symdiff.go - hugo - [fork] hugo port for 9front
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       ---
       symdiff.go (1809B)
       ---
            1 // Copyright 2018 The Hugo Authors. All rights reserved.
            2 //
            3 // Licensed under the Apache License, Version 2.0 (the "License");
            4 // you may not use this file except in compliance with the License.
            5 // You may obtain a copy of the License at
            6 // http://www.apache.org/licenses/LICENSE-2.0
            7 //
            8 // Unless required by applicable law or agreed to in writing, software
            9 // distributed under the License is distributed on an "AS IS" BASIS,
           10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
           11 // See the License for the specific language governing permissions and
           12 // limitations under the License.
           13 
           14 package collections
           15 
           16 import (
           17         "fmt"
           18         "reflect"
           19 )
           20 
           21 // SymDiff returns the symmetric difference of s1 and s2.
           22 // Arguments must be either a slice or an array of comparable types.
           23 func (ns *Namespace) SymDiff(s2, s1 any) (any, error) {
           24         ids1, err := collectIdentities(s1)
           25         if err != nil {
           26                 return nil, err
           27         }
           28         ids2, err := collectIdentities(s2)
           29         if err != nil {
           30                 return nil, err
           31         }
           32 
           33         var slice reflect.Value
           34         var sliceElemType reflect.Type
           35 
           36         for i, s := range []any{s1, s2} {
           37                 v := reflect.ValueOf(s)
           38 
           39                 switch v.Kind() {
           40                 case reflect.Array, reflect.Slice:
           41                         if i == 0 {
           42                                 sliceType := v.Type()
           43                                 sliceElemType = sliceType.Elem()
           44                                 slice = reflect.MakeSlice(sliceType, 0, 0)
           45                         }
           46 
           47                         for i := range v.Len() {
           48                                 ev, _ := indirectInterface(v.Index(i))
           49                                 key := normalize(ev)
           50 
           51                                 // Append if the key is not in their intersection.
           52                                 if ids1[key] != ids2[key] {
           53                                         v, err := convertValue(ev, sliceElemType)
           54                                         if err != nil {
           55                                                 return nil, fmt.Errorf("symdiff: failed to convert value: %w", err)
           56                                         }
           57                                         slice = reflect.Append(slice, v)
           58                                 }
           59                         }
           60                 default:
           61                         return nil, fmt.Errorf("arguments to symdiff must be slices or arrays")
           62                 }
           63         }
           64 
           65         return slice.Interface(), nil
           66 }