neo-go/pkg/io/size.go
Roman Khimov 07cdbb815c *: drop unnecessary fmt.Sprintf uses
gosimple: S1039: unnecessary use of fmt.Sprintf
2021-05-12 18:29:39 +03:00

96 lines
2.6 KiB
Go

package io
import (
"fmt"
"reflect"
)
// This structure is used to calculate the wire size of the serializable
// structure. It's an io.Writer that doesn't do any real writes, but instead
// just counts the number of bytes to be written.
type counterWriter struct {
counter int
}
// Write implements the io.Writer interface.
func (cw *counterWriter) Write(p []byte) (int, error) {
n := len(p)
cw.counter += n
return n, nil
}
// getVarIntSize returns the size in number of bytes of a variable integer.
// (reference: GetVarSize(int value), https://github.com/neo-project/neo/blob/master/neo/IO/Helper.cs)
func getVarIntSize(value int) int {
var size uintptr
if value < 0xFD {
size = 1 // unit8
} else if value <= 0xFFFF {
size = 3 // byte + uint16
} else {
size = 5 // byte + uint32
}
return int(size)
}
// GetVarSize returns the number of bytes in a serialized variable. It supports ints/uints (estimating
// them using variable-length encoding that is used in NEO), strings, pointers to Serializable structures,
// slices and arrays of ints/uints or Serializable structures. It's similar to GetVarSize<T>(this T[] value)
// used in C#, but differs in that it also supports things like Uint160 or Uint256.
func GetVarSize(value interface{}) int {
v := reflect.ValueOf(value)
switch v.Kind() {
case reflect.String:
valueSize := len([]byte(v.String()))
return getVarIntSize(valueSize) + valueSize
case reflect.Int,
reflect.Int8,
reflect.Int16,
reflect.Int32,
reflect.Int64:
return getVarIntSize(int(v.Int()))
case reflect.Uint,
reflect.Uint8,
reflect.Uint16,
reflect.Uint32,
reflect.Uint64:
return getVarIntSize(int(v.Uint()))
case reflect.Ptr:
vser, ok := v.Interface().(Serializable)
if !ok {
panic("unable to calculate GetVarSize for a non-Serializable pointer")
}
cw := counterWriter{}
w := NewBinWriterFromIO(&cw)
vser.EncodeBinary(w)
if w.Err != nil {
panic(fmt.Sprintf("error serializing %s: %s", reflect.TypeOf(value), w.Err.Error()))
}
return cw.counter
case reflect.Slice, reflect.Array:
valueLength := v.Len()
valueSize := 0
if valueLength != 0 {
switch reflect.ValueOf(value).Index(0).Interface().(type) {
case Serializable:
for i := 0; i < valueLength; i++ {
valueSize += GetVarSize(v.Index(i).Interface())
}
case uint8, int8:
valueSize = valueLength
case uint16, int16:
valueSize = valueLength * 2
case uint32, int32:
valueSize = valueLength * 4
case uint64, int64:
valueSize = valueLength * 8
}
}
return getVarIntSize(valueLength) + valueSize
default:
panic(fmt.Sprintf("unable to calculate GetVarSize, %s", reflect.TypeOf(value)))
}
}