roc/crates/compiler/builtins/bitcode/src/list.zig

988 lines
31 KiB
Zig

const std = @import("std");
const utils = @import("utils.zig");
const UpdateMode = utils.UpdateMode;
const mem = std.mem;
const math = std.math;
const expect = std.testing.expect;
const EqFn = fn (?[*]u8, ?[*]u8) callconv(.C) bool;
const CompareFn = fn (?[*]u8, ?[*]u8, ?[*]u8) callconv(.C) u8;
const Opaque = ?[*]u8;
const Inc = fn (?[*]u8) callconv(.C) void;
const IncN = fn (?[*]u8, usize) callconv(.C) void;
const Dec = fn (?[*]u8) callconv(.C) void;
const HasTagId = fn (u16, ?[*]u8) callconv(.C) extern struct { matched: bool, data: ?[*]u8 };
const SEAMLESS_SLICE_BIT: usize =
@bitCast(usize, @as(isize, std.math.minInt(isize)));
pub const RocList = extern struct {
bytes: ?[*]u8,
length: usize,
// This technically points to directly after the refcount.
// This is an optimization that enables use one code path for regular lists and slices for geting the refcount ptr.
capacity_or_ref_ptr: usize,
pub inline fn len(self: RocList) usize {
return self.length;
}
pub fn getCapacity(self: RocList) usize {
const list_capacity = self.capacity_or_ref_ptr;
const slice_capacity = self.length;
const slice_mask = self.seamlessSliceMask();
const capacity = (list_capacity & ~slice_mask) | (slice_capacity & slice_mask);
return capacity;
}
pub fn isSeamlessSlice(self: RocList) bool {
return @bitCast(isize, self.capacity_or_ref_ptr) < 0;
}
// This returns all ones if the list is a seamless slice.
// Otherwise, it returns all zeros.
// This is done without branching for optimization purposes.
pub fn seamlessSliceMask(self: RocList) usize {
return @bitCast(usize, @bitCast(isize, self.capacity_or_ref_ptr) >> (@bitSizeOf(isize) - 1));
}
pub fn isEmpty(self: RocList) bool {
return self.len() == 0;
}
pub fn empty() RocList {
return RocList{ .bytes = null, .length = 0, .capacity_or_ref_ptr = 0 };
}
pub fn eql(self: RocList, other: RocList) bool {
if (self.len() != other.len()) {
return false;
}
// Their lengths are the same, and one is empty; they're both empty!
if (self.isEmpty()) {
return true;
}
var index: usize = 0;
const self_bytes = self.bytes orelse unreachable;
const other_bytes = other.bytes orelse unreachable;
while (index < self.len()) {
if (self_bytes[index] != other_bytes[index]) {
return false;
}
index += 1;
}
return true;
}
pub fn fromSlice(comptime T: type, slice: []const T) RocList {
if (slice.len == 0) {
return RocList.empty();
}
var list = allocate(@alignOf(T), slice.len, @sizeOf(T));
if (slice.len > 0) {
const dest = list.bytes orelse unreachable;
const src = @ptrCast([*]const u8, slice.ptr);
const num_bytes = slice.len * @sizeOf(T);
@memcpy(dest, src, num_bytes);
}
return list;
}
// returns a pointer to just after the refcount.
// It is just after the refcount as an optimization for other shared code paths.
// For regular list, it just returns their bytes pointer.
// For seamless slices, it returns the pointer stored in capacity_or_ref_ptr.
pub fn getRefcountPtr(self: RocList) ?[*]u8 {
const list_ref_ptr = @ptrToInt(self.bytes);
const slice_ref_ptr = self.capacity_or_ref_ptr << 1;
const slice_mask = self.seamlessSliceMask();
const ref_ptr = (list_ref_ptr & ~slice_mask) | (slice_ref_ptr & slice_mask);
return @intToPtr(?[*]u8, ref_ptr);
}
pub fn decref(self: RocList, alignment: u32) void {
// We use the raw capacity to ensure we always decrement the refcount of seamless slices.
utils.decref(self.getRefcountPtr(), self.capacity_or_ref_ptr, alignment);
}
pub fn elements(self: RocList, comptime T: type) ?[*]T {
return @ptrCast(?[*]T, @alignCast(@alignOf(T), self.bytes));
}
pub fn isUnique(self: RocList) bool {
return self.refcountMachine() == utils.REFCOUNT_ONE;
}
fn refcountMachine(self: RocList) usize {
if (self.getCapacity() == 0 and !self.isSeamlessSlice()) {
// the zero-capacity is Clone, copying it will not leak memory
return utils.REFCOUNT_ONE;
}
const ptr: [*]usize = @ptrCast([*]usize, @alignCast(@alignOf(usize), self.bytes));
return (ptr - 1)[0];
}
fn refcountHuman(self: RocList) usize {
return self.refcountMachine() - utils.REFCOUNT_ONE + 1;
}
pub fn makeUniqueExtra(self: RocList, alignment: u32, element_width: usize, update_mode: UpdateMode) RocList {
if (update_mode == .InPlace) {
return self;
} else {
return self.makeUnique(alignment, element_width);
}
}
pub fn makeUnique(self: RocList, alignment: u32, element_width: usize) RocList {
if (self.isUnique()) {
return self;
}
if (self.isEmpty()) {
// Empty is not necessarily unique on it's own.
// The list could have capacity and be shared.
self.decref(alignment);
return RocList.empty();
}
// unfortunately, we have to clone
var new_list = RocList.allocate(alignment, self.length, element_width);
var old_bytes: [*]u8 = @ptrCast([*]u8, self.bytes);
var new_bytes: [*]u8 = @ptrCast([*]u8, new_list.bytes);
const number_of_bytes = self.len() * element_width;
@memcpy(new_bytes, old_bytes, number_of_bytes);
// NOTE we fuse an increment of all keys/values with a decrement of the input list.
self.decref(alignment);
return new_list;
}
pub fn allocate(
alignment: u32,
length: usize,
element_width: usize,
) RocList {
if (length == 0) {
return empty();
}
const capacity = utils.calculateCapacity(0, length, element_width);
const data_bytes = capacity * element_width;
return RocList{
.bytes = utils.allocateWithRefcount(data_bytes, alignment),
.length = length,
.capacity_or_ref_ptr = capacity,
};
}
pub fn allocateExact(
alignment: u32,
length: usize,
element_width: usize,
) RocList {
if (length == 0) {
return empty();
}
const data_bytes = length * element_width;
return RocList{
.bytes = utils.allocateWithRefcount(data_bytes, alignment),
.length = length,
.capacity_or_ref_ptr = length,
};
}
pub fn reallocate(
self: RocList,
alignment: u32,
new_length: usize,
element_width: usize,
) RocList {
if (self.bytes) |source_ptr| {
if (self.isUnique() and !self.isSeamlessSlice()) {
const capacity = self.capacity_or_ref_ptr;
if (capacity >= new_length) {
return RocList{ .bytes = self.bytes, .length = new_length, .capacity_or_ref_ptr = capacity };
} else {
const new_capacity = utils.calculateCapacity(capacity, new_length, element_width);
const new_source = utils.unsafeReallocate(source_ptr, alignment, capacity, new_capacity, element_width);
return RocList{ .bytes = new_source, .length = new_length, .capacity_or_ref_ptr = new_capacity };
}
}
return self.reallocateFresh(alignment, new_length, element_width);
}
return RocList.allocate(alignment, new_length, element_width);
}
/// reallocate by explicitly making a new allocation and copying elements over
fn reallocateFresh(
self: RocList,
alignment: u32,
new_length: usize,
element_width: usize,
) RocList {
const old_length = self.length;
const delta_length = new_length - old_length;
const result = RocList.allocate(alignment, new_length, element_width);
// transfer the memory
if (self.bytes) |source_ptr| {
const dest_ptr = result.bytes orelse unreachable;
@memcpy(dest_ptr, source_ptr, old_length * element_width);
@memset(dest_ptr + old_length * element_width, 0, delta_length * element_width);
}
self.decref(alignment);
return result;
}
};
const Caller0 = fn (?[*]u8, ?[*]u8) callconv(.C) void;
const Caller1 = fn (?[*]u8, ?[*]u8, ?[*]u8) callconv(.C) void;
const Caller2 = fn (?[*]u8, ?[*]u8, ?[*]u8, ?[*]u8) callconv(.C) void;
const Caller3 = fn (?[*]u8, ?[*]u8, ?[*]u8, ?[*]u8, ?[*]u8) callconv(.C) void;
const Caller4 = fn (?[*]u8, ?[*]u8, ?[*]u8, ?[*]u8, ?[*]u8, ?[*]u8) callconv(.C) void;
pub fn listMap(
list: RocList,
caller: Caller1,
data: Opaque,
inc_n_data: IncN,
data_is_owned: bool,
alignment: u32,
old_element_width: usize,
new_element_width: usize,
) callconv(.C) RocList {
if (list.bytes) |source_ptr| {
const size = list.len();
var i: usize = 0;
const output = RocList.allocate(alignment, size, new_element_width);
const target_ptr = output.bytes orelse unreachable;
if (data_is_owned) {
inc_n_data(data, size);
}
while (i < size) : (i += 1) {
caller(data, source_ptr + (i * old_element_width), target_ptr + (i * new_element_width));
}
return output;
} else {
return RocList.empty();
}
}
fn decrementTail(list: RocList, start_index: usize, element_width: usize, dec: Dec) void {
if (list.bytes) |source| {
var i = start_index;
while (i < list.len()) : (i += 1) {
const element = source + i * element_width;
dec(element);
}
}
}
pub fn listMap2(
list1: RocList,
list2: RocList,
caller: Caller2,
data: Opaque,
inc_n_data: IncN,
data_is_owned: bool,
alignment: u32,
a_width: usize,
b_width: usize,
c_width: usize,
dec_a: Dec,
dec_b: Dec,
) callconv(.C) RocList {
const output_length = std.math.min(list1.len(), list2.len());
// if the lists don't have equal length, we must consume the remaining elements
// In this case we consume by (recursively) decrementing the elements
decrementTail(list1, output_length, a_width, dec_a);
decrementTail(list2, output_length, b_width, dec_b);
if (data_is_owned) {
inc_n_data(data, output_length);
}
if (list1.bytes) |source_a| {
if (list2.bytes) |source_b| {
const output = RocList.allocate(alignment, output_length, c_width);
const target_ptr = output.bytes orelse unreachable;
var i: usize = 0;
while (i < output_length) : (i += 1) {
const element_a = source_a + i * a_width;
const element_b = source_b + i * b_width;
const target = target_ptr + i * c_width;
caller(data, element_a, element_b, target);
}
return output;
} else {
return RocList.empty();
}
} else {
return RocList.empty();
}
}
pub fn listMap3(
list1: RocList,
list2: RocList,
list3: RocList,
caller: Caller3,
data: Opaque,
inc_n_data: IncN,
data_is_owned: bool,
alignment: u32,
a_width: usize,
b_width: usize,
c_width: usize,
d_width: usize,
dec_a: Dec,
dec_b: Dec,
dec_c: Dec,
) callconv(.C) RocList {
const smaller_length = std.math.min(list1.len(), list2.len());
const output_length = std.math.min(smaller_length, list3.len());
decrementTail(list1, output_length, a_width, dec_a);
decrementTail(list2, output_length, b_width, dec_b);
decrementTail(list3, output_length, c_width, dec_c);
if (data_is_owned) {
inc_n_data(data, output_length);
}
if (list1.bytes) |source_a| {
if (list2.bytes) |source_b| {
if (list3.bytes) |source_c| {
const output = RocList.allocate(alignment, output_length, d_width);
const target_ptr = output.bytes orelse unreachable;
var i: usize = 0;
while (i < output_length) : (i += 1) {
const element_a = source_a + i * a_width;
const element_b = source_b + i * b_width;
const element_c = source_c + i * c_width;
const target = target_ptr + i * d_width;
caller(data, element_a, element_b, element_c, target);
}
return output;
} else {
return RocList.empty();
}
} else {
return RocList.empty();
}
} else {
return RocList.empty();
}
}
pub fn listMap4(
list1: RocList,
list2: RocList,
list3: RocList,
list4: RocList,
caller: Caller4,
data: Opaque,
inc_n_data: IncN,
data_is_owned: bool,
alignment: u32,
a_width: usize,
b_width: usize,
c_width: usize,
d_width: usize,
e_width: usize,
dec_a: Dec,
dec_b: Dec,
dec_c: Dec,
dec_d: Dec,
) callconv(.C) RocList {
const output_length = std.math.min(std.math.min(list1.len(), list2.len()), std.math.min(list3.len(), list4.len()));
decrementTail(list1, output_length, a_width, dec_a);
decrementTail(list2, output_length, b_width, dec_b);
decrementTail(list3, output_length, c_width, dec_c);
decrementTail(list4, output_length, d_width, dec_d);
if (data_is_owned) {
inc_n_data(data, output_length);
}
if (list1.bytes) |source_a| {
if (list2.bytes) |source_b| {
if (list3.bytes) |source_c| {
if (list4.bytes) |source_d| {
const output = RocList.allocate(alignment, output_length, e_width);
const target_ptr = output.bytes orelse unreachable;
var i: usize = 0;
while (i < output_length) : (i += 1) {
const element_a = source_a + i * a_width;
const element_b = source_b + i * b_width;
const element_c = source_c + i * c_width;
const element_d = source_d + i * d_width;
const target = target_ptr + i * e_width;
caller(data, element_a, element_b, element_c, element_d, target);
}
return output;
} else {
return RocList.empty();
}
} else {
return RocList.empty();
}
} else {
return RocList.empty();
}
} else {
return RocList.empty();
}
}
pub fn listWithCapacity(
capacity: usize,
alignment: u32,
element_width: usize,
) callconv(.C) RocList {
return listReserve(RocList.empty(), alignment, capacity, element_width, .InPlace);
}
pub fn listReserve(
list: RocList,
alignment: u32,
spare: usize,
element_width: usize,
update_mode: UpdateMode,
) callconv(.C) RocList {
const old_length = list.len();
if ((update_mode == .InPlace or list.isUnique()) and list.getCapacity() >= list.len() + spare) {
return list;
} else {
var output = list.reallocate(alignment, old_length + spare, element_width);
output.length = old_length;
return output;
}
}
pub fn listReleaseExcessCapacity(
list: RocList,
alignment: u32,
element_width: usize,
update_mode: UpdateMode,
) callconv(.C) RocList {
const old_length = list.len();
// We use the direct list.capacity_or_ref_ptr to make sure both that there is no extra capacity and that it isn't a seamless slice.
if ((update_mode == .InPlace or list.isUnique()) and list.capacity_or_ref_ptr == old_length) {
return list;
} else if (old_length == 0) {
list.decref(alignment);
return RocList.empty();
} else {
var output = RocList.allocateExact(alignment, old_length, element_width);
if (list.bytes) |source_ptr| {
const dest_ptr = output.bytes orelse unreachable;
@memcpy(dest_ptr, source_ptr, old_length * element_width);
}
list.decref(alignment);
return output;
}
}
pub fn listAppendUnsafe(
list: RocList,
element: Opaque,
element_width: usize,
) callconv(.C) RocList {
const old_length = list.len();
var output = list;
output.length += 1;
if (output.bytes) |target| {
if (element) |source| {
@memcpy(target + old_length * element_width, source, element_width);
}
}
return output;
}
fn listAppend(list: RocList, alignment: u32, element: Opaque, element_width: usize, update_mode: UpdateMode) callconv(.C) RocList {
const with_capacity = listReserve(list, alignment, 1, element_width, update_mode);
return listAppendUnsafe(with_capacity, element, element_width);
}
pub fn listPrepend(list: RocList, alignment: u32, element: Opaque, element_width: usize) callconv(.C) RocList {
const old_length = list.len();
// TODO: properly wire in update mode.
var with_capacity = listReserve(list, alignment, 1, element_width, .Immutable);
with_capacity.length += 1;
// can't use one memcpy here because source and target overlap
if (with_capacity.bytes) |target| {
var i: usize = old_length;
while (i > 0) {
i -= 1;
// move the ith element to the (i + 1)th position
@memcpy(target + (i + 1) * element_width, target + i * element_width, element_width);
}
// finally copy in the new first element
if (element) |source| {
@memcpy(target, source, element_width);
}
}
return with_capacity;
}
pub fn listSwap(
list: RocList,
alignment: u32,
element_width: usize,
index_1: usize,
index_2: usize,
update_mode: UpdateMode,
) callconv(.C) RocList {
const size = list.len();
if (index_1 == index_2 or index_1 >= size or index_2 >= size) {
// Either index out of bounds so we just return
return list;
}
const newList = blk: {
if (update_mode == .InPlace) {
break :blk list;
} else {
break :blk list.makeUnique(alignment, element_width);
}
};
const source_ptr = @ptrCast([*]u8, newList.bytes);
swapElements(source_ptr, element_width, index_1, index_2);
return newList;
}
pub fn listSublist(
list: RocList,
alignment: u32,
element_width: usize,
start: usize,
len: usize,
dec: Dec,
) callconv(.C) RocList {
const size = list.len();
if (len == 0 or start >= size) {
// Decrement the reference counts of all elements.
if (list.bytes) |source_ptr| {
var i: usize = 0;
while (i < size) : (i += 1) {
const element = source_ptr + i * element_width;
dec(element);
}
}
if (list.isUnique()) {
var output = list;
output.length = 0;
return output;
}
list.decref(alignment);
return RocList.empty();
}
if (list.bytes) |source_ptr| {
const keep_len = std.math.min(len, size - start);
const drop_start_len = start;
const drop_end_len = size - (start + keep_len);
// Decrement the reference counts of elements before `start`.
var i: usize = 0;
while (i < drop_start_len) : (i += 1) {
const element = source_ptr + i * element_width;
dec(element);
}
// Decrement the reference counts of elements after `start + keep_len`.
i = 0;
while (i < drop_end_len) : (i += 1) {
const element = source_ptr + (start + keep_len + i) * element_width;
dec(element);
}
if (start == 0 and list.isUnique()) {
var output = list;
output.length = keep_len;
return output;
} else {
const list_ref_ptr = (@ptrToInt(source_ptr) >> 1) | SEAMLESS_SLICE_BIT;
const slice_ref_ptr = list.capacity_or_ref_ptr;
const slice_mask = list.seamlessSliceMask();
const ref_ptr = (list_ref_ptr & ~slice_mask) | (slice_ref_ptr & slice_mask);
return RocList{
.bytes = source_ptr + start * element_width,
.length = keep_len,
.capacity_or_ref_ptr = ref_ptr,
};
}
}
return RocList.empty();
}
pub fn listDropAt(
list: RocList,
alignment: u32,
element_width: usize,
drop_index: usize,
dec: Dec,
) callconv(.C) RocList {
const size = list.len();
// If droping the first or last element, return a seamless slice.
// For simplicity, do this by calling listSublist.
// In the future, we can test if it is faster to manually inline the important parts here.
if (drop_index == 0) {
return listSublist(list, alignment, element_width, 1, size -| 1, dec);
} else if (drop_index == size -| 1) {
return listSublist(list, alignment, element_width, 0, size -| 1, dec);
}
if (list.bytes) |source_ptr| {
if (drop_index >= size) {
return list;
}
if (drop_index < size) {
const element = source_ptr + drop_index * element_width;
dec(element);
}
// NOTE
// we need to return an empty list explicitly,
// because we rely on the pointer field being null if the list is empty
// which also requires duplicating the utils.decref call to spend the RC token
if (size < 2) {
list.decref(alignment);
return RocList.empty();
}
if (list.isUnique()) {
var i = drop_index;
while (i < size - 1) : (i += 1) {
const copy_target = source_ptr + i * element_width;
const copy_source = copy_target + element_width;
@memcpy(copy_target, copy_source, element_width);
}
var new_list = list;
new_list.length -= 1;
return new_list;
}
const output = RocList.allocate(alignment, size - 1, element_width);
const target_ptr = output.bytes orelse unreachable;
const head_size = drop_index * element_width;
@memcpy(target_ptr, source_ptr, head_size);
const tail_target = target_ptr + drop_index * element_width;
const tail_source = source_ptr + (drop_index + 1) * element_width;
const tail_size = (size - drop_index - 1) * element_width;
@memcpy(tail_target, tail_source, tail_size);
list.decref(alignment);
return output;
} else {
return RocList.empty();
}
}
fn partition(source_ptr: [*]u8, transform: Opaque, wrapper: CompareFn, element_width: usize, low: isize, high: isize) isize {
const pivot = source_ptr + (@intCast(usize, high) * element_width);
var i = (low - 1); // Index of smaller element and indicates the right position of pivot found so far
var j = low;
while (j <= high - 1) : (j += 1) {
const current_elem = source_ptr + (@intCast(usize, j) * element_width);
const ordering = wrapper(transform, current_elem, pivot);
const order = @intToEnum(utils.Ordering, ordering);
switch (order) {
utils.Ordering.LT => {
// the current element is smaller than the pivot; swap it
i += 1;
swapElements(source_ptr, element_width, @intCast(usize, i), @intCast(usize, j));
},
utils.Ordering.EQ, utils.Ordering.GT => {},
}
}
swapElements(source_ptr, element_width, @intCast(usize, i + 1), @intCast(usize, high));
return (i + 1);
}
fn quicksort(source_ptr: [*]u8, transform: Opaque, wrapper: CompareFn, element_width: usize, low: isize, high: isize) void {
if (low < high) {
// partition index
const pi = partition(source_ptr, transform, wrapper, element_width, low, high);
_ = quicksort(source_ptr, transform, wrapper, element_width, low, pi - 1); // before pi
_ = quicksort(source_ptr, transform, wrapper, element_width, pi + 1, high); // after pi
}
}
pub fn listSortWith(
input: RocList,
caller: CompareFn,
data: Opaque,
inc_n_data: IncN,
data_is_owned: bool,
alignment: u32,
element_width: usize,
) callconv(.C) RocList {
var list = input.makeUnique(alignment, element_width);
if (data_is_owned) {
inc_n_data(data, list.len());
}
if (list.bytes) |source_ptr| {
const low = 0;
const high: isize = @intCast(isize, list.len()) - 1;
quicksort(source_ptr, data, caller, element_width, low, high);
}
return list;
}
// SWAP ELEMENTS
inline fn swapHelp(width: usize, temporary: [*]u8, ptr1: [*]u8, ptr2: [*]u8) void {
@memcpy(temporary, ptr1, width);
@memcpy(ptr1, ptr2, width);
@memcpy(ptr2, temporary, width);
}
fn swap(width_initial: usize, p1: [*]u8, p2: [*]u8) void {
const threshold: usize = 64;
var width = width_initial;
var ptr1 = p1;
var ptr2 = p2;
var buffer_actual: [threshold]u8 = undefined;
var buffer: [*]u8 = buffer_actual[0..];
while (true) {
if (width < threshold) {
swapHelp(width, buffer, ptr1, ptr2);
return;
} else {
swapHelp(threshold, buffer, ptr1, ptr2);
ptr1 += threshold;
ptr2 += threshold;
width -= threshold;
}
}
}
fn swapElements(source_ptr: [*]u8, element_width: usize, index_1: usize, index_2: usize) void {
var element_at_i = source_ptr + (index_1 * element_width);
var element_at_j = source_ptr + (index_2 * element_width);
return swap(element_width, element_at_i, element_at_j);
}
pub fn listConcat(list_a: RocList, list_b: RocList, alignment: u32, element_width: usize) callconv(.C) RocList {
// NOTE we always use list_a! because it is owned, we must consume it, and it may have unused capacity
if (list_b.isEmpty()) {
if (list_a.getCapacity() == 0) {
// a could be a seamless slice, so we still need to decref.
list_a.decref(alignment);
return list_b;
} else {
// we must consume this list. Even though it has no elements, it could still have capacity
list_b.decref(alignment);
return list_a;
}
} else if (list_a.isUnique()) {
const total_length: usize = list_a.len() + list_b.len();
const resized_list_a = list_a.reallocate(alignment, total_length, element_width);
// These must exist, otherwise, the lists would have been empty.
const source_a = resized_list_a.bytes orelse unreachable;
const source_b = list_b.bytes orelse unreachable;
@memcpy(source_a + list_a.len() * element_width, source_b, list_b.len() * element_width);
// decrement list b.
list_b.decref(alignment);
return resized_list_a;
} else if (list_b.isUnique()) {
const total_length: usize = list_a.len() + list_b.len();
const resized_list_b = list_b.reallocate(alignment, total_length, element_width);
// These must exist, otherwise, the lists would have been empty.
const source_a = list_a.bytes orelse unreachable;
const source_b = resized_list_b.bytes orelse unreachable;
// This is a bit special, we need to first copy the elements of list_b to the end,
// then copy the elements of list_a to the beginning.
// This first call must use mem.copy because the slices might overlap.
const byte_count_a = list_a.len() * element_width;
const byte_count_b = list_b.len() * element_width;
mem.copyBackwards(u8, source_b[byte_count_a .. byte_count_a + byte_count_b], source_b[0..byte_count_b]);
@memcpy(source_b, source_a, byte_count_a);
// decrement list a.
list_a.decref(alignment);
return resized_list_b;
}
const total_length: usize = list_a.len() + list_b.len();
const output = RocList.allocate(alignment, total_length, element_width);
// These must exist, otherwise, the lists would have been empty.
const target = output.bytes orelse unreachable;
const source_a = list_a.bytes orelse unreachable;
const source_b = list_b.bytes orelse unreachable;
@memcpy(target, source_a, list_a.len() * element_width);
@memcpy(target + list_a.len() * element_width, source_b, list_b.len() * element_width);
// decrement list a and b.
list_a.decref(alignment);
list_b.decref(alignment);
return output;
}
pub fn listReplaceInPlace(
list: RocList,
index: usize,
element: Opaque,
element_width: usize,
out_element: ?[*]u8,
) callconv(.C) RocList {
// INVARIANT: bounds checking happens on the roc side
//
// at the time of writing, the function is implemented roughly as
// `if inBounds then LowLevelListReplace input index item else input`
// so we don't do a bounds check here. Hence, the list is also non-empty,
// because inserting into an empty list is always out of bounds
return listReplaceInPlaceHelp(list, index, element, element_width, out_element);
}
pub fn listReplace(
list: RocList,
alignment: u32,
index: usize,
element: Opaque,
element_width: usize,
out_element: ?[*]u8,
) callconv(.C) RocList {
// INVARIANT: bounds checking happens on the roc side
//
// at the time of writing, the function is implemented roughly as
// `if inBounds then LowLevelListReplace input index item else input`
// so we don't do a bounds check here. Hence, the list is also non-empty,
// because inserting into an empty list is always out of bounds
return listReplaceInPlaceHelp(list.makeUnique(alignment, element_width), index, element, element_width, out_element);
}
inline fn listReplaceInPlaceHelp(
list: RocList,
index: usize,
element: Opaque,
element_width: usize,
out_element: ?[*]u8,
) RocList {
// the element we will replace
var element_at_index = (list.bytes orelse undefined) + (index * element_width);
// copy out the old element
@memcpy(out_element orelse undefined, element_at_index, element_width);
// copy in the new element
@memcpy(element_at_index, element orelse undefined, element_width);
return list;
}
pub fn listIsUnique(
list: RocList,
) callconv(.C) bool {
return list.isEmpty() or list.isUnique();
}
pub fn listCapacity(
list: RocList,
) callconv(.C) usize {
return list.getCapacity();
}
pub fn listRefcountPtr(
list: RocList,
) callconv(.C) ?[*]u8 {
return list.getRefcountPtr();
}
test "listConcat: non-unique with unique overlapping" {
var nonUnique = RocList.fromSlice(u8, ([_]u8{1})[0..]);
var bytes: [*]u8 = @ptrCast([*]u8, nonUnique.bytes);
const ptr_width = @sizeOf(usize);
const refcount_ptr = @ptrCast([*]isize, @alignCast(ptr_width, bytes) - ptr_width);
utils.increfC(&refcount_ptr[0], 1);
defer nonUnique.decref(@sizeOf(u8)); // listConcat will dec the other refcount
var unique = RocList.fromSlice(u8, ([_]u8{ 2, 3, 4 })[0..]);
defer unique.decref(@sizeOf(u8));
var concatted = listConcat(nonUnique, unique, 1, 1);
var wanted = RocList.fromSlice(u8, ([_]u8{ 1, 2, 3, 4 })[0..]);
defer wanted.decref(@sizeOf(u8));
try expect(concatted.eql(wanted));
}