Add generators::generate_as

src/generators.rs

@@ -1,6 +1,48 @@
 //! Generators for common graphs.
 
-use crate::traits::{GraphTopology, GraphTopologyAddition};
+use crate::models::AppendGraph;
+use crate::traits::{GraphTopology, GraphTopologyAddition, GraphTopologyConversion};
+
+/// Builds a graph of type `G` by running a generator on a temporary [`AppendGraph`].
+///
+/// `generate_as` fills a temporary graph and converts it to `G`. It returns the handles of the
+/// elements it created as handles of the resulting graph. This makes it possible to obtain graph
+/// types directly that do not implement [`GraphTopologyAddition`], such as [`FrozenGraph`].
+///
+/// # Examples
+///
+/// ```
+/// use grapherity::generators;
+/// use grapherity::models::FrozenGraph;
+/// use grapherity::traits::GraphTopology;
+///
+/// let (graph, vertices, edges) = generators::generate_as::<FrozenGraph, _, _>(generators::petersen);
+/// assert_eq!(graph.vertex_count(), 10);
+/// assert_eq!(graph.edge_count(), 15);
+/// assert!(graph.vertices().all(|v| graph.degree(v) == 3));
+/// ```
+///
+/// [`FrozenGraph`]: crate::models::FrozenGraph
+pub fn generate_as<G, const V: usize, const E: usize>(
+    generator: impl FnOnce(
+        &mut AppendGraph,
+    ) -> (
+        [<AppendGraph as GraphTopology>::Vertex; V],
+        [<AppendGraph as GraphTopology>::Edge; E],
+    ),
+) -> (G, [G::Vertex; V], [G::Edge; E])
+where
+    G: GraphTopologyConversion,
+{
+    let mut builder = AppendGraph::new();
+    let (vertices, edges) = generator(&mut builder);
+    let (graph, iso) = G::convert(&builder);
+    (
+        graph,
+        vertices.map(|v| iso.vertex(v)),
+        edges.map(|e| iso.edge(e)),
+    )
+}
 
 /// Generates a Petersen graph.
 ///
@@ -43,7 +85,6 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::models::AppendGraph;
 
     #[test]
     fn petersen() {