common

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 Go to latest Published: Sep 6, 2017 License: GPL-3.0 Imports: 12 Imported by: 253

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/ethereumproject/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 (
	DefaultIPCSocket = "geth.ipc"  // Default (relative) name of the IPC RPC socket
	DefaultHTTPHost  = "localhost" // Default host interface for the HTTP RPC server
	DefaultHTTPPort  = 8545        // Default TCP port for the HTTP RPC server
	DefaultWSHost    = "localhost" // Default host interface for the websocket RPC server
	DefaultWSPort    = 8546        // Default TCP port for the websocket RPC server
)
View Source 
const (
	HashLength    = 32
	AddressLength = 20
)

Variables

View Source 
var (
	Big1      = big.NewInt(1)
	Big2      = big.NewInt(2)
	Big3      = big.NewInt(3)
	BigTrue   = Big1
	BigFalse  = big.NewInt(0)
	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, _ = new(big.Int).SetString("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16)
)

Common big integers often used

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 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 Bytes2Hex 

func Bytes2Hex(d []byte) string

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 DefaultDataDir 

func DefaultDataDir() string

DefaultDataDir is the default data directory to use for the databases and other persistence requirements.

func DefaultUnclassicDataDir 

func DefaultUnclassicDataDir() string

DefaultUnclassicDataDir is the default data directory to check for preexisting unclassic persisted data.

func EmptyHash added in v0.9.32 

func EmptyHash(h Hash) bool

func EnsurePathAbsoluteOrRelativeTo 

func EnsurePathAbsoluteOrRelativeTo(Datadir string, filename string) string

func FirstBitSet 

func FirstBitSet(v *big.Int) int

func FromHex 

func FromHex(s string) []byte

func Hex2Bytes 

func Hex2Bytes(str string) []byte

func Hex2BytesFixed 

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

func HomeDir added in v1.3.1 

func HomeDir() string

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 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 RightPadBytes 

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

func S256 

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

func ToHex 

func ToHex(b []byte) string

func U256 

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

Types

type Address 

type Address [AddressLength]byte

func BigToAddress 

func BigToAddress(b *big.Int) Address

func BytesToAddress 

func BytesToAddress(b []byte) Address

///////// Address

func HexToAddress 

func HexToAddress(s string) Address

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(data []byte) error

Parse address from raw json data

type Hash 

type Hash [HashLength]byte

func BigToHash 

func BigToHash(b *big.Int) Hash

func BytesToHash 

func BytesToHash(b []byte) Hash

func HexToHash 

func HexToHash(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) IsEmpty 

func (h Hash) IsEmpty() bool

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 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
ethreg

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