source: code/trunk/vendor/git.sr.ht/~sircmpwn/go-bare/marshal.go@ 822

Last change on this file since 822 was 822, checked in by yakumo.izuru, 22 months ago

Prefer immortal.run over runit and rc.d, use vendored modules
for convenience.

Signed-off-by: Izuru Yakumo <yakumo.izuru@…>
File size: 6.3 KB
Line 
1package bare
2
3import (
4 "bytes"
5 "errors"
6 "fmt"
7 "reflect"
8 "sync"
9)
10
11// A type which implements this interface will be responsible for marshaling
12// itself when encountered.
13type Marshalable interface {
14 Marshal(w *Writer) error
15}
16
17var encoderBufferPool = sync.Pool{
18 New: func() interface{} {
19 buf := &bytes.Buffer{}
20 buf.Grow(32)
21 return buf
22 },
23}
24
25// Marshals a value (val, which must be a pointer) into a BARE message.
26//
27// The encoding of each struct field can be customized by the format string
28// stored under the "bare" key in the struct field's tag.
29//
30// As a special case, if the field tag is "-", the field is always omitted.
31func Marshal(val interface{}) ([]byte, error) {
32 // reuse buffers from previous serializations
33 b := encoderBufferPool.Get().(*bytes.Buffer)
34 defer func() {
35 b.Reset()
36 encoderBufferPool.Put(b)
37 }()
38
39 w := NewWriter(b)
40 err := MarshalWriter(w, val)
41
42 msg := make([]byte, b.Len())
43 copy(msg, b.Bytes())
44
45 return msg, err
46}
47
48// Marshals a value (val, which must be a pointer) into a BARE message and
49// writes it to a Writer. See Marshal for details.
50func MarshalWriter(w *Writer, val interface{}) error {
51 t := reflect.TypeOf(val)
52 v := reflect.ValueOf(val)
53 if t.Kind() != reflect.Ptr {
54 return errors.New("Expected val to be pointer type")
55 }
56
57 return getEncoder(t.Elem())(w, v.Elem())
58}
59
60type encodeFunc func(w *Writer, v reflect.Value) error
61
62var encodeFuncCache sync.Map // map[reflect.Type]encodeFunc
63
64// get decoder from cache
65func getEncoder(t reflect.Type) encodeFunc {
66 if f, ok := encodeFuncCache.Load(t); ok {
67 return f.(encodeFunc)
68 }
69
70 f := encoderFunc(t)
71 encodeFuncCache.Store(t, f)
72 return f
73}
74
75var marshalableInterface = reflect.TypeOf((*Unmarshalable)(nil)).Elem()
76
77func encoderFunc(t reflect.Type) encodeFunc {
78 if reflect.PtrTo(t).Implements(marshalableInterface) {
79 return func(w *Writer, v reflect.Value) error {
80 uv := v.Addr().Interface().(Marshalable)
81 return uv.Marshal(w)
82 }
83 }
84
85 if t.Kind() == reflect.Interface && t.Implements(unionInterface) {
86 return encodeUnion(t)
87 }
88
89 switch t.Kind() {
90 case reflect.Ptr:
91 return encodeOptional(t.Elem())
92 case reflect.Struct:
93 return encodeStruct(t)
94 case reflect.Array:
95 return encodeArray(t)
96 case reflect.Slice:
97 return encodeSlice(t)
98 case reflect.Map:
99 return encodeMap(t)
100 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
101 return encodeUint
102 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
103 return encodeInt
104 case reflect.Float32, reflect.Float64:
105 return encodeFloat
106 case reflect.Bool:
107 return encodeBool
108 case reflect.String:
109 return encodeString
110 }
111
112 return func(w *Writer, v reflect.Value) error {
113 return &UnsupportedTypeError{v.Type()}
114 }
115}
116
117func encodeOptional(t reflect.Type) encodeFunc {
118 return func(w *Writer, v reflect.Value) error {
119 if v.IsNil() {
120 return w.WriteBool(false)
121 }
122
123 if err := w.WriteBool(true); err != nil {
124 return err
125 }
126
127 return getEncoder(t)(w, v.Elem())
128 }
129}
130
131func encodeStruct(t reflect.Type) encodeFunc {
132 n := t.NumField()
133 encoders := make([]encodeFunc, n)
134 for i := 0; i < n; i++ {
135 field := t.Field(i)
136 if field.Tag.Get("bare") == "-" {
137 continue
138 }
139 encoders[i] = getEncoder(field.Type)
140 }
141
142 return func(w *Writer, v reflect.Value) error {
143 for i := 0; i < n; i++ {
144 if encoders[i] == nil {
145 continue
146 }
147 err := encoders[i](w, v.Field(i))
148 if err != nil {
149 return err
150 }
151 }
152 return nil
153 }
154}
155
156func encodeArray(t reflect.Type) encodeFunc {
157 f := getEncoder(t.Elem())
158 len := t.Len()
159
160 return func(w *Writer, v reflect.Value) error {
161 for i := 0; i < len; i++ {
162 if err := f(w, v.Index(i)); err != nil {
163 return err
164 }
165 }
166 return nil
167 }
168}
169
170func encodeSlice(t reflect.Type) encodeFunc {
171 elem := t.Elem()
172 f := getEncoder(elem)
173
174 return func(w *Writer, v reflect.Value) error {
175 if err := w.WriteUint(uint64(v.Len())); err != nil {
176 return err
177 }
178
179 for i := 0; i < v.Len(); i++ {
180 if err := f(w, v.Index(i)); err != nil {
181 return err
182 }
183 }
184 return nil
185 }
186}
187
188func encodeMap(t reflect.Type) encodeFunc {
189 keyType := t.Key()
190 keyf := getEncoder(keyType)
191
192 valueType := t.Elem()
193 valf := getEncoder(valueType)
194
195 return func(w *Writer, v reflect.Value) error {
196 if err := w.WriteUint(uint64(v.Len())); err != nil {
197 return err
198 }
199
200 iter := v.MapRange()
201 for iter.Next() {
202 if err := keyf(w, iter.Key()); err != nil {
203 return err
204 }
205 if err := valf(w, iter.Value()); err != nil {
206 return err
207 }
208 }
209 return nil
210 }
211}
212
213func encodeUnion(t reflect.Type) encodeFunc {
214 ut, ok := unionRegistry[t]
215 if !ok {
216 return func(w *Writer, v reflect.Value) error {
217 return fmt.Errorf("Union type %s is not registered", t.Name())
218 }
219 }
220
221 encoders := make(map[uint64]encodeFunc)
222 for tag, t := range ut.types {
223 encoders[tag] = getEncoder(t)
224 }
225
226 return func(w *Writer, v reflect.Value) error {
227 t := v.Elem().Type()
228 if t.Kind() == reflect.Ptr {
229 // If T is a valid union value type, *T is valid too.
230 t = t.Elem()
231 v = v.Elem()
232 }
233 tag, ok := ut.tags[t]
234 if !ok {
235 return fmt.Errorf("Invalid union value: %s", v.Elem().String())
236 }
237
238 if err := w.WriteUint(tag); err != nil {
239 return err
240 }
241
242 return encoders[tag](w, v.Elem())
243 }
244}
245
246func encodeUint(w *Writer, v reflect.Value) error {
247 switch getIntKind(v.Type()) {
248 case reflect.Uint:
249 return w.WriteUint(v.Uint())
250
251 case reflect.Uint8:
252 return w.WriteU8(uint8(v.Uint()))
253
254 case reflect.Uint16:
255 return w.WriteU16(uint16(v.Uint()))
256
257 case reflect.Uint32:
258 return w.WriteU32(uint32(v.Uint()))
259
260 case reflect.Uint64:
261 return w.WriteU64(uint64(v.Uint()))
262 }
263
264 panic("not uint")
265}
266
267func encodeInt(w *Writer, v reflect.Value) error {
268 switch getIntKind(v.Type()) {
269 case reflect.Int:
270 return w.WriteInt(v.Int())
271
272 case reflect.Int8:
273 return w.WriteI8(int8(v.Int()))
274
275 case reflect.Int16:
276 return w.WriteI16(int16(v.Int()))
277
278 case reflect.Int32:
279 return w.WriteI32(int32(v.Int()))
280
281 case reflect.Int64:
282 return w.WriteI64(int64(v.Int()))
283 }
284
285 panic("not int")
286}
287
288func encodeFloat(w *Writer, v reflect.Value) error {
289 switch v.Type().Kind() {
290 case reflect.Float32:
291 return w.WriteF32(float32(v.Float()))
292 case reflect.Float64:
293 return w.WriteF64(v.Float())
294 }
295
296 panic("not float")
297}
298
299func encodeBool(w *Writer, v reflect.Value) error {
300 return w.WriteBool(v.Bool())
301}
302
303func encodeString(w *Writer, v reflect.Value) error {
304 if v.Kind() != reflect.String {
305 panic("not string")
306 }
307 return w.WriteString(v.String())
308}
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