正则表达式用根相对链接替换相对链接 [英] Regex to replace relative link with root relative link

问题描述

我有一个包含所有不同类型链接（相对，绝对，根相对）的html的文本字符串。我需要一个可以由PHP的 preg_replace 执行的正则表达式，用相对链接替换所有相对链接，而不触及任何其他链接。我已经有了根路径。

I have a string of text that contains html with all different types of links (relative, absolute, root-relative). I need a regex that can be executed by PHP's preg_replace to replace all relative links with root-relative links, without touching any of the other links. I have the root path already.

替换了链接：

<tag ... href="path/to_file.ext" ... >   --->   <tag ... href="/basepath/path/to_file.ext" ... >
<tag ... href="path/to_file.ext" ... />   --->   <tag ... href="/basepath/path/to_file.ext" ... />

未触动的链接：

<tag ... href="/any/path" ... >
<tag ... href="/any/path" ... />
<tag ... href="protocol://domain.com/any/path" ... >
<tag ... href="protocol://domain.com/any/path" ... />

推荐答案

如果您只想更改基本URI，可以尝试 BASE 元素：

If you just want to change the base URI, you can try the BASE element:

<base href="/basepath/">

但请注意，更改基URI会影响所有相对URI，而不仅仅是相对URI路径。

But note that changing the base URI affects all relative URIs and not just relative URI paths.

否则，如果您真的想使用正则表达式，请考虑您想要的相对路径必须是 path-noscheme <的类型/ em>（参见 RFC 3986 ）：

Otherwise, if you really want to use regular expression, consider that a relative path like you want must be of the type path-noscheme (see RFC 3986):

path-noscheme = segment-nz-nc *( "/" segment )
segment       = *pchar
segment-nz-nc = 1*( unreserved / pct-encoded / sub-delims / "@" )
                ; non-zero-length segment without any colon ":"
pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"
pct-encoded   = "%" HEXDIG HEXDIG
unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
sub-delims    = "!" / "$" / "&" / "'" / "(" / ")"
              / "*" / "+" / "," / ";" / "="

因此URI的开头必须匹配：

So the begin of the URI must match:

^([a-zA-Z0-9-._~!$&'()*+,;=@]|%[0-9a-fA-F]{2})+($|/)

但是请使用适当的HTML解析器来解析HTML，从而构建一个DOM。然后，您可以查询DOM以获取 href 属性，并使用上面的正则表达式测试该值。

But please use a proper HTML parser for parsing the HTML an build a DOM out of that. Then you can query the DOM to get the href attributes and test the value with the regular expression above.

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