From 8a02635ef9825f38b5d2ce5a0cabb84dc548e4fc Mon Sep 17 00:00:00 2001
From: oleh <olehmisar@gmail.com>
Date: Wed, 23 Oct 2024 03:54:00 +0200
Subject: [PATCH] feat: array slice

---
 README.md    | 12 +++++++++++-
 src/array.nr | 15 +++++++++++++++
 src/lib.nr   |  1 +
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index cb1c07d..a08b697 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ Put this into your Nargo.toml.
 If you are using Noir:
 
 ```toml
-nodash = { git = "https://github.com/olehmisar/nodash/", tag = "v0.35.1" }
+nodash = { git = "https://github.com/olehmisar/nodash/", tag = "v0.35.3" }
 ```
 
 The version of nodash matches the version of Noir. The patch version may be different if a bugfix or a new feature is added for the same version of Noir. E.g., nodash@v0.35.0 and nodash@v0.35.1 are compatible with noir@v0.35.0.
@@ -98,6 +98,16 @@ assert(str_to_u64("02345678912345678912") == 02345678912345678912);
 
 ### `ArrayExtensions`
 
+#### `slice`
+
+Returns a slice of the array.
+
+```rs
+use nodash::ArrayExtensions;
+
+assert([1, 2, 3, 4, 5].slice::<3>(1, 4) == [2, 3, 4]);
+```
+
 #### `concat`
 
 Concatenates two arrays.
diff --git a/src/array.nr b/src/array.nr
index 10c985f..215325c 100644
--- a/src/array.nr
+++ b/src/array.nr
@@ -1,4 +1,14 @@
 impl<T, let N: u32> crate::ArrayExtensions<T, N> for [T; N] {
+    fn slice<let M: u32>(self, start: u32, end: u32) -> [T; M] {
+        assert(start + M == end, "slice: invalid slice length");
+        assert(end <= N, "slice: slice end out of bounds");
+        let mut result = [self[0]; M];
+        for i in 0..M {
+            result[i] = self[start + i];
+        }
+        result
+    }
+
     fn concat<let M: u32>(self, other: [T; M]) -> [T; N + M] {
         let mut result = [self[0]; N + M];
         for i in 0..N {
@@ -30,6 +40,11 @@ impl<T, let N: u32> crate::ArrayExtensions<T, N> for [T; N] {
 }
 
 mod tests {
+    #[test]
+    fn test_slice() {
+        assert([1, 2, 3, 4, 5].slice::<3>(1, 4) == [2, 3, 4]);
+    }
+
     #[test]
     fn test_simple() {
         assert([1, 2, 3].concat([4, 5]) == [1, 2, 3, 4, 5]);
diff --git a/src/lib.nr b/src/lib.nr
index 669f4ca..d795b63 100644
--- a/src/lib.nr
+++ b/src/lib.nr
@@ -8,6 +8,7 @@ pub use string::{to_hex_string_bytes, str_to_u64};
 pub use math::{clamp, div_ceil, sqrt::sqrt};
 
 trait ArrayExtensions<T, let N: u32> {
+    fn slice<let M: u32>(self, start: u32, end: u32) -> [T; M];
     fn concat<let M: u32>(self, other: [T; M]) -> [T; N + M];
     fn pad_start<let M: u32>(self, pad_value: T) -> [T; M];
     fn pad_end<let M: u32>(self, pad_value: T) -> [T; M];