plugeth/ethutil
2014-04-01 14:20:55 +02:00
..
.gitignore The great merge 2014-02-14 23:56:09 +01:00
.travis.yml Rename .travil.yml to .travis.yml 2014-03-03 18:13:08 +01:00
big.go Added BigCopy 2014-02-28 12:19:21 +01:00
bytes.go The great merge 2014-02-14 23:56:09 +01:00
common_test.go PoC reactor pattern 2014-03-03 00:55:10 +01:00
common.go Test fixes and removed old code. Added VM gas fees 2014-03-24 13:20:34 +01:00
config.go Some minor updates 2014-03-20 17:27:48 +01:00
db.go Added a GetKeys method to support multiple accounts 2014-02-28 12:18:41 +01:00
encoding_test.go adding compact decode tests 2014-02-17 15:46:16 -08:00
encoding.go Rlp update 2014-02-18 01:34:06 +01:00
helpers.go Added new address 2014-02-18 12:10:21 +01:00
key.go Added a GetKeys method to support multiple accounts 2014-02-28 12:18:41 +01:00
parsing_test.go Merge pull request #8 from josephyzhou/develop 2014-02-24 12:53:30 +01:00
parsing.go Test fixes and removed old code. Added VM gas fees 2014-03-24 13:20:34 +01:00
rand.go The great merge 2014-02-14 23:56:09 +01:00
reactor_test.go Reactor implemented 2014-03-02 02:22:20 +01:00
reactor.go PoC reactor pattern 2014-03-03 00:55:10 +01:00
README.md Updated readme#trie 2014-02-28 12:19:01 +01:00
rlp_test.go Merge conflicts 2014-04-01 14:20:55 +02:00
rlp.go Fixed typo 2014-03-27 15:38:55 +01:00
trie_test.go More blockchain testing 2014-03-31 12:54:37 +02:00
trie.go Removed comments 2014-03-06 13:09:55 +01:00
value_test.go Partially refactored server/txpool/block manager/block chain 2014-03-05 10:42:51 +01:00
value.go Added a IsList method for type checking []interface{} 2014-03-27 19:42:01 +01:00

ethutil

Build
Status

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)