1

我正在尝试使用 Ruby 的树梢打开 Packages.gz，但在使关键字和值明确时遇到了麻烦。这是我的树顶语法：

grammar Debian
  rule collection
    entry+
  end
  rule entry
    (tag space value)
  end

  rule package_details
    tag value &[^$]
  end
  rule tag 
    [A-Za-z0-9\-]+ ":"
  end
  rule value
    (!tag value_line+ "\n")+
  end
  rule value_line
    ([A-Za-z0-9 <>@()=\.\-|/,_"':])+
  end
  rule space
    [ \t]+
  end
end

这是我的示例输入：

Package: acct
Priority: optional
Section: admin
Installed-Size: 352
Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
Original-Maintainer: Mathieu Trudel <mathieu.tl@gmail.com>
Architecture: i386
Version: 6.5.4-2ubuntu1
Depends: dpkg (>= 1.15.4) | install-info, libc6 (>= 2.4)
Filename: pool/main/a/acct/acct_6.5.4-2ubuntu1_i386.deb
Size: 111226
MD5sum: 10cba1458ace8c31169c0e9e915c9a0f
SHA1: 6c2dcdc480144a9922329cd4fa22c7d1cb83fcbb
SHA256: bf8d8bb8eef3939786a1cefc39f94079f43464b71099f4a59b61b24cafdbc010
Description: The GNU Accounting utilities for process and login accounting
 GNU Accounting Utilities is a set of utilities which reports and summarizes
 data about user connect times and process execution statistics.
 .
 "Login accounting" provides summaries of system resource usage based on connect
 time, and "process accounting" provides summaries based on the commands
 executed on the system.
 .
 The 'last' command is provided by the sysvinit package and not included here.
Homepage: http://www.gnu.org/software/acct/
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Origin: Ubuntu
Supported: 18m

这几乎可以 100% 工作，但是在检查 url 时会失败。问题是一个 URL 包含一个“：”，我似乎无法抓住它。当我编辑示例的主页条目并将“：”替换为“_”时，它会直接通过。

这是我的第一个 PEG 语法，但我可以说我需要使它不那么模棱两可/更简洁。查看高级文档，我想将标签定义为

rule tag
  !(!'\n' .) [A-Za-z0-9\-]+ ":"
end

但我不完全明白它在做什么。标签不能（没有换行或任何东西）我的意思是（换行或什么都没有）。微妙之处逃过了我的...

切换到那种格式会帮助我吗？有人知道为什么不匹配吗？

4

1 回答 1

0

在这一点上，我似乎已经掌握了一种有效的语法：

grammar Debian
  # The file is too big for us to emit a package_list. Look at parser.rb to see how I just split the string.
  #rule package_list
  #  (package "\n"?)+ <DebianSyntaxNode::PackageList>
  #end
  rule package
    (tag / value)+ <DebianSyntaxNode::Package>
  end

  rule tag
    tag_value tag_stop <DebianSyntaxNode::Tag>
  end
  rule tag_value
    [\w\-]+ <DebianSyntaxNode::TagValue>
  end
  rule tag_stop
    ": " <DebianSyntaxNode::TagStop>
  end

  rule value
    value_line value_stop <DebianSyntaxNode::Value>
    # value_line value_stop <DebianSyntaxNode::Value>
  end
  rule value_line
    (!"\n" .)+ <DebianSyntaxNode::ValueLine>
    # ([\w \. " , \- ' : / < > @ ( ) = | \[ \] + ; ~ í á * % `])+ <DebianSyntaxNode::ValueLine>
  end
  rule value_stop
    "\n"? <DebianSyntaxNode::ValueStop>
  end
end

问题是现在 value_line 在它是多行条目时不包含“\n”。另外，我必须在解析器中组合多行条目。

如果您想查看这段代码的去向，请查看我开始的 github 小项目：https ://github.com/derdewey/Debian-Packages-Parser

于 2010-11-10T19:19:26.017 回答