v0.0.0b

sub/core/src/arrays.rs

@@ -0,0 +1,80 @@
+use core::fmt::{Debug, Formatter};
+
+pub fn fill_with<T, F: FnMut(usize) -> T>(slice: &mut [T], mut func: F) {
+    slice.iter_mut().enumerate().for_each(|(i,v)|*v = func(i))
+}
+
+
+pub struct FixedVec<const MAX_LEN: usize, T> {
+    length: usize,
+    buffer: [core::mem::MaybeUninit<T>;MAX_LEN],
+}
+
+impl<const MAX_LEN: usize, T: Sized> FixedVec<MAX_LEN, T> {
+
+    pub fn new() -> Self {
+        unsafe { core::mem::zeroed() }
+    }
+
+    pub fn push(&mut self, value: T) -> Option<()> {
+        if self.length >= MAX_LEN { return None }
+        unsafe { *self.buffer[self.length].as_mut_ptr() = value };
+        self.length += 1;
+        Some(())
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        if self.length == 0 { return None }
+        self.length -= 1;
+        Some(unsafe { self.buffer[self.length].assume_init_read() })
+    }
+
+    pub fn extend<Iter: Iterator<Item=T>>(&mut self, mut iter: Iter) -> Result<usize, usize> {
+        let mut count = 0;
+        loop {
+            if self.length == MAX_LEN {
+                return Err(count);
+            }
+            match iter.next() {
+                None => return Ok(count),
+                Some(value) => {
+                    unsafe { *self.buffer[self.length].as_mut_ptr() = value };
+                    self.length += 1;
+                    count += 1;
+                }
+            }
+
+        }
+    }
+
+    pub fn as_slice(&self) -> &[T] {
+        // length can't be larger than MaxLen, use unsafe to dodge the panic
+        unsafe { core::slice::from_raw_parts(self.buffer.as_ptr() as *const T, self.length) }
+    }
+
+    pub fn clear(&mut self) {
+        self.length = 0;
+    }
+
+}
+
+impl<const MAX_LEN: usize, T: Debug> Debug for FixedVec<MAX_LEN, T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        Debug::fmt(self.as_slice(), f)
+    }
+}
+
+impl<const MAX_LEN: usize, T> Drop for FixedVec<MAX_LEN, T> {
+    fn drop(&mut self) {
+        for e in &mut self.buffer[..self.length] {
+            unsafe { e.assume_init_drop() }
+        }
+    }
+}
+
+impl<const MAX_LEN: usize> core::fmt::Write for FixedVec<MAX_LEN, u8> {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        _=self.extend(s.as_bytes().iter().cloned());
+        Ok(())
+    }
+}