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Commit 27f4166e authored by Andrew Gerrand's avatar Andrew Gerrand
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undo CL 13180043 / 318540e7857f 

Accidentally submitted.

««« original CL description
encoding/json: add "overflow" struct tag option

Fixes #6213.

R=golang-dev, dsymonds, bradfitz
CC=golang-dev
https://golang.org/cl/13180043
»»»

R=golang-dev
CC=golang-dev
https://golang.org/cl/13234045
parent 10e2ffdf
Show whitespace changes
Inline Side-by-side
Showing with 49 additions and 240 deletions
src/pkg/encoding/json/decode.go
View file @ 27f4166e
......@@ -61,10 +61,6 @@ import (
// Instead, they are replaced by the Unicode replacement
// character U+FFFD.
//
// When unmarshalling into struct values, a struct field of map type with the
// "overflow" option will store values whose keys do not match the other struct
// fields.
//
func Unmarshal(data []byte, v interface{}) error {
// Check for well-formedness.
// Avoids filling out half a data structure
......@@ -493,6 +489,8 @@ func (d *decodeState) object(v reflect.Value) {
return
}
var mapElem reflect.Value
for {
// Read opening " of string key or closing }.
op := d.scanWhile(scanSkipSpace)
......@@ -514,7 +512,44 @@ func (d *decodeState) object(v reflect.Value) {
}
// Figure out field corresponding to key.
subv, mapv, destring := subValue(v, key)
var subv reflect.Value
destring := false // whether the value is wrapped in a string to be decoded first
if v.Kind() == reflect.Map {
elemType := v.Type().Elem()
if !mapElem.IsValid() {
mapElem = reflect.New(elemType).Elem()
} else {
mapElem.Set(reflect.Zero(elemType))
}
subv = mapElem
} else {
var f *field
fields := cachedTypeFields(v.Type())
for i := range fields {
ff := &fields[i]
if ff.name == key {
f = ff
break
}
if f == nil && strings.EqualFold(ff.name, key) {
f = ff
}
}
if f != nil {
subv = v
destring = f.quoted
for _, i := range f.index {
if subv.Kind() == reflect.Ptr {
if subv.IsNil() {
subv.Set(reflect.New(subv.Type().Elem()))
}
subv = subv.Elem()
}
subv = subv.Field(i)
}
}
}
// Read : before value.
if op == scanSkipSpace {
......@@ -534,9 +569,9 @@ func (d *decodeState) object(v reflect.Value) {
// Write value back to map;
// if using struct, subv points into struct already.
if mapv.IsValid() {
kv := reflect.ValueOf(key).Convert(mapv.Type().Key())
mapv.SetMapIndex(kv, subv)
if v.Kind() == reflect.Map {
kv := reflect.ValueOf(key).Convert(v.Type().Key())
v.SetMapIndex(kv, subv)
}
// Next token must be , or }.
......@@ -550,57 +585,6 @@ func (d *decodeState) object(v reflect.Value) {
}
}
// subValue returns (and allocates, if necessary) the field in the struct or
// map v whose name matches key.
func subValue(v reflect.Value, key string) (subv, mapv reflect.Value, destring bool) {
// Create new map element.
if v.Kind() == reflect.Map {
subv = reflect.New(v.Type().Elem()).Elem()
mapv = v
return
}
// Get struct field.
var f *field
fields := cachedTypeFields(v.Type())
for i := range fields {
ff := &fields[i]
if ff.name == key {
f = ff
break
}
if f == nil && strings.EqualFold(ff.name, key) {
f = ff
}
}
if f != nil {
subv = fieldByIndex(v, f.index, true)
destring = f.quoted
return
}
// Decode into overflow field if present.
for _, f := range fields {
if f.overflow {
// Find overflow field.
mapv = fieldByIndex(v, f.index, true)
if k := mapv.Kind(); k != reflect.Map {
panic("unsupported overflow field kind: " + k.String())
}
// Make map if necessary.
if mapv.IsNil() {
mapv.Set(reflect.MakeMap(mapv.Type()))
}
// Create new map element.
subv = reflect.New(mapv.Type().Elem()).Elem()
return
}
}
// Not found.
return
}
// literal consumes a literal from d.data[d.off-1:], decoding into the value v.
// The first byte of the literal has been read already
// (that's how the caller knows it's a literal).
......
src/pkg/encoding/json/decode_test.go
View file @ 27f4166e
......@@ -1275,23 +1275,3 @@ func TestSkipArrayObjects(t *testing.T) {
t.Errorf("got error %q, want nil", err)
}
}
func TestDecodeOverflow(t *testing.T) {
json := `{"A":1,"B":2,"C":3}`
type S struct {
A int
E map[string]interface{} `json:",overflow"`
C int
}
var (
want = S{1, map[string]interface{}{"B": float64(2)}, 3}
dest S
)
err := Unmarshal([]byte(json), &dest)
if err != nil {
t.Errorf("got error %q, want nil", err)
}
if !reflect.DeepEqual(dest, want) {
t.Errorf("Got %+v; want %+v", dest, want)
}
}
src/pkg/encoding/json/encode.go
View file @ 27f4166e
......@@ -109,10 +109,6 @@ import (
// an anonymous struct field in both current and earlier versions, give the field
// a JSON tag of "-".
//
// The "overflow" option may be used with a struct field of a map type to
// indicate that the map contents should be marshalled as if the keys are part
// of the struct object itself.
//
// Map values encode as JSON objects.
// The map's key type must be string; the object keys are used directly
// as map keys.
......@@ -243,32 +239,6 @@ var hex = "0123456789abcdef"
type encodeState struct {
bytes.Buffer // accumulated output
scratch [64]byte
overflow int
}
func (e *encodeState) startOverflow() {
e.overflow = e.Len()
}
func (e *encodeState) endOverflow() {
if e.overflow == 0 {
panic("endOverflow called before startOverflow")
}
start, end := e.overflow, e.Len()
b := e.Bytes()
if b[start] == '{' && b[end-1] == '}' {
// Remove surrounding { and }.
copy(b[start:], b[start+1:])
e.Truncate(end - 2)
} else if bytes.Equal(b[start:end], []byte("null")) {
// Drop "null".
e.Truncate(start)
}
// Remove trailing comma if overflow value was null or {}.
if start > 0 && e.Len() == start && b[start-1] == ',' {
e.Truncate(start - 1)
}
e.overflow = 0
}
// TODO(bradfitz): use a sync.Cache here
......@@ -612,7 +582,7 @@ func (se *structEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
e.WriteByte('{')
first := true
for i, f := range se.fields {
fv := fieldByIndex(v, f.index, false)
fv := fieldByIndex(v, f.index)
if !fv.IsValid() || f.omitEmpty && isEmptyValue(fv) {
continue
}
......@@ -621,16 +591,6 @@ func (se *structEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
} else {
e.WriteByte(',')
}
if f.overflow {
if tenc := se.fieldEncs[i]; tenc != nil {
e.startOverflow()
tenc(e, fv, f.quoted)
e.endOverflow()
} else {
panic("no encoder for " + fv.String())
}
continue
}
e.string(f.name)
e.WriteByte(':')
if tenc := se.fieldEncs[i]; tenc != nil {
......@@ -650,7 +610,7 @@ func newStructEncoder(t reflect.Type, vx reflect.Value) encoderFunc {
fieldEncs: make([]encoderFunc, len(fields)),
}
for i, f := range fields {
vxf := fieldByIndex(vx, f.index, false)
vxf := fieldByIndex(vx, f.index)
if vxf.IsValid() {
se.fieldEncs[i] = typeEncoder(vxf.Type(), vxf)
}
......@@ -790,17 +750,12 @@ func isValidTag(s string) bool {
return true
}
// fieldByIndex fetches (and allocates, if create is true) the field in v
// indentified by index.
func fieldByIndex(v reflect.Value, index []int, create bool) reflect.Value {
func fieldByIndex(v reflect.Value, index []int) reflect.Value {
for _, i := range index {
if v.Kind() == reflect.Ptr {
if v.IsNil() {
if !create {
return reflect.Value{}
}
v.Set(reflect.New(v.Type().Elem()))
}
v = v.Elem()
}
v = v.Field(i)
......@@ -971,7 +926,6 @@ type field struct {
typ reflect.Type
omitEmpty bool
quoted bool
overflow bool
}
// byName sorts field by name, breaking ties with depth,
......@@ -1073,15 +1027,8 @@ func typeFields(t reflect.Type) []field {
if name == "" {
name = sf.Name
}
fields = append(fields, field{
name: name,
tag: tagged,
index: index,
typ: ft,
omitEmpty: opts.Contains("omitempty"),
quoted: opts.Contains("string"),
overflow: opts.Contains("overflow")},
)
fields = append(fields, field{name, tagged, index, ft,
opts.Contains("omitempty"), opts.Contains("string")})
if count[f.typ] > 1 {
// If there were multiple instances, add a second,
// so that the annihilation code will see a duplicate.
......
src/pkg/encoding/json/encode_test.go
View file @ 27f4166e
......@@ -401,59 +401,3 @@ func TestStringBytes(t *testing.T) {
t.Errorf("encodings differ at %#q vs %#q", enc, encBytes)
}
}
func TestEncodeOverflow(t *testing.T) {
for _, c := range []struct {
in interface{}
want string
}{
{
struct {
A int
E map[string]interface{} `json:",overflow"`
C int
}{
A: 12,
E: map[string]interface{}{"B": 42},
C: 64,
},
`{"A":12,"B":42,"C":64}`,
},
{
struct {
E map[string]interface{} `json:",overflow"`
}{
E: map[string]interface{}{"B": 42},
},
`{"B":42}`,
},
{
struct {
A int
E map[string]interface{} `json:",overflow"`
}{
A: 12,
},
`{"A":12}`,
},
{
struct {
A int
E map[string]interface{} `json:",overflow"`
}{
A: 12,
E: map[string]interface{}{},
},
`{"A":12}`,
},
} {
b, err := Marshal(c.in)
if err != nil {
t.Error(err)
continue
}
if got := string(b); got != c.want {
t.Errorf("Marshal(%q) = %s, want %s", c.in, got, c.want)
}
}
}
src/pkg/encoding/json/example_test.go
View file @ 27f4166e
......@@ -33,29 +33,6 @@ func ExampleMarshal() {
// {"ID":1,"Name":"Reds","Colors":["Crimson","Red","Ruby","Maroon"]}
}
func ExampleMarshal_overflow() {
type Record struct {
ID string
Seq int
Meta map[string]string `json:",overflow"`
}
r := Record{
ID: "CheeseWhiz",
Seq: 42,
Meta: map[string]string{
"Created": "1980-06-20",
"Destroyed": "1998-02-06",
},
}
b, err := json.Marshal(r)
if err != nil {
fmt.Println("error:", err)
}
os.Stdout.Write(b)
// Output:
// {"ID":"CheeseWhiz","Seq":42,"Created":"1980-06-20","Destroyed":"1998-02-06"}
}
func ExampleUnmarshal() {
var jsonBlob = []byte(`[
{"Name": "Platypus", "Order": "Monotremata"},
......@@ -75,29 +52,6 @@ func ExampleUnmarshal() {
// [{Name:Platypus Order:Monotremata} {Name:Quoll Order:Dasyuromorphia}]
}
func ExampleUnmarshal_overflow() {
var jsonBlob = []byte(`
{
"Token": "Kaip4uM1ieng6Eiw",
"User": "bimmler",
"Animal": "rabbit"
}
`)
type Auth struct {
Token string
User string
Extra map[string]string `json:",overflow"`
}
var auth Auth
err := json.Unmarshal(jsonBlob, &auth)
if err != nil {
fmt.Println("error:", err)
}
fmt.Printf("%+v", auth)
// Output:
// {Token:Kaip4uM1ieng6Eiw User:bimmler Extra:map[Animal:rabbit]}
}
// This example uses a Decoder to decode a stream of distinct JSON values.
func ExampleDecoder() {
const jsonStream = `
......
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