tpl/collections: Simplify the reflect usage

* Use helper funcs in hreflect package when possible.
* Use hreflect.ConvertIfPossible to handle conversions when possible.

Author: bep

common/hreflect/convert.go

@@ -0,0 +1,90 @@
+// Copyright 2025 The Hugo Authors. All rights reserved.
+// Some functions in this file (see comments) is based on the Go source code,
+// copyright The Go Authors and  governed by a BSD-style license.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hreflect
+
+import (
+	"fmt"
+	"reflect"
+)
+
+var (
+	typeInt64   = reflect.TypeFor[int64]()
+	typeFloat64 = reflect.TypeFor[float64]()
+	typeString  = reflect.TypeFor[string]()
+)
+
+// ToInt64 converts v to int64 if possible, returning an error if not.
+func ToInt64E(v reflect.Value) (int64, error) {
+	if v, ok := ConvertIfPossible(v, typeInt64); ok {
+		return v.Int(), nil
+	}
+	return 0, errConvert(v, "int64")
+}
+
+// ToInt64 converts v to int64 if possible, panicking if not.
+func ToInt64(v reflect.Value) int64 {
+	vv, err := ToInt64E(v)
+	if err != nil {
+		panic(err)
+	}
+	return vv
+}
+
+// ToIntFloat64 converts v to float64 if possible, returning an error if not.
+func ToFloat64E(v reflect.Value) (float64, error) {
+	if v, ok := ConvertIfPossible(v, typeFloat64); ok {
+		return v.Float(), nil
+	}
+	return 0, errConvert(v, "float64")
+}
+
+// ToFloat64 converts v to float64 if possible, panicking if not.
+func ToFloat64(v reflect.Value) float64 {
+	vv, err := ToFloat64E(v)
+	if err != nil {
+		panic(err)
+	}
+	return vv
+}
+
+// ToStringE converts v to string if possible, returning an error if not.
+func ToStringE(v reflect.Value) (string, error) {
+	vv, err := ToStringValueE(v)
+	if err != nil {
+		return "", err
+	}
+	return vv.String(), nil
+}
+
+func ToStringValueE(v reflect.Value) (reflect.Value, error) {
+	if v, ok := ConvertIfPossible(v, typeString); ok {
+		return v, nil
+	}
+	return reflect.Value{}, errConvert(v, "string")
+}
+
+// ToString converts v to string if possible, panicking if not.
+func ToString(v reflect.Value) string {
+	vv, err := ToStringE(v)
+	if err != nil {
+		panic(err)
+	}
+	return vv
+}
+
+func errConvert(v reflect.Value, s string) error {
+	return fmt.Errorf("unable to convert value of type %q to %q", v.Type().String(), s)
+}

common/hreflect/convert_test.go

@@ -0,0 +1,37 @@
+// Copyright 2025 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hreflect
+
+import (
+	"reflect"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"github.com/gohugoio/hugo/htesting/hqt"
+)
+
+func TestToFuncs(t *testing.T) {
+	c := qt.New(t)
+
+	c.Assert(ToInt64(reflect.ValueOf(int(42))), qt.Equals, int64(42))
+	c.Assert(ToFloat64(reflect.ValueOf(float32(3.14))), hqt.IsSameFloat64, float64(3.14))
+	c.Assert(ToString(reflect.ValueOf("hello")), qt.Equals, "hello")
+}
+
+func BenchmarkToInt64(b *testing.B) {
+	v := reflect.ValueOf(int(42))
+	for i := 0; i < b.N; i++ {
+		ToInt64(v)
+	}
+}

common/hreflect/helpers.go

@@ -1,4 +1,4 @@
-// Copyright 2024 The Hugo Authors. All rights reserved.
+// Copyright 2025 The Hugo Authors. All rights reserved.
 // Some functions in this file (see comments) is based on the Go source code,
 // copyright The Go Authors and  governed by a BSD-style license.
 //
@@ -318,37 +318,119 @@ func IsContextType(tp reflect.Type) bool {
 // This conversion is lossless.
 // See Issue 14079.
 func ConvertIfPossible(val reflect.Value, typ reflect.Type) (reflect.Value, bool) {
+	if val.Kind() == reflect.Interface {
+		val = val.Elem()
+	}
+
+	if val.Type().AssignableTo(typ) {
+		// No conversion needed.
+		return val, true
+	}
+
 	if IsInt(typ.Kind()) {
-		if IsInt(val.Kind()) {
-			if typ.OverflowInt(val.Int()) {
-				return reflect.Value{}, false
-			}
-			return val.Convert(typ), true
+		return convertToIntIfPossible(val, typ)
+	}
+	if IsFloat(typ.Kind()) {
+		return convertToFloatIfPossible(val, typ)
+	}
+	if IsUint(typ.Kind()) {
+		return convertToUintIfPossible(val, typ)
+	}
+	return reflect.Value{}, false
+}
+
+func convertToUintIfPossible(val reflect.Value, typ reflect.Type) (reflect.Value, bool) {
+	if IsInt(val.Kind()) {
+		i := val.Int()
+		if i < 0 {
+			return reflect.Value{}, false
 		}
-		if IsUint(val.Kind()) {
-			if val.Uint() > uint64(math.MaxInt64) {
-				return reflect.Value{}, false
-			}
-			if typ.OverflowInt(int64(val.Uint())) {
-				return reflect.Value{}, false
-			}
-			return val.Convert(typ), true
+		u := uint64(i)
+		if typ.OverflowUint(u) {
+			return reflect.Value{}, false
 		}
-		if IsFloat(val.Kind()) {
-			f := val.Float()
-			if f < float64(math.MinInt64) || f > float64(math.MaxInt64) {
-				return reflect.Value{}, false
-			}
-			i := int64(f)
-			if typ.OverflowInt(i) {
-				return reflect.Value{}, false
-			}
-			// Check for lossless conversion.
-			if float64(i) != f {
-				return reflect.Value{}, false
-			}
-			return val.Convert(typ), true
+		return reflect.ValueOf(u).Convert(typ), true
+	}
+	if IsUint(val.Kind()) {
+		if typ.OverflowUint(val.Uint()) {
+			return reflect.Value{}, false
 		}
+		return val.Convert(typ), true
 	}
+	if IsFloat(val.Kind()) {
+		f := val.Float()
+		if f < 0 || f > float64(math.MaxUint64) {
+			return reflect.Value{}, false
+		}
+		if f != math.Trunc(f) {
+			return reflect.Value{}, false
+		}
+		u := uint64(f)
+		if typ.OverflowUint(u) {
+			return reflect.Value{}, false
+		}
+		return reflect.ValueOf(u).Convert(typ), true
+	}
+	return reflect.Value{}, false
+}
+
+func convertToFloatIfPossible(val reflect.Value, typ reflect.Type) (reflect.Value, bool) {
+	if IsInt(val.Kind()) {
+		i := val.Int()
+		f := float64(i)
+		if typ.OverflowFloat(f) {
+			return reflect.Value{}, false
+		}
+		return reflect.ValueOf(f).Convert(typ), true
+	}
+	if IsUint(val.Kind()) {
+		u := val.Uint()
+		f := float64(u)
+		if typ.OverflowFloat(f) {
+			return reflect.Value{}, false
+		}
+		return reflect.ValueOf(f).Convert(typ), true
+	}
+	if IsFloat(val.Kind()) {
+		if typ.OverflowFloat(val.Float()) {
+			return reflect.Value{}, false
+		}
+		return val.Convert(typ), true
+	}
+
+	return reflect.Value{}, false
+}
+
+func convertToIntIfPossible(val reflect.Value, typ reflect.Type) (reflect.Value, bool) {
+	if IsInt(val.Kind()) {
+		if typ.OverflowInt(val.Int()) {
+			return reflect.Value{}, false
+		}
+		return val.Convert(typ), true
+	}
+	if IsUint(val.Kind()) {
+		if val.Uint() > uint64(math.MaxInt64) {
+			return reflect.Value{}, false
+		}
+		if typ.OverflowInt(int64(val.Uint())) {
+			return reflect.Value{}, false
+		}
+		return val.Convert(typ), true
+	}
+	if IsFloat(val.Kind()) {
+		f := val.Float()
+		if f < float64(math.MinInt64) || f > float64(math.MaxInt64) {
+			return reflect.Value{}, false
+		}
+		if f != math.Trunc(f) {
+			return reflect.Value{}, false
+		}
+		if typ.OverflowInt(int64(f)) {
+			return reflect.Value{}, false
+		}
+		return reflect.ValueOf(int64(f)).Convert(typ), true
+
+	}
+
 	return reflect.Value{}, false
 }