Official Go implementation of the Ethereum protocol
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 
go-ethereum/common
Felix Lange 80901e8288 common: remove config.go 9 years ago
..
compiler all: update license headers to distiguish GPL/LGPL 9 years ago
docserver all: update license headers to distiguish GPL/LGPL 9 years ago
math all: update license headers to distiguish GPL/LGPL 9 years ago
natspec all: update license headers to distiguish GPL/LGPL 9 years ago
number all: update license headers to distiguish GPL/LGPL 9 years ago
registrar all: update license headers to distiguish GPL/LGPL 9 years ago
.gitignore Moved ethutil => common 10 years ago
.travis.yml Moved ethutil => common 10 years ago
README.md Moved ethutil => common 10 years ago
big.go all: update license headers to distiguish GPL/LGPL 9 years ago
big_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
bytes.go all: update license headers to distiguish GPL/LGPL 9 years ago
bytes_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
db.go all: update license headers to distiguish GPL/LGPL 9 years ago
debug.go all: update license headers to distiguish GPL/LGPL 9 years ago
list.go all: update license headers to distiguish GPL/LGPL 9 years ago
main_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
package.go all: update license headers to distiguish GPL/LGPL 9 years ago
path.go all: update license headers to distiguish GPL/LGPL 9 years ago
path_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
rlp.go all: update license headers to distiguish GPL/LGPL 9 years ago
rlp_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
size.go all: update license headers to distiguish GPL/LGPL 9 years ago
size_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
test_utils.go all: update license headers to distiguish GPL/LGPL 9 years ago
types.go all: update license headers to distiguish GPL/LGPL 9 years ago
types_template.go all: update license headers to distiguish GPL/LGPL 9 years ago
types_test.go all: update license headers to distiguish GPL/LGPL 9 years ago
value.go all: update license headers to distiguish GPL/LGPL 9 years ago
value_test.go all: update license headers to distiguish GPL/LGPL 9 years ago

README.md

ethutil

BuildStatus

The ethutil package contains the ethereum utility library.

Installation

go get github.com/ethereum/ethutil-go

Usage

RLP (Recursive Linear Prefix) Encoding

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

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

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

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

Patricia Trie

Patricie Tree is a merkle trie utilized 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 ethutil/db.go.

db := NewDatabase()

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