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Add Encoder/Decoder types
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Usage is similar to the stdlibs JSON encoder/decoder but I tried to
leave the general structure of the code the same.

Main motivation was to support encoding/decoding options to allow
encoding string-type map keys as quoted TOML keys.
This was implemented on the Encoder with QuoteMapKeys(bool).

> The TOML spec supports using UTF-8 strings as keys.
> https://github.com/toml-lang/toml/blob/master/versions/en/toml-v0.4.0.md#table
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@robertgzr
robertgzr committed Oct 24, 2017
1 parent 8c31c2e commit d32b181
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Showing 2 changed files with 215 additions and 41 deletions.
182 changes: 141 additions & 41 deletions marshal.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import (
"bytes"
"errors"
"fmt"
"io"
"reflect"
"strconv"
"strings"
Expand All @@ -18,6 +19,14 @@ type tomlOpts struct {
omitempty bool
}

type encOpts struct {
quoteMapKeys bool
}

var encOptsDefaults = encOpts{
quoteMapKeys: false,
}

var timeType = reflect.TypeOf(time.Time{})
var marshalerType = reflect.TypeOf(new(Marshaler)).Elem()

Expand Down Expand Up @@ -125,6 +134,47 @@ Tree primitive types and corresponding marshal types:
time.Time time.Time{}, pointers to same
*/
func Marshal(v interface{}) ([]byte, error) {
return NewEncoder(nil).marshal(v)
}

// Encoder writes TOML values to an output stream.
type Encoder struct {
w io.Writer
encOpts
}

// NewEncoder returns a new encoder that writes to w.
func NewEncoder(w io.Writer) *Encoder {
return &Encoder{
w: w,
encOpts: encOptsDefaults,
}
}

// Encode writes the TOML encoding of v to the stream.
//
// See the documentation for Marshal for details.
func (e *Encoder) Encode(v interface{}) error {
b, err := e.marshal(v)
if err != nil {
return err
}
if _, err := e.w.Write(b); err != nil {
return err
}
return nil
}

// QuoteMapKeys sets up the encoder to encode
// maps with string type keys with quoted TOML keys.
//
// This relieves the character limitations on map keys.
func (e *Encoder) QuoteMapKeys(v bool) *Encoder {
e.quoteMapKeys = v
return e
}

func (e *Encoder) marshal(v interface{}) ([]byte, error) {
mtype := reflect.TypeOf(v)
if mtype.Kind() != reflect.Struct {
return []byte{}, errors.New("Only a struct can be marshaled to TOML")
Expand All @@ -133,7 +183,7 @@ func Marshal(v interface{}) ([]byte, error) {
if isCustomMarshaler(mtype) {
return callCustomMarshaler(sval)
}
t, err := valueToTree(mtype, sval)
t, err := e.valueToTree(mtype, sval)
if err != nil {
return []byte{}, err
}
Expand All @@ -142,9 +192,9 @@ func Marshal(v interface{}) ([]byte, error) {
}

// Convert given marshal struct or map value to toml tree
func valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, error) {
func (e *Encoder) valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, error) {
if mtype.Kind() == reflect.Ptr {
return valueToTree(mtype.Elem(), mval.Elem())
return e.valueToTree(mtype.Elem(), mval.Elem())
}
tval := newTree()
switch mtype.Kind() {
Expand All @@ -153,7 +203,7 @@ func valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, error) {
mtypef, mvalf := mtype.Field(i), mval.Field(i)
opts := tomlOptions(mtypef)
if opts.include && (!opts.omitempty || !isZero(mvalf)) {
val, err := valueToToml(mtypef.Type, mvalf)
val, err := e.valueToToml(mtypef.Type, mvalf)
if err != nil {
return nil, err
}
Expand All @@ -163,21 +213,29 @@ func valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, error) {
case reflect.Map:
for _, key := range mval.MapKeys() {
mvalf := mval.MapIndex(key)
val, err := valueToToml(mtype.Elem(), mvalf)
val, err := e.valueToToml(mtype.Elem(), mvalf)
if err != nil {
return nil, err
}
tval.Set(key.String(), "", false, val)
if e.quoteMapKeys {
keyStr, err := tomlValueStringRepresentation(key.String())
if err != nil {
return nil, err
}
tval.SetPath([]string{keyStr}, "", false, val)
} else {
tval.Set(key.String(), "", false, val)
}
}
}
return tval, nil
}

// Convert given marshal slice to slice of Toml trees
func valueToTreeSlice(mtype reflect.Type, mval reflect.Value) ([]*Tree, error) {
func (e *Encoder) valueToTreeSlice(mtype reflect.Type, mval reflect.Value) ([]*Tree, error) {
tval := make([]*Tree, mval.Len(), mval.Len())
for i := 0; i < mval.Len(); i++ {
val, err := valueToTree(mtype.Elem(), mval.Index(i))
val, err := e.valueToTree(mtype.Elem(), mval.Index(i))
if err != nil {
return nil, err
}
Expand All @@ -187,10 +245,10 @@ func valueToTreeSlice(mtype reflect.Type, mval reflect.Value) ([]*Tree, error) {
}

// Convert given marshal slice to slice of toml values
func valueToOtherSlice(mtype reflect.Type, mval reflect.Value) (interface{}, error) {
func (e *Encoder) valueToOtherSlice(mtype reflect.Type, mval reflect.Value) (interface{}, error) {
tval := make([]interface{}, mval.Len(), mval.Len())
for i := 0; i < mval.Len(); i++ {
val, err := valueToToml(mtype.Elem(), mval.Index(i))
val, err := e.valueToToml(mtype.Elem(), mval.Index(i))
if err != nil {
return nil, err
}
Expand All @@ -200,19 +258,19 @@ func valueToOtherSlice(mtype reflect.Type, mval reflect.Value) (interface{}, err
}

// Convert given marshal value to toml value
func valueToToml(mtype reflect.Type, mval reflect.Value) (interface{}, error) {
func (e *Encoder) valueToToml(mtype reflect.Type, mval reflect.Value) (interface{}, error) {
if mtype.Kind() == reflect.Ptr {
return valueToToml(mtype.Elem(), mval.Elem())
return e.valueToToml(mtype.Elem(), mval.Elem())
}
switch {
case isCustomMarshaler(mtype):
return callCustomMarshaler(mval)
case isTree(mtype):
return valueToTree(mtype, mval)
return e.valueToTree(mtype, mval)
case isTreeSlice(mtype):
return valueToTreeSlice(mtype, mval)
return e.valueToTreeSlice(mtype, mval)
case isOtherSlice(mtype):
return valueToOtherSlice(mtype, mval)
return e.valueToOtherSlice(mtype, mval)
default:
switch mtype.Kind() {
case reflect.Bool:
Expand All @@ -237,17 +295,16 @@ func valueToToml(mtype reflect.Type, mval reflect.Value) (interface{}, error) {
// Neither Unmarshaler interfaces nor UnmarshalTOML functions are supported for
// sub-structs, and only definite types can be unmarshaled.
func (t *Tree) Unmarshal(v interface{}) error {
mtype := reflect.TypeOf(v)
if mtype.Kind() != reflect.Ptr || mtype.Elem().Kind() != reflect.Struct {
return errors.New("Only a pointer to struct can be unmarshaled from TOML")
}
d := Decoder{tval: t}
return d.unmarshal(v)
}

sval, err := valueFromTree(mtype.Elem(), t)
if err != nil {
return err
}
reflect.ValueOf(v).Elem().Set(sval)
return nil
// Marshal returns the TOML encoding of Tree.
// See Marshal() documentation for types mapping table.
func (t *Tree) Marshal() ([]byte, error) {
var buf bytes.Buffer
err := NewEncoder(&buf).Encode(t)
return buf.Bytes(), err
}

// Unmarshal parses the TOML-encoded data and stores the result in the value
Expand All @@ -269,10 +326,52 @@ func Unmarshal(data []byte, v interface{}) error {
return t.Unmarshal(v)
}

// Decoder reads and decodes TOML values from an input stream.
type Decoder struct {
r io.Reader
tval *Tree
encOpts
}

// NewDecoder returns a new decoder that reads from r.
func NewDecoder(r io.Reader) *Decoder {
return &Decoder{
r: r,
encOpts: encOptsDefaults,
}
}

// Decode reads a TOML-encoded value from it's input
// and unmarshals it in the value pointed at by v.
//
// See the documentation for Marshal for details.
func (d *Decoder) Decode(v interface{}) error {
var err error
d.tval, err = LoadReader(d.r)
if err != nil {
return err
}
return d.unmarshal(v)
}

func (d *Decoder) unmarshal(v interface{}) error {
mtype := reflect.TypeOf(v)
if mtype.Kind() != reflect.Ptr || mtype.Elem().Kind() != reflect.Struct {
return errors.New("Only a pointer to struct can be unmarshaled from TOML")
}

sval, err := d.valueFromTree(mtype.Elem(), d.tval)
if err != nil {
return err
}
reflect.ValueOf(v).Elem().Set(sval)
return nil
}

// Convert toml tree to marshal struct or map, using marshal type
func valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value, error) {
func (d *Decoder) valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value, error) {
if mtype.Kind() == reflect.Ptr {
return unwrapPointer(mtype, tval)
return d.unwrapPointer(mtype, tval)
}
var mval reflect.Value
switch mtype.Kind() {
Expand All @@ -290,7 +389,7 @@ func valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value, error) {
continue
}
val := tval.Get(key)
mvalf, err := valueFromToml(mtypef.Type, val)
mvalf, err := d.valueFromToml(mtypef.Type, val)
if err != nil {
return mval, formatError(err, tval.GetPosition(key))
}
Expand All @@ -302,8 +401,9 @@ func valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value, error) {
case reflect.Map:
mval = reflect.MakeMap(mtype)
for _, key := range tval.Keys() {
val := tval.Get(key)
mvalf, err := valueFromToml(mtype.Elem(), val)
// TODO: path splits key
val := tval.GetPath([]string{key})
mvalf, err := d.valueFromToml(mtype.Elem(), val)
if err != nil {
return mval, formatError(err, tval.GetPosition(key))
}
Expand All @@ -314,10 +414,10 @@ func valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value, error) {
}

// Convert toml value to marshal struct/map slice, using marshal type
func valueFromTreeSlice(mtype reflect.Type, tval []*Tree) (reflect.Value, error) {
func (d *Decoder) valueFromTreeSlice(mtype reflect.Type, tval []*Tree) (reflect.Value, error) {
mval := reflect.MakeSlice(mtype, len(tval), len(tval))
for i := 0; i < len(tval); i++ {
val, err := valueFromTree(mtype.Elem(), tval[i])
val, err := d.valueFromTree(mtype.Elem(), tval[i])
if err != nil {
return mval, err
}
Expand All @@ -327,10 +427,10 @@ func valueFromTreeSlice(mtype reflect.Type, tval []*Tree) (reflect.Value, error)
}

// Convert toml value to marshal primitive slice, using marshal type
func valueFromOtherSlice(mtype reflect.Type, tval []interface{}) (reflect.Value, error) {
func (d *Decoder) valueFromOtherSlice(mtype reflect.Type, tval []interface{}) (reflect.Value, error) {
mval := reflect.MakeSlice(mtype, len(tval), len(tval))
for i := 0; i < len(tval); i++ {
val, err := valueFromToml(mtype.Elem(), tval[i])
val, err := d.valueFromToml(mtype.Elem(), tval[i])
if err != nil {
return mval, err
}
Expand All @@ -340,27 +440,27 @@ func valueFromOtherSlice(mtype reflect.Type, tval []interface{}) (reflect.Value,
}

// Convert toml value to marshal value, using marshal type
func valueFromToml(mtype reflect.Type, tval interface{}) (reflect.Value, error) {
func (d *Decoder) valueFromToml(mtype reflect.Type, tval interface{}) (reflect.Value, error) {
if mtype.Kind() == reflect.Ptr {
return unwrapPointer(mtype, tval)
return d.unwrapPointer(mtype, tval)
}

switch tval.(type) {
case *Tree:
if isTree(mtype) {
return valueFromTree(mtype, tval.(*Tree))
return d.valueFromTree(mtype, tval.(*Tree))
} else {
return reflect.ValueOf(nil), fmt.Errorf("Can't convert %v(%T) to a tree", tval, tval)
}
case []*Tree:
if isTreeSlice(mtype) {
return valueFromTreeSlice(mtype, tval.([]*Tree))
return d.valueFromTreeSlice(mtype, tval.([]*Tree))
} else {
return reflect.ValueOf(nil), fmt.Errorf("Can't convert %v(%T) to trees", tval, tval)
}
case []interface{}:
if isOtherSlice(mtype) {
return valueFromOtherSlice(mtype, tval.([]interface{}))
return d.valueFromOtherSlice(mtype, tval.([]interface{}))
} else {
return reflect.ValueOf(nil), fmt.Errorf("Can't convert %v(%T) to a slice", tval, tval)
}
Expand Down Expand Up @@ -462,8 +562,8 @@ func valueFromToml(mtype reflect.Type, tval interface{}) (reflect.Value, error)
}
}

func unwrapPointer(mtype reflect.Type, tval interface{}) (reflect.Value, error) {
val, err := valueFromToml(mtype.Elem(), tval)
func (d *Decoder) unwrapPointer(mtype reflect.Type, tval interface{}) (reflect.Value, error) {
val, err := d.valueFromToml(mtype.Elem(), tval)
if err != nil {
return reflect.ValueOf(nil), err
}
Expand Down
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