add const generic

examples/mnist.rs

@@ -1,6 +1,7 @@
 use mnist::{Mnist, MnistBuilder};
 use rand::Rng;
 use rulinalg::matrix::{BaseMatrix, Matrix};
+use std::convert::TryInto;
 
 fn load_mnist(
     size: u32,
@@ -34,7 +35,7 @@ fn main() {
         .test_set_length(tst_size)
         .finalize();
 
-    let ann = voyager_rs::Voyager::new(28 * 28);
+    let ann = voyager_rs::Voyager::new();
     let mut rng = rand::thread_rng();
 
     for i in 0..trn_size {
@@ -46,8 +47,9 @@ fn main() {
             .into_iter()
             .map(|v| v as f32)
             .collect::<Vec<_>>();
-
-        ann.add_item(&img_to_vec, None);
+
+        let v: [f32; 28*28] = img_to_vec.try_into().unwrap();
+        ann.add_item(v, None);
 
         if i % 1_000 == 0 {
             println!("Add item {}/{}.", i, trn_size);
@@ -72,7 +74,8 @@ fn main() {
             .map(|v| v as f32)
             .collect::<Vec<_>>();
 
-        let (result, _distance) = ann.query(&img_to_vec, 1, None);
+        let v: [f32; 28*28] = img_to_vec.try_into().unwrap();
+        let (result, _distance) = ann.query(v, 1, None);
         let actual = result
             .into_iter()
             .map(|v| trn_lbl[v as usize])
@@ -86,4 +89,4 @@ fn main() {
             println!("{}\n{}", trn, tst);
         }
     }
-}
+}

src/lib.rs

@@ -1,6 +1,5 @@
 use std::ffi::CString;
 use std::path::Path;
-
 use libc::{c_float, c_int, c_uint, c_void};
 
 pub enum Index {}
@@ -43,24 +42,30 @@ mod ffi {
     }
 }
 
-pub struct Voyager(*mut Index);
+pub struct Voyager<const N : usize> {
+    ix: *mut Index
+}
+
+impl<const N: usize> Voyager<N> {
+    pub fn new() -> Self {
+        let n = Voyager::<N>::dimension();
+        let index = unsafe { ffi::init_index(n as u32) };
 
-impl Voyager {
-    pub fn new(n: u32) -> Self {
-        let index = unsafe { ffi::init_index(n) };
-        Voyager(index)
+        Voyager { ix: index }
     }
 
-    pub fn add_item(&self, w: &[f32], id: Option<u32>) {
+    pub const fn dimension() -> usize { N }
+
+    pub fn add_item(&self, w: [f32; N], id: Option<u32>) {
         let len = w.len();
         let is_some: c_int = id.is_some() as c_int;
 
         unsafe {
-            ffi::add_item(self.0, w.as_ptr(), len, is_some, id.unwrap_or(0));
+            ffi::add_item(self.ix, w.as_ptr(), len, is_some, id.unwrap_or(0));
         }
     }
 
-    pub fn query(&self, w: &[f32], k: i32, ef: Option<i32>) -> (Vec<usize>, Vec<f32>) {
+    pub fn query(&self, w: [f32; N], k: i32, ef: Option<i32>) -> (Vec<usize>, Vec<f32>) {
         let len = w.len();
 
         let mut result = Vec::with_capacity(k as usize);
@@ -71,7 +76,7 @@ impl Voyager {
 
         unsafe {
             ffi::query(
-                self.0,
+                self.ix,
                 w.as_ptr(),
                 len,
                 result_ptr,
@@ -87,26 +92,26 @@ impl Voyager {
         (a.to_vec(), b.to_vec())
     }
 
-    pub fn get_distance(&self, w1: &[f32], w2: &[f32]) -> f32 {
+    pub fn get_distance(&self, w1: [f32; N], w2: [f32; N]) -> f32 {
         let len = w1.len();
 
-        unsafe { ffi::get_distance(self.0, w1.as_ptr(), w2.as_ptr(), len) }
+        unsafe { ffi::get_distance(self.ix, w1.as_ptr(), w2.as_ptr(), len) }
     }
 
     pub fn save<P: AsRef<Path>>(&self, path: P) {
         unsafe {
             if let Some(f) = path.as_ref().as_os_str().to_str() {
                 let path_str_c = CString::new(f).unwrap();
-                ffi::save_index(self.0, path_str_c.as_ptr() as *const c_void);
+                ffi::save_index(self.ix, path_str_c.as_ptr() as *const c_void);
             }
         }
     }
 }
 
-impl Drop for Voyager {
+impl<const N: usize> Drop for Voyager<N> {
     fn drop(&mut self) {
         unsafe {
-            ffi::dispose(self.0);
+            ffi::dispose(self.ix);
         }
     }
 }
@@ -117,10 +122,10 @@ mod test {
 
     #[test]
     fn test_voyager() {
-        let v = Voyager::new(5);
+        let v = Voyager::new();
 
-        let v1 = &[1.0, 2.0, 3.0, 4.0, 5.0];
-        let v2 = &[6.0, 7.0, 8.0, 9.0, 10.0];
+        let v1 = [1.0, 2.0, 3.0, 4.0, 5.0];
+        let v2 = [6.0, 7.0, 8.0, 9.0, 10.0];
 
         v.add_item(v1, Some(1));
         v.add_item(v2, Some(2));
@@ -133,10 +138,10 @@ mod test {
 
     #[test]
     fn test_distance() {
-        let v = Voyager::new(5);
+        let v = Voyager::new();
 
-        let v1 = &[1.0, 2.0, 3.0, 4.0, 5.0];
-        let v2 = &[6.0, 7.0, 8.0, 9.0, 10.0];
+        let v1 = [1.0, 2.0, 3.0, 4.0, 5.0];
+        let v2 = [6.0, 7.0, 8.0, 9.0, 10.0];
 
         let distance = v.get_distance(v1, v2);
 
@@ -145,10 +150,10 @@ mod test {
 
     #[test]
     fn test_save() {
-        let v = Voyager::new(5);
+        let v = Voyager::new();
 
-        let v1 = &[1.0, 2.0, 3.0, 4.0, 5.0];
-        let v2 = &[6.0, 7.0, 8.0, 9.0, 10.0];
+        let v1 = [1.0, 2.0, 3.0, 4.0, 5.0];
+        let v2 = [6.0, 7.0, 8.0, 9.0, 10.0];
 
         v.add_item(v1, Some(1));
         v.add_item(v2, Some(2));