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encoder.go
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encoder.go
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package json
import (
"fmt"
"math/big"
"reflect"
"github.com/aws/smithy-go/document"
"github.com/aws/smithy-go/document/internal/serde"
smithyjson "github.com/aws/smithy-go/encoding/json"
)
// EncoderOptions is the set of options that can be configured for an Encoder.
type EncoderOptions struct{}
// Encoder is a Smithy document decoder for JSON based protocols.
type Encoder struct {
options EncoderOptions
}
// Encode returns the JSON encoding of v.
func (e *Encoder) Encode(v interface{}) ([]byte, error) {
encoder := smithyjson.NewEncoder()
if err := e.encode(jsonValueProvider(encoder.Value), reflect.ValueOf(v), serde.Tag{}); err != nil {
return nil, err
}
encodedBytes := encoder.Bytes()
if len(encodedBytes) == 0 {
return nil, nil
}
return encodedBytes, nil
}
// valueProvider is an interface for retrieving a JSON Value type used for encoding.
type valueProvider interface {
GetValue() smithyjson.Value
}
// jsonValueProvider is a valueProvider that returns the JSON value encoder as is.
type jsonValueProvider smithyjson.Value
func (p jsonValueProvider) GetValue() smithyjson.Value {
return smithyjson.Value(p)
}
// jsonObjectKeyProvider is a valueProvider that returns a JSON value type for encoding a value for the given JSON object
// key.
type jsonObjectKeyProvider struct {
Object *smithyjson.Object
Key string
}
func (p jsonObjectKeyProvider) GetValue() smithyjson.Value {
return p.Object.Key(p.Key)
}
// jsonArrayProvider is a valueProvider that returns a JSON value type for encoding a value in the given JSON array.
type jsonArrayProvider struct {
Array *smithyjson.Array
}
func (p jsonArrayProvider) GetValue() smithyjson.Value {
return p.Array.Value()
}
func (e *Encoder) encode(vp valueProvider, rv reflect.Value, tag serde.Tag) error {
// Zero values are serialized as null, or skipped if omitEmpty.
if serde.IsZeroValue(rv) {
if tag.OmitEmpty {
return nil
}
return e.encodeZeroValue(vp, rv)
}
// Handle both pointers and interface conversion into types
rv = serde.ValueElem(rv)
switch rv.Kind() {
case reflect.Invalid:
if tag.OmitEmpty {
return nil
}
vp.GetValue().Null()
return nil
case reflect.Struct:
return e.encodeStruct(vp, rv)
case reflect.Map:
return e.encodeMap(vp, rv)
case reflect.Slice, reflect.Array:
return e.encodeSlice(vp, rv)
case reflect.Chan, reflect.Func, reflect.UnsafePointer:
// skip unsupported types
return nil
default:
return e.encodeScalar(vp, rv)
}
}
func (e *Encoder) encodeZeroValue(vp valueProvider, rv reflect.Value) error {
switch rv.Kind() {
case reflect.Invalid:
vp.GetValue().Null()
case reflect.Array:
vp.GetValue().Array().Close()
case reflect.Map, reflect.Slice:
vp.GetValue().Null()
case reflect.String:
vp.GetValue().String("")
case reflect.Bool:
vp.GetValue().Boolean(false)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
vp.GetValue().Long(0)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
vp.GetValue().ULong(0)
case reflect.Float32, reflect.Float64:
vp.GetValue().Double(0)
case reflect.Interface, reflect.Ptr:
vp.GetValue().Null()
default:
return &document.InvalidMarshalError{Message: fmt.Sprintf("unknown value type: %s", rv.String())}
}
return nil
}
func (e *Encoder) encodeStruct(vp valueProvider, rv reflect.Value) error {
if rv.CanInterface() && document.IsNoSerde(rv.Interface()) {
return &document.UnmarshalTypeError{
Value: fmt.Sprintf("unsupported type"),
Type: rv.Type(),
}
}
switch {
case rv.Type().ConvertibleTo(serde.ReflectTypeOf.Time):
return &document.InvalidMarshalError{
Message: fmt.Sprintf("unsupported type %s", rv.Type().String()),
}
case rv.Type().ConvertibleTo(serde.ReflectTypeOf.BigFloat):
fallthrough
case rv.Type().ConvertibleTo(serde.ReflectTypeOf.BigInt):
return e.encodeNumber(vp, rv)
}
object := vp.GetValue().Object()
defer object.Close()
fields := serde.GetStructFields(rv.Type())
for _, f := range fields.All() {
if f.Name == "" {
return &document.InvalidMarshalError{Message: "map key cannot be empty"}
}
fv, found := serde.EncoderFieldByIndex(rv, f.Index)
if !found {
continue
}
err := e.encode(jsonObjectKeyProvider{
Object: object,
Key: f.Name,
}, fv, f.Tag)
if err != nil {
return err
}
}
return nil
}
func (e *Encoder) encodeMap(vp valueProvider, rv reflect.Value) error {
object := vp.GetValue().Object()
defer object.Close()
for _, key := range rv.MapKeys() {
keyName := fmt.Sprint(key.Interface())
if keyName == "" {
return &document.InvalidMarshalError{Message: "map key cannot be empty"}
}
ev := rv.MapIndex(key)
err := e.encode(jsonObjectKeyProvider{
Object: object,
Key: keyName,
}, ev, serde.Tag{})
if err != nil {
return err
}
}
return nil
}
func (e *Encoder) encodeSlice(value valueProvider, rv reflect.Value) error {
array := value.GetValue().Array()
defer array.Close()
for i := 0; i < rv.Len(); i++ {
err := e.encode(jsonArrayProvider{Array: array}, rv.Index(i), serde.Tag{})
if err != nil {
return err
}
}
return nil
}
func (e *Encoder) encodeScalar(vp valueProvider, rv reflect.Value) error {
if rv.Type() == serde.ReflectTypeOf.DocumentNumber {
number := rv.Interface().(document.Number)
if !isValidJSONNumber(number.String()) {
return &document.InvalidMarshalError{Message: fmt.Sprintf("invalid number literal: %s", number)}
}
vp.GetValue().Write([]byte(number))
}
switch rv.Kind() {
case reflect.Bool:
vp.GetValue().Boolean(rv.Bool())
case reflect.String:
vp.GetValue().String(rv.String())
default:
// Fallback to encoding numbers, will return invalid type if not supported
err := e.encodeNumber(vp, rv)
if err != nil {
return err
}
}
return nil
}
func (e *Encoder) encodeNumber(vp valueProvider, rv reflect.Value) error {
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
vp.GetValue().Long(rv.Int())
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
vp.GetValue().ULong(rv.Uint())
case reflect.Float32:
vp.GetValue().Float(float32(rv.Float()))
case reflect.Float64:
vp.GetValue().Double(rv.Float())
default:
rvt := rv.Type()
switch {
case rvt.ConvertibleTo(serde.ReflectTypeOf.BigInt):
bi := rv.Convert(serde.ReflectTypeOf.BigInt).Interface().(big.Int)
vp.GetValue().BigInteger(&bi)
case rvt.ConvertibleTo(serde.ReflectTypeOf.BigFloat):
bf := rv.Convert(serde.ReflectTypeOf.BigFloat).Interface().(big.Float)
vp.GetValue().BigDecimal(&bf)
default:
return &document.InvalidMarshalError{Message: fmt.Sprintf("incompatible type: %s", rvt.String())}
}
}
return nil
}
// isValidJSONNumber reports whether s is a valid JSON number literal.
// From https://golang.org/src/encoding/json/encode.go#L652 isValidNumber
// Copyright 2010 The Go Authors.
func isValidJSONNumber(s string) bool {
// This function implements the JSON numbers grammar.
// See https://tools.ietf.org/html/rfc7159#section-6
// and https://www.json.org/img/number.png
if s == "" {
return false
}
// Optional -
if s[0] == '-' {
s = s[1:]
if s == "" {
return false
}
}
// Digits
switch {
default:
return false
case s[0] == '0':
s = s[1:]
case '1' <= s[0] && s[0] <= '9':
s = s[1:]
for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
s = s[1:]
}
}
// . followed by 1 or more digits.
if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' {
s = s[2:]
for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
s = s[1:]
}
}
// e or E followed by an optional - or + and
// 1 or more digits.
if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
s = s[1:]
if s[0] == '+' || s[0] == '-' {
s = s[1:]
if s == "" {
return false
}
}
for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
s = s[1:]
}
}
// Make sure we are at the end.
return s == ""
}