plugeth/ethutil
2015-02-18 17:18:07 +01:00
..
number Added WIP number package 2015-02-18 17:18:07 +01:00
.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_test.go Merge branch 'develop' of https://github.com/tgerring/go-ethereum 2014-11-14 15:01:52 -06:00
big.go Fixed EXP gas 2014-12-01 22:05:38 +01:00
bytes_test.go Merge branch 'develop' of https://github.com/tgerring/go-ethereum 2014-11-14 15:01:52 -06:00
bytes.go Proper delete 2014-10-02 17:03:36 +02:00
common_test.go Update ethutil/common tests to checker 2014-11-16 12:08:27 -06:00
common.go updated tests 2015-01-13 00:25:45 +01:00
config.go Refactored ethutil.Config.Db out 2015-01-07 13:17:48 +01:00
db.go Moved keyring to ethutil & removed old methods. Implements #20 2014-05-14 13:54:40 +02:00
list.go Updated to use ethereum.js 2014-10-31 10:50:16 +01:00
main_test.go update imports order per goimports 2014-11-15 20:21:55 -06:00
package.go Implemented ethereum package reader 2014-04-23 11:50:17 +02:00
path_test.go Merge branch 'develop' of https://github.com/tgerring/go-ethereum 2014-11-14 15:01:52 -06:00
path.go Minor fixed and additions for block proc 2015-01-08 16:37:06 +01:00
rand_test.go Merge branch 'develop' of https://github.com/tgerring/go-ethereum 2014-11-14 15:01:52 -06:00
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 moved err check 2014-12-17 12:57:35 +01:00
rlp.go Minor fixed and additions for block proc 2015-01-08 16:37:06 +01:00
script_unix.go Removed mutan. Closes #183 2014-12-04 17:13:23 +01:00
script_windows.go Removed mutan. Closes #183 2014-12-04 17:13:23 +01:00
set.go Improved catching up and refactored 2014-09-15 15:42:12 +02:00
size_test.go Merge branch 'develop' of https://github.com/tgerring/go-ethereum 2014-11-14 15:01:52 -06:00
size.go Block size 2014-08-25 12:53:06 +02:00
value_test.go update imports order per goimports 2014-11-15 20:21:55 -06:00
value.go idx should return -1 2014-12-18 11:55:46 +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)