open_hypergraphs/lax/functor/
dyn_functor.rs

1//! Allow defining functors of lax OpenHypergraphs in terms of strict ones.
2use crate::array::vec::VecKind;
3use crate::lax::open_hypergraph::*;
4use crate::operations::Operations;
5use crate::strict;
6
7use super::traits::Functor;
8
9/// Define the `map_arrow` function of a lax [`Functor`] by translating it to a `strit::Functor`,
10/// applying it, and translating back.
11pub fn define_map_arrow<
12    F: Functor<O1, A1, O2, A2> + Clone,
13    O1: Clone + PartialEq,
14    A1: Clone,
15    O2: Clone + PartialEq,
16    A2: Clone,
17>(
18    functor: &F,
19    f: &OpenHypergraph<O1, A1>,
20) -> OpenHypergraph<O2, A2> {
21    // Default implementation using strict::functor::Functor
22    let strict_functor: DynFunctor<F, O1, A1, O2, A2> = to_dyn_functor(functor.clone());
23    let strict_f = to_strict(f.clone());
24    let strict_g = <_ as strict::functor::Functor<VecKind, O1, A1, O2, A2>>::map_arrow(
25        &strict_functor,
26        &strict_f,
27    );
28    OpenHypergraph::from_strict(strict_g)
29}
30
31pub fn to_dyn_functor<F: Functor<O1, A1, O2, A2>, O1, A1, O2, A2>(
32    functor: F,
33) -> DynFunctor<F, O1, A1, O2, A2> {
34    DynFunctor {
35        inner: functor,
36        _phantom: std::marker::PhantomData,
37    }
38}
39
40fn to_strict<O: Clone + PartialEq, A: Clone>(
41    f: OpenHypergraph<O, A>,
42) -> strict::OpenHypergraph<VecKind, O, A> {
43    f.to_strict()
44}
45
46// A dynamic functor using closures for map_object and map_operation
47pub struct DynFunctor<F: Functor<O1, A1, O2, A2>, O1, A1, O2, A2> {
48    inner: F,
49    _phantom: std::marker::PhantomData<(O1, A1, O2, A2)>,
50}
51
52impl<
53        F: Functor<O1, A1, O2, A2>,
54        O1: Clone + PartialEq,
55        A1: Clone,
56        O2: Clone + PartialEq,
57        A2: Clone,
58    > strict::functor::Functor<VecKind, O1, A1, O2, A2> for DynFunctor<F, O1, A1, O2, A2>
59{
60    fn map_object(
61        &self,
62        a: &strict::SemifiniteFunction<VecKind, O1>,
63    ) -> strict::IndexedCoproduct<VecKind, strict::SemifiniteFunction<VecKind, O2>> {
64        let mut sizes = Vec::new();
65        let mut values = Vec::new();
66
67        for obj in a.0 .0.iter() {
68            let iter = self.inner.map_object(obj);
69            sizes.push(iter.len());
70            values.extend(iter);
71        }
72
73        use crate::array::vec::VecArray;
74        use crate::semifinite::SemifiniteFunction;
75        let sizes = SemifiniteFunction::<VecKind, usize>(VecArray(sizes));
76        let values = SemifiniteFunction(VecArray(values));
77        strict::IndexedCoproduct::from_semifinite(sizes, values).unwrap()
78    }
79
80    fn map_operations(
81        &self,
82        ops: Operations<VecKind, O1, A1>,
83    ) -> strict::OpenHypergraph<VecKind, O2, A2> {
84        // TODO: add a *slice* iterator for IndexedCoproduct<VecKind, _>
85        let op_iter = ops.x.0 .0.iter();
86        let source_iter = ops.a.into_iter();
87        let target_iter = ops.b.into_iter();
88
89        let mut acc: OpenHypergraph<O2, A2> = OpenHypergraph::empty();
90        for (op, (source, target)) in op_iter.zip(source_iter.zip(target_iter)) {
91            acc.tensor_assign(self.inner.map_operation(op, &source.0, &target.0))
92        }
93
94        acc.to_strict()
95    }
96
97    fn map_arrow(
98        &self,
99        f: &strict::OpenHypergraph<VecKind, O1, A1>,
100    ) -> strict::OpenHypergraph<VecKind, O2, A2> {
101        strict::functor::define_map_arrow(self, f)
102    }
103}
104
105/// The identity functor for lax open hypergraphs.
106#[derive(Clone)]
107pub struct Identity;
108
109impl<O: PartialEq + Clone, A: Clone + PartialEq> Functor<O, A, O, A> for Identity {
110    fn map_object(&self, o: &O) -> impl ExactSizeIterator<Item = O> {
111        std::iter::once(o.clone())
112    }
113
114    fn map_operation(&self, a: &A, source: &[O], target: &[O]) -> crate::lax::OpenHypergraph<O, A> {
115        OpenHypergraph::singleton(a.clone(), source.to_vec(), target.to_vec())
116    }
117
118    fn map_arrow(&self, f: &crate::lax::OpenHypergraph<O, A>) -> crate::lax::OpenHypergraph<O, A> {
119        define_map_arrow(self, f)
120    }
121}
open_hypergraphs/lax/functor/dyn_functor.rs

open_hypergraphs/lax/functor/
dyn_functor.rs
