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std.SegmentedList: add constIterator

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Natalia Cholewa 2022-04-24 19:09:10 +02:00 committed by Andrew Kelley
parent 3b8187072f
commit 0e49142ce4
1 changed files with 82 additions and 52 deletions
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134
lib/std/segmented_list.zig
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@ -294,71 +294,75 @@ pub fn SegmentedList(comptime T: type, comptime prealloc_item_count: usize) type
}
}
pub const Iterator = struct {
list: *Self,
index: usize,
box_index: usize,
shelf_index: ShelfIndex,
shelf_size: usize,
pub const Iterator = BaseIterator(*Self, *T);
pub const ConstIterator = BaseIterator(*const Self, *const T);
fn BaseIterator(comptime SelfType: type, comptime ElementPtr: type) type {
return struct {
list: SelfType,
index: usize,
box_index: usize,
shelf_index: ShelfIndex,
shelf_size: usize,
pub fn next(it: *Iterator) ?*T {
if (it.index >= it.list.len) return null;
if (it.index < prealloc_item_count) {
const ptr = &it.list.prealloc_segment[it.index];
pub fn next(it: *@This()) ?ElementPtr {
if (it.index >= it.list.len) return null;
if (it.index < prealloc_item_count) {
const ptr = &it.list.prealloc_segment[it.index];
it.index += 1;
if (it.index == prealloc_item_count) {
it.box_index = 0;
it.shelf_index = 0;
it.shelf_size = prealloc_item_count * 2;
}
return ptr;
}
const ptr = &it.list.dynamic_segments[it.shelf_index][it.box_index];
it.index += 1;
if (it.index == prealloc_item_count) {
it.box_index += 1;
if (it.box_index == it.shelf_size) {
it.shelf_index += 1;
it.box_index = 0;
it.shelf_index = 0;
it.shelf_size = prealloc_item_count * 2;
it.shelf_size *= 2;
}
return ptr;
}
const ptr = &it.list.dynamic_segments[it.shelf_index][it.box_index];
it.index += 1;
it.box_index += 1;
if (it.box_index == it.shelf_size) {
it.shelf_index += 1;
it.box_index = 0;
it.shelf_size *= 2;
}
return ptr;
}
pub fn prev(it: *@This()) ?ElementPtr {
if (it.index == 0) return null;
pub fn prev(it: *Iterator) ?*T {
if (it.index == 0) return null;
it.index -= 1;
if (it.index < prealloc_item_count) return &it.list.prealloc_segment[it.index];
it.index -= 1;
if (it.index < prealloc_item_count) return &it.list.prealloc_segment[it.index];
if (it.box_index == 0) {
it.shelf_index -= 1;
it.shelf_size /= 2;
it.box_index = it.shelf_size - 1;
} else {
it.box_index -= 1;
}
if (it.box_index == 0) {
it.shelf_index -= 1;
it.shelf_size /= 2;
it.box_index = it.shelf_size - 1;
} else {
it.box_index -= 1;
return &it.list.dynamic_segments[it.shelf_index][it.box_index];
}
return &it.list.dynamic_segments[it.shelf_index][it.box_index];
}
pub fn peek(it: *@This()) ?ElementPtr {
if (it.index >= it.list.len)
return null;
if (it.index < prealloc_item_count)
return &it.list.prealloc_segment[it.index];
pub fn peek(it: *Iterator) ?*T {
if (it.index >= it.list.len)
return null;
if (it.index < prealloc_item_count)
return &it.list.prealloc_segment[it.index];
return &it.list.dynamic_segments[it.shelf_index][it.box_index];
}
return &it.list.dynamic_segments[it.shelf_index][it.box_index];
}
pub fn set(it: *Iterator, index: usize) void {
it.index = index;
if (index < prealloc_item_count) return;
it.shelf_index = shelfIndex(index);
it.box_index = boxIndex(index, it.shelf_index);
it.shelf_size = shelfSize(it.shelf_index);
}
};
pub fn set(it: *@This(), index: usize) void {
it.index = index;
if (index < prealloc_item_count) return;
it.shelf_index = shelfIndex(index);
it.box_index = boxIndex(index, it.shelf_index);
it.shelf_size = shelfSize(it.shelf_index);
}
};
}
pub fn iterator(self: *Self, start_index: usize) Iterator {
var it = Iterator{
@ -371,10 +375,22 @@ pub fn SegmentedList(comptime T: type, comptime prealloc_item_count: usize) type
it.set(start_index);
return it;
}
pub fn constIterator(self: *const Self, start_index: usize) ConstIterator {
var it = ConstIterator{
.list = self,
.index = undefined,
.shelf_index = undefined,
.box_index = undefined,
.shelf_size = undefined,
};
it.set(start_index);
return it;
}
};
}
test "basic usage" {
test "SegmentedList basic usage" {
try testSegmentedList(0);
try testSegmentedList(1);
try testSegmentedList(2);
@ -418,6 +434,20 @@ fn testSegmentedList(comptime prealloc: usize) !void {
try testing.expect(x == 0);
}
{
var it = list.constIterator(0);
var x: i32 = 0;
while (it.next()) |item| {
x += 1;
try testing.expect(item.* == x);
}
try testing.expect(x == 100);
while (it.prev()) |item| : (x -= 1) {
try testing.expect(item.* == x);
}
try testing.expect(x == 0);
}
try testing.expect(list.pop().? == 100);
try testing.expect(list.len == 99);