336 lines
12 KiB
Go
336 lines
12 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package json
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import (
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"encoding"
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"errors"
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"reflect"
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"github.com/go-json-experiment/json/internal"
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"github.com/go-json-experiment/json/internal/jsonflags"
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"github.com/go-json-experiment/json/internal/jsonopts"
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"github.com/go-json-experiment/json/internal/jsonwire"
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"github.com/go-json-experiment/json/jsontext"
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)
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var errNonStringValue = errors.New("JSON value must be string type")
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// Interfaces for custom serialization.
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var (
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jsonMarshalerType = reflect.TypeFor[Marshaler]()
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jsonMarshalerToType = reflect.TypeFor[MarshalerTo]()
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jsonUnmarshalerType = reflect.TypeFor[Unmarshaler]()
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jsonUnmarshalerFromType = reflect.TypeFor[UnmarshalerFrom]()
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textAppenderType = reflect.TypeFor[encoding.TextAppender]()
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textMarshalerType = reflect.TypeFor[encoding.TextMarshaler]()
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textUnmarshalerType = reflect.TypeFor[encoding.TextUnmarshaler]()
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allMarshalerTypes = []reflect.Type{jsonMarshalerToType, jsonMarshalerType, textAppenderType, textMarshalerType}
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allUnmarshalerTypes = []reflect.Type{jsonUnmarshalerFromType, jsonUnmarshalerType, textUnmarshalerType}
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allMethodTypes = append(allMarshalerTypes, allUnmarshalerTypes...)
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)
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// Marshaler is implemented by types that can marshal themselves.
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// It is recommended that types implement [MarshalerTo] unless the implementation
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// is trying to avoid a hard dependency on the "jsontext" package.
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//
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// It is recommended that implementations return a buffer that is safe
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// for the caller to retain and potentially mutate.
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type Marshaler interface {
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MarshalJSON() ([]byte, error)
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}
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// MarshalerTo is implemented by types that can marshal themselves.
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// It is recommended that types implement MarshalerTo instead of [Marshaler]
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// since this is both more performant and flexible.
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// If a type implements both Marshaler and MarshalerTo,
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// then MarshalerTo takes precedence. In such a case, both implementations
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// should aim to have equivalent behavior for the default marshal options.
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//
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// The implementation must write only one JSON value to the Encoder and
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// must not retain the pointer to [jsontext.Encoder].
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type MarshalerTo interface {
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MarshalJSONTo(*jsontext.Encoder) error
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// TODO: Should users call the MarshalEncode function or
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// should/can they call this method directly? Does it matter?
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}
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// Unmarshaler is implemented by types that can unmarshal themselves.
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// It is recommended that types implement [UnmarshalerFrom] unless the implementation
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// is trying to avoid a hard dependency on the "jsontext" package.
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//
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// The input can be assumed to be a valid encoding of a JSON value
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// if called from unmarshal functionality in this package.
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// UnmarshalJSON must copy the JSON data if it is retained after returning.
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// It is recommended that UnmarshalJSON implement merge semantics when
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// unmarshaling into a pre-populated value.
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//
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// Implementations must not retain or mutate the input []byte.
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type Unmarshaler interface {
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UnmarshalJSON([]byte) error
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}
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// UnmarshalerFrom is implemented by types that can unmarshal themselves.
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// It is recommended that types implement UnmarshalerFrom instead of [Unmarshaler]
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// since this is both more performant and flexible.
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// If a type implements both Unmarshaler and UnmarshalerFrom,
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// then UnmarshalerFrom takes precedence. In such a case, both implementations
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// should aim to have equivalent behavior for the default unmarshal options.
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//
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// The implementation must read only one JSON value from the Decoder.
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// It is recommended that UnmarshalJSONFrom implement merge semantics when
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// unmarshaling into a pre-populated value.
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//
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// Implementations must not retain the pointer to [jsontext.Decoder].
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type UnmarshalerFrom interface {
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UnmarshalJSONFrom(*jsontext.Decoder) error
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// TODO: Should users call the UnmarshalDecode function or
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// should/can they call this method directly? Does it matter?
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}
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func makeMethodArshaler(fncs *arshaler, t reflect.Type) *arshaler {
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// Avoid injecting method arshaler on the pointer or interface version
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// to avoid ever calling the method on a nil pointer or interface receiver.
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// Let it be injected on the value receiver (which is always addressable).
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if t.Kind() == reflect.Pointer || t.Kind() == reflect.Interface {
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return fncs
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}
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if needAddr, ok := implements(t, textMarshalerType); ok {
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fncs.nonDefault = true
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prevMarshal := fncs.marshal
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fncs.marshal = func(enc *jsontext.Encoder, va addressableValue, mo *jsonopts.Struct) error {
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if mo.Flags.Get(jsonflags.CallMethodsWithLegacySemantics) &&
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(needAddr && va.forcedAddr) {
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return prevMarshal(enc, va, mo)
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}
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marshaler := va.Addr().Interface().(encoding.TextMarshaler)
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if err := export.Encoder(enc).AppendRaw('"', false, func(b []byte) ([]byte, error) {
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b2, err := marshaler.MarshalText()
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return append(b, b2...), err
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}); err != nil {
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err = wrapSkipFunc(err, "marshal method")
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if mo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return internal.NewMarshalerError(va.Addr().Interface(), err, "MarshalText") // unlike unmarshal, always wrapped
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}
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if !isSemanticError(err) && !export.IsIOError(err) {
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err = newMarshalErrorBefore(enc, t, err)
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}
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return err
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}
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return nil
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}
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}
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if needAddr, ok := implements(t, textAppenderType); ok {
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fncs.nonDefault = true
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prevMarshal := fncs.marshal
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fncs.marshal = func(enc *jsontext.Encoder, va addressableValue, mo *jsonopts.Struct) (err error) {
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if mo.Flags.Get(jsonflags.CallMethodsWithLegacySemantics) &&
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(needAddr && va.forcedAddr) {
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return prevMarshal(enc, va, mo)
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}
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appender := va.Addr().Interface().(encoding.TextAppender)
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if err := export.Encoder(enc).AppendRaw('"', false, appender.AppendText); err != nil {
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err = wrapSkipFunc(err, "append method")
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if mo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return internal.NewMarshalerError(va.Addr().Interface(), err, "AppendText") // unlike unmarshal, always wrapped
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}
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if !isSemanticError(err) && !export.IsIOError(err) {
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err = newMarshalErrorBefore(enc, t, err)
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}
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return err
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}
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return nil
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}
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}
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if needAddr, ok := implements(t, jsonMarshalerType); ok {
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fncs.nonDefault = true
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prevMarshal := fncs.marshal
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fncs.marshal = func(enc *jsontext.Encoder, va addressableValue, mo *jsonopts.Struct) error {
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if mo.Flags.Get(jsonflags.CallMethodsWithLegacySemantics) &&
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((needAddr && va.forcedAddr) || export.Encoder(enc).Tokens.Last.NeedObjectName()) {
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return prevMarshal(enc, va, mo)
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}
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marshaler := va.Addr().Interface().(Marshaler)
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val, err := marshaler.MarshalJSON()
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if err != nil {
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err = wrapSkipFunc(err, "marshal method")
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if mo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return internal.NewMarshalerError(va.Addr().Interface(), err, "MarshalJSON") // unlike unmarshal, always wrapped
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}
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err = newMarshalErrorBefore(enc, t, err)
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return collapseSemanticErrors(err)
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}
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if err := enc.WriteValue(val); err != nil {
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if mo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return internal.NewMarshalerError(va.Addr().Interface(), err, "MarshalJSON") // unlike unmarshal, always wrapped
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}
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if isSyntacticError(err) {
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err = newMarshalErrorBefore(enc, t, err)
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}
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return err
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}
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return nil
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}
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}
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if needAddr, ok := implements(t, jsonMarshalerToType); ok {
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fncs.nonDefault = true
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prevMarshal := fncs.marshal
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fncs.marshal = func(enc *jsontext.Encoder, va addressableValue, mo *jsonopts.Struct) error {
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if mo.Flags.Get(jsonflags.CallMethodsWithLegacySemantics) &&
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((needAddr && va.forcedAddr) || export.Encoder(enc).Tokens.Last.NeedObjectName()) {
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return prevMarshal(enc, va, mo)
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}
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xe := export.Encoder(enc)
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prevDepth, prevLength := xe.Tokens.DepthLength()
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xe.Flags.Set(jsonflags.WithinArshalCall | 1)
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err := va.Addr().Interface().(MarshalerTo).MarshalJSONTo(enc)
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xe.Flags.Set(jsonflags.WithinArshalCall | 0)
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currDepth, currLength := xe.Tokens.DepthLength()
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if (prevDepth != currDepth || prevLength+1 != currLength) && err == nil {
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err = errNonSingularValue
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}
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if err != nil {
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err = wrapSkipFunc(err, "marshal method")
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if mo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return internal.NewMarshalerError(va.Addr().Interface(), err, "MarshalJSONTo") // unlike unmarshal, always wrapped
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}
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if !export.IsIOError(err) {
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err = newSemanticErrorWithPosition(enc, t, prevDepth, prevLength, err)
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}
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return err
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}
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return nil
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}
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}
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if _, ok := implements(t, textUnmarshalerType); ok {
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fncs.nonDefault = true
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fncs.unmarshal = func(dec *jsontext.Decoder, va addressableValue, uo *jsonopts.Struct) error {
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xd := export.Decoder(dec)
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var flags jsonwire.ValueFlags
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val, err := xd.ReadValue(&flags)
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if err != nil {
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return err // must be a syntactic or I/O error
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}
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if val.Kind() == 'n' {
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if !uo.Flags.Get(jsonflags.MergeWithLegacySemantics) {
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va.SetZero()
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}
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return nil
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}
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if val.Kind() != '"' {
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return newUnmarshalErrorAfter(dec, t, errNonStringValue)
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}
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s := jsonwire.UnquoteMayCopy(val, flags.IsVerbatim())
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unmarshaler := va.Addr().Interface().(encoding.TextUnmarshaler)
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if err := unmarshaler.UnmarshalText(s); err != nil {
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err = wrapSkipFunc(err, "unmarshal method")
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if uo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return err // unlike marshal, never wrapped
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}
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if !isSemanticError(err) && !isSyntacticError(err) && !export.IsIOError(err) {
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err = newUnmarshalErrorAfter(dec, t, err)
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}
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return err
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}
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return nil
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}
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}
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if _, ok := implements(t, jsonUnmarshalerType); ok {
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fncs.nonDefault = true
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prevUnmarshal := fncs.unmarshal
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fncs.unmarshal = func(dec *jsontext.Decoder, va addressableValue, uo *jsonopts.Struct) error {
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if uo.Flags.Get(jsonflags.CallMethodsWithLegacySemantics) &&
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export.Decoder(dec).Tokens.Last.NeedObjectName() {
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return prevUnmarshal(dec, va, uo)
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}
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val, err := dec.ReadValue()
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if err != nil {
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return err // must be a syntactic or I/O error
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}
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unmarshaler := va.Addr().Interface().(Unmarshaler)
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if err := unmarshaler.UnmarshalJSON(val); err != nil {
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err = wrapSkipFunc(err, "unmarshal method")
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if uo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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return err // unlike marshal, never wrapped
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}
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err = newUnmarshalErrorAfter(dec, t, err)
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return collapseSemanticErrors(err)
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}
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return nil
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}
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}
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if _, ok := implements(t, jsonUnmarshalerFromType); ok {
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fncs.nonDefault = true
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prevUnmarshal := fncs.unmarshal
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fncs.unmarshal = func(dec *jsontext.Decoder, va addressableValue, uo *jsonopts.Struct) error {
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if uo.Flags.Get(jsonflags.CallMethodsWithLegacySemantics) &&
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export.Decoder(dec).Tokens.Last.NeedObjectName() {
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return prevUnmarshal(dec, va, uo)
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}
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xd := export.Decoder(dec)
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prevDepth, prevLength := xd.Tokens.DepthLength()
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xd.Flags.Set(jsonflags.WithinArshalCall | 1)
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err := va.Addr().Interface().(UnmarshalerFrom).UnmarshalJSONFrom(dec)
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xd.Flags.Set(jsonflags.WithinArshalCall | 0)
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currDepth, currLength := xd.Tokens.DepthLength()
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if (prevDepth != currDepth || prevLength+1 != currLength) && err == nil {
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err = errNonSingularValue
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}
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if err != nil {
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err = wrapSkipFunc(err, "unmarshal method")
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if uo.Flags.Get(jsonflags.ReportErrorsWithLegacySemantics) {
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if err2 := xd.SkipUntil(prevDepth, prevLength+1); err2 != nil {
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return err2
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}
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return err // unlike marshal, never wrapped
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}
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if !isSyntacticError(err) && !export.IsIOError(err) {
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err = newSemanticErrorWithPosition(dec, t, prevDepth, prevLength, err)
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}
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return err
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}
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return nil
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}
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}
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return fncs
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}
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// implementsAny is like t.Implements(ifaceType) for a list of interfaces,
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// but checks whether either t or reflect.PointerTo(t) implements the interface.
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func implementsAny(t reflect.Type, ifaceTypes ...reflect.Type) bool {
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for _, ifaceType := range ifaceTypes {
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if _, ok := implements(t, ifaceType); ok {
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return true
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}
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}
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return false
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}
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// implements is like t.Implements(ifaceType) but checks whether
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// either t or reflect.PointerTo(t) implements the interface.
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// It also reports whether the value needs to be addressed
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// in order to satisfy the interface.
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func implements(t, ifaceType reflect.Type) (needAddr, ok bool) {
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switch {
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case t.Implements(ifaceType):
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return false, true
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case reflect.PointerTo(t).Implements(ifaceType):
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return true, true
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default:
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return false, false
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}
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}
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