common

package
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 Go to latest Published: Nov 28, 2016 License: GPL-3.0 Imports: 20 Imported by: 54,045

README

common

Build Status

The common package contains the ethereum utility library.

Installation

As a subdirectory the main go-ethereum repository, you get it with go get github.com/ethereum/go-ethereum.

Usage

RLP (Recursive Linear Prefix) Encoding

RLP Encoding is an encoding scheme used by the Ethereum project. It encodes any native value or list to a string.

More in depth information about the encoding scheme see the Wiki article.

rlp := common.Encode("doge")
fmt.Printf("%q\n", rlp) // => "\0x83dog"

rlp = common.Encode([]interface{}{"dog", "cat"})
fmt.Printf("%q\n", rlp) // => "\0xc8\0x83dog\0x83cat"
decoded := common.Decode(rlp)
fmt.Println(decoded) // => ["dog" "cat"]

Patricia Trie

Patricie Tree is a merkle trie used by the Ethereum project.

More in depth information about the (modified) Patricia Trie can be found on the Wiki.

The patricia trie uses a db as backend and could be anything as long as it satisfies the Database interface found in common/db.go.

db := NewDatabase()

// db, root
trie := common.NewTrie(db, "")

trie.Put("puppy", "dog")
trie.Put("horse", "stallion")
trie.Put("do", "verb")
trie.Put("doge", "coin")

// Look up the key "do" in the trie
out := trie.Get("do")
fmt.Println(out) // => verb

trie.Delete("puppy")

The patricia trie, in combination with RLP, provides a robust, cryptographically authenticated data structure that can be used to store all (key, value) bindings.

// ... Create db/trie

// Note that RLP uses interface slices as list
value := common.Encode([]interface{}{"one", 2, "three", []interface{}{42}})
// Store the RLP encoded value of the list
trie.Put("mykey", value)

Value

Value is a Generic Value which is used in combination with RLP data or ([])interface{} structures. It may serve as a bridge between RLP data and actual real values and takes care of all the type checking and casting. Unlike Go's reflect.Value it does not panic if it's unable to cast to the requested value. It simple returns the base value of that type (e.g. Slice() returns []interface{}, Uint() return 0, etc).

Creating a new Value

NewEmptyValue() returns a new *Value with it's initial value set to a []interface{}

AppendList() appends a list to the current value.

Append(v) appends the value (v) to the current value/list.

val := common.NewEmptyValue().Append(1).Append("2")
val.AppendList().Append(3)
Retrieving values

Get(i) returns the i item in the list.

Uint() returns the value as an unsigned int64.

Slice() returns the value as a interface slice.

Str() returns the value as a string.

Bytes() returns the value as a byte slice.

Len() assumes current to be a slice and returns its length.

Byte() returns the value as a single byte.

val := common.NewValue([]interface{}{1,"2",[]interface{}{3}})
val.Get(0).Uint() // => 1
val.Get(1).Str()  // => "2"
s := val.Get(2)   // => Value([]interface{}{3})
s.Get(0).Uint()   // => 3

Decoding

Decoding streams of RLP data is simplified

val := common.NewValueFromBytes(rlpData)
val.Get(0).Uint()

Encoding

Encoding from Value to RLP is done with the Encode method. The underlying value can be anything RLP can encode (int, str, lists, bytes)

val := common.NewValue([]interface{}{1,"2",[]interface{}{3}})
rlp := val.Encode()
// Store the rlp data
Store(rlp)

Documentation

Overview

Package common contains various helper functions.

Index

Constants

View Source 
const (
	HashLength    = 32
	AddressLength = 20
)

Variables

View Source 
var (
	Big1     = big.NewInt(1)
	Big2     = big.NewInt(2)
	Big3     = big.NewInt(3)
	Big0     = big.NewInt(0)
	BigTrue  = Big1
	BigFalse = Big0
	Big32    = big.NewInt(32)
	Big36    = big.NewInt(36)
	Big97    = big.NewInt(97)
	Big98    = big.NewInt(98)
	Big256   = big.NewInt(0xff)
	Big257   = big.NewInt(257)
	MaxBig   = String2Big("0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff")
)

Common big integers often used

View Source 
var (
	Base36Chars          = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	ICAPLengthError      = errors.New("Invalid ICAP length")
	ICAPEncodingError    = errors.New("Invalid ICAP encoding")
	ICAPChecksumError    = errors.New("Invalid ICAP checksum")
	ICAPCountryCodeError = errors.New("Invalid ICAP country code")
	ICAPAssetIdentError  = errors.New("Invalid ICAP asset identifier")
	ICAPInstCodeError    = errors.New("Invalid ICAP institution code")
	ICAPClientIdentError = errors.New("Invalid ICAP client identifier")
)
View Source 
var (
	Douglas  = BigPow(10, 42)
	Einstein = BigPow(10, 21)
	Ether    = BigPow(10, 18)
	Finney   = BigPow(10, 15)
	Szabo    = BigPow(10, 12)
	Shannon  = BigPow(10, 9)
	Babbage  = BigPow(10, 6)
	Ada      = BigPow(10, 3)
	Wei      = big.NewInt(1)
)

The different number of units

Functions

func AbsolutePath 

func AbsolutePath(Datadir string, filename string) string

func AddressToICAP added in v1.3.1 

func AddressToICAP(a Address) (string, error)

func AddressToIndirectICAP added in v1.3.1 

func AddressToIndirectICAP(a Address, instCode string) (string, error)

TODO: integrate with ICAP namereg when it's available

func Big 

func Big(num string) *big.Int

Big

Shortcut for new(big.Int).SetString(..., 0)

func BigCopy 

func BigCopy(src *big.Int) *big.Int

Big copy

Creates a copy of the given big integer

func BigD 

func BigD(data []byte) *big.Int

func BigMax 

func BigMax(x, y *big.Int) *big.Int

Big max

Returns the maximum size big integer

func BigMin 

func BigMin(x, y *big.Int) *big.Int

Big min

Returns the minimum size big integer

func BigPow 

func BigPow(a, b int) *big.Int

Big pow

Returns the power of two big integers

func BigToBytes 

func BigToBytes(num *big.Int, base int) []byte

Big to bytes

Returns the bytes of a big integer with the size specified by **base** Attempts to pad the byte array with zeros.

func BitTest 

func BitTest(num *big.Int, i int) bool

func ByteSliceToInterface 

func ByteSliceToInterface(slice [][]byte) (ret []interface{})

func Bytes2Big 

func Bytes2Big(data []byte) *big.Int

func Bytes2Hex 

func Bytes2Hex(d []byte) string

func BytesToBig added in v0.9.28 

func BytesToBig(data []byte) *big.Int

Bytes2Big

func BytesToNumber 

func BytesToNumber(b []byte) uint64

Bytes to number

Attempts to cast a byte slice to a unsigned integer

func CopyBytes 

func CopyBytes(b []byte) (copiedBytes []byte)

Copy bytes

Returns an exact copy of the provided bytes

func CurrencyToString 

func CurrencyToString(num *big.Int) string

Currency to string Returns a string representing a human readable format

func EmptyHash added in v0.9.32 

func EmptyHash(h Hash) bool

func FileExist 

func FileExist(filePath string) bool

func FirstBitSet 

func FirstBitSet(v *big.Int) int

func FormatData 

func FormatData(data string) []byte

func FromHex 

func FromHex(s string) []byte

func HasHexPrefix 

func HasHexPrefix(str string) bool

func Hex2Bytes 

func Hex2Bytes(str string) []byte

func Hex2BytesFixed 

func Hex2BytesFixed(str string, flen int) []byte

func IsHex 

func IsHex(str string) bool

func IsHexAddress added in v1.4.0 

func IsHexAddress(s string) bool

IsHexAddress verifies whether a string can represent a valid hex-encoded Ethereum address or not.

func LeftPadBytes 

func LeftPadBytes(slice []byte, l int) []byte

func LeftPadString 

func LeftPadString(str string, l int) string

func LoadJSON added in v0.9.34 

func LoadJSON(file string, val interface{}) error

LoadJSON reads the given file and unmarshals its content.

func MakeName 

func MakeName(name, version string) string

MakeName creates a node name that follows the ethereum convention for such names. It adds the operation system name and Go runtime version the name.

func NumberToBytes 

func NumberToBytes(num interface{}, bits int) []byte

Number to bytes

Returns the number in bytes with the specified base

func PP added in v0.9.30 

func PP(value []byte) string

PP Pretty Prints a byte slice in the following format: 

hex(value[:4])...(hex[len(value)-4:])

func ParseData 

func ParseData(data ...interface{}) (ret []byte)

func PrintDepricationWarning added in v1.4.0 

func PrintDepricationWarning(str string)

PrintDepricationWarning prinst the given string in a box using fmt.Println.

func ReadVarInt 

func ReadVarInt(buff []byte) (ret uint64)

Read variable int

Read a variable length number in big endian byte order

func Report 

func Report(extra ...interface{})

Report gives off a warning requesting the user to submit an issue to the github tracker.

func RightPadBytes 

func RightPadBytes(slice []byte, l int) []byte

func RightPadString 

func RightPadString(str string, l int) string

func S256 

func S256(x *big.Int) *big.Int

func String2Big 

func String2Big(num string) *big.Int

func StringToByteFunc 

func StringToByteFunc(str string, cb func(str string) []byte) (ret []byte)

func ToAddress 

func ToAddress(slice []byte) (addr []byte)

func ToHex 

func ToHex(b []byte) string

func U256 

func U256(x *big.Int) *big.Int

Types

type Address 

type Address [AddressLength]byte

Address represents the 20 byte address of an Ethereum account.

func BigToAddress 

func BigToAddress(b *big.Int) Address

func BytesToAddress 

func BytesToAddress(b []byte) Address

///////// Address

func HexToAddress 

func HexToAddress(s string) Address

func ICAPToAddress added in v1.3.1 

func ICAPToAddress(s string) (Address, error)

func StringToAddress 

func StringToAddress(s string) Address

func (Address) Big 

func (a Address) Big() *big.Int

func (Address) Bytes 

func (a Address) Bytes() []byte

func (Address) Hash 

func (a Address) Hash() Hash

func (Address) Hex 

func (a Address) Hex() string

func (Address) MarshalJSON added in v1.4.0 

func (a Address) MarshalJSON() ([]byte, error)

Serialize given address to JSON

func (*Address) Set 

func (a *Address) Set(other Address)

Sets a to other

func (*Address) SetBytes 

func (a *Address) SetBytes(b []byte)

Sets the address to the value of b. If b is larger than len(a) it will panic

func (*Address) SetString 

func (a *Address) SetString(s string)

Set string `s` to a. If s is larger than len(a) it will panic

func (Address) Str 

func (a Address) Str() string

Get the string representation of the underlying address

func (*Address) UnmarshalJSON added in v1.4.0 

func (a *Address) UnmarshalJSON(input []byte) error

Parse address from raw json data

type Hash 

type Hash [HashLength]byte

Hash represents the 32 byte Keccak256 hash of arbitrary data.

func BigToHash 

func BigToHash(b *big.Int) Hash

func BytesToHash 

func BytesToHash(b []byte) Hash

func HexToHash 

func HexToHash(s string) Hash

func StringToHash 

func StringToHash(s string) Hash

func (Hash) Big 

func (h Hash) Big() *big.Int

func (Hash) Bytes 

func (h Hash) Bytes() []byte

func (Hash) Generate 

func (h Hash) Generate(rand *rand.Rand, size int) reflect.Value

Generate implements testing/quick.Generator.

func (Hash) Hex 

func (h Hash) Hex() string

func (Hash) MarshalJSON added in v1.4.0 

func (h Hash) MarshalJSON() ([]byte, error)

Serialize given hash to JSON

func (*Hash) Set 

func (h *Hash) Set(other Hash)

Sets h to other

func (*Hash) SetBytes 

func (h *Hash) SetBytes(b []byte)

Sets the hash to the value of b. If b is larger than len(h) it will panic

func (*Hash) SetString 

func (h *Hash) SetString(s string)

Set string `s` to h. If s is larger than len(h) it will panic

func (Hash) Str 

func (h Hash) Str() string

Get the string representation of the underlying hash

func (*Hash) UnmarshalJSON added in v1.4.0 

func (h *Hash) UnmarshalJSON(input []byte) error

UnmarshalJSON parses a hash in its hex from to a hash.

type List 

type List struct {
	Length int
	// contains filtered or unexported fields
}

The list type is an anonymous slice handler which can be used for containing any slice type to use in an environment which does not support slice types (e.g., JavaScript, QML)

func EmptyList 

func EmptyList() *List

func NewList 

func NewList(t interface{}) *List

Initialise a new list. Panics if non-slice type is given.

func (*List) Append 

func (self *List) Append(v interface{})

Appends value at the end of the slice. Panics when incompatible value is given.

func (*List) Get 

func (self *List) Get(i int) interface{}

Get N element from the embedded slice. Returns nil if OOB.

func (*List) GetAsJson 

func (self *List) GetAsJson(i int) interface{}

func (*List) Interface 

func (self *List) Interface() interface{}

Returns the underlying slice as interface.

func (*List) ToJSON 

func (self *List) ToJSON() string

For JavaScript <3

type PrettyDuration added in v1.5.0 

type PrettyDuration time.Duration

PrettyDuration is a pretty printed version of a time.Duration value that cuts the unnecessary precision off from the formatted textual representation.

func (PrettyDuration) String added in v1.5.0 

func (d PrettyDuration) String() string

String implements the Stringer interface, allowing pretty printing of duration values rounded to three decimals.

type StorageSize 

type StorageSize float64

func (StorageSize) Int64 

func (self StorageSize) Int64() int64

func (StorageSize) String 

func (self StorageSize) String() string

Source Files

View all Source files

Directories

Path Synopsis
Package compiler wraps the Solidity compiler executable (solc).
 Package compiler wraps the Solidity compiler executable (solc).
Package hexutil implements hex encoding with 0x prefix.
 Package hexutil implements hex encoding with 0x prefix.
package mclock is a wrapper for a monotonic clock source
 package mclock is a wrapper for a monotonic clock source

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