From 1b25ca34fa28274299a3ee3b6be2483403536530 Mon Sep 17 00:00:00 2001 From: Joe Mooring Date: Thu, 10 Nov 2022 21:28:22 -0800 Subject: Update the findRE and replaceRE functions (#1881) Co-authored-by: anakinsleftleg <77084568+anakinsleftleg@users.noreply.github.com> Closes #1793 --- content/en/functions/findRe.md | 46 ++++++++++++++++------------------- content/en/functions/replacere.md | 51 ++++++++++++++++++++++++--------------- 2 files changed, 53 insertions(+), 44 deletions(-) diff --git a/content/en/functions/findRe.md b/content/en/functions/findRe.md index b6375be9c..2896e3cd1 100644 --- a/content/en/functions/findRe.md +++ b/content/en/functions/findRe.md @@ -1,44 +1,40 @@ --- title: findRE -description: Returns a list of strings that match the regular expression. -date: 2017-02-01 -publishdate: 2017-02-01 -lastmod: 2017-02-01 +description: Returns a slice of strings that match the regular expression. categories: [functions] menu: docs: - parent: "functions" + parent: functions keywords: [regex] -signature: ["findRE PATTERN INPUT [LIMIT]"] -workson: [] -hugoversion: -relatedfuncs: [] -deprecated: false +signature: + - "findRE PATTERN INPUT [LIMIT]" + - "strings.FindRE PATTERN INPUT [LIMIT]" +relatedfuncs: [replaceRE] aliases: [] --- +By default, the `findRE` function finds all matches. You can limit the number of matches with an optional LIMIT paramater. -By default all matches will be included. The number of matches can be limited with an optional third parameter. +When specifying the regular expression, use a raw [string literal] (backticks) instead of an interpreted string literal (double quotes) to simplify the syntax. With an interpreted string literal you must escape backslashes. -The example below returns a list of all second level headers (`

`) in the content: +The syntax of the regular expression is the same general syntax used by Perl, Python, and other languages. More precisely, it is the syntax accepted by [RE2] except for `\C`. -``` -{{ findRE "(.|\n)*?

" .Content }} +This example returns a slice of all second level headings (`h2` elements) within the rendered `.Content`: + +```go-html-template +{{ findRE `(?s).*?` .Content }} ``` -You can limit the number of matches in the list with a third parameter. The following example shows how to limit the returned value to just one match (or none, if there are no matched substrings): +The `s` flag causes `.` to match `\n` as well, allowing us to find an `h2` element that contains newlines. -``` -{{ findRE "(.|\n)*?" .Content 1 }} - +To limit the number of matches to one: + +```go-html-template +{{ findRE `(?s).*?` .Content 1 }} ``` {{% note %}} -Hugo uses Go's [Regular Expression package](https://golang.org/pkg/regexp/), which is the same general syntax used by Perl, Python, and other languages but with a few minor differences for those coming from a background in PCRE. For a full syntax listing, see the [GitHub wiki for re2](https://github.com/google/re2/wiki/Syntax). - -If you are just learning RegEx, or at least Go's flavor, you can practice pattern matching in the browser at . +You can write and test your regular expression using [regex101.com](https://regex101.com/). Be sure to select the Go flavor before you begin. {{% /note %}} -[partials]: /templates/partials/ -[`plainify`]: /functions/plainify/ -[toc]: /content-management/toc/ -[`urlize`]: /functions/urlize +[RE2]: https://github.com/google/re2/wiki/Syntax +[string literal]: https://go.dev/ref/spec#String_literals diff --git a/content/en/functions/replacere.md b/content/en/functions/replacere.md index a2149b6d3..f1e34ba65 100644 --- a/content/en/functions/replacere.md +++ b/content/en/functions/replacere.md @@ -1,34 +1,47 @@ --- title: replaceRE -description: Replaces all occurrences of a regular expression with the replacement pattern. -date: 2017-02-01 -publishdate: 2017-02-01 -lastmod: 2020-09-07 +description: Returns a string, replacing all occurrences of a regular expression with a replacement pattern. categories: [functions] menu: docs: - parent: "functions" + parent: functions keywords: [regex] -signature: ["strings.ReplaceRE PATTERN REPLACEMENT INPUT [LIMIT]", "replaceRE PATTERN REPLACEMENT INPUT [LIMIT]"] -workson: [] -hugoversion: -relatedfuncs: [] -deprecated: false +signature: + - "replaceRE PATTERN REPLACEMENT INPUT [LIMIT]" + - "strings.ReplaceRE PATTERN REPLACEMENT INPUT [LIMIT]" +relatedfuncs: [findRE] aliases: [] --- +By default, the `replaceRE` function replaces all matches. You can limit the number of matches with an optional LIMIT paramater. -`strings.ReplaceRE` returns a copy of `INPUT`, replacing all matches of the regular -expression `PATTERN` with the replacement text `REPLACEMENT`. -The number of replacements can be limited with an optional `LIMIT` parameter. +When specifying the regular expression, use a raw [string literal] (backticks) instead of an interpreted string literal (double quotes) to simplify the syntax. With an interpreted string literal you must escape backslashes. +The syntax of the regular expression is the same general syntax used by Perl, Python, and other languages. More precisely, it is the syntax accepted by [RE2] except for `\C`. + +This example replaces two or more consecutive hyphens with a single hyphen: + +```go-html-template +{{ $s := "a-b--c---d" }} +{{ replaceRE `(-{2,})` "-" $s }} → a-b-c-d ``` -{{ replaceRE "^https?://([^/]+).*" "$1" "http://gohugo.io/docs" }}` → "gohugo.io" -{{ "http://gohugo.io/docs" | replaceRE "^https?://([^/]+).*" "$1" }}` → "gohugo.io" -{{ replaceRE "a+b" "X" "aabbaabbab" 1 }} → "Xbaabbab" + +To limit the number of replacements to one: + +```go-html-template +{{ $s := "a-b--c---d" }} +{{ replaceRE `(-{2,})` "-" $s 1 }} → a-b-c---d ``` -{{% note %}} -Hugo uses Go's [Regular Expression package](https://golang.org/pkg/regexp/), which is the same general syntax used by Perl, Python, and other languages but with a few minor differences for those coming from a background in PCRE. For a full syntax listing, see the [GitHub wiki for re2](https://github.com/google/re2/wiki/Syntax). +You can use `$1`, `$2`, etc. within the replacement string to insert the groups captured within the regular expression: -If you are just learning RegEx, or at least Go's flavor, you can practice pattern matching in the browser at . +```go-html-template +{{ $s := "http://gohugo.io/docs" }} +{{ replaceRE "^https?://([^/]+).*" "$1" $s }} → gohugo.io +``` + +{{% note %}} +You can write and test your regular expression using [regex101.com](https://regex101.com/). Be sure to select the Go flavor before you begin. {{% /note %}} + +[RE2]: https://github.com/google/re2/wiki/Syntax +[string literal]: https://go.dev/ref/spec#String_literals -- cgit v1.2.3