/usr/share/gocode/src/github.com/mitchellh/reflectwalk/reflectwalk.go is in golang-github-mitchellh-reflectwalk-dev 0.0~git20150527.0.eecf4c7-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 | // reflectwalk is a package that allows you to "walk" complex structures
// similar to how you may "walk" a filesystem: visiting every element one
// by one and calling callback functions allowing you to handle and manipulate
// those elements.
package reflectwalk
import (
"reflect"
)
// PrimitiveWalker implementations are able to handle primitive values
// within complex structures. Primitive values are numbers, strings,
// booleans, funcs, chans.
//
// These primitive values are often members of more complex
// structures (slices, maps, etc.) that are walkable by other interfaces.
type PrimitiveWalker interface {
Primitive(reflect.Value) error
}
// MapWalker implementations are able to handle individual elements
// found within a map structure.
type MapWalker interface {
Map(m reflect.Value) error
MapElem(m, k, v reflect.Value) error
}
// SliceWalker implementations are able to handle slice elements found
// within complex structures.
type SliceWalker interface {
Slice(reflect.Value) error
SliceElem(int, reflect.Value) error
}
// StructWalker is an interface that has methods that are called for
// structs when a Walk is done.
type StructWalker interface {
Struct(reflect.Value) error
StructField(reflect.StructField, reflect.Value) error
}
// EnterExitWalker implementations are notified before and after
// they walk deeper into complex structures (into struct fields,
// into slice elements, etc.)
type EnterExitWalker interface {
Enter(Location) error
Exit(Location) error
}
// PointerWalker implementations are notified when the value they're
// walking is a pointer or not. Pointer is called for _every_ value whether
// it is a pointer or not.
type PointerWalker interface {
PointerEnter(bool) error
PointerExit(bool) error
}
// Walk takes an arbitrary value and an interface and traverses the
// value, calling callbacks on the interface if they are supported.
// The interface should implement one or more of the walker interfaces
// in this package, such as PrimitiveWalker, StructWalker, etc.
func Walk(data, walker interface{}) (err error) {
v := reflect.ValueOf(data)
ew, ok := walker.(EnterExitWalker)
if ok {
err = ew.Enter(WalkLoc)
}
if err == nil {
err = walk(v, walker)
}
if ok && err == nil {
err = ew.Exit(WalkLoc)
}
return
}
func walk(v reflect.Value, w interface{}) (err error) {
// Determine if we're receiving a pointer and if so notify the walker.
pointer := false
if v.Kind() == reflect.Ptr {
pointer = true
v = reflect.Indirect(v)
}
if pw, ok := w.(PointerWalker); ok {
if err = pw.PointerEnter(pointer); err != nil {
return
}
defer func() {
if err != nil {
return
}
err = pw.PointerExit(pointer)
}()
}
// We preserve the original value here because if it is an interface
// type, we want to pass that directly into the walkPrimitive, so that
// we can set it.
originalV := v
if v.Kind() == reflect.Interface {
v = v.Elem()
}
k := v.Kind()
if k >= reflect.Int && k <= reflect.Complex128 {
k = reflect.Int
}
switch k {
// Primitives
case reflect.Bool, reflect.Chan, reflect.Func, reflect.Int, reflect.String, reflect.Invalid:
err = walkPrimitive(originalV, w)
return
case reflect.Map:
err = walkMap(v, w)
return
case reflect.Slice:
err = walkSlice(v, w)
return
case reflect.Struct:
err = walkStruct(v, w)
return
default:
panic("unsupported type: " + k.String())
}
}
func walkMap(v reflect.Value, w interface{}) error {
ew, ewok := w.(EnterExitWalker)
if ewok {
ew.Enter(Map)
}
if mw, ok := w.(MapWalker); ok {
if err := mw.Map(v); err != nil {
return err
}
}
for _, k := range v.MapKeys() {
kv := v.MapIndex(k)
if mw, ok := w.(MapWalker); ok {
if err := mw.MapElem(v, k, kv); err != nil {
return err
}
}
ew, ok := w.(EnterExitWalker)
if ok {
ew.Enter(MapKey)
}
if err := walk(k, w); err != nil {
return err
}
if ok {
ew.Exit(MapKey)
ew.Enter(MapValue)
}
if err := walk(kv, w); err != nil {
return err
}
if ok {
ew.Exit(MapValue)
}
}
if ewok {
ew.Exit(Map)
}
return nil
}
func walkPrimitive(v reflect.Value, w interface{}) error {
if pw, ok := w.(PrimitiveWalker); ok {
return pw.Primitive(v)
}
return nil
}
func walkSlice(v reflect.Value, w interface{}) (err error) {
ew, ok := w.(EnterExitWalker)
if ok {
ew.Enter(Slice)
}
if sw, ok := w.(SliceWalker); ok {
if err := sw.Slice(v); err != nil {
return err
}
}
for i := 0; i < v.Len(); i++ {
elem := v.Index(i)
if sw, ok := w.(SliceWalker); ok {
if err := sw.SliceElem(i, elem); err != nil {
return err
}
}
ew, ok := w.(EnterExitWalker)
if ok {
ew.Enter(SliceElem)
}
if err := walk(elem, w); err != nil {
return err
}
if ok {
ew.Exit(SliceElem)
}
}
ew, ok = w.(EnterExitWalker)
if ok {
ew.Exit(Slice)
}
return nil
}
func walkStruct(v reflect.Value, w interface{}) (err error) {
ew, ewok := w.(EnterExitWalker)
if ewok {
ew.Enter(Struct)
}
if sw, ok := w.(StructWalker); ok {
if err = sw.Struct(v); err != nil {
return
}
}
vt := v.Type()
for i := 0; i < vt.NumField(); i++ {
sf := vt.Field(i)
f := v.FieldByIndex([]int{i})
if sw, ok := w.(StructWalker); ok {
err = sw.StructField(sf, f)
if err != nil {
return
}
}
ew, ok := w.(EnterExitWalker)
if ok {
ew.Enter(StructField)
}
err = walk(f, w)
if err != nil {
return
}
if ok {
ew.Exit(StructField)
}
}
if ewok {
ew.Exit(Struct)
}
return nil
}
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