+impl<T: CoordNum> CoordTrait for (T, T) {
+    type T = T;
+
+    fn nth_unchecked(&self, n: usize) -> Self::T {
+        match n {
+            0 => self.x(),
+            1 => self.y(),
+            _ => panic!("(T, T) only supports 2 dimensions"),
+        }
+    }
+
+    fn dim(&self) -> Dimensions {
+        Dimensions::Xy
+    }
+
+    fn x(&self) -> Self::T {
+        self.0
+    }
+
+    fn y(&self) -> Self::T {
+        self.1
+    }
+}
+
+/// An empty struct that implements [CoordTrait].
+///
+/// This can be used as the `CoordType` of the `GeometryTrait` by implementations that don't have a
+/// Coord concept
+pub struct UnimplementedCoord<T: CoordNum>(PhantomData<T>);
+
+impl<T: CoordNum> CoordTrait for UnimplementedCoord<T> {
+    type T = T;
+
+    fn dim(&self) -> Dimensions {
+        unimplemented!()
+    }
+
+    fn nth_unchecked(&self, _n: usize) -> Self::T {
+        unimplemented!()
+    }
+
+    fn x(&self) -> Self::T {
+        unimplemented!()
+    }
+
+    fn y(&self) -> Self::T {
+        unimplemented!()
+    }
+}

geo-traits/src/dimension.rs

@@ -0,0 +1,33 @@
+/// The logical dimension of the geometry.
+///
+///
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Dimensions {
+    /// A two-dimensional geometry with X and Y values
+    Xy,
+
+    /// A three-dimensional geometry with X, Y, and Z values
+    Xyz,
+
+    /// A three-dimensional geometry with X, Y, and M values
+    Xym,
+
+    /// A four-dimensional geometry with X, Y, Z, and M values
+    Xyzm,
+
+    /// A geometry with unknown logical type. The contained `usize` value represents the number of
+    /// physical dimensions.
+    Unknown(usize),
+}
+
+impl Dimensions {
+    /// The physical number of dimensions in this geometry.
+    pub fn size(&self) -> usize {
+        match self {
+            Self::Xy => 2,
+            Self::Xyz | Self::Xym => 3,
+            Self::Xyzm => 4,
+            Self::Unknown(val) => *val,
+        }
+    }
+}