typed alloc

std/mem/mem.bro

@@ -1,22 +1,58 @@
 c :: import "@ffi/c"
 
-Allocator :: struct {
-	context ?*mut anyopaque
+AllocatorVTable :: struct {
 	alloc @func(context ?*mut anyopaque, size usize, alignment usize) ?*mut u8
 	realloc @func(context ?*mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8
 	free @func(context ?*mut anyopaque, memory ?*mut u8, size usize, alignment usize) void
 }
 
-alloc func(allocator Allocator, size usize, alignment usize) ?*mut u8 {
-	return allocator.alloc(allocator.context, size, alignment)
+Allocator :: struct {
+	context ?*mut anyopaque
+	vtable @AllocatorVTable
 }
 
-realloc func(allocator Allocator, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
-	return allocator.realloc(allocator.context, memory, old_size, new_size, alignment)
+AllocError :: enum {
+	out_of_memory
 }
 
-free func(allocator Allocator, memory ?*mut u8, size usize, alignment usize) void {
-	allocator.free(allocator.context, memory, size, alignment)
+raw_alloc func(allocator Allocator, size usize, alignment usize) ?*mut u8 {
+	return allocator.vtable.alloc(allocator.context, size, alignment)
+}
+
+raw_realloc func(allocator Allocator, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
+	return allocator.vtable.realloc(allocator.context, memory, old_size, new_size, alignment)
+}
+
+raw_free func(allocator Allocator, memory ?*mut u8, size usize, alignment usize) void {
+	allocator.vtable.free(allocator.context, memory, size, alignment)
+}
+
+_empty_storage [1]mut u64 = [0]
+
+_empty_slice func($T type, count usize) []mut T {
+	pointer *mut T :: ptr_cast(T, (&_empty_storage).ptr)
+	return pointer[..count]
+}
+
+alloc func($T type, allocator Allocator, count usize) []mut T ! AllocError {
+	if count == 0 {
+		return _empty_slice(T, 0)
+	}
+
+	element_size usize :: size_of(T)
+	if element_size == 0 {
+		return _empty_slice(T, count)
+	}
+	if count > max_value(usize) / element_size {
+		return .out_of_memory
+	}
+
+	memory ?*mut u8 = raw_alloc(allocator, count * element_size, align_of(T))
+	if memory |bytes| {
+		pointer *mut T :: ptr_cast(T, bytes)
+		return pointer[..count]
+	}
+	return .out_of_memory
 }
 
 _malloc_alignment usize :: 16 # ponytail: aarch64-macos libc malloc alignment assumption.
@@ -93,9 +129,13 @@ _c_free func(_ ?*mut anyopaque, memory ?*mut u8, _ usize, _ usize) void {
 	c.free(memory)
 }
 
-c_allocator Allocator :: Allocator {
-	context = none,
+_c_vtable AllocatorVTable :: AllocatorVTable {
 	alloc = _c_alloc,
 	realloc = _c_realloc,
 	free = _c_free,
 }
+
+c_allocator Allocator :: Allocator {
+	context = none,
+	vtable = &_c_vtable,
+}