github.com/xfond/eth-implementation@v1.8.9-0.20180514135602-f6bc65fc6811/rlp/decode_tail_test.go (about)

     1  // Copyright 2015 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package rlp
    18  
    19  import (
    20  	"bytes"
    21  	"fmt"
    22  )
    23  
    24  type structWithTail struct {
    25  	A, B uint
    26  	C    []uint `rlp:"tail"`
    27  }
    28  
    29  func ExampleDecode_structTagTail() {
    30  	// In this example, the "tail" struct tag is used to decode lists of
    31  	// differing length into a struct.
    32  	var val structWithTail
    33  
    34  	err := Decode(bytes.NewReader([]byte{0xC4, 0x01, 0x02, 0x03, 0x04}), &val)
    35  	fmt.Printf("with 4 elements: err=%v val=%v\n", err, val)
    36  
    37  	err = Decode(bytes.NewReader([]byte{0xC6, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06}), &val)
    38  	fmt.Printf("with 6 elements: err=%v val=%v\n", err, val)
    39  
    40  	// Note that at least two list elements must be present to
    41  	// fill fields A and B:
    42  	err = Decode(bytes.NewReader([]byte{0xC1, 0x01}), &val)
    43  	fmt.Printf("with 1 element: err=%q\n", err)
    44  
    45  	// Output:
    46  	// with 4 elements: err=<nil> val={1 2 [3 4]}
    47  	// with 6 elements: err=<nil> val={1 2 [3 4 5 6]}
    48  	// with 1 element: err="rlp: too few elements for rlp.structWithTail"
    49  }