reflect_helpers.go (4988B)
1 // Copyright 2017 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 "errors"
21
22 "github.com/mitchellh/hashstructure"
23 )
24
25 var (
26 zero reflect.Value
27 errorType = reflect.TypeOf((*error)(nil)).Elem()
28 )
29
30 func numberToFloat(v reflect.Value) (float64, error) {
31 switch kind := v.Kind(); {
32 case isFloat(kind):
33 return v.Float(), nil
34 case isInt(kind):
35 return float64(v.Int()), nil
36 case isUint(kind):
37 return float64(v.Uint()), nil
38 case kind == reflect.Interface:
39 return numberToFloat(v.Elem())
40 default:
41 return 0, fmt.Errorf("invalid kind %s in numberToFloat", kind)
42 }
43 }
44
45 // normalizes different numeric types if isNumber
46 // or get the hash values if not Comparable (such as map or struct)
47 // to make them comparable
48 func normalize(v reflect.Value) any {
49 k := v.Kind()
50
51 switch {
52 case !v.Type().Comparable():
53 h, err := hashstructure.Hash(v.Interface(), nil)
54 if err != nil {
55 panic(err)
56 }
57 return h
58 case isNumber(k):
59 f, err := numberToFloat(v)
60 if err == nil {
61 return f
62 }
63 }
64 return v.Interface()
65 }
66
67 // collects identities from the slices in seqs into a set. Numeric values are normalized,
68 // pointers unwrapped.
69 func collectIdentities(seqs ...any) (map[any]bool, error) {
70 seen := make(map[any]bool)
71 for _, seq := range seqs {
72 v := reflect.ValueOf(seq)
73 switch v.Kind() {
74 case reflect.Array, reflect.Slice:
75 for i := 0; i < v.Len(); i++ {
76 ev, _ := indirectInterface(v.Index(i))
77
78 if !ev.Type().Comparable() {
79 return nil, errors.New("elements must be comparable")
80 }
81
82 seen[normalize(ev)] = true
83 }
84 default:
85 return nil, fmt.Errorf("arguments must be slices or arrays")
86 }
87 }
88
89 return seen, nil
90 }
91
92 // We have some different numeric and string types that we try to behave like
93 // they were the same.
94 func convertValue(v reflect.Value, to reflect.Type) (reflect.Value, error) {
95 if v.Type().AssignableTo(to) {
96 return v, nil
97 }
98 switch kind := to.Kind(); {
99 case kind == reflect.String:
100 s, err := toString(v)
101 return reflect.ValueOf(s), err
102 case isNumber(kind):
103 return convertNumber(v, kind)
104 default:
105 return reflect.Value{}, fmt.Errorf("%s is not assignable to %s", v.Type(), to)
106 }
107 }
108
109 // There are potential overflows in this function, but the downconversion of
110 // int64 etc. into int8 etc. is coming from the synthetic unit tests for Union etc.
111 // TODO(bep) We should consider normalizing the slices to int64 etc.
112 func convertNumber(v reflect.Value, to reflect.Kind) (reflect.Value, error) {
113 var n reflect.Value
114 if isFloat(to) {
115 f, err := toFloat(v)
116 if err != nil {
117 return n, err
118 }
119 switch to {
120 case reflect.Float32:
121 n = reflect.ValueOf(float32(f))
122 default:
123 n = reflect.ValueOf(float64(f))
124 }
125 } else if isInt(to) {
126 i, err := toInt(v)
127 if err != nil {
128 return n, err
129 }
130 switch to {
131 case reflect.Int:
132 n = reflect.ValueOf(int(i))
133 case reflect.Int8:
134 n = reflect.ValueOf(int8(i))
135 case reflect.Int16:
136 n = reflect.ValueOf(int16(i))
137 case reflect.Int32:
138 n = reflect.ValueOf(int32(i))
139 case reflect.Int64:
140 n = reflect.ValueOf(int64(i))
141 }
142 } else if isUint(to) {
143 i, err := toUint(v)
144 if err != nil {
145 return n, err
146 }
147 switch to {
148 case reflect.Uint:
149 n = reflect.ValueOf(uint(i))
150 case reflect.Uint8:
151 n = reflect.ValueOf(uint8(i))
152 case reflect.Uint16:
153 n = reflect.ValueOf(uint16(i))
154 case reflect.Uint32:
155 n = reflect.ValueOf(uint32(i))
156 case reflect.Uint64:
157 n = reflect.ValueOf(uint64(i))
158 }
159
160 }
161
162 if !n.IsValid() {
163 return n, errors.New("invalid values")
164 }
165
166 return n, nil
167 }
168
169 func newSliceElement(items any) any {
170 tp := reflect.TypeOf(items)
171 if tp == nil {
172 return nil
173 }
174 switch tp.Kind() {
175 case reflect.Array, reflect.Slice:
176 tp = tp.Elem()
177 if tp.Kind() == reflect.Ptr {
178 tp = tp.Elem()
179 }
180
181 return reflect.New(tp).Interface()
182 }
183 return nil
184 }
185
186 func isNumber(kind reflect.Kind) bool {
187 return isInt(kind) || isUint(kind) || isFloat(kind)
188 }
189
190 func isInt(kind reflect.Kind) bool {
191 switch kind {
192 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
193 return true
194 default:
195 return false
196 }
197 }
198
199 func isUint(kind reflect.Kind) bool {
200 switch kind {
201 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
202 return true
203 default:
204 return false
205 }
206 }
207
208 func isFloat(kind reflect.Kind) bool {
209 switch kind {
210 case reflect.Float32, reflect.Float64:
211 return true
212 default:
213 return false
214 }
215 }