algebra/
lib.rs

1//! Types and traits for working with various algebras and modules, with
2//! a focus on the Steenrod algebra and its modules.
3
4// TODO: Write descriptions of each module therein.
5
6#![deny(clippy::use_self, unsafe_op_in_unsafe_fn)]
7
8pub mod module;
9pub mod steenrod_evaluator;
10pub(crate) mod steenrod_parser;
11
12mod algebra;
13
14pub use crate::algebra::*;
15
16pub(crate) fn module_gens_from_json(
17    gens: &serde_json::Value,
18) -> (
19    bivec::BiVec<usize>,
20    bivec::BiVec<Vec<String>>,
21    impl for<'a> Fn(&'a str) -> anyhow::Result<(i32, usize)> + '_,
22) {
23    use anyhow::anyhow;
24    let gens = gens.as_object().unwrap();
25
26    let degrees = gens
27        .iter()
28        .map(|(_, x)| x.as_i64().unwrap() as i32)
29        .collect::<Vec<_>>();
30
31    let min_degree = degrees.iter().copied().min().unwrap_or(0);
32    let max_degree = degrees.iter().copied().max().unwrap_or(-1) + 1;
33
34    let mut gen_to_idx = rustc_hash::FxHashMap::default();
35    let mut graded_dimension = bivec::BiVec::with_capacity(min_degree, max_degree);
36    let mut gen_names = bivec::BiVec::with_capacity(min_degree, max_degree);
37
38    for _ in min_degree..max_degree {
39        graded_dimension.push(0);
40        gen_names.push(vec![]);
41    }
42
43    for (name, degree) in gens {
44        let degree = degree.as_i64().unwrap() as i32;
45        gen_names[degree].push(name.clone());
46        gen_to_idx.insert(name.clone(), (degree, graded_dimension[degree]));
47        graded_dimension[degree] += 1;
48    }
49    (graded_dimension, gen_names, move |g| {
50        gen_to_idx
51            .get(g)
52            .copied()
53            .ok_or_else(|| anyhow!("Invalid generator: {g}"))
54    })
55}
56
57#[cfg(test)]
58pub mod tests {
59    pub fn joker_json() -> serde_json::Value {
60        use serde_json::json;
61
62        json!({
63            "type" : "finite dimensional module",
64            "p": 2,
65            "gens": {
66                "x0": 0,
67                "x1": 1,
68                "x2": 2,
69                "x3": 3,
70                "x4": 4
71            },
72            "actions": [
73                "Sq1 x0 = x1",
74                "Sq2 x1 = x3",
75                "Sq1 x3 = x4",
76                "Sq2 x0 = x2",
77                "Sq2 x2 = x4"
78            ]
79        })
80    }
81}
algebra/lib.rs

algebra/
lib.rs
