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json: skip nil in UnmarshalJSON and (for symmetry) MarshalJSON

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R=dsymonds, r
CC=golang-dev
https://golang.org/cl/5050049
This commit is contained in:
Russ Cox 2011-09-19 11:50:41 -04:00
parent 003bfa0e26
commit fc5889d4ff
3 changed files with 42 additions and 13 deletions
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21
src/pkg/json/decode.go
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@ -22,16 +22,11 @@ import (
// Unmarshal parses the JSON-encoded data and stores the result
// in the value pointed to by v.
//
// Unmarshal traverses the value v recursively.
// If an encountered value implements the Unmarshaler interface,
// Unmarshal calls its UnmarshalJSON method with a well-formed
// JSON encoding.
//
// Otherwise, Unmarshal uses the inverse of the encodings that
// Unmarshal uses the inverse of the encodings that
// Marshal uses, allocating maps, slices, and pointers as necessary,
// with the following additional rules:
//
// To unmarshal a JSON value into a nil interface value, the
// To unmarshal JSON into a nil interface value, the
// type stored in the interface value is one of:
//
// bool, for JSON booleans
@ -41,6 +36,12 @@ import (
// map[string]interface{}, for JSON objects
// nil for JSON null
//
// To unmarshal JSON into a pointer, Unmarshal first handles the case of
// the JSON being the JSON literal null. In that case, Unmarshal sets
// the pointer to nil. Otherwise, Unmarshal unmarshals the JSON into
// the value pointed at by the pointer. If the pointer is nil, Unmarshal
// allocates a new value for it to point to.
//
// If a JSON value is not appropriate for a given target type,
// or if a JSON number overflows the target type, Unmarshal
// skips that field and completes the unmarshalling as best it can.
@ -250,8 +251,8 @@ func (d *decodeState) value(v reflect.Value) {
// indirect walks down v allocating pointers as needed,
// until it gets to a non-pointer.
// if it encounters an Unmarshaler, indirect stops and returns that.
// if wantptr is true, indirect stops at the last pointer.
func (d *decodeState) indirect(v reflect.Value, wantptr bool) (Unmarshaler, reflect.Value) {
// if decodingNull is true, indirect stops at the last pointer so it can be set to nil.
func (d *decodeState) indirect(v reflect.Value, decodingNull bool) (Unmarshaler, reflect.Value) {
// If v is a named type and is addressable,
// start with its address, so that if the type has pointer methods,
// we find them.
@ -277,7 +278,7 @@ func (d *decodeState) indirect(v reflect.Value, wantptr bool) (Unmarshaler, refl
break
}
if pv.Elem().Kind() != reflect.Ptr && wantptr && pv.CanSet() && !isUnmarshaler {
if pv.Elem().Kind() != reflect.Ptr && decodingNull && pv.CanSet() {
return nil, pv
}
if pv.IsNil() {