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std.MultiArrayList: ensureUnusedCapacity/ensureTotalCapacity

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Same as c8ae581fef6506a8234cdba1355ba7f0f449031a, but for
MultiArrayList.
This commit is contained in:
Andrew Kelley 2021-04-19 15:02:37 -07:00
parent 27d4bea9a4
commit 22015c1b3b
1 changed files with 16 additions and 7 deletions
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23
lib/std/multi_array_list.zig
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@ -147,7 +147,7 @@ pub fn MultiArrayList(comptime S: type) type {
/// Extend the list by 1 element. Allocates more memory as necessary.
pub fn append(self: *Self, gpa: *Allocator, elem: S) !void {
try self.ensureCapacity(gpa, self.len + 1);
try self.ensureUnusedCapacity(gpa, 1);
self.appendAssumeCapacity(elem);
}
@ -162,7 +162,7 @@ pub fn MultiArrayList(comptime S: type) type {
/// Adjust the list's length to `new_len`.
/// Does not initialize added items, if any.
pub fn resize(self: *Self, gpa: *Allocator, new_len: usize) !void {
try self.ensureCapacity(gpa, new_len);
try self.ensureTotalCapacity(gpa, new_len);
self.len = new_len;
}
@ -224,10 +224,13 @@ pub fn MultiArrayList(comptime S: type) type {
self.len = new_len;
}
/// Deprecated: call `ensureUnusedCapacity` or `ensureTotalCapacity`.
pub const ensureCapacity = ensureTotalCapacity;
/// Modify the array so that it can hold at least `new_capacity` items.
/// Implements super-linear growth to achieve amortized O(1) append operations.
/// Invalidates pointers if additional memory is needed.
pub fn ensureCapacity(self: *Self, gpa: *Allocator, new_capacity: usize) !void {
pub fn ensureTotalCapacity(self: *Self, gpa: *Allocator, new_capacity: usize) !void {
var better_capacity = self.capacity;
if (better_capacity >= new_capacity) return;
@ -239,6 +242,12 @@ pub fn MultiArrayList(comptime S: type) type {
return self.setCapacity(gpa, better_capacity);
}
/// Modify the array so that it can hold at least `additional_count` **more** items.
/// Invalidates pointers if additional memory is needed.
pub fn ensureUnusedCapacity(self: *Self, gpa: *Allocator, additional_count: usize) !void {
return self.ensureTotalCapacity(gpa, self.len + additional_count);
}
/// Modify the array so that it can hold exactly `new_capacity` items.
/// Invalidates pointers if additional memory is needed.
/// `new_capacity` must be greater or equal to `len`.
@ -305,7 +314,7 @@ test "basic usage" {
testing.expectEqual(@as(usize, 0), list.items(.a).len);
try list.ensureCapacity(ally, 2);
try list.ensureTotalCapacity(ally, 2);
list.appendAssumeCapacity(.{
.a = 1,
@ -382,7 +391,7 @@ test "regression test for @reduce bug" {
}){};
defer list.deinit(ally);
try list.ensureCapacity(ally, 20);
try list.ensureTotalCapacity(ally, 20);
try list.append(ally, .{ .tag = .keyword_const, .start = 0 });
try list.append(ally, .{ .tag = .identifier, .start = 6 });
@ -462,7 +471,7 @@ test "ensure capacity on empty list" {
var list = MultiArrayList(Foo){};
defer list.deinit(ally);
try list.ensureCapacity(ally, 2);
try list.ensureTotalCapacity(ally, 2);
list.appendAssumeCapacity(.{ .a = 1, .b = 2 });
list.appendAssumeCapacity(.{ .a = 3, .b = 4 });
@ -477,7 +486,7 @@ test "ensure capacity on empty list" {
testing.expectEqualSlices(u8, &[_]u8{ 6, 8 }, list.items(.b));
list.len = 0;
try list.ensureCapacity(ally, 16);
try list.ensureTotalCapacity(ally, 16);
list.appendAssumeCapacity(.{ .a = 9, .b = 10 });
list.appendAssumeCapacity(.{ .a = 11, .b = 12 });