blob: 3b06555deb98215c6366f3b0aaff1f88e1d26b4d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
// SPDX-License-Identifier: MIT
// Copyright (c) 2015-2021 Zig Contributors
// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
// The MIT license requires this copyright notice to be included in all copies
// and substantial portions of the software.
const std = @import("../std.zig");
const io = std.io;
const testing = std.testing;
/// A Reader that counts how many bytes has been read from it.
pub fn CountingReader(comptime ReaderType: anytype) type {
return struct {
child_reader: ReaderType,
bytes_read: u64 = 0,
pub const Error = ReaderType.Error;
pub const Reader = io.Reader(*@This(), Error, read);
pub fn read(self: *@This(), buf: []u8) Error!usize {
const amt = try self.child_reader.read(buf);
self.bytes_read += amt;
return amt;
}
pub fn reader(self: *@This()) Reader {
return .{ .context = self };
}
};
}
pub fn countingReader(reader: anytype) CountingReader(@TypeOf(reader)) {
return .{ .child_reader = reader };
}
test "io.CountingReader" {
const bytes = "yay" ** 100;
var fbs = io.fixedBufferStream(bytes);
var counting_stream = countingReader(fbs.reader());
const stream = counting_stream.reader();
//read and discard all bytes
while (stream.readByte()) |_| {} else |err| {
try testing.expect(err == error.EndOfStream);
}
try testing.expect(counting_stream.bytes_read == bytes.len);
}
|
