pulumi/sdk/go/common/encoding/marshal.go

// Copyright 2016-2018, Pulumi Corporation.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package encoding

import (
	"encoding/json"
	"fmt"
	"path/filepath"
	"reflect"
	"strings"

	yaml "gopkg.in/yaml.v2"
)

var JSONExt = ".json"
var YAMLExt = ".yaml"

// Exts contains a list of all the valid marshalable extension types.
var Exts = []string{
	JSONExt,
	YAMLExt,
	// Although ".yml" is not a sanctioned YAML extension, it is used quite broadly; so we will support it.
	".yml",
}

// Detect auto-detects a marshaler for the given path.
func Detect(path string) (Marshaler, string) {
	ext := filepath.Ext(path)
	if ext == "" {
		ext = DefaultExt() // default to the first (preferred) marshaler.
	}
	return Marshalers[ext], ext
}

// Marshalers is a map of extension to a Marshaler object for that extension.
var Marshalers map[string]Marshaler

// Default returns the default marshaler object.
func Default() Marshaler {
	return Marshalers[DefaultExt()]
}

// DefaultExt returns the default extension to use.
func DefaultExt() string {
	return Exts[0]
}

// Marshaler is a type that knows how to marshal and unmarshal data in one format.
type Marshaler interface {
	IsJSONLike() bool
	IsYAMLLike() bool
	Marshal(v interface{}) ([]byte, error)
	Unmarshal(data []byte, v interface{}) error
}

var JSON Marshaler = &jsonMarshaler{}

type jsonMarshaler struct {
}

func (m *jsonMarshaler) IsJSONLike() bool {
	return true
}

func (m *jsonMarshaler) IsYAMLLike() bool {
	return false
}

func (m *jsonMarshaler) Marshal(v interface{}) ([]byte, error) {
	return json.MarshalIndent(v, "", "    ")
}

func (m *jsonMarshaler) Unmarshal(data []byte, v interface{}) error {
	// IDEA: use a "strict" marshaler, so that we can warn on unrecognized keys (avoiding silly mistakes).  We should
	//     set aside an officially sanctioned area in the metadata for extensibility by 3rd parties.
	return json.Unmarshal(data, v)
}

var YAML Marshaler = &yamlMarshaler{}

type yamlMarshaler struct {
}

func (m *yamlMarshaler) IsJSONLike() bool {
	return false
}

func (m *yamlMarshaler) IsYAMLLike() bool {
	return true
}

func (m *yamlMarshaler) Marshal(v interface{}) ([]byte, error) {
	o, err := yaml.Marshal(v)
	if err != nil {
		return o, err
	}
	if v, ok := getExtraFields(v); ok {
		if !v.IsZero() {
			extra, err := yaml.Marshal(v.Interface())
			if err != nil {
				return nil, err
			}
			o = append(o, '\n')
			o = append(o, extra...)
		}
	}
	return o, nil
}

func (m *yamlMarshaler) Unmarshal(data []byte, v interface{}) error {
	// IDEA: use a "strict" marshaler, so that we can warn on unrecognized keys (avoiding silly mistakes).  We should
	//     set aside an officially sanctioned area in the metadata for extensibility by 3rd parties.

	err := yaml.Unmarshal(data, v)
	if err != nil {
		// Return type errors directly
		if _, ok := err.(*yaml.TypeError); ok {
			return err
		}
		// Other errors will be parse errors due to invalid syntax
		return fmt.Errorf("invalid YAML file: %w", err)
	}

	if extra, ok := getExtraFields(v); ok {
		unusedFields := collectUnusedFields(data, v)
		extra.Set(reflect.ValueOf(unusedFields))
	}

	return nil
}

func getExtraFields(v interface{}) (reflect.Value, bool) {
	vv := reflect.ValueOf(v)
	if vv.IsValid() && vv.Kind() == reflect.Ptr {
		t := vv.Type().Elem()
		if t.Kind() == reflect.Struct {
			_, ok := t.FieldByName("ExtraFields")
			if ok {
				return vv.Elem().FieldByName("ExtraFields"), true
			}
		}
	}
	var out reflect.Value
	return out, false
}

func collectUnusedFields(data []byte, i interface{}) map[string]interface{} {
	v := reflect.ValueOf(i)
	if v.Type().Kind() == reflect.Ptr {
		if v.IsNil() {
			return nil
		}
		v = v.Elem()
	}

	if v.Kind() != reflect.Struct {
		return nil
	}

	topLevel := map[string]interface{}{}
	if err := yaml.Unmarshal(data, &topLevel); err != nil {
		return nil
	}
	out := map[string]interface{}{}
	names := map[string]struct{}{}
	for i := 0; i < v.Type().NumField(); i++ {
		names[v.Type().Field(i).Name] = struct{}{}
	}
	for k, kv := range topLevel {
		name := strings.ToUpper(k[:1]) + k[1:]
		if _, ok := v.Type().FieldByName(name); !ok {
			out[k] = kv
		}
	}
	return out
}