plugeth/ethutil
2014-09-22 14:51:41 +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 Refactored CALLDATALOAD to use big int 2014-07-21 20:38:43 +02:00
bytes_test.go Added better data parser 2014-07-30 13:06:59 +02:00
bytes.go Improved catching up and refactored 2014-09-15 15:42:12 +02:00
common_test.go Change shorthands 2014-05-20 14:53:34 +02:00
common.go Dump bytes instead of strings 2014-08-17 12:42:32 +02:00
config.go Clean up and util methods 2014-07-26 11:24:44 +02:00
db.go Moved keyring to ethutil & removed old methods. Implements #20 2014-05-14 13:54:40 +02:00
list.go Added JavaScript JSON helper 2014-09-22 14:51:41 +02:00
package.go Implemented ethereum package reader 2014-04-23 11:50:17 +02:00
path.go Truncate when writing 2014-09-17 15:57:07 +02:00
rand.go The great merge 2014-02-14 23:56:09 +01:00
README.md Updated readme#trie 2014-02-28 12:19:01 +01:00
rlp_test.go Added big data test and updating to reader 2014-07-29 23:31:33 +02:00
rlp.go Fixed deref ptr 2014-09-19 13:19:19 +02:00
script.go Serpent! :-) 2014-08-24 00:16:32 +02:00
set.go Improved catching up and refactored 2014-09-15 15:42:12 +02:00
size_test.go Block size 2014-08-25 12:53:06 +02:00
size.go Block size 2014-08-25 12:53:06 +02:00
value_test.go added string casting 2014-09-13 13:14:24 +02:00
value.go BigInt accept string 2014-09-22 14:50:53 +02:00

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)