package toml import ( "bufio" "errors" "fmt" "io" "reflect" "sort" "strconv" "strings" "time" ) type tomlEncodeError struct{ error } var ( errArrayMixedElementTypes = errors.New( "can't encode array with mixed element types") errArrayNilElement = errors.New( "can't encode array with nil element") errNonString = errors.New( "can't encode a map with non-string key type") errAnonNonStruct = errors.New( "can't encode an anonymous field that is not a struct") errArrayNoTable = errors.New( "TOML array element can't contain a table") errNoKey = errors.New( "top-level values must be a Go map or struct") errAnything = errors.New("") // used in testing ) var quotedReplacer = strings.NewReplacer( "\t", "\\t", "\n", "\\n", "\r", "\\r", "\"", "\\\"", "\\", "\\\\", ) // Encoder controls the encoding of Go values to a TOML document to some // io.Writer. // // The indentation level can be controlled with the Indent field. type Encoder struct { // A single indentation level. By default it is two spaces. Indent string // hasWritten is whether we have written any output to w yet. hasWritten bool w *bufio.Writer } // NewEncoder returns a TOML encoder that encodes Go values to the io.Writer // given. By default, a single indentation level is 2 spaces. func NewEncoder(w io.Writer) *Encoder { return &Encoder{ w: bufio.NewWriter(w), Indent: " ", } } // Encode writes a TOML representation of the Go value to the underlying // io.Writer. If the value given cannot be encoded to a valid TOML document, // then an error is returned. // // The mapping between Go values and TOML values should be precisely the same // as for the Decode* functions. Similarly, the TextMarshaler interface is // supported by encoding the resulting bytes as strings. (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 (i.e., Go maps or structs), keys without any // sub-hashes are encoded first. // // If a Go map is encoded, then its keys are sorted alphabetically for // deterministic output. More control over this behavior may be provided if // there is demand for it. // // Encoding Go values without a corresponding TOML representation---like map // types with non-string keys---will cause an error to be returned. Similarly // for mixed arrays/slices, arrays/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 OK // and so is []map[string][]string.) 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) { // Special case. Time needs to be in ISO8601 format. // Special case. If we can marshal the type to text, then we used that. // Basically, this prevents the encoder for handling these types as // generic structs (or whatever the underlying type of a TextMarshaler is). switch rv.Interface().(type) { case time.Time, TextMarshaler: enc.keyEqElement(key, rv) 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.keyEqElement(key, rv) case reflect.Array, reflect.Slice: if typeEqual(tomlArrayHash, tomlTypeOfGo(rv)) { enc.eArrayOfTables(key, rv) } else { enc.keyEqElement(key, rv) } 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: panic(e("Unsupported type for key '%s': %s", key, k)) } } // eElement encodes any value that can be an array element (primitives and // arrays). func (enc *Encoder) eElement(rv reflect.Value) { switch v := rv.Interface().(type) { case time.Time: // Special case time.Time as a primitive. Has to come before // TextMarshaler below because time.Time implements // encoding.TextMarshaler, but we need to always use UTC. enc.wf(v.In(time.FixedZone("UTC", 0)).Format("2006-01-02T15:04:05Z")) return case TextMarshaler: // Special case. Use text marshaler if it's available for this value. if s, err := v.MarshalText(); err != nil { encPanic(err) } else { enc.writeQuoted(string(s)) } return } switch rv.Kind() { 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: enc.wf(floatAddDecimal(strconv.FormatFloat(rv.Float(), 'f', -1, 32))) case reflect.Float64: enc.wf(floatAddDecimal(strconv.FormatFloat(rv.Float(), 'f', -1, 64))) case reflect.Array, reflect.Slice: enc.eArrayOrSliceElement(rv) case reflect.Interface: enc.eElement(rv.Elem()) case reflect.String: enc.writeQuoted(rv.String()) default: panic(e("Unexpected primitive type: %s", rv.Kind())) } } // 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\"", quotedReplacer.Replace(s)) } func (enc *Encoder) eArrayOrSliceElement(rv reflect.Value) { length := rv.Len() enc.wf("[") for i := 0; i < length; i++ { elem := 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) } panicIfInvalidKey(key, true) for i := 0; i < rv.Len(); i++ { trv := rv.Index(i) if isNil(trv) { continue } enc.newline() enc.wf("%s[[%s]]", enc.indentStr(key), key.String()) enc.newline() enc.eMapOrStruct(key, trv) } } func (enc *Encoder) eTable(key Key, rv reflect.Value) { if len(key) == 1 { // Output an extra new line between top-level tables. // (The newline isn't written if nothing else has been written though.) enc.newline() } if len(key) > 0 { panicIfInvalidKey(key, true) enc.wf("%s[%s]", enc.indentStr(key), key.String()) enc.newline() } enc.eMapOrStruct(key, rv) } func (enc *Encoder) eMapOrStruct(key Key, rv reflect.Value) { switch rv := eindirect(rv); rv.Kind() { case reflect.Map: enc.eMap(key, rv) case reflect.Struct: enc.eStruct(key, rv) default: panic("eTable: unhandled reflect.Value Kind: " + rv.Kind().String()) } } func (enc *Encoder) eMap(key Key, rv reflect.Value) { 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 typeIsHash(tomlTypeOfGo(rv.MapIndex(mapKey))) { mapKeysSub = append(mapKeysSub, k) } else { mapKeysDirect = append(mapKeysDirect, k) } } var writeMapKeys = func(mapKeys []string) { sort.Strings(mapKeys) for _, mapKey := range mapKeys { mrv := rv.MapIndex(reflect.ValueOf(mapKey)) if isNil(mrv) { // Don't write anything for nil fields. continue } enc.encode(key.add(mapKey), mrv) } } writeMapKeys(mapKeysDirect) writeMapKeys(mapKeysSub) } func (enc *Encoder) eStruct(key Key, rv reflect.Value) { // 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). rt := rv.Type() var fieldsDirect, fieldsSub [][]int var 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) // skip unexporded fields if f.PkgPath != "" { continue } frv := rv.Field(i) if f.Anonymous { frv := eindirect(frv) t := frv.Type() if t.Kind() != reflect.Struct { encPanic(errAnonNonStruct) } addFields(t, frv, f.Index) } else if typeIsHash(tomlTypeOfGo(frv)) { fieldsSub = append(fieldsSub, append(start, f.Index...)) } else { fieldsDirect = append(fieldsDirect, append(start, f.Index...)) } } } addFields(rt, rv, nil) var writeFields = func(fields [][]int) { for _, fieldIndex := range fields { sft := rt.FieldByIndex(fieldIndex) sf := rv.FieldByIndex(fieldIndex) if isNil(sf) { // Don't write anything for nil fields. continue } keyName := sft.Tag.Get("toml") if keyName == "-" { continue } if keyName == "" { keyName = sft.Name } enc.encode(key.add(keyName), sf) } } writeFields(fieldsDirect) writeFields(fieldsSub) } // tomlTypeName 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. // Returns the TOML type of a Go value. 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 } 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 typeEqual(tomlHash, tomlArrayType(rv)) { return tomlArrayHash } else { return tomlArray } case reflect.Ptr, reflect.Interface: return tomlTypeOfGo(rv.Elem()) case reflect.String: return tomlString case reflect.Map: return tomlHash case reflect.Struct: switch rv.Interface().(type) { case time.Time: return tomlDatetime case TextMarshaler: return tomlString default: return tomlHash } default: panic("unexpected reflect.Kind: " + rv.Kind().String()) } } // tomlArrayType returns the element type of a TOML array. The type returned // may be nil if it cannot be determined (e.g., a nil slice or a zero length // slize). This function may also panic if it finds a type that cannot be // expressed in TOML (such as nil elements, heterogeneous arrays or directly // nested arrays of tables). func tomlArrayType(rv reflect.Value) tomlType { if isNil(rv) || !rv.IsValid() || rv.Len() == 0 { return nil } firstType := tomlTypeOfGo(rv.Index(0)) if firstType == nil { encPanic(errArrayNilElement) } rvlen := rv.Len() for i := 1; i < rvlen; i++ { elem := rv.Index(i) switch elemType := tomlTypeOfGo(elem); { case elemType == nil: encPanic(errArrayNilElement) case !typeEqual(firstType, elemType): encPanic(errArrayMixedElementTypes) } } // If we have a nested array, then we must make sure that the nested // array contains ONLY primitives. // This checks arbitrarily nested arrays. if typeEqual(firstType, tomlArray) || typeEqual(firstType, tomlArrayHash) { nest := tomlArrayType(eindirect(rv.Index(0))) if typeEqual(nest, tomlHash) || typeEqual(nest, tomlArrayHash) { encPanic(errArrayNoTable) } } return firstType } func (enc *Encoder) newline() { if enc.hasWritten { enc.wf("\n") } } func (enc *Encoder) keyEqElement(key Key, val reflect.Value) { if len(key) == 0 { encPanic(errNoKey) } panicIfInvalidKey(key, false) enc.wf("%s%s = ", enc.indentStr(key), key[len(key)-1]) enc.eElement(val) enc.newline() } func (enc *Encoder) wf(format string, v ...interface{}) { if _, err := fmt.Fprintf(enc.w, format, v...); 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}) } func eindirect(v reflect.Value) reflect.Value { switch v.Kind() { case reflect.Ptr, reflect.Interface: return eindirect(v.Elem()) default: return v } } func isNil(rv reflect.Value) bool { switch rv.Kind() { case reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice: return rv.IsNil() default: return false } } func panicIfInvalidKey(key Key, hash bool) { if hash { for _, k := range key { if !isValidTableName(k) { encPanic(e("Key '%s' is not a valid table name. Table names "+ "cannot contain '[', ']' or '.'.", key.String())) } } } else { if !isValidKeyName(key[len(key)-1]) { encPanic(e("Key '%s' is not a name. Key names "+ "cannot contain whitespace.", key.String())) } } } func isValidTableName(s string) bool { if len(s) == 0 { return false } for _, r := range s { if r == '[' || r == ']' || r == '.' { return false } } return true } func isValidKeyName(s string) bool { if len(s) == 0 { return false } return true }