Improve template helper functions: string/slice (#24266)

Follow #23328

The improvements:

1. The `contains` functions are covered by tests
2. The inconsistent behavior of `containGeneric` is replaced by
`StringUtils.Contains` and `SliceUtils.Contains`
3. In the future we can move more help functions into XxxUtils to
simplify the `helper.go` and reduce unnecessary global functions.

FAQ:

1. Why it's called `StringUtils.Contains` but not `strings.Contains`
like Golang?

Because our `StringUtils` is not Golang's `strings` package. There will
be our own string functions.

---------

Co-authored-by: silverwind <me@silverwind.io>

5 files changed, 96 insertions, 31 deletions

diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index 42680827eb..c5b77989be 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -15,7 +15,6 @@ import (
 	"mime"
 	"net/url"
 	"path/filepath"
-	"reflect"
 	"regexp"
 	"strings"
 	"time"
@@ -68,11 +67,15 @@ func NewFuncMap() []template.FuncMap {
 		"PathEscape":         url.PathEscape,
 		"PathEscapeSegments": util.PathEscapeSegments,
 
+		// utils
+		"StringUtils": NewStringUtils,
+		"SliceUtils":  NewSliceUtils,
+
 		// -----------------------------------------------------------------
 		// string / json
+		// TODO: move string helper functions to StringUtils
 		"Join":           strings.Join,
 		"DotEscape":      DotEscape,
-		"HasPrefix":      strings.HasPrefix,
 		"EllipsisString": base.EllipsisString,
 		"DumpVar":        dumpVar,
 
@@ -145,35 +148,6 @@ func NewFuncMap() []template.FuncMap {
 		},
 
 		// -----------------------------------------------------------------
-		// slice
-		"containGeneric": func(arr, v interface{}) bool {
-			arrV := reflect.ValueOf(arr)
-			if arrV.Kind() == reflect.String && reflect.ValueOf(v).Kind() == reflect.String {
-				return strings.Contains(arr.(string), v.(string))
-			}
-			if arrV.Kind() == reflect.Slice {
-				for i := 0; i < arrV.Len(); i++ {
-					iV := arrV.Index(i)
-					if !iV.CanInterface() {
-						continue
-					}
-					if iV.Interface() == v {
-						return true
-					}
-				}
-			}
-			return false
-		},
-		"contain": func(s []int64, id int64) bool {
-			for i := 0; i < len(s); i++ {
-				if s[i] == id {
-					return true
-				}
-			}
-			return false
-		},
-
-		// -----------------------------------------------------------------
 		// setting
 		"AppName": func() string {
 			return setting.AppName
diff --git a/modules/templates/util.go b/modules/templates/util_dict.go
index c83f22449c..c83f22449c 100644
--- a/modules/templates/util.go
+++ b/modules/templates/util_dict.go
diff --git a/modules/templates/util_slice.go b/modules/templates/util_slice.go
new file mode 100644
index 0000000000..a3318cc11a
--- /dev/null
+++ b/modules/templates/util_slice.go
@@ -0,0 +1,35 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package templates
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type SliceUtils struct{}
+
+func NewSliceUtils() *SliceUtils {
+	return &SliceUtils{}
+}
+
+func (su *SliceUtils) Contains(s, v any) bool {
+	if s == nil {
+		return false
+	}
+	sv := reflect.ValueOf(s)
+	if sv.Kind() != reflect.Slice && sv.Kind() != reflect.Array {
+		panic(fmt.Sprintf("invalid type, expected slice or array, but got: %T", s))
+	}
+	for i := 0; i < sv.Len(); i++ {
+		it := sv.Index(i)
+		if !it.CanInterface() {
+			continue
+		}
+		if it.Interface() == v {
+			return true
+		}
+	}
+	return false
+}
diff --git a/modules/templates/util_string.go b/modules/templates/util_string.go
new file mode 100644
index 0000000000..e86bbe9e70
--- /dev/null
+++ b/modules/templates/util_string.go
@@ -0,0 +1,20 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package templates
+
+import "strings"
+
+type StringUtils struct{}
+
+func NewStringUtils() *StringUtils {
+	return &StringUtils{}
+}
+
+func (su *StringUtils) HasPrefix(s, prefix string) bool {
+	return strings.HasPrefix(s, prefix)
+}
+
+func (su *StringUtils) Contains(s, substr string) bool {
+	return strings.Contains(s, substr)
+}
diff --git a/modules/templates/util_test.go b/modules/templates/util_test.go
index dfa691c5e2..febaf7fa88 100644
--- a/modules/templates/util_test.go
+++ b/modules/templates/util_test.go
@@ -4,6 +4,9 @@
 package templates
 
 import (
+	"html/template"
+	"io"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -41,3 +44,36 @@ func TestDict(t *testing.T) {
 		assert.Error(t, err)
 	}
 }
+
+func TestUtils(t *testing.T) {
+	execTmpl := func(code string, data any) string {
+		tmpl := template.New("test")
+		tmpl.Funcs(template.FuncMap{"SliceUtils": NewSliceUtils, "StringUtils": NewStringUtils})
+		template.Must(tmpl.Parse(code))
+		w := &strings.Builder{}
+		assert.NoError(t, tmpl.Execute(w, data))
+		return w.String()
+	}
+
+	actual := execTmpl("{{SliceUtils.Contains .Slice .Value}}", map[string]any{"Slice": []string{"a", "b"}, "Value": "a"})
+	assert.Equal(t, "true", actual)
+
+	actual = execTmpl("{{SliceUtils.Contains .Slice .Value}}", map[string]any{"Slice": []string{"a", "b"}, "Value": "x"})
+	assert.Equal(t, "false", actual)
+
+	actual = execTmpl("{{SliceUtils.Contains .Slice .Value}}", map[string]any{"Slice": []int64{1, 2}, "Value": int64(2)})
+	assert.Equal(t, "true", actual)
+
+	actual = execTmpl("{{StringUtils.Contains .String .Value}}", map[string]any{"String": "abc", "Value": "b"})
+	assert.Equal(t, "true", actual)
+
+	actual = execTmpl("{{StringUtils.Contains .String .Value}}", map[string]any{"String": "abc", "Value": "x"})
+	assert.Equal(t, "false", actual)
+
+	tmpl := template.New("test")
+	tmpl.Funcs(template.FuncMap{"SliceUtils": NewSliceUtils, "StringUtils": NewStringUtils})
+	template.Must(tmpl.Parse("{{SliceUtils.Contains .Slice .Value}}"))
+	// error is like this: `template: test:1:12: executing "test" at <SliceUtils.Contains>: error calling Contains: ...`
+	err := tmpl.Execute(io.Discard, map[string]any{"Slice": struct{}{}})
+	assert.ErrorContains(t, err, "invalid type, expected slice or array")
+}