Add regexp compile helper function for templates (#601)

## Tests
unit test

libs/template/helpers.go

@@ -2,6 +2,7 @@ package template
 
 import (
 	"fmt"
+	"regexp"
 	"text/template"
 )
 
@@ -17,4 +18,8 @@ var helperFuncs = template.FuncMap{
 	"fail": func(format string, args ...any) (any, error) {
 		return nil, ErrFail{fmt.Sprintf(format, args...)}
 	},
+	// Alias for https://pkg.go.dev/regexp#Compile. Allows usage of all methods of regexp.Regexp
+	"regexp": func(expr string) (*regexp.Regexp, error) {
+		return regexp.Compile(expr)
+	},
 }

libs/template/helpers_test.go

@@ -0,0 +1,25 @@
+package template
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTemplateRegexpCompileFunction(t *testing.T) {
+	ctx := context.Background()
+	tmpDir := t.TempDir()
+
+	r, err := newRenderer(ctx, nil, "./testdata/regexp-compile/template", "./testdata/regexp-compile/library", tmpDir)
+	require.NoError(t, err)
+
+	err = r.walk()
+	assert.NoError(t, err)
+
+	assert.Len(t, r.files, 1)
+	content := string(r.files[0].content)
+	assert.Contains(t, content, "0:food")
+	assert.Contains(t, content, "1:fool")
+}

libs/template/testdata/regexp-compile/template/hello.tmpl

@@ -0,0 +1,5 @@
+{{with (regexp "foo.?")}}
+{{range $index, $element := (.FindAllString "seafood fool" -1) }}
+{{print $index ":" $element}}
+{{end}}
+{{end}}