Cherry pick v1.7 into master

vendor/github.com/mitchellh/mapstructure/mapstructure.go

@@ -114,12 +114,12 @@ type Metadata struct {
 	Unused []string
 }
 
-// Decode takes a map and uses reflection to convert it into the
-// given Go native structure. val must be a pointer to a struct.
-func Decode(m interface{}, rawVal interface{}) error {
+// Decode takes an input structure and uses reflection to translate it to
+// the output structure. output must be a pointer to a map or struct.
+func Decode(input interface{}, output interface{}) error {
 	config := &DecoderConfig{
 		Metadata: nil,
-		Result:   rawVal,
+		Result:   output,
 	}
 
 	decoder, err := NewDecoder(config)
@@ -127,7 +127,7 @@ func Decode(m interface{}, rawVal interface{}) error {
 		return err
 	}
 
-	return decoder.Decode(m)
+	return decoder.Decode(input)
 }
 
 // WeakDecode is the same as Decode but is shorthand to enable
@@ -147,6 +147,40 @@ func WeakDecode(input, output interface{}) error {
 	return decoder.Decode(input)
 }
 
+// DecodeMetadata is the same as Decode, but is shorthand to
+// enable metadata collection. See DecoderConfig for more info.
+func DecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error {
+	config := &DecoderConfig{
+		Metadata: metadata,
+		Result:   output,
+	}
+
+	decoder, err := NewDecoder(config)
+	if err != nil {
+		return err
+	}
+
+	return decoder.Decode(input)
+}
+
+// WeakDecodeMetadata is the same as Decode, but is shorthand to
+// enable both WeaklyTypedInput and metadata collection. See
+// DecoderConfig for more info.
+func WeakDecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error {
+	config := &DecoderConfig{
+		Metadata:         metadata,
+		Result:           output,
+		WeaklyTypedInput: true,
+	}
+
+	decoder, err := NewDecoder(config)
+	if err != nil {
+		return err
+	}
+
+	return decoder.Decode(input)
+}
+
 // NewDecoder returns a new decoder for the given configuration. Once
 // a decoder has been returned, the same configuration must not be used
 // again.
@@ -184,70 +218,91 @@ func NewDecoder(config *DecoderConfig) (*Decoder, error) {
 
 // Decode decodes the given raw interface to the target pointer specified
 // by the configuration.
-func (d *Decoder) Decode(raw interface{}) error {
-	return d.decode("", raw, reflect.ValueOf(d.config.Result).Elem())
+func (d *Decoder) Decode(input interface{}) error {
+	return d.decode("", input, reflect.ValueOf(d.config.Result).Elem())
 }
 
 // Decodes an unknown data type into a specific reflection value.
-func (d *Decoder) decode(name string, data interface{}, val reflect.Value) error {
-	if data == nil {
-		// If the data is nil, then we don't set anything.
+func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) error {
+	var inputVal reflect.Value
+	if input != nil {
+		inputVal = reflect.ValueOf(input)
+
+		// We need to check here if input is a typed nil. Typed nils won't
+		// match the "input == nil" below so we check that here.
+		if inputVal.Kind() == reflect.Ptr && inputVal.IsNil() {
+			input = nil
+		}
+	}
+
+	if input == nil {
+		// If the data is nil, then we don't set anything, unless ZeroFields is set
+		// to true.
+		if d.config.ZeroFields {
+			outVal.Set(reflect.Zero(outVal.Type()))
+
+			if d.config.Metadata != nil && name != "" {
+				d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
+			}
+		}
 		return nil
 	}
 
-	dataVal := reflect.ValueOf(data)
-	if !dataVal.IsValid() {
-		// If the data value is invalid, then we just set the value
+	if !inputVal.IsValid() {
+		// If the input value is invalid, then we just set the value
 		// to be the zero value.
-		val.Set(reflect.Zero(val.Type()))
+		outVal.Set(reflect.Zero(outVal.Type()))
+		if d.config.Metadata != nil && name != "" {
+			d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
+		}
 		return nil
 	}
 
 	if d.config.DecodeHook != nil {
-		// We have a DecodeHook, so let's pre-process the data.
+		// We have a DecodeHook, so let's pre-process the input.
 		var err error
-		data, err = DecodeHookExec(
+		input, err = DecodeHookExec(
 			d.config.DecodeHook,
-			dataVal.Type(), val.Type(), data)
+			inputVal.Type(), outVal.Type(), input)
 		if err != nil {
 			return fmt.Errorf("error decoding '%s': %s", name, err)
 		}
 	}
 
 	var err error
-	dataKind := getKind(val)
-	switch dataKind {
+	outputKind := getKind(outVal)
+	switch outputKind {
 	case reflect.Bool:
-		err = d.decodeBool(name, data, val)
+		err = d.decodeBool(name, input, outVal)
 	case reflect.Interface:
-		err = d.decodeBasic(name, data, val)
+		err = d.decodeBasic(name, input, outVal)
 	case reflect.String:
-		err = d.decodeString(name, data, val)
+		err = d.decodeString(name, input, outVal)
 	case reflect.Int:
-		err = d.decodeInt(name, data, val)
+		err = d.decodeInt(name, input, outVal)
 	case reflect.Uint:
-		err = d.decodeUint(name, data, val)
+		err = d.decodeUint(name, input, outVal)
 	case reflect.Float32:
-		err = d.decodeFloat(name, data, val)
+		err = d.decodeFloat(name, input, outVal)
 	case reflect.Struct:
-		err = d.decodeStruct(name, data, val)
+		err = d.decodeStruct(name, input, outVal)
 	case reflect.Map:
-		err = d.decodeMap(name, data, val)
+		err = d.decodeMap(name, input, outVal)
 	case reflect.Ptr:
-		err = d.decodePtr(name, data, val)
+		err = d.decodePtr(name, input, outVal)
 	case reflect.Slice:
-		err = d.decodeSlice(name, data, val)
+		err = d.decodeSlice(name, input, outVal)
 	case reflect.Array:
-		err = d.decodeArray(name, data, val)
+		err = d.decodeArray(name, input, outVal)
 	case reflect.Func:
-		err = d.decodeFunc(name, data, val)
+		err = d.decodeFunc(name, input, outVal)
 	default:
 		// If we reached this point then we weren't able to decode it
-		return fmt.Errorf("%s: unsupported type: %s", name, dataKind)
+		return fmt.Errorf("%s: unsupported type: %s", name, outputKind)
 	}
 
 	// If we reached here, then we successfully decoded SOMETHING, so
-	// mark the key as used if we're tracking metadata.
+	// mark the key as used if we're tracking metainput.
 	if d.config.Metadata != nil && name != "" {
 		d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
 	}
@@ -258,7 +313,19 @@ func (d *Decoder) decode(name string, data interface{}, val reflect.Value) error
 // This decodes a basic type (bool, int, string, etc.) and sets the
 // value to "data" of that type.
 func (d *Decoder) decodeBasic(name string, data interface{}, val reflect.Value) error {
+	if val.IsValid() && val.Elem().IsValid() {
+		return d.decode(name, data, val.Elem())
+	}
+
 	dataVal := reflect.ValueOf(data)
+
+	// If the input data is a pointer, and the assigned type is the dereference
+	// of that exact pointer, then indirect it so that we can assign it.
+	// Example: *string to string
+	if dataVal.Kind() == reflect.Ptr && dataVal.Type().Elem() == val.Type() {
+		dataVal = reflect.Indirect(dataVal)
+	}
+
 	if !dataVal.IsValid() {
 		dataVal = reflect.Zero(val.Type())
 	}
@@ -275,7 +342,7 @@ func (d *Decoder) decodeBasic(name string, data interface{}, val reflect.Value)
 }
 
 func (d *Decoder) decodeString(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 
 	converted := true
@@ -327,7 +394,7 @@ func (d *Decoder) decodeString(name string, data interface{}, val reflect.Value)
 }
 
 func (d *Decoder) decodeInt(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 	dataType := dataVal.Type()
 
@@ -369,7 +436,7 @@ func (d *Decoder) decodeInt(name string, data interface{}, val reflect.Value) er
 }
 
 func (d *Decoder) decodeUint(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 
 	switch {
@@ -412,7 +479,7 @@ func (d *Decoder) decodeUint(name string, data interface{}, val reflect.Value) e
 }
 
 func (d *Decoder) decodeBool(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 
 	switch {
@@ -443,7 +510,7 @@ func (d *Decoder) decodeBool(name string, data interface{}, val reflect.Value) e
 }
 
 func (d *Decoder) decodeFloat(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 	dataType := dataVal.Type()
 
@@ -499,38 +566,68 @@ func (d *Decoder) decodeMap(name string, data interface{}, val reflect.Value) er
 		valMap = reflect.MakeMap(mapType)
 	}
 
-	// Check input type
+	// Check input type and based on the input type jump to the proper func
 	dataVal := reflect.Indirect(reflect.ValueOf(data))
-	if dataVal.Kind() != reflect.Map {
-		// In weak mode, we accept a slice of maps as an input...
+	switch dataVal.Kind() {
+	case reflect.Map:
+		return d.decodeMapFromMap(name, dataVal, val, valMap)
+
+	case reflect.Struct:
+		return d.decodeMapFromStruct(name, dataVal, val, valMap)
+
+	case reflect.Array, reflect.Slice:
 		if d.config.WeaklyTypedInput {
-			switch dataVal.Kind() {
-			case reflect.Array, reflect.Slice:
-				// Special case for BC reasons (covered by tests)
-				if dataVal.Len() == 0 {
-					val.Set(valMap)
-					return nil
-				}
-
-				for i := 0; i < dataVal.Len(); i++ {
-					err := d.decode(
-						fmt.Sprintf("%s[%d]", name, i),
-						dataVal.Index(i).Interface(), val)
-					if err != nil {
-						return err
-					}
-				}
-
-				return nil
-			}
+			return d.decodeMapFromSlice(name, dataVal, val, valMap)
 		}
 
+		fallthrough
+
+	default:
 		return fmt.Errorf("'%s' expected a map, got '%s'", name, dataVal.Kind())
 	}
+}
+
+func (d *Decoder) decodeMapFromSlice(name string, dataVal reflect.Value, val reflect.Value, valMap reflect.Value) error {
+	// Special case for BC reasons (covered by tests)
+	if dataVal.Len() == 0 {
+		val.Set(valMap)
+		return nil
+	}
+
+	for i := 0; i < dataVal.Len(); i++ {
+		err := d.decode(
+			fmt.Sprintf("%s[%d]", name, i),
+			dataVal.Index(i).Interface(), val)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (d *Decoder) decodeMapFromMap(name string, dataVal reflect.Value, val reflect.Value, valMap reflect.Value) error {
+	valType := val.Type()
+	valKeyType := valType.Key()
+	valElemType := valType.Elem()
 
 	// Accumulate errors
 	errors := make([]string, 0)
 
+	// If the input data is empty, then we just match what the input data is.
+	if dataVal.Len() == 0 {
+		if dataVal.IsNil() {
+			if !val.IsNil() {
+				val.Set(dataVal)
+			}
+		} else {
+			// Set to empty allocated value
+			val.Set(valMap)
+		}
+
+		return nil
+	}
+
 	for _, k := range dataVal.MapKeys() {
 		fieldName := fmt.Sprintf("%s[%s]", name, k)
 
@@ -563,22 +660,128 @@ func (d *Decoder) decodeMap(name string, data interface{}, val reflect.Value) er
 	return nil
 }
 
+func (d *Decoder) decodeMapFromStruct(name string, dataVal reflect.Value, val reflect.Value, valMap reflect.Value) error {
+	typ := dataVal.Type()
+	for i := 0; i < typ.NumField(); i++ {
+		// Get the StructField first since this is a cheap operation. If the
+		// field is unexported, then ignore it.
+		f := typ.Field(i)
+		if f.PkgPath != "" {
+			continue
+		}
+
+		// Next get the actual value of this field and verify it is assignable
+		// to the map value.
+		v := dataVal.Field(i)
+		if !v.Type().AssignableTo(valMap.Type().Elem()) {
+			return fmt.Errorf("cannot assign type '%s' to map value field of type '%s'", v.Type(), valMap.Type().Elem())
+		}
+
+		tagValue := f.Tag.Get(d.config.TagName)
+		tagParts := strings.Split(tagValue, ",")
+
+		// Determine the name of the key in the map
+		keyName := f.Name
+		if tagParts[0] != "" {
+			if tagParts[0] == "-" {
+				continue
+			}
+			keyName = tagParts[0]
+		}
+
+		// If "squash" is specified in the tag, we squash the field down.
+		squash := false
+		for _, tag := range tagParts[1:] {
+			if tag == "squash" {
+				squash = true
+				break
+			}
+		}
+		if squash && v.Kind() != reflect.Struct {
+			return fmt.Errorf("cannot squash non-struct type '%s'", v.Type())
+		}
+
+		switch v.Kind() {
+		// this is an embedded struct, so handle it differently
+		case reflect.Struct:
+			x := reflect.New(v.Type())
+			x.Elem().Set(v)
+
+			vType := valMap.Type()
+			vKeyType := vType.Key()
+			vElemType := vType.Elem()
+			mType := reflect.MapOf(vKeyType, vElemType)
+			vMap := reflect.MakeMap(mType)
+
+			err := d.decode(keyName, x.Interface(), vMap)
+			if err != nil {
+				return err
+			}
+
+			if squash {
+				for _, k := range vMap.MapKeys() {
+					valMap.SetMapIndex(k, vMap.MapIndex(k))
+				}
+			} else {
+				valMap.SetMapIndex(reflect.ValueOf(keyName), vMap)
+			}
+
+		default:
+			valMap.SetMapIndex(reflect.ValueOf(keyName), v)
+		}
+	}
+
+	if val.CanAddr() {
+		val.Set(valMap)
+	}
+
+	return nil
+}
+
 func (d *Decoder) decodePtr(name string, data interface{}, val reflect.Value) error {
+	// If the input data is nil, then we want to just set the output
+	// pointer to be nil as well.
+	isNil := data == nil
+	if !isNil {
+		switch v := reflect.Indirect(reflect.ValueOf(data)); v.Kind() {
+		case reflect.Chan,
+			reflect.Func,
+			reflect.Interface,
+			reflect.Map,
+			reflect.Ptr,
+			reflect.Slice:
+			isNil = v.IsNil()
+		}
+	}
+	if isNil {
+		if !val.IsNil() && val.CanSet() {
+			nilValue := reflect.New(val.Type()).Elem()
+			val.Set(nilValue)
+		}
+
+		return nil
+	}
+
 	// Create an element of the concrete (non pointer) type and decode
 	// into that. Then set the value of the pointer to this type.
 	valType := val.Type()
 	valElemType := valType.Elem()
+	if val.CanSet() {
+		realVal := val
+		if realVal.IsNil() || d.config.ZeroFields {
+			realVal = reflect.New(valElemType)
+		}
 
-	realVal := val
-	if realVal.IsNil() || d.config.ZeroFields {
-		realVal = reflect.New(valElemType)
+		if err := d.decode(name, data, reflect.Indirect(realVal)); err != nil {
+			return err
+		}
+
+		val.Set(realVal)
+	} else {
+		if err := d.decode(name, data, reflect.Indirect(val)); err != nil {
+			return err
+		}
 	}
-
-	if err := d.decode(name, data, reflect.Indirect(realVal)); err != nil {
-		return err
-	}
-
-	val.Set(realVal)
 	return nil
 }
 
@@ -604,30 +807,44 @@ func (d *Decoder) decodeSlice(name string, data interface{}, val reflect.Value)
 
 	valSlice := val
 	if valSlice.IsNil() || d.config.ZeroFields {
+		if d.config.WeaklyTypedInput {
+			switch {
+			// Slice and array we use the normal logic
+			case dataValKind == reflect.Slice, dataValKind == reflect.Array:
+				break
+
+			// Empty maps turn into empty slices
+			case dataValKind == reflect.Map:
+				if dataVal.Len() == 0 {
+					val.Set(reflect.MakeSlice(sliceType, 0, 0))
+					return nil
+				}
+				// Create slice of maps of other sizes
+				return d.decodeSlice(name, []interface{}{data}, val)
+
+			case dataValKind == reflect.String && valElemType.Kind() == reflect.Uint8:
+				return d.decodeSlice(name, []byte(dataVal.String()), val)
+
+			// All other types we try to convert to the slice type
+			// and "lift" it into it. i.e. a string becomes a string slice.
+			default:
+				// Just re-try this function with data as a slice.
+				return d.decodeSlice(name, []interface{}{data}, val)
+			}
+		}
+
 		// Check input type
 		if dataValKind != reflect.Array && dataValKind != reflect.Slice {
-			if d.config.WeaklyTypedInput {
-				switch {
-				// Empty maps turn into empty slices
-				case dataValKind == reflect.Map:
-					if dataVal.Len() == 0 {
-						val.Set(reflect.MakeSlice(sliceType, 0, 0))
-						return nil
-					}
-
-				// All other types we try to convert to the slice type
-				// and "lift" it into it. i.e. a string becomes a string slice.
-				default:
-					// Just re-try this function with data as a slice.
-					return d.decodeSlice(name, []interface{}{data}, val)
-				}
-			}
-
 			return fmt.Errorf(
 				"'%s': source data must be an array or slice, got %s", name, dataValKind)
 
 		}
 
+		// If the input value is empty, then don't allocate since non-nil != nil
+		if dataVal.Len() == 0 {
+			return nil
+		}
+
 		// Make a new slice to hold our result, same size as the original data.
 		valSlice = reflect.MakeSlice(sliceType, dataVal.Len(), dataVal.Len())
 	}
@@ -737,10 +954,29 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 	}
 
 	dataValKind := dataVal.Kind()
-	if dataValKind != reflect.Map {
-		return fmt.Errorf("'%s' expected a map, got '%s'", name, dataValKind)
-	}
+	switch dataValKind {
+	case reflect.Map:
+		return d.decodeStructFromMap(name, dataVal, val)
 
+	case reflect.Struct:
+		// Not the most efficient way to do this but we can optimize later if
+		// we want to. To convert from struct to struct we go to map first
+		// as an intermediary.
+		m := make(map[string]interface{})
+		mval := reflect.Indirect(reflect.ValueOf(&m))
+		if err := d.decodeMapFromStruct(name, dataVal, mval, mval); err != nil {
+			return err
+		}
+
+		result := d.decodeStructFromMap(name, mval, val)
+		return result
+
+	default:
+		return fmt.Errorf("'%s' expected a map, got '%s'", name, dataVal.Kind())
+	}
+}
+
+func (d *Decoder) decodeStructFromMap(name string, dataVal, val reflect.Value) error {
 	dataValType := dataVal.Type()
 	if kind := dataValType.Key().Kind(); kind != reflect.String && kind != reflect.Interface {
 		return fmt.Errorf(