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std: add new array list functions

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Andrew Kelley 2020-07-06 06:09:47 +00:00
parent 8fb392dbb4
commit a2fd8f72c1
1 changed files with 60 additions and 0 deletions
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60
lib/std/array_list.zig
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@ -257,6 +257,24 @@ pub fn ArrayListAligned(comptime T: type, comptime alignment: ?u29) type {
return &self.items[self.items.len - 1];
}
/// Resize the array, adding `n` new elements, which have `undefined` values.
/// The return value is an array pointing to the newly allocated elements.
pub fn addManyAsArray(self: *Self, comptime n: usize) !*[n]T {
const prev_len = self.items.len;
try self.resize(self.items.len + n);
return self.items[prev_len..][0..n];
}
/// Resize the array, adding `n` new elements, which have `undefined` values.
/// The return value is an array pointing to the newly allocated elements.
/// Asserts that there is already space for the new item without allocating more.
pub fn addManyAsArrayAssumeCapacity(self: *Self, comptime n: usize) *[n]T {
assert(self.items.len + n <= self.capacity);
const prev_len = self.items.len;
self.items.len += n;
return self.items[prev_len..][0..n];
}
/// Remove and return the last element from the list.
/// Asserts the list has at least one item.
pub fn pop(self: *Self) T {
@ -488,6 +506,24 @@ pub fn ArrayListAlignedUnmanaged(comptime T: type, comptime alignment: ?u29) typ
return &self.items[self.items.len - 1];
}
/// Resize the array, adding `n` new elements, which have `undefined` values.
/// The return value is an array pointing to the newly allocated elements.
pub fn addManyAsArray(self: *Self, allocator: *Allocator, comptime n: usize) !*[n]T {
const prev_len = self.items.len;
try self.resize(allocator, self.items.len + n);
return self.items[prev_len..][0..n];
}
/// Resize the array, adding `n` new elements, which have `undefined` values.
/// The return value is an array pointing to the newly allocated elements.
/// Asserts that there is already space for the new item without allocating more.
pub fn addManyAsArrayAssumeCapacity(self: *Self, comptime n: usize) *[n]T {
assert(self.items.len + n <= self.capacity);
const prev_len = self.items.len;
self.items.len += n;
return self.items[prev_len..][0..n];
}
/// Remove and return the last element from the list.
/// Asserts the list has at least one item.
/// This operation does not invalidate any element pointers.
@ -727,3 +763,27 @@ test "std.ArrayList.writer" {
try writer.writeAll("efg");
testing.expectEqualSlices(u8, list.items, "abcdefg");
}
test "addManyAsArray" {
const a = std.testing.allocator;
{
var list = ArrayList(u8).init(a);
defer list.deinit();
(try list.addManyAsArray(4)).* = "aoeu".*;
try list.ensureCapacity(8);
list.addManyAsArrayAssumeCapacity(4).* = "asdf".*;
testing.expectEqualSlices(u8, list.items, "aoeuasdf");
}
{
var list = ArrayListUnmanaged(u8){};
defer list.deinit(a);
(try list.addManyAsArray(a, 4)).* = "aoeu".*;
try list.ensureCapacity(a, 8);
list.addManyAsArrayAssumeCapacity(4).* = "asdf".*;
testing.expectEqualSlices(u8, list.items, "aoeuasdf");
}
}