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/*
* Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
* Copyright (c) 2022, Eli Youngs <eli.m.youngs@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/DeprecatedString.h>
#include <AK/Random.h>
#include <AK/Vector.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/Stream.h>
#include <LibCore/System.h>
#include <LibMain/Main.h>
#include <stdlib.h>
ErrorOr<int> serenity_main(Main::Arguments arguments)
{
TRY(Core::System::pledge("stdio rpath"));
Core::ArgsParser args_parser;
StringView path;
Optional<size_t> head_count;
bool is_zero_terminated = false;
args_parser.add_positional_argument(path, "File", "file", Core::ArgsParser::Required::No);
args_parser.add_option(head_count, "Output at most \"count\" lines", "head-count", 'n', "count");
args_parser.add_option(is_zero_terminated, "Split input on \\0, not newline", "zero-terminated", 'z');
args_parser.parse(arguments);
auto file = TRY(Core::Stream::File::open_file_or_standard_stream(path, Core::Stream::OpenMode::Read));
ByteBuffer buffer = TRY(file->read_until_eof());
u8 input_delimiter = is_zero_terminated ? '\0' : '\n';
Vector<Bytes> lines;
auto bytes = buffer.span();
size_t line_start = 0;
size_t line_length = 0;
for (size_t i = 0; i < bytes.size(); ++i) {
if (bytes[i] == input_delimiter) {
lines.append(bytes.slice(line_start, line_length));
line_start = i + 1;
line_length = 0;
} else {
++line_length;
}
}
if (line_length > 0) {
lines.append(bytes.slice(line_start));
}
if (lines.is_empty())
return 0;
// Fisher-Yates shuffle
Bytes tmp;
for (size_t i = lines.size() - 1; i >= 1; --i) {
size_t j = get_random_uniform(i + 1);
// Swap i and j
if (i == j)
continue;
tmp = lines[j];
lines[j] = lines[i];
lines[i] = tmp;
}
Array<u8, 1> output_delimiter = { '\n' };
for (size_t i = 0; i < min(head_count.value_or(lines.size()), lines.size()); ++i) {
TRY(Core::System::write(STDOUT_FILENO, lines.at(i)));
TRY(Core::System::write(STDOUT_FILENO, output_delimiter));
}
return 0;
}
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