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// 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 assert = std.debug.assert;
const testing = std.testing;
pub fn BufferedReader(comptime buffer_size: usize, comptime ReaderType: type) type {
return struct {
unbuffered_reader: ReaderType,
fifo: FifoType = FifoType.init(),
pub const Error = ReaderType.Error;
pub const Reader = io.Reader(*Self, Error, read);
const Self = @This();
const FifoType = std.fifo.LinearFifo(u8, std.fifo.LinearFifoBufferType{ .Static = buffer_size });
pub fn read(self: *Self, dest: []u8) Error!usize {
var dest_index: usize = 0;
while (dest_index < dest.len) {
const written = self.fifo.read(dest[dest_index..]);
if (written == 0) {
// fifo empty, fill it
const writable = self.fifo.writableSlice(0);
assert(writable.len > 0);
const n = try self.unbuffered_reader.read(writable);
if (n == 0) {
// reading from the unbuffered stream returned nothing
// so we have nothing left to read.
return dest_index;
}
self.fifo.update(n);
}
dest_index += written;
}
return dest.len;
}
pub fn reader(self: *Self) Reader {
return .{ .context = self };
}
};
}
pub fn bufferedReader(underlying_stream: anytype) BufferedReader(4096, @TypeOf(underlying_stream)) {
return .{ .unbuffered_reader = underlying_stream };
}
test "io.BufferedReader" {
const OneByteReadReader = struct {
str: []const u8,
curr: usize,
const Error = error{NoError};
const Self = @This();
const Reader = io.Reader(*Self, Error, read);
fn init(str: []const u8) Self {
return Self{
.str = str,
.curr = 0,
};
}
fn read(self: *Self, dest: []u8) Error!usize {
if (self.str.len <= self.curr or dest.len == 0)
return 0;
dest[0] = self.str[self.curr];
self.curr += 1;
return 1;
}
fn reader(self: *Self) Reader {
return .{ .context = self };
}
};
const str = "This is a test";
var one_byte_stream = OneByteReadReader.init(str);
var buf_reader = bufferedReader(one_byte_stream.reader());
const stream = buf_reader.reader();
const res = try stream.readAllAlloc(testing.allocator, str.len + 1);
defer testing.allocator.free(res);
testing.expectEqualSlices(u8, str, res);
}
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