package toml
import (
"bufio"
"encoding"
"encoding/json"
"errors"
"fmt"
"io"
"math"
"reflect"
"sort"
"strconv"
"strings"
"time"
"github.com/BurntSushi/toml/internal"
)
type tomlEncodeError struct{ error }
var (
errArrayNilElement = errors.New("toml: cannot encode array with nil element")
errNonString = errors.New("toml: cannot encode a map with non-string key type")
errNoKey = errors.New("toml: top-level values must be Go maps or structs")
errAnything = errors.New("") // used in testing
)
var dblQuotedReplacer = strings.NewReplacer(
"\"", "\\\"",
"\\", "\\\\",
"\x00", `\u0000`,
"\x01", `\u0001`,
"\x02", `\u0002`,
"\x03", `\u0003`,
"\x04", `\u0004`,
"\x05", `\u0005`,
"\x06", `\u0006`,
"\x07", `\u0007`,
"\b", `\b`,
"\t", `\t`,
"\n", `\n`,
"\x0b", `\u000b`,
"\f", `\f`,
"\r", `\r`,
"\x0e", `\u000e`,
"\x0f", `\u000f`,
"\x10", `\u0010`,
"\x11", `\u0011`,
"\x12", `\u0012`,
"\x13", `\u0013`,
"\x14", `\u0014`,
"\x15", `\u0015`,
"\x16", `\u0016`,
"\x17", `\u0017`,
"\x18", `\u0018`,
"\x19", `\u0019`,
"\x1a", `\u001a`,
"\x1b", `\u001b`,
"\x1c", `\u001c`,
"\x1d", `\u001d`,
"\x1e", `\u001e`,
"\x1f", `\u001f`,
"\x7f", `\u007f`,
)
var (
marshalToml = reflect.TypeOf((*Marshaler)(nil)).Elem()
marshalText = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
timeType = reflect.TypeOf((*time.Time)(nil)).Elem()
)
// Marshaler is the interface implemented by types that can marshal themselves
// into valid TOML.
type Marshaler interface {
MarshalTOML() ([]byte, error)
}
// Encoder encodes a Go to a TOML document.
//
// The mapping between Go values and TOML values should be precisely the same as
// for [Decode].
//
// time.Time is encoded as a RFC 3339 string, and time.Duration as its string
// representation.
//
// The [Marshaler] and [encoding.TextMarshaler] interfaces are supported to
// encoding the value as custom TOML.
//
// If you want to write arbitrary binary data then you will need to use
// something like base64 since TOML does not have any binary types.
//
// When encoding TOML hashes (Go maps or structs), keys without any sub-hashes
// are encoded first.
//
// Go maps will be sorted alphabetically by key for deterministic output.
//
// The toml struct tag can be used to provide the key name; if omitted the
// struct field name will be used. If the "omitempty" option is present the
// following value will be skipped:
//
// - arrays, slices, maps, and string with len of 0
// - struct with all zero values
// - bool false
//
// If omitzero is given all int and float types with a value of 0 will be
// skipped.
//
// Encoding Go values without a corresponding TOML representation will return an
// error. Examples of this includes maps with non-string keys, slices with nil
// elements, embedded non-struct types, and nested slices containing maps or
// structs. (e.g. [][]map[string]string is not allowed but []map[string]string
// is okay, as is []map[string][]string).
//
// NOTE: only exported keys are encoded due to the use of reflection. Unexported
// keys are silently discarded.
type Encoder struct {
// String to use for a single indentation level; default is two spaces.
Indent string
w *bufio.Writer
hasWritten bool // written any output to w yet?
}
// NewEncoder create a new Encoder.
func NewEncoder(w io.Writer) *Encoder {
return &Encoder{
w: bufio.NewWriter(w),
Indent: " ",
}
}
// Encode writes a TOML representation of the Go value to the [Encoder]'s writer.
//
// An error is returned if the value given cannot be encoded to a valid TOML
// document.
func (enc *Encoder) Encode(v interface{}) error {
rv := eindirect(reflect.ValueOf(v))
if err := enc.safeEncode(Key([]string{}), rv); err != nil {
return err
}
return enc.w.Flush()
}
func (enc *Encoder) safeEncode(key Key, rv reflect.Value) (err error) {
defer func() {
if r := recover(); r != nil {
if terr, ok := r.(tomlEncodeError); ok {
err = terr.error
return
}
panic(r)
}
}()
enc.encode(key, rv)
return nil
}
func (enc *Encoder) encode(key Key, rv reflect.Value) {
// If we can marshal the type to text, then we use that. This prevents the
// encoder for handling these types as generic structs (or whatever the
// underlying type of a TextMarshaler is).
switch {
case isMarshaler(rv):
enc.writeKeyValue(key, rv, false)
return
case rv.Type() == primitiveType: // TODO: #76 would make this superfluous after implemented.
enc.encode(key, reflect.ValueOf(rv.Interface().(Primitive).undecoded))
return
}
k := rv.Kind()
switch k {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
reflect.Uint64,
reflect.Float32, reflect.Float64, reflect.String, reflect.Bool:
enc.writeKeyValue(key, rv, false)
case reflect.Array, reflect.Slice:
if typeEqual(tomlArrayHash, tomlTypeOfGo(rv)) {
enc.eArrayOfTables(key, rv)
} else {
enc.writeKeyValue(key, rv, false)
}
case reflect.Interface:
if rv.IsNil() {
return
}
enc.encode(key, rv.Elem())
case reflect.Map:
if rv.IsNil() {
return
}
enc.eTable(key, rv)
case reflect.Ptr:
if rv.IsNil() {
return
}
enc.encode(key, rv.Elem())
case reflect.Struct:
enc.eTable(key, rv)
default:
encPanic(fmt.Errorf("unsupported type for key '%s': %s", key, k))
}
}
// eElement encodes any value that can be an array element.
func (enc *Encoder) eElement(rv reflect.Value) {
switch v := rv.Interface().(type) {
case time.Time: // Using TextMarshaler adds extra quotes, which we don't want.
format := time.RFC3339Nano
switch v.Location() {
case internal.LocalDatetime:
format = "2006-01-02T15:04:05.999999999"
case internal.LocalDate:
format = "2006-01-02"
case internal.LocalTime:
format = "15:04:05.999999999"
}
switch v.Location() {
default:
enc.wf(v.Format(format))
case internal.LocalDatetime, internal.LocalDate, internal.LocalTime:
enc.wf(v.In(time.UTC).Format(format))
}
return
case Marshaler:
s, err := v.MarshalTOML()
if err != nil {
encPanic(err)
}
if s == nil {
encPanic(errors.New("MarshalTOML returned nil and no error"))
}
enc.w.Write(s)
return
case encoding.TextMarshaler:
s, err := v.MarshalText()
if err != nil {
encPanic(err)
}
if s == nil {
encPanic(errors.New("MarshalText returned nil and no error"))
}
enc.writeQuoted(string(s))
return
case time.Duration:
enc.writeQuoted(v.String())
return
case json.Number:
n, _ := rv.Interface().(json.Number)
if n == "" { /// Useful zero value.
enc.w.WriteByte('0')
return
} else if v, err := n.Int64(); err == nil {
enc.eElement(reflect.ValueOf(v))
return
} else if v, err := n.Float64(); err == nil {
enc.eElement(reflect.ValueOf(v))
return
}
encPanic(fmt.Errorf("unable to convert %q to int64 or float64", n))
}
switch rv.Kind() {
case reflect.Ptr:
enc.eElement(rv.Elem())
return
case reflect.String:
enc.writeQuoted(rv.String())
case reflect.Bool:
enc.wf(strconv.FormatBool(rv.Bool()))
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
enc.wf(strconv.FormatInt(rv.Int(), 10))
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
enc.wf(strconv.FormatUint(rv.Uint(), 10))
case reflect.Float32:
f := rv.Float()
if math.IsNaN(f) {
enc.wf("nan")
} else if math.IsInf(f, 0) {
enc.wf("%cinf", map[bool]byte{true: '-', false: '+'}[math.Signbit(f)])
} else {
enc.wf(floatAddDecimal(strconv.FormatFloat(f, 'f', -1, 32)))
}
case reflect.Float64:
f := rv.Float()
if math.IsNaN(f) {
enc.wf("nan")
} else if math.IsInf(f, 0) {
enc.wf("%cinf", map[bool]byte{true: '-', false: '+'}[math.Signbit(f)])
} else {
enc.wf(floatAddDecimal(strconv.FormatFloat(f, 'f', -1, 64)))
}
case reflect.Array, reflect.Slice:
enc.eArrayOrSliceElement(rv)
case reflect.Struct:
enc.eStruct(nil, rv, true)
case reflect.Map:
enc.eMap(nil, rv, true)
case reflect.Interface:
enc.eElement(rv.Elem())
default:
encPanic(fmt.Errorf("unexpected type: %T", rv.Interface()))
}
}
// By the TOML spec, all floats must have a decimal with at least one number on
// either side.
func floatAddDecimal(fstr string) string {
if !strings.Contains(fstr, ".") {
return fstr + ".0"
}
return fstr
}
func (enc *Encoder) writeQuoted(s string) {
enc.wf("\"%s\"", dblQuotedReplacer.Replace(s))
}
func (enc *Encoder) eArrayOrSliceElement(rv reflect.Value) {
length := rv.Len()
enc.wf("[")
for i := 0; i < length; i++ {
elem := eindirect(rv.Index(i))
enc.eElement(elem)
if i != length-1 {
enc.wf(", ")
}
}
enc.wf("]")
}
func (enc *Encoder) eArrayOfTables(key Key, rv reflect.Value) {
if len(key) == 0 {
encPanic(errNoKey)
}
for i := 0; i < rv.Len(); i++ {
trv := eindirect(rv.Index(i))
if isNil(trv) {
continue
}
enc.newline()
enc.wf("%s[[%s]]", enc.indentStr(key), key)
enc.newline()
enc.eMapOrStruct(key, trv, false)
}
}
func (enc *Encoder) eTable(key Key, rv reflect.Value) {
if len(key) == 1 {
// Output an extra newline between top-level tables.
// (The newline isn't written if nothing else has been written though.)
enc.newline()
}
if len(key) > 0 {
enc.wf("%s[%s]", enc.indentStr(key), key)
enc.newline()
}
enc.eMapOrStruct(key, rv, false)
}
func (enc *Encoder) eMapOrStruct(key Key, rv reflect.Value, inline bool) {
switch rv.Kind() {
case reflect.Map:
enc.eMap(key, rv, inline)
case reflect.Struct:
enc.eStruct(key, rv, inline)
default:
// Should never happen?
panic("eTable: unhandled reflect.Value Kind: " + rv.Kind().String())
}
}
func (enc *Encoder) eMap(key Key, rv reflect.Value, inline bool) {
rt := rv.Type()
if rt.Key().Kind() != reflect.String {
encPanic(errNonString)
}
// Sort keys so that we have deterministic output. And write keys directly
// underneath this key first, before writing sub-structs or sub-maps.
var mapKeysDirect, mapKeysSub []string
for _, mapKey := range rv.MapKeys() {
k := mapKey.String()
if typeIsTable(tomlTypeOfGo(eindirect(rv.MapIndex(mapKey)))) {
mapKeysSub = append(mapKeysSub, k)
} else {
mapKeysDirect = append(mapKeysDirect, k)
}
}
var writeMapKeys = func(mapKeys []string, trailC bool) {
sort.Strings(mapKeys)
for i, mapKey := range mapKeys {
val := eindirect(rv.MapIndex(reflect.ValueOf(mapKey)))
if isNil(val) {
continue
}
if inline {
enc.writeKeyValue(Key{mapKey}, val, true)
if trailC || i != len(mapKeys)-1 {
enc.wf(", ")
}
} else {
enc.encode(key.add(mapKey), val)
}
}
}
if inline {
enc.wf("{")
}
writeMapKeys(mapKeysDirect, len(mapKeysSub) > 0)
writeMapKeys(mapKeysSub, false)
if inline {
enc.wf("}")
}
}
const is32Bit = (32 << (^uint(0) >> 63)) == 32
func pointerTo(t reflect.Type) reflect.Type {
if t.Kind() == reflect.Ptr {
return pointerTo(t.Elem())
}
return t
}
func (enc *Encoder) eStruct(key Key, rv reflect.Value, inline bool) {
// Write keys for fields directly under this key first, because if we write
// a field that creates a new table then all keys under it will be in that
// table (not the one we're writing here).
//
// Fields is a [][]int: for fieldsDirect this always has one entry (the
// struct index). For fieldsSub it contains two entries: the parent field
// index from tv, and the field indexes for the fields of the sub.
var (
rt = rv.Type()
fieldsDirect, fieldsSub [][]int
addFields func(rt reflect.Type, rv reflect.Value, start []int)
)
addFields = func(rt reflect.Type, rv reflect.Value, start []int) {
for i := 0; i < rt.NumField(); i++ {
f := rt.Field(i)
isEmbed := f.Anonymous && pointerTo(f.Type).Kind() == reflect.Struct
if f.PkgPath != "" && !isEmbed { /// Skip unexported fields.
continue
}
opts := getOptions(f.Tag)
if opts.skip {
continue
}
frv := eindirect(rv.Field(i))
// Treat anonymous struct fields with tag names as though they are
// not anonymous, like encoding/json does.
//
// Non-struct anonymous fields use the normal encoding logic.
if isEmbed {
if getOptions(f.Tag).name == "" && frv.Kind() == reflect.Struct {
addFields(frv.Type(), frv, append(start, f.Index...))
continue
}
}
if typeIsTable(tomlTypeOfGo(frv)) {
fieldsSub = append(fieldsSub, append(start, f.Index...))
} else {
// Copy so it works correct on 32bit archs; not clear why this
// is needed. See #314, and https://www.reddit.com/r/golang/comments/pnx8v4
// This also works fine on 64bit, but 32bit archs are somewhat
// rare and this is a wee bit faster.
if is32Bit {
copyStart := make([]int, len(start))
copy(copyStart, start)
fieldsDirect = append(fieldsDirect, append(copyStart, f.Index...))
} else {
fieldsDirect = append(fieldsDirect, append(start, f.Index...))
}
}
}
}
addFields(rt, rv, nil)
writeFields := func(fields [][]int) {
for _, fieldIndex := range fields {
fieldType := rt.FieldByIndex(fieldIndex)
fieldVal := eindirect(rv.FieldByIndex(fieldIndex))
if isNil(fieldVal) { /// Don't write anything for nil fields.
continue
}
opts := getOptions(fieldType.Tag)
if opts.skip {
continue
}
keyName := fieldType.Name
if opts.name != "" {
keyName = opts.name
}
if opts.omitempty && enc.isEmpty(fieldVal) {
continue
}
if opts.omitzero && isZero(fieldVal) {
continue
}
if inline {
enc.writeKeyValue(Key{keyName}, fieldVal, true)
if fieldIndex[0] != len(fields)-1 {
enc.wf(", ")
}
} else {
enc.encode(key.add(keyName), fieldVal)
}
}
}
if inline {
enc.wf("{")
}
writeFields(fieldsDirect)
writeFields(fieldsSub)
if inline {
enc.wf("}")
}
}
// tomlTypeOfGo returns the TOML type name of the Go value's type.
//
// It is used to determine whether the types of array elements are mixed (which
// is forbidden). If the Go value is nil, then it is illegal for it to be an
// array element, and valueIsNil is returned as true.
//
// The type may be `nil`, which means no concrete TOML type could be found.
func tomlTypeOfGo(rv reflect.Value) tomlType {
if isNil(rv) || !rv.IsValid() {
return nil
}
if rv.Kind() == reflect.Struct {
if rv.Type() == timeType {
return tomlDatetime
}
if isMarshaler(rv) {
return tomlString
}
return tomlHash
}
if isMarshaler(rv) {
return tomlString
}
switch rv.Kind() {
case reflect.Bool:
return tomlBool
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32,
reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32,
reflect.Uint64:
return tomlInteger
case reflect.Float32, reflect.Float64:
return tomlFloat
case reflect.Array, reflect.Slice:
if isTableArray(rv) {
return tomlArrayHash
}
return tomlArray
case reflect.Ptr, reflect.Interface:
return tomlTypeOfGo(rv.Elem())
case reflect.String:
return tomlString
case reflect.Map:
return tomlHash
default:
encPanic(errors.New("unsupported type: " + rv.Kind().String()))
panic("unreachable")
}
}
func isMarshaler(rv reflect.Value) bool {
return rv.Type().Implements(marshalText) || rv.Type().Implements(marshalToml)
}
// isTableArray reports if all entries in the array or slice are a table.
func isTableArray(arr reflect.Value) bool {
if isNil(arr) || !arr.IsValid() || arr.Len() == 0 {
return false
}
ret := true
for i := 0; i < arr.Len(); i++ {
tt := tomlTypeOfGo(eindirect(arr.Index(i)))
// Don't allow nil.
if tt == nil {
encPanic(errArrayNilElement)
}
if ret && !typeEqual(tomlHash, tt) {
ret = false
}
}
return ret
}
type tagOptions struct {
skip bool // "-"
name string
omitempty bool
omitzero bool
}
func getOptions(tag reflect.StructTag) tagOptions {
t := tag.Get("toml")
if t == "-" {
return tagOptions{skip: true}
}
var opts tagOptions
parts := strings.Split(t, ",")
opts.name = parts[0]
for _, s := range parts[1:] {
switch s {
case "omitempty":
opts.omitempty = true
case "omitzero":
opts.omitzero = true
}
}
return opts
}
func isZero(rv reflect.Value) bool {
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return rv.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
return rv.Uint() == 0
case reflect.Float32, reflect.Float64:
return rv.Float() == 0.0
}
return false
}
func (enc *Encoder) isEmpty(rv reflect.Value) bool {
switch rv.Kind() {
case reflect.Array, reflect.Slice, reflect.Map, reflect.String:
return rv.Len() == 0
case reflect.Struct:
if rv.Type().Comparable() {
return reflect.Zero(rv.Type()).Interface() == rv.Interface()
}
// Need to also check if all the fields are empty, otherwise something
// like this with uncomparable types will always return true:
//
// type a struct{ field b }
// type b struct{ s []string }
// s := a{field: b{s: []string{"AAA"}}}
for i := 0; i < rv.NumField(); i++ {
if !enc.isEmpty(rv.Field(i)) {
return false
}
}
return true
case reflect.Bool:
return !rv.Bool()
}
return false
}
func (enc *Encoder) newline() {
if enc.hasWritten {
enc.wf("\n")
}
}
// Write a key/value pair:
//
// key = <any value>
//
// This is also used for "k = v" in inline tables; so something like this will
// be written in three calls:
//
// ┌───────────────────┐
// │ ┌───┐ ┌────┐│
// v v v v vv
// key = {k = 1, k2 = 2}
func (enc *Encoder) writeKeyValue(key Key, val reflect.Value, inline bool) {
if len(key) == 0 {
encPanic(errNoKey)
}
enc.wf("%s%s = ", enc.indentStr(key), key.maybeQuoted(len(key)-1))
enc.eElement(val)
if !inline {
enc.newline()
}
}
func (enc *Encoder) wf(format string, v ...interface{}) {
_, err := fmt.Fprintf(enc.w, format, v...)
if err != nil {
encPanic(err)
}
enc.hasWritten = true
}
func (enc *Encoder) indentStr(key Key) string {
return strings.Repeat(enc.Indent, len(key)-1)
}
func encPanic(err error) {
panic(tomlEncodeError{err})
}
// Resolve any level of pointers to the actual value (e.g. **string → string).
func eindirect(v reflect.Value) reflect.Value {
if v.Kind() != reflect.Ptr && v.Kind() != reflect.Interface {
if isMarshaler(v) {
return v
}
if v.CanAddr() { /// Special case for marshalers; see #358.
if pv := v.Addr(); isMarshaler(pv) {
return pv
}
}
return v
}
if v.IsNil() {
return v
}
return eindirect(v.Elem())
}
func isNil(rv reflect.Value) bool {
switch rv.Kind() {
case reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
return rv.IsNil()
default:
return false
}
}
