path: root/vendor/github.com/naoina/toml/encode.go

package toml

import (
    "bytes"
    "encoding"
    "fmt"
    "io"
    "reflect"
    "sort"
    "strconv"
    "time"

    "github.com/naoina/toml/ast"
)

const (
    tagOmitempty = "omitempty"
    tagSkip      = "-"
)

// Marshal returns the TOML encoding of v.
//
// Struct values encode as TOML. Each exported struct field becomes a field of
// the TOML structure unless
//   - the field's tag is "-", or
//   - the field is empty and its tag specifies the "omitempty" option.
//
// The "toml" key in the struct field's tag value is the key name, followed by
// an optional comma and options. Examples:
//
//   // Field is ignored by this package.
//   Field int `toml:"-"`
//
//   // Field appears in TOML as key "myName".
//   Field int `toml:"myName"`
//
//   // Field appears in TOML as key "myName" and the field is omitted from the
//   // result of encoding if its value is empty.
//   Field int `toml:"myName,omitempty"`
//
//   // Field appears in TOML as key "field", but the field is skipped if
//   // empty. Note the leading comma.
//   Field int `toml:",omitempty"`
func (cfg *Config) Marshal(v interface{}) ([]byte, error) {
    buf := new(bytes.Buffer)
    err := cfg.NewEncoder(buf).Encode(v)
    return buf.Bytes(), err
}

// A Encoder writes TOML to an output stream.
type Encoder struct {
    w   io.Writer
    cfg *Config
}

// NewEncoder returns a new Encoder that writes to w.
func (cfg *Config) NewEncoder(w io.Writer) *Encoder {
    return &Encoder{w, cfg}
}

// Encode writes the TOML of v to the stream.
// See the documentation for Marshal for details about the conversion of Go values to TOML.
func (e *Encoder) Encode(v interface{}) error {
    rv := reflect.ValueOf(v)
    for rv.Kind() == reflect.Ptr {
        if rv.IsNil() {
            return &marshalNilError{rv.Type()}
        }
        rv = rv.Elem()
    }
    buf := &tableBuf{typ: ast.TableTypeNormal}
    var err error
    switch rv.Kind() {
    case reflect.Struct:
        err = buf.structFields(e.cfg, rv)
    case reflect.Map:
        err = buf.mapFields(e.cfg, rv)
    default:
        err = &marshalTableError{rv.Type()}
    }
    if err != nil {
        return err
    }
    return buf.writeTo(e.w, "")
}

// Marshaler can be implemented to override the encoding of TOML values. The returned text
// must be a simple TOML value (i.e. not a table) and is inserted into marshaler output.
//
// This interface exists for backwards-compatibility reasons. You probably want to
// implement encoding.TextMarshaler or MarshalerRec instead.
type Marshaler interface {
    MarshalTOML() ([]byte, error)
}

// MarshalerRec can be implemented to override the TOML encoding of a type.
// The returned value is marshaled in place of the receiver.
type MarshalerRec interface {
    MarshalTOML() (interface{}, error)
}

type tableBuf struct {
    name       string // already escaped / quoted
    body       []byte
    children   []*tableBuf
    typ        ast.TableType
    arrayDepth int
}

func (b *tableBuf) writeTo(w io.Writer, prefix string) error {
    key := b.name // TODO: escape dots
    if prefix != "" {
        key = prefix + "." + key
    }

    if b.name != "" {
        head := "[" + key + "]"
        if b.typ == ast.TableTypeArray {
            head = "[" + head + "]"
        }
        head += "\n"
        if _, err := io.WriteString(w, head); err != nil {
            return err
        }
    }
    if _, err := w.Write(b.body); err != nil {
        return err
    }

    for i, child := range b.children {
        if len(b.body) > 0 || i > 0 {
            if _, err := w.Write([]byte("\n")); err != nil {
                return err
            }
        }
        if err := child.writeTo(w, key); err != nil {
            return err
        }
    }
    return nil
}

func (b *tableBuf) newChild(name string) *tableBuf {
    child := &tableBuf{name: quoteName(name), typ: ast.TableTypeNormal}
    if b.arrayDepth > 0 {
        child.typ = ast.TableTypeArray
    }
    return child
}

func (b *tableBuf) addChild(child *tableBuf) {
    // Empty table elision: we can avoid writing a table that doesn't have any keys on its
    // own. Array tables can't be elided because they define array elements (which would
    // be missing if elided).
    if len(child.body) == 0 && child.typ == ast.TableTypeNormal {
        for _, gchild := range child.children {
            gchild.name = child.name + "." + gchild.name
            b.addChild(gchild)
        }
        return
    }
    b.children = append(b.children, child)
}

func (b *tableBuf) structFields(cfg *Config, rv reflect.Value) error {
    rt := rv.Type()
    for i := 0; i < rv.NumField(); i++ {
        ft := rt.Field(i)
        if ft.PkgPath != "" && !ft.Anonymous { // not exported
            continue
        }
        name, rest := extractTag(ft.Tag.Get(fieldTagName))
        if name == tagSkip {
            continue
        }
        fv := rv.Field(i)
        if rest == tagOmitempty && isEmptyValue(fv) {
            continue
        }
        if name == "" {
            name = cfg.FieldToKey(rt, ft.Name)
        }
        if err := b.field(cfg, name, fv); err != nil {
            return err
        }
    }
    return nil
}

type mapKeyList []struct {
    key   string
    value reflect.Value
}

func (l mapKeyList) Len() int           { return len(l) }
func (l mapKeyList) Swap(i, j int)      { l[i], l[j] = l[j], l[i] }
func (l mapKeyList) Less(i, j int) bool { return l[i].key < l[j].key }

func (b *tableBuf) mapFields(cfg *Config, rv reflect.Value) error {
    keys := rv.MapKeys()
    keylist := make(mapKeyList, len(keys))
    for i, key := range keys {
        var err error
        keylist[i].key, err = encodeMapKey(key)
        if err != nil {
            return err
        }
        keylist[i].value = rv.MapIndex(key)
    }
    sort.Sort(keylist)

    for _, kv := range keylist {
        if err := b.field(cfg, kv.key, kv.value); err != nil {
            return err
        }
    }
    return nil
}

func (b *tableBuf) field(cfg *Config, name string, rv reflect.Value) error {
    off := len(b.body)
    b.body = append(b.body, quoteName(name)...)
    b.body = append(b.body, " = "...)
    isTable, err := b.value(cfg, rv, name)
    if isTable {
        b.body = b.body[:off] // rub out "key ="
    } else {
        b.body = append(b.body, '\n')
    }
    return err
}

func (b *tableBuf) value(cfg *Config, rv reflect.Value, name string) (bool, error) {
    isMarshaler, isTable, err := b.marshaler(cfg, rv, name)
    if isMarshaler {
        return isTable, err
    }
    switch rv.Kind() {
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        b.body = strconv.AppendInt(b.body, rv.Int(), 10)
    case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
        b.body = strconv.AppendUint(b.body, rv.Uint(), 10)
    case reflect.Float32, reflect.Float64:
        b.body = strconv.AppendFloat(b.body, rv.Float(), 'e', -1, 64)
    case reflect.Bool:
        b.body = strconv.AppendBool(b.body, rv.Bool())
    case reflect.String:
        b.body = strconv.AppendQuote(b.body, rv.String())
    case reflect.Ptr, reflect.Interface:
        if rv.IsNil() {
            return false, &marshalNilError{rv.Type()}
        }
        return b.value(cfg, rv.Elem(), name)
    case reflect.Slice, reflect.Array:
        rvlen := rv.Len()
        if rvlen == 0 {
            b.body = append(b.body, '[', ']')
            return false, nil
        }

        b.arrayDepth++
        wroteElem := false
        b.body = append(b.body, '[')
        for i := 0; i < rvlen; i++ {
            isTable, err := b.value(cfg, rv.Index(i), name)
            if err != nil {
                return isTable, err
            }
            wroteElem = wroteElem || !isTable
            if wroteElem {
                if i < rvlen-1 {
                    b.body = append(b.body, ',', ' ')
                } else {
                    b.body = append(b.body, ']')
                }
            }
        }
        if !wroteElem {
            b.body = b.body[:len(b.body)-1] // rub out '['
        }
        b.arrayDepth--
        return !wroteElem, nil
    case reflect.Struct:
        child := b.newChild(name)
        err := child.structFields(cfg, rv)
        b.addChild(child)
        return true, err
    case reflect.Map:
        child := b.newChild(name)
        err := child.mapFields(cfg, rv)
        b.addChild(child)
        return true, err
    default:
        return false, fmt.Errorf("toml: marshal: unsupported type %v", rv.Kind())
    }
    return false, nil
}

func (b *tableBuf) marshaler(cfg *Config, rv reflect.Value, name string) (handled, isTable bool, err error) {
    switch t := rv.Interface().(type) {
    case encoding.TextMarshaler:
        enc, err := t.MarshalText()
        if err != nil {
            return true, false, err
        }
        b.body = encodeTextMarshaler(b.body, string(enc))
        return true, false, nil
    case MarshalerRec:
        newval, err := t.MarshalTOML()
        if err != nil {
            return true, false, err
        }
        isTable, err = b.value(cfg, reflect.ValueOf(newval), name)
        return true, isTable, err
    case Marshaler:
        enc, err := t.MarshalTOML()
        if err != nil {
            return true, false, err
        }
        b.body = append(b.body, enc...)
        return true, false, nil
    }
    return false, false, nil
}

func encodeTextMarshaler(buf []byte, v string) []byte {
    // Emit the value without quotes if possible.
    if v == "true" || v == "false" {
        return append(buf, v...)
    } else if _, err := time.Parse(time.RFC3339Nano, v); err == nil {
        return append(buf, v...)
    } else if _, err := strconv.ParseInt(v, 10, 64); err == nil {
        return append(buf, v...)
    } else if _, err := strconv.ParseUint(v, 10, 64); err == nil {
        return append(buf, v...)
    } else if _, err := strconv.ParseFloat(v, 64); err == nil {
        return append(buf, v...)
    }
    return strconv.AppendQuote(buf, v)
}

func encodeMapKey(rv reflect.Value) (string, error) {
    if rv.Kind() == reflect.String {
        return rv.String(), nil
    }
    if tm, ok := rv.Interface().(encoding.TextMarshaler); ok {
        b, err := tm.MarshalText()
        return string(b), err
    }
    switch rv.Kind() {
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        return strconv.FormatInt(rv.Int(), 10), nil
    case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
        return strconv.FormatUint(rv.Uint(), 10), nil
    }
    return "", fmt.Errorf("toml: invalid map key type %v", rv.Type())
}

func isEmptyValue(v reflect.Value) bool {
    switch v.Kind() {
    case reflect.Array:
        // encoding/json treats all arrays with non-zero length as non-empty. We check the
        // array content here because zero-length arrays are almost never used.
        len := v.Len()
        for i := 0; i < len; i++ {
            if !isEmptyValue(v.Index(i)) {
                return false
            }
        }
        return true
    case reflect.Map, reflect.Slice, reflect.String:
        return v.Len() == 0
    case reflect.Bool:
        return !v.Bool()
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        return v.Int() == 0
    case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
        return v.Uint() == 0
    case reflect.Float32, reflect.Float64:
        return v.Float() == 0
    case reflect.Interface, reflect.Ptr:
        return v.IsNil()
    }
    return false
}

func quoteName(s string) string {
    if len(s) == 0 {
        return strconv.Quote(s)
    }
    for _, r := range s {
        if r >= '0' && r <= '9' || r >= 'A' && r <= 'Z' || r >= 'a' && r <= 'z' || r == '-' || r == '_' {
            continue
        }
        return strconv.Quote(s)
    }
    return s
}