lang/funcs: add 'strrev' interpolation function. (#21091)

lang/functions.go

@@ -99,6 +99,7 @@ func (s *Scope) Functions() map[string]function.Function {
 			"slice":            funcs.SliceFunc,
 			"sort":             funcs.SortFunc,
 			"split":            funcs.SplitFunc,
+			"strrev":           stdlib.ReverseFunc,
 			"substr":           stdlib.SubstrFunc,
 			"timestamp":        funcs.TimestampFunc,
 			"timeadd":          funcs.TimeAddFunc,

website/docs/configuration/functions/reverse.html.md

@@ -25,3 +25,7 @@ with all of the same elements as the given sequence but in reverse order.
   1,
 ]
 ```
+
+## Related Functions
+
+* [`strrev`](./strrev.html) reverses a string.

website/docs/configuration/functions/strrev.html.md

@@ -0,0 +1,29 @@
+---
+layout: "functions"
+page_title: "strrev - Functions - Configuration Language"
+sidebar_current: "docs-funcs-string-strrev"
+description: |-
+  The strrev function reverses a string.
+---
+
+# `strrev` Function
+
+`strrev` reverses the characters in a string.
+Note that the characters are treated as _Unicode characters_ (in technical terms, Unicode [grapheme cluster boundaries](https://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries) are respected).
+
+```hcl
+strrev(string)
+```
+
+## Examples
+
+```
+> strrev("hello")
+olleh
+> strrev("a ☃")
+☃ a
+```
+
+## Related Functions
+
+* [`reverse`](./reverse.html) reverses a sequence.

website/layouts/functions.erb

@@ -87,6 +87,10 @@
                 <a href="/docs/configuration/functions/split.html">split</a>
               </li>
 
+              <li>
+                <a href="/docs/configuration/functions/strrev.html">strrev</a>
+              </li>
+
               <li>
                 <a href="/docs/configuration/functions/substr.html">substr</a>
               </li>