113 lines
2.9 KiB
Go
113 lines
2.9 KiB
Go
// Copyright 2019 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 collections
|
|
|
|
import (
|
|
"fmt"
|
|
"reflect"
|
|
)
|
|
|
|
// Append appends from to a slice to and returns the resulting slice.
|
|
// If length of from is one and the only element is a slice of same type as to,
|
|
// it will be appended.
|
|
func Append(to interface{}, from ...interface{}) (interface{}, error) {
|
|
tov, toIsNil := indirect(reflect.ValueOf(to))
|
|
|
|
toIsNil = toIsNil || to == nil
|
|
var tot reflect.Type
|
|
|
|
if !toIsNil {
|
|
if tov.Kind() != reflect.Slice {
|
|
return nil, fmt.Errorf("expected a slice, got %T", to)
|
|
}
|
|
|
|
tot = tov.Type().Elem()
|
|
toIsNil = tov.Len() == 0
|
|
|
|
if len(from) == 1 {
|
|
fromv := reflect.ValueOf(from[0])
|
|
if fromv.Kind() == reflect.Slice {
|
|
if toIsNil {
|
|
// If we get nil []string, we just return the []string
|
|
return from[0], nil
|
|
}
|
|
|
|
fromt := reflect.TypeOf(from[0]).Elem()
|
|
|
|
// If we get []string []string, we append the from slice to to
|
|
if tot == fromt {
|
|
return reflect.AppendSlice(tov, fromv).Interface(), nil
|
|
} else if !fromt.AssignableTo(tot) {
|
|
// Fall back to a []interface{} slice.
|
|
return appendToInterfaceSliceFromValues(tov, fromv)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if toIsNil {
|
|
return Slice(from...), nil
|
|
}
|
|
|
|
for _, f := range from {
|
|
fv := reflect.ValueOf(f)
|
|
if !fv.Type().AssignableTo(tot) {
|
|
// Fall back to a []interface{} slice.
|
|
tov, _ := indirect(reflect.ValueOf(to))
|
|
return appendToInterfaceSlice(tov, from...)
|
|
}
|
|
tov = reflect.Append(tov, fv)
|
|
}
|
|
|
|
return tov.Interface(), nil
|
|
}
|
|
|
|
func appendToInterfaceSliceFromValues(slice1, slice2 reflect.Value) ([]interface{}, error) {
|
|
var tos []interface{}
|
|
|
|
for _, slice := range []reflect.Value{slice1, slice2} {
|
|
for i := 0; i < slice.Len(); i++ {
|
|
tos = append(tos, slice.Index(i).Interface())
|
|
}
|
|
}
|
|
|
|
return tos, nil
|
|
}
|
|
|
|
func appendToInterfaceSlice(tov reflect.Value, from ...interface{}) ([]interface{}, error) {
|
|
var tos []interface{}
|
|
|
|
for i := 0; i < tov.Len(); i++ {
|
|
tos = append(tos, tov.Index(i).Interface())
|
|
}
|
|
|
|
tos = append(tos, from...)
|
|
|
|
return tos, nil
|
|
}
|
|
|
|
// indirect is borrowed from the Go stdlib: 'text/template/exec.go'
|
|
// TODO(bep) consolidate
|
|
func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
|
|
for ; v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface; v = v.Elem() {
|
|
if v.IsNil() {
|
|
return v, true
|
|
}
|
|
if v.Kind() == reflect.Interface && v.NumMethod() > 0 {
|
|
break
|
|
}
|
|
}
|
|
return v, false
|
|
}
|