ArrayList(u8) support writer interface

master
Jonathan Marler 2020-06-13 11:35:18 -06:00 committed by Andrew Kelley
parent 593db7e8d0
commit f0b8791da7
1 changed files with 29 additions and 12 deletions

View File

@ -162,19 +162,24 @@ pub fn ArrayListAligned(comptime T: type, comptime alignment: ?u29) type {
mem.copy(T, self.items[oldlen..], items);
}
/// Same as `append` except it returns the number of bytes written, which is always the same
/// as `m.len`. The purpose of this function existing is to match `std.io.OutStream` API.
/// This function may be called only when `T` is `u8`.
fn appendWrite(self: *Self, m: []const u8) !usize {
try self.appendSlice(m);
return m.len;
}
pub usingnamespace if (T != u8) struct { } else struct {
pub const Writer = std.io.Writer(*Self, error{OutOfMemory}, appendWrite);
/// Initializes an OutStream which will append to the list.
/// This function may be called only when `T` is `u8`.
pub fn outStream(self: *Self) std.io.OutStream(*Self, error{OutOfMemory}, appendWrite) {
return .{ .context = self };
}
/// Initializes a Writer which will append to the list.
pub fn writer(self: *Self) Writer {
return .{ .context = self };
}
/// Deprecated: use `writer`
pub const outStream = writer;
/// Same as `append` except it returns the number of bytes written, which is always the same
/// as `m.len`. The purpose of this function existing is to match `std.io.Writer` API.
fn appendWrite(self: *Self, m: []const u8) !usize {
try self.appendSlice(m);
return m.len;
}
};
/// Append a value to the list `n` times.
/// Allocates more memory as necessary.
@ -694,3 +699,15 @@ test "std.ArrayList.shrink still sets length on error.OutOfMemory" {
list.shrink(1);
testing.expect(list.items.len == 1);
}
test "std.ArrayList.writer" {
var list = ArrayList(u8).init(std.testing.allocator);
defer list.deinit();
const writer = list.writer();
try writer.writeAll("a");
try writer.writeAll("bc");
try writer.writeAll("d");
try writer.writeAll("efg");
testing.expectEqualSlices(u8, list.items, "abcdefg");
}