From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Wed, 17 Aug 2022 13:28:01 +0000 (+0100)
Subject: asv
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=2c3449c702268463836de05986061c2e6a2d7721;p=rust-experiments.git

asv
---

diff --git a/src/main.rs b/src/main.rs
index d5e0cbd..476e59c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,80 +5,24 @@
 use std::mem;
 use std::mem::MaybeUninit;
 
-type S = &'static str;
+pub fn default<T: Default>() -> T { Default::default() }
 
-
-#[repr(C)]
-struct Concat<const A: usize, const B: usize>(
-    [S; A], 
-    [S; B],
-);
-
-trait Ish {
-    const N: usize;
-}
-
-trait Has<const N: usize> {
-    const F: [S; N];
-}
-
-struct Inner { i: usize, }
-
-impl Ish for Inner {
-    const N: usize = 1;
-}
-impl Has<1> for Inner {
-    const F: [S; 1] = ["i"];
+#[derive(Debug)]
+struct AutoStackVec<const N: usize, T> {
+    used: usize,
+    buf: [T; N],
 }
 
-struct Outer { o: usize, p: usize }
-
-impl Ish for Outer {
-    const N: usize = Inner::N + 2;
-}
-impl Has<{ Inner::N + 2 }> for Outer {
-    const F: [S; Inner::N + 2] = {
-        const TUPLE: Concat<
-                2,
-                { Inner::N },
-            > = Concat(
-                ["o", "p"],
-                Inner::F,
-            );
-        unsafe { mem::transmute(TUPLE) }
-    };
-}
-
-/*
-const fn plus<const N: usize>
-(x: &'static [S],
- b: &'static [S],
- ary: &mut [MaybeUninit<S>],
-)
- -> &'static [S]
-{
-//    unsafe {
-        
-//    }
-    panic!()
-}
-
-struct Outer { o: usize, }
-impl Ish for Outer {
-    const N: usize = Inner::N + 1;
-    const F: &'static [S] = {
-        static mut ARY: [MaybeUninit<S>; Inner::N + 1] = [MaybeUninit::uninit(); Inner::N + 1];
-
-        plus::<{Inner::N + 1}>(
-            Inner::F,
-            &["o"],
-            &mut ARY[..],
-        )
-    };
+impl<const N: usize, T> AutoStackVec<N,T> {
+    fn new() -> Self where T: Default {
+        AutoStackVec {
+            used: 0,
+            buf: std::array::from_fn(|_| default()),
+        }
+    }
 }
-*/
 
 fn main(){
-    eprintln!("IF {:?}", Inner::F);
-    eprintln!("OF {:?}", Outer::F);
+    let asv = AutoStackVec::<4, i32>::new();
+    eprintln!("N {:?}", asv);
 }