--- /dev/null
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package json_test
+
+import (
+ "encoding/json"
+ "fmt"
+ "log"
+ "strings"
+)
+
+type Size int
+
+const (
+ Unrecognized Size = iota
+ Small
+ Large
+)
+
+func (s *Size) UnmarshalText(text []byte) error {
+ switch strings.ToLower(string(text)) {
+ default:
+ *s = Unrecognized
+ case "small":
+ *s = Small
+ case "large":
+ *s = Large
+ }
+ return nil
+}
+
+func (s Size) MarshalText() ([]byte, error) {
+ var name string
+ switch s {
+ default:
+ name = "unrecognized"
+ case Small:
+ name = "small"
+ case Large:
+ name = "large"
+ }
+ return []byte(name), nil
+}
+
+func Example_textMarshalJSON() {
+ blob := `["small","regular","large","unrecognized","small","normal","small","large"]`
+ var inventory []Size
+ if err := json.Unmarshal([]byte(blob), &inventory); err != nil {
+ log.Fatal(err)
+ }
+
+ counts := make(map[Size]int)
+ for _, size := range inventory {
+ counts[size] += 1
+ }
+
+ fmt.Printf("Inventory Counts:\n* Small: %d\n* Large: %d\n* Unrecognized: %d\n",
+ counts[Small], counts[Large], counts[Unrecognized])
+
+ // Output:
+ // Inventory Counts:
+ // * Small: 3
+ // * Large: 2
+ // * Unrecognized: 3
+}
--- /dev/null
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xml_test
+
+import (
+ "encoding/xml"
+ "fmt"
+ "log"
+ "strings"
+)
+
+type Animal int
+
+const (
+ Unknown Animal = iota
+ Gopher
+ Zebra
+)
+
+func (a *Animal) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+ var s string
+ if err := d.DecodeElement(&s, &start); err != nil {
+ return err
+ }
+ switch strings.ToLower(s) {
+ default:
+ *a = Unknown
+ case "gopher":
+ *a = Gopher
+ case "zebra":
+ *a = Zebra
+ }
+
+ return nil
+}
+
+func (a Animal) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+ var s string
+ switch a {
+ default:
+ s = "unknown"
+ case Gopher:
+ s = "gopher"
+ case Zebra:
+ s = "zebra"
+ }
+ return e.EncodeElement(s, start)
+}
+
+func Example_customMarshalXML() {
+ blob := `
+ <animals>
+ <animal>gopher</animal>
+ <animal>armadillo</animal>
+ <animal>zebra</animal>
+ <animal>unknown</animal>
+ <animal>gopher</animal>
+ <animal>bee</animal>
+ <animal>gopher</animal>
+ <animal>zebra</animal>
+ </animals>`
+ var zoo struct {
+ Animals []Animal `xml:"animal"`
+ }
+ if err := xml.Unmarshal([]byte(blob), &zoo); err != nil {
+ log.Fatal(err)
+ }
+
+ census := make(map[Animal]int)
+ for _, animal := range zoo.Animals {
+ census[animal] += 1
+ }
+
+ fmt.Printf("Zoo Census:\n* Gophers: %d\n* Zebras: %d\n* Unknown: %d\n",
+ census[Gopher], census[Zebra], census[Unknown])
+
+ // Output:
+ // Zoo Census:
+ // * Gophers: 3
+ // * Zebras: 2
+ // * Unknown: 3
+}
--- /dev/null
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xml_test
+
+import (
+ "encoding/xml"
+ "fmt"
+ "log"
+ "strings"
+)
+
+type Size int
+
+const (
+ Unrecognized Size = iota
+ Small
+ Large
+)
+
+func (s *Size) UnmarshalText(text []byte) error {
+ switch strings.ToLower(string(text)) {
+ default:
+ *s = Unrecognized
+ case "small":
+ *s = Small
+ case "large":
+ *s = Large
+ }
+ return nil
+}
+
+func (s Size) MarshalText() ([]byte, error) {
+ var name string
+ switch s {
+ default:
+ name = "unrecognized"
+ case Small:
+ name = "small"
+ case Large:
+ name = "large"
+ }
+ return []byte(name), nil
+}
+
+func Example_textMarshalXML() {
+ blob := `
+ <sizes>
+ <size>small</size>
+ <size>regular</size>
+ <size>large</size>
+ <size>unrecognized</size>
+ <size>small</size>
+ <size>normal</size>
+ <size>small</size>
+ <size>large</size>
+ </sizes>`
+ var inventory struct {
+ Sizes []Size `xml:"size"`
+ }
+ if err := xml.Unmarshal([]byte(blob), &inventory); err != nil {
+ log.Fatal(err)
+ }
+
+ counts := make(map[Size]int)
+ for _, size := range inventory.Sizes {
+ counts[size] += 1
+ }
+
+ fmt.Printf("Inventory Counts:\n* Small: %d\n* Large: %d\n* Unrecognized: %d\n",
+ counts[Small], counts[Large], counts[Unrecognized])
+
+ // Output:
+ // Inventory Counts:
+ // * Small: 3
+ // * Large: 2
+ // * Unrecognized: 3
+}
// string of length zero.
// - an anonymous struct field is handled as if the fields of its
// value were part of the outer struct.
+// - a field implementing Marshaler is written by calling its MarshalXML
+// method.
+// - a field implementing encoding.TextMarshaler is written by encoding the
+// result of its MarshalText method as text.
//
// If a field uses a tag "a>b>c", then the element c will be nested inside
// parent elements a and b. Fields that appear next to each other that name
//
// * A struct field with tag "-" is never unmarshaled into.
//
+// If Unmarshal encounters a field type that implements the Unmarshaler
+// interface, Unmarshal calls its UnmarshalXML method to produce the value from
+// the XML element. Otherwise, if the value implements
+// encoding.TextUnmarshaler, Unmarshal calls that value's UnmarshalText method.
+//
// Unmarshal maps an XML element to a string or []byte by saving the
// concatenation of that element's character data in the string or
// []byte. The saved []byte is never nil.