fixed_string.go

package column

import (
	"encoding"
	"fmt"
	"reflect"

	"github.com/kshvakov/clickhouse/lib/binary"
)

type FixedString struct {
	base
	len      int
	scanType reflect.Type
}

func (str *FixedString) Read(decoder *binary.Decoder) (interface{}, error) {
	v, err := decoder.Fixed(str.len)
	if err != nil {
		return "", err
	}
	return string(v), nil
}

func (str *FixedString) Write(encoder *binary.Encoder, v interface{}) error {
	var fixedString []byte
	switch v := v.(type) {
	case string:
		fixedString = binary.Str2Bytes(v)
	case []byte:
		fixedString = v
	case encoding.BinaryMarshaler:
		bytes, err := v.MarshalBinary()
		if err != nil {
			return err
		}
		fixedString = bytes
	default:
		return &ErrUnexpectedType{
			T:      v,
			Column: str,
		}
	}
	switch {
	case len(fixedString) > str.len:
		return fmt.Errorf("too large value '%s' (expected %d, got %d)", fixedString, str.len, len(fixedString))
	case len(fixedString) < str.len:
		tmp := make([]byte, str.len)
		copy(tmp, fixedString)
		fixedString = tmp
	}
	if _, err := encoder.Write(fixedString); err != nil {
		return err
	}
	return nil
}

func parseFixedString(name, chType string) (*FixedString, error) {
	var strLen int
	if _, err := fmt.Sscanf(chType, "FixedString(%d)", &strLen); err != nil {
		return nil, err
	}
	return &FixedString{
		base: base{
			name:    name,
			chType:  chType,
			valueOf: baseTypes[string("")],
		},
		len: strLen,
	}, nil
}