| // Copyright 2015 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // This file implements encoding/decoding of Ints. |
| |
| package big |
| |
| import ( |
| "bytes" |
| "fmt" |
| ) |
| |
| // Gob codec version. Permits backward-compatible changes to the encoding. |
| const intGobVersion byte = 1 |
| |
| // GobEncode implements the gob.GobEncoder interface. |
| func (x *Int) GobEncode() ([]byte, error) { |
| if x == nil { |
| return nil, nil |
| } |
| buf := make([]byte, 1+len(x.abs)*_S) // extra byte for version and sign bit |
| i := x.abs.bytes(buf) - 1 // i >= 0 |
| b := intGobVersion << 1 // make space for sign bit |
| if x.neg { |
| b |= 1 |
| } |
| buf[i] = b |
| return buf[i:], nil |
| } |
| |
| // GobDecode implements the gob.GobDecoder interface. |
| func (z *Int) GobDecode(buf []byte) error { |
| if len(buf) == 0 { |
| // Other side sent a nil or default value. |
| *z = Int{} |
| return nil |
| } |
| b := buf[0] |
| if b>>1 != intGobVersion { |
| return fmt.Errorf("Int.GobDecode: encoding version %d not supported", b>>1) |
| } |
| z.neg = b&1 != 0 |
| z.abs = z.abs.setBytes(buf[1:]) |
| return nil |
| } |
| |
| // MarshalText implements the encoding.TextMarshaler interface. |
| func (x *Int) MarshalText() (text []byte, err error) { |
| if x == nil { |
| return []byte("<nil>"), nil |
| } |
| return x.abs.itoa(x.neg, 10), nil |
| } |
| |
| // UnmarshalText implements the encoding.TextUnmarshaler interface. |
| func (z *Int) UnmarshalText(text []byte) error { |
| if _, ok := z.setFromScanner(bytes.NewReader(text), 0); !ok { |
| return fmt.Errorf("math/big: cannot unmarshal %q into a *big.Int", text) |
| } |
| return nil |
| } |
| |
| // The JSON marshalers are only here for API backward compatibility |
| // (programs that explicitly look for these two methods). JSON works |
| // fine with the TextMarshaler only. |
| |
| // MarshalJSON implements the json.Marshaler interface. |
| func (x *Int) MarshalJSON() ([]byte, error) { |
| if x == nil { |
| return []byte("null"), nil |
| } |
| return x.abs.itoa(x.neg, 10), nil |
| } |
| |
| // UnmarshalJSON implements the json.Unmarshaler interface. |
| func (z *Int) UnmarshalJSON(text []byte) error { |
| // Ignore null, like in the main JSON package. |
| if string(text) == "null" { |
| return nil |
| } |
| return z.UnmarshalText(text) |
| } |