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Add writeToSlice method to SegmentedList. (#5405)

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Walter Mays 2020-05-26 12:04:25 -05:00 committed by GitHub
parent cb6bc5bdb5
commit 19a04d8ebd
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1 changed files with 53 additions and 4 deletions
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57
lib/std/segmented_list.zig
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@ -213,6 +213,34 @@ pub fn SegmentedList(comptime T: type, comptime prealloc_item_count: usize) type
self.len = new_len;
}
pub fn writeToSlice(self: *Self, dest: []T, start: usize) void {
const end = start + dest.len;
assert(end <= self.len);
var i = start;
if (end <= prealloc_item_count) {
std.mem.copy(T, dest[i - start ..], self.prealloc_segment[i..end]);
return;
} else if (i < prealloc_item_count) {
std.mem.copy(T, dest[i - start ..], self.prealloc_segment[i..]);
i = prealloc_item_count;
}
while (i < end) {
const shelf_index = shelfIndex(i);
const copy_start = boxIndex(i, shelf_index);
const copy_end = std.math.min(shelfSize(shelf_index), copy_start + end - i);
std.mem.copy(
T,
dest[i - start ..],
self.dynamic_segments[shelf_index][copy_start..copy_end],
);
i += (copy_end - copy_start);
}
}
pub fn uncheckedAt(self: var, index: usize) AtType(@TypeOf(self)) {
if (index < prealloc_item_count) {
return &self.prealloc_segment[index];
@ -395,10 +423,31 @@ fn testSegmentedList(comptime prealloc: usize, allocator: *Allocator) !void {
try list.pushMany(&[_]i32{});
testing.expect(list.len == 99);
var i: i32 = 99;
while (list.pop()) |item| : (i -= 1) {
testing.expect(item == i);
list.shrinkCapacity(list.len);
{
var i: i32 = 99;
while (list.pop()) |item| : (i -= 1) {
testing.expect(item == i);
list.shrinkCapacity(list.len);
}
}
{
var control: [100]i32 = undefined;
var dest: [100]i32 = undefined;
var i: i32 = 0;
while (i < 100) : (i += 1) {
try list.push(i + 1);
control[@intCast(usize, i)] = i + 1;
}
std.mem.set(i32, dest[0..], 0);
list.writeToSlice(dest[0..], 0);
testing.expect(std.mem.eql(i32, control[0..], dest[0..]));
std.mem.set(i32, dest[0..], 0);
list.writeToSlice(dest[50..], 50);
testing.expect(std.mem.eql(i32, control[50..], dest[50..]));
}
try list.setCapacity(0);