README
¶
common
The common package contains the expanse utility library.
Installation
As a subdirectory the main go-expanse repository, you get it with
go get github.com/expanse-org/go-expanse.
Usage
RLP (Recursive Linear Prefix) Encoding
RLP Encoding is an encoding scheme used by the Expanse 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 Expanse 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
- Variables
- func AbsolutePath(Datadir string, filename string) string
- func Bytes2Hex(d []byte) string
- func CopyBytes(b []byte) (copiedBytes []byte)
- func EmptyHash(h Hash) bool
- func FileExist(filePath string) bool
- func FromHex(s string) []byte
- func HasHexPrefix(str string) bool
- func Hex2Bytes(str string) []byte
- func Hex2BytesFixed(str string, flen int) []byte
- func IsHex(str string) bool
- func IsHexAddress(s string) bool
- func LeftPadBytes(slice []byte, l int) []byte
- func LoadJSON(file string, val interface{}) error
- func MakeName(name, version string) string
- func PrintDepricationWarning(str string)
- func Report(extra ...interface{})
- func RightPadBytes(slice []byte, l int) []byte
- func ToHex(b []byte) string
- type Address
- func (a Address) Big() *big.Int
- func (a Address) Bytes() []byte
- func (a Address) Format(s fmt.State, c rune)
- func (a Address) Hash() Hash
- func (a Address) Hex() string
- func (a Address) MarshalText() ([]byte, error)
- func (a *Address) Set(other Address)
- func (a *Address) SetBytes(b []byte)
- func (a *Address) SetString(s string)
- func (a Address) Str() string
- func (a Address) String() string
- func (a *Address) UnmarshalText(input []byte) error
- type Hash
- func (h Hash) Big() *big.Int
- func (h Hash) Bytes() []byte
- func (h Hash) Format(s fmt.State, c rune)
- func (h Hash) Generate(rand *rand.Rand, size int) reflect.Value
- func (h Hash) Hex() string
- func (h Hash) MarshalText() ([]byte, error)
- func (h *Hash) Set(other Hash)
- func (h *Hash) SetBytes(b []byte)
- func (h *Hash) SetString(s string)
- func (h Hash) Str() string
- func (h Hash) String() string
- func (h Hash) TerminalString() string
- func (h *Hash) UnmarshalText(input []byte) error
- type PrettyDuration
- type StorageSize
- type UnprefixedAddress
- type UnprefixedHash
Constants ¶
const ( HashLength = 32 AddressLength = 20 )
Variables ¶
var ( Big1 = big.NewInt(1) Big2 = big.NewInt(2) Big3 = big.NewInt(3) Big0 = big.NewInt(0) Big32 = big.NewInt(32) Big256 = big.NewInt(0xff) Big257 = big.NewInt(257) )
Common big integers often used
Functions ¶
func AbsolutePath ¶
func HasHexPrefix ¶
func Hex2BytesFixed ¶
func IsHexAddress ¶ added in v1.4.4
IsHexAddress verifies whether a string can represent a valid hex-encoded Ethereum address or not.
func LeftPadBytes ¶
func MakeName ¶
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 PrintDepricationWarning ¶ added in v1.4.4
func PrintDepricationWarning(str string)
PrintDepricationWarning prinst the given string in a box using fmt.Println.
func Report ¶
func Report(extra ...interface{})
Report gives off a warning requesting the user to submit an issue to the github tracker.
func RightPadBytes ¶
Types ¶
type Address ¶
type Address [AddressLength]byte
Address represents the 20 byte address of an Ethereum account.
func BigToAddress ¶
func BytesToAddress ¶
func HexToAddress ¶
func StringToAddress ¶
func (Address) Format ¶ added in v1.6.6
Format implements fmt.Formatter, forcing the byte slice to be formatted as is, without going through the stringer interface used for logging.
func (Address) MarshalText ¶ added in v1.6.6
MarshalText returns the hex representation of a.
func (*Address) SetBytes ¶
Sets the address to the value of b. If b is larger than len(a) it will panic
func (Address) String ¶ added in v1.6.6
String implements the stringer interface and is used also by the logger.
func (*Address) UnmarshalText ¶ added in v1.6.6
UnmarshalText parses a hash in hex syntax.
type Hash ¶
type Hash [HashLength]byte
Hash represents the 32 byte Keccak256 hash of arbitrary data.
func BytesToHash ¶
func StringToHash ¶
func (Hash) Format ¶ added in v1.6.6
Format implements fmt.Formatter, forcing the byte slice to be formatted as is, without going through the stringer interface used for logging.
func (Hash) MarshalText ¶ added in v1.6.6
MarshalText returns the hex representation of h.
func (Hash) String ¶ added in v1.6.6
String implements the stringer interface and is used also by the logger when doing full logging into a file.
func (Hash) TerminalString ¶ added in v1.6.6
TerminalString implements log.TerminalStringer, formatting a string for console output during logging.
func (*Hash) UnmarshalText ¶ added in v1.6.6
UnmarshalText parses a hash in hex syntax.
type PrettyDuration ¶ added in v1.6.6
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 v1.6.6
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
type UnprefixedAddress ¶ added in v1.6.6
type UnprefixedAddress Address
UnprefixedHash allows marshaling an Address without 0x prefix.
func (UnprefixedAddress) MarshalText ¶ added in v1.6.6
func (a UnprefixedAddress) MarshalText() ([]byte, error)
MarshalText encodes the address as hex.
func (*UnprefixedAddress) UnmarshalText ¶ added in v1.6.6
func (a *UnprefixedAddress) UnmarshalText(input []byte) error
UnmarshalText decodes the address from hex. The 0x prefix is optional.
type UnprefixedHash ¶ added in v1.6.6
type UnprefixedHash Hash
UnprefixedHash allows marshaling a Hash without 0x prefix.
func (UnprefixedHash) MarshalText ¶ added in v1.6.6
func (h UnprefixedHash) MarshalText() ([]byte, error)
MarshalText encodes the hash as hex.
func (*UnprefixedHash) UnmarshalText ¶ added in v1.6.6
func (h *UnprefixedHash) UnmarshalText(input []byte) error
UnmarshalText decodes the hash from hex. The 0x prefix is optional.
Source Files
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Directories
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| Path | Synopsis |
|---|---|
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Package bitutil implements fast bitwise operations.
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Package bitutil implements fast bitwise operations. |
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Package compiler wraps the Solidity compiler executable (solc).
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Package compiler wraps the Solidity compiler executable (solc). |
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Package hexutil implements hex encoding with 0x prefix.
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Package hexutil implements hex encoding with 0x prefix. |
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Package math provides integer math utilities.
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Package math provides integer math utilities. |
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package mclock is a wrapper for a monotonic clock source
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package mclock is a wrapper for a monotonic clock source |