Add files via upload

[kn1g78]

archive/zip.Reader 在第一次通过 Open / ReadDir 以 fs.FS 方式访问归档时，会先构建一份文件索引。

原来的实现会把 ZIP 中每个条目的隐式父目录都提前补齐，再把这些目录和真实文件一起排序。在目录层级很深、条目很多的归档上，初始化时损耗的资源会变得很高。很多时间都花在构造和整理这些中间目录上，而不是花在真正的查找上。

这次调整优化了如下几条：

• 初始化时只保留归档中真实存在的条目，并建立按完整路径查找的索引
• 不再在构建阶段预先展开所有隐式父目录
• 当 Open 命中一个未显式存在的目录时，再根据前缀判断它是否是一个隐式目录
• 当 ReadDir 枚举目录时，再按前缀整理当前层级的直接子项

这样做之后，Reader 不需要在第一次访问时把整棵中间目录树先拼出来，尤其能避免深层路径场景下的大量重复工作。

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[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

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[gopherbot]

Message from Ian Lance Taylor:

Patch Set 1:

(1 comment)

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