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89 lines
2.1 KiB
Markdown
89 lines
2.1 KiB
Markdown
---
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title: findRESubmatch
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description: Returns a slice of all successive matches of the regular expression. Each element is a slice of strings holding the text of the leftmost match of the regular expression and the matches, if any, of its subexpressions.
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categories: [functions]
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menu:
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docs:
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parent: functions
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keywords: [regex]
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signature:
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- "findRESubmatch PATTERN INPUT [LIMIT]"
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- "strings.FindRESubmatch PATTERN INPUT [LIMIT]"
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relatedfuncs: [findRE, replaceRE]
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---
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By default, `findRESubmatch` finds all matches. You can limit the number of matches with an optional LIMIT parameter. A return value of nil indicates no match.
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{{% readfile file="/functions/common/regular-expressions.md" %}}
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## Demonstrative examples
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```go-html-template
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{{ findRESubmatch `a(x*)b` "-ab-" }} → [["ab" ""]]
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{{ findRESubmatch `a(x*)b` "-axxb-" }} → [["axxb" "xx"]]
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{{ findRESubmatch `a(x*)b` "-ab-axb-" }} → [["ab" ""] ["axb" "x"]]
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{{ findRESubmatch `a(x*)b` "-axxb-ab-" }} → [["axxb" "xx"] ["ab" ""]]
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{{ findRESubmatch `a(x*)b` "-axxb-ab-" 1 }} → [["axxb" "xx"]]
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```
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## Practical example
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This markdown:
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```text
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- [Example](https://example.org)
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- [Hugo](https://gohugo.io)
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```
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Produces this HTML:
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```html
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<ul>
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<li><a href="https://example.org">Example</a></li>
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<li><a href="https://gohugo.io">Hugo</a></li>
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</ul>
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```
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To match the anchor elements, capturing the link destination and text:
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```go-html-template
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{{ $regex := `<a\s*href="(.+?)">(.+?)</a>` }}
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{{ $matches := findRESubmatch $regex .Content }}
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```
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Viewed as JSON, the data structure of `$matches` in the code above is:
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```json
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[
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[
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"<a href=\"https://example.org\"></a>Example</a>",
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"https://example.org",
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"Example"
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],
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[
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"<a href=\"https://gohugo.io\">Hugo</a>",
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"https://gohugo.io",
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"Hugo"
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]
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]
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```
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To render the `href` attributes:
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```go-html-template
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{{ range $matches }}
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{{ index . 1 }}
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{{ end }}
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```
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Result:
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```text
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https://example.org
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https://gohugo.io
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```
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{{% note %}}
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You can write and test your regular expression using [regex101.com](https://regex101.com/). Be sure to select the Go flavor before you begin.
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{{% /note %}}
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