如何使用正则表达式匹配子字符串并在匹配之前和之后获得一些额外的字符串

Question

在下面的字符串中，我想提取子字符串。

场景：

1. 只要wafers_starts在字符串中匹配，就应该从之前的匹配<ac:structured-macro中选择字符串。 （以下示例中有两个，我只需要在wafers_starts之前的那个）
2. 应该选择子字符串，直到它匹配wafers_ends加上第一个结束标记</ac:structured-macro>。

示例代码：

if ($matches -ne $null) { Remove-Variable $matches }

$confluenceHtml = "<h2>Description</h2><ac:structured-macro ac:macro-id=""77f3n751-39w7-4746-acd4-bee7586449ed"" ac:name=""warning"" ac:schema-version=""1""><ac:parameter ac:name=""title"">Compatibility</ac:parameter><ac:rich-text-body><p class=""auto-cursor-target""><br/></p><table class=""wrapped""><colgroup> <col/> <col/> <col/> </colgroup><tbody><tr><th><p>Prerequisite</p><p>This needs a progressive rollout </p></td></tr></tbody></table><p class=""auto-cursor-target""><br/></p><p class=""auto-cursor-target""><br/></p><ac:structured-macro ac:macro-id=""4657sd53-e024-4ea3-a5e2-4586667542da"" ac:name=""excerpt"" ac:schema-version=""1""><ac:parameter ac:name=""hidden"">true</ac:parameter><ac:parameter ac:name=""atlassian-macro-output-type"">INLINE</ac:parameter><ac:rich-text-body><p>wafers_starts</p></ac:rich-text-body></ac:structured-macro><h2>Deployment Notes</h2><ac:structured-macro ac:macro-id=""77f5e121-31d7-4576-awq4-bej57t6d39ed"" ac:name=""warning"" ac:schema-version=""1""><ac:parameter ac:name=""title"">Compatibility</ac:parameter>  <ac:rich-text-body><p class=""auto-cursor-target""><br/></p><table class=""wrapped""><colgroup> <col/> <col/> <col/> </colgroup><tbody><tr><th><p>Prerequisite</p><p>This needs a progressive rollout 2,3,4,5 and so on</p></td></tr></tbody></table><p class=""auto-cursor-target""><br/></p><ac:structured-macro ac:macro-id=""72d7h552-a5dd-44cc-a4re-6f3247574fbd"" ac:name=""excerpt"" ac:schema-version=""1""><ac:parameter ac:name=""hidden"">true</ac:parameter><ac:parameter ac:name=""atlassian-macro-output-type"">INLINE</ac:parameter><ac:rich-text-body><p>wafers_ends</p></ac:rich-text-body></ac:structured-macro><p class=""auto-cursor-target""><br/></p></ac:structured-macro>"

if ($confluenceHtml -match '\<ac:structured-macro.+?wafers_starts([\s\S]*)wafers_ends.+?\<\/ac:structured-macro\>') {  
    $matches[0]
}

OUTPUT：

<ac:structured-macro ac:macro-id="77f3n751-39w7-4746-acd4-bee7586449ed" ac:name="warning" ac:schema-version="1"><ac:parameter ac:name="title">Compatibility</ac:parameter><ac:rich-text-body><p class="auto-cursor-target"><br/></p><table class="wrapped"><colgroup> <col/> <col/> <col/> </colgroup><tbody><tr><th><p>Prerequisite</p><p>This needs a progressive rollout </p></td></tr></tbody></table><p class="auto-cursor-target"><br/></p><p class="auto-cursor-target"><br/></p><ac:structured-macro ac:macro-id="4657sd53-e024-4ea3-a5e2-4586667542da" ac:name="excerpt" ac:schema-version="1"><ac:parameter ac:name="hidden">true</ac:parameter><ac:parameter ac:name="atlassian-macro-output-type">INLINE</ac:parameter><ac:rich-text-body><p>wafers_starts</p></ac:rich-text-body></ac:structured-macro><h2>Deployment Notes</h2><ac:structured-macro ac:macro-id="77f5e121-31d7-4576-awq4-bej57t6d39ed" ac:name="warning" ac:schema-version="1"><ac:parameter ac:name="title">Compatibility</ac:parameter>  <ac:rich-text-body><p class="auto-cursor-target"><br/></p><table class="wrapped"><colgroup> <col/> <col/> <col/> </colgroup><tbody><tr><th><p>Prerequisite</p><p>This needs a progressive rollout 2,3,4,5 and so on</p></td></tr></tbody></table><p class="auto-cursor-target"><br/></p><ac:structured-macro ac:macro-id="72d7h552-a5dd-44cc-a4re-6f3247574fbd" ac:name="excerpt" ac:schema-version="1"><ac:parameter ac:name="hidden">true</ac:parameter><ac:parameter ac:name="atlassian-macro-output-type">INLINE</ac:parameter><ac:rich-text-body><p>wafers_ends</p></ac:rich-text-body></ac:structured-macro>

问题：

子串的结尾是OK。但是，即使经过多次尝试也无法获得子串的开头。正则表达式包括从<ac:structured-macro第一次出现的开始。

期望的输出：

我只想要下面的子字符串，它只包含<ac:structured-macro一次，就在第一个匹配的字符串wafers_starts之前

<ac:structured-macro ac:macro-id="4657sd53-e024-4ea3-a5e2-4586667542da" ac:name="excerpt" ac:schema-version="1"><ac:parameter ac:name="hidden">true</ac:parameter><ac:parameter ac:name="atlassian-macro-output-type">INLINE</ac:parameter><ac:rich-text-body><p>wafers_starts</p></ac:rich-text-body></ac:structured-macro><h2>Deployment Notes</h2><ac:structured-macro ac:macro-id="77f5e121-31d7-4576-awq4-bej57t6d39ed" ac:name="warning" ac:schema-version="1"><ac:parameter ac:name="title">Compatibility</ac:parameter>  <ac:rich-text-body><p class="auto-cursor-target"><br/></p><table class="wrapped"><colgroup> <col/> <col/> <col/> </colgroup><tbody><tr><th><p>Prerequisite</p><p>This needs a progressive rollout 2,3,4,5 and so on</p></td></tr></tbody></table><p class="auto-cursor-target"><br/></p><ac:structured-macro ac:macro-id="72d7h552-a5dd-44cc-a4re-6f3247574fbd" ac:name="excerpt" ac:schema-version="1"><ac:parameter ac:name="hidden">true</ac:parameter><ac:parameter ac:name="atlassian-macro-output-type">INLINE</ac:parameter><ac:rich-text-body><p>wafers_ends</p></ac:rich-text-body></ac:structured-macro>

题：

寻找纠正/工作的正则表达式模式。

Answer 1

你需要使用这个正则表达式，它使用tempered greedy token (?:(?!ac:structured-macro).)+模式拒绝ac:structured-macro在第一次匹配后的任何进一步匹配。

<ac:structured-macro(?:(?!ac:structured-macro).)+wafers_starts([\s\S]*)wafers_ends.+?<\/ac:structured-macro>

Demo