rssn 0.2.9

A comprehensive scientific computing library for Rust, aiming for feature parity with NumPy and SymPy.
Documentation 
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//! Handle-based FFI API for numerical topology.

use std::ptr;

use crate::numerical::graph::Graph;
use crate::numerical::topology;

/// Finds the connected components of a graph.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_num_topology_find_connected_components(
    graph_ptr: *const Graph
) -> *mut Vec<Vec<usize>> {
    unsafe {
        if graph_ptr.is_null() {
            return ptr::null_mut();
        }

        let graph = &*graph_ptr;

        let components = topology::find_connected_components(graph);

        Box::into_raw(Box::new(components))
    }
}

/// Computes the Betti numbers for a point cloud.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_num_topology_betti_numbers(
    points: *const *const f64,
    n_points: usize,
    dim: usize,
    epsilon: f64,
    max_dim: usize,
    result: *mut usize,
) -> i32 {
    unsafe {
        if points.is_null() || result.is_null() {
            return -1;
        }

        let mut pt_slices = Vec::with_capacity(n_points);

        for i in 0..n_points {
            pt_slices.push(std::slice::from_raw_parts(*points.add(i), dim));
        }

        let betti = topology::betti_numbers_at_radius(&pt_slices, epsilon, max_dim);

        let n_betti = betti.len();

        std::ptr::copy_nonoverlapping(betti.as_ptr(), result, n_betti);

        0
    }
}

/// Computes the Euclidean distance between two points.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_num_topology_euclidean_distance(
    p1: *const f64,
    p2: *const f64,
    dim: usize,
) -> f64 {
    unsafe {
        if p1.is_null() || p2.is_null() {
            return f64::NAN;
        }

        let s1 = std::slice::from_raw_parts(p1, dim);

        let s2 = std::slice::from_raw_parts(p2, dim);

        topology::euclidean_distance(s1, s2)
    }
}