如何在Perl6中逐行读取gz文件

Question

我试图在Perl6中逐行读取一个巨大的gz文件.

我正在尝试做这样的事情

my $file = 'huge_file.gz';
for $file.IO.lines -> $line {
    say $line;
}

但是这给出了错误,即我有一个格式错误的UTF-8.我无法看到如何从帮助页面https://docs.perl6.org/language/unicode#UTF8-C8或https://docs.perl6.org/language/io阅读gzip资料

我想完成与Perl5相同的事情:http://blog-en.openalfa.com/how-to-read-and-write-compressed-files-in-perl

如何在Perl6中逐行读取gz文件？

谢谢

Answer 1

我建议将模块Compress::Zlib用于此目的.你可以在github上找到自述文件和代码并安装它zef install Compress::Zlib.

此示例取自标题为"wrap"的测试文件编号3:

use Test;
use Compress::Zlib;

gzspurt("t/compressed.gz", "this\nis\na\ntest");

my $wrap = zwrap(open("t/compressed.gz"), :gzip);
is $wrap.get, "this\n", 'first line roundtrips';
is $wrap.get, "is\n", 'second line roundtrips';
is $wrap.get, "a\n", 'third line roundtrips';
is $wrap.get, "test", 'fourth line roundtrips';

这可能是获得您想要的最简单方法.

Answer 2

使用 read-file-content该方法存档:: Libarchive模块,但我不知道是否该方法读取所有行到内存中一次:

use Archive::Libarchive; 
use Archive::Libarchive::Constants;

my $a = Archive::Libarchive.new: operation => LibarchiveRead, file => 'test.tar.gz';
my Archive::Libarchive::Entry $e .= new;

my $log = '';
while $a.next-header($e) {
    $log = get-log($a,$e) if $e.pathname.ends-with('.txt');
}

sub get-log($a, $e) {
    return $a.read-file-content($e).decode('UTF8-C8');
}

Answer 3

如果您正在使用快速解决方案,则可以从gzip进程的stdout管道中读取行:

my $proc = run :out, "gzip", "--to-stdout", "--decompress", "MyFile.gz"

for $proc.out.lines -> $line {
    say $line;
}

$proc.out.close;