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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/Random.h>
#include <AK/Vector.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
#include <LibCore/System.h>
#include <LibMain/Main.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;
bool allow_repeats = 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(allow_repeats, "Pick lines at random rather than shuffling. The program will continue indefinitely if no `-n` option is specified", "repeat", 'r');
args_parser.add_option(is_zero_terminated, "Split input on \\0, not newline", "zero-terminated", 'z');
args_parser.parse(arguments);
auto file = TRY(Core::File::open_file_or_standard_stream(path, Core::File::OpenMode::Read));
ByteBuffer buffer = TRY(file->read_until_eof());
u8 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] == 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;
Array<u8, 1> delimiter_bytes { delimiter };
if (allow_repeats) {
for (size_t line_count = 0; !head_count.has_value() || line_count < head_count.value(); ++line_count) {
size_t i = get_random_uniform(lines.size());
out(lines.at(i));
out(delimiter_bytes);
}
} else {
shuffle(lines);
for (size_t i = 0; i < min(head_count.value_or(lines.size()), lines.size()); ++i) {
out(lines.at(i));
out(delimiter_bytes);
}
}
return 0;
}
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