Commit a3aed82a78f2d18269efbd86f8784e8989e5d4da
Update spec.md
wanderer authored on 3/1/2018, 2:13:26 AMGitHub committed on 3/1/2018, 2:13:26 AM
Parent: 343203ced157299bd2c071287e5c9945a760fe45
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| 1 | 1 … | This documnet provides the structure of the [Dfinity's Radix Tree.](https://ipfs.io/ipns/QmdJiuMWp2FxyaerfLrtdLF6Nr1EWpL7dPAxA9oKSPYYgV/wiki/Radix_tree.html) | |
| 2 | -The radix tree data structure stores the key-values; the tree is an instances of nodes that contains the value and the key is the path to the node in the tree. | ||
| 2 … | +The radix tree data structure stores the key-values; the tree is an instances of nodes that contains the value and the key is the path to the node in the tree. All values are encoded with [CBOR](http://cbor.io) | ||
| 3 | 3 … | ||
| 4 | 4 … | ## Node | |
| 5 | 5 … | Each node has a type and contains at most four elements: | |
| 6 | 6 … | "extension", "left branch", "right branch" and "value". | |
| @@ -52,44 +52,4 @@ | |||
| 52 | 52 … | `0x03, 0x04` | |
| 53 | 53 … | ||
| 54 | 54 … | where 3 is the the shared path length and the `0x04` is the shared path encoded | |
| 55 | 55 … | as a little endian byte array. | |
| 56 | - | ||
| 57 | -## Examples | ||
| 58 | - | ||
| 59 | -An empty tree has a merkle root which is a hash of sha256(0x00) or `6e340b9cffb37a989ca544e6bb780a2c78901d3f`. | ||
| 60 | - | ||
| 61 | - | ||
| 62 | -A tree with a single node with key 'binary' and value of 'tree' is encoded as | ||
| 63 | - | ||
| 64 | -``` | ||
| 65 | -0x093062696e61727974726565 | ||
| 66 | - | ||
| 67 | -0x09 this node has an extention and value | ||
| 68 | -0x30 the extention has a length of 48 bits or 6 bytes | ||
| 69 | -0x62696e617279 the key 'binary' | ||
| 70 | -0x4726565 the value 'tree' | ||
| 71 | -``` | ||
| 72 | - | ||
| 73 | -If we add another key-value with the key "bin" and the value "number" to the tree, the tree will have two nodes | ||
| 74 | - | ||
| 75 | -The root node will be | ||
| 76 | - | ||
| 77 | -``` | ||
| 78 | -0x0b1862696eaf39aa98eb0350611f230cbeb2e68dbe95ab5ecc6e756d626572 | ||
| 79 | - | ||
| 80 | -0xb this node has an extention, a right branch and a value | ||
| 81 | -0x18 this the extention has a length of 24 bits | ||
| 82 | -0x62696e the value extention "bin" | ||
| 83 | -0xaf39aa98eb0350611f230cbeb2e68dbe95ab5ecc a merkle link to another node | ||
| 84 | -0x6e756d626572 the value "number" | ||
| 85 | - | ||
| 86 | -the link 0xaf39aa98eb0350611f230cbeb2e68dbe95ab5ecc points to the node | ||
| 87 | - | ||
| 88 | -0x091730b93c74726565 | ||
| 89 | - | ||
| 90 | -0x09 this node has an extention and value | ||
| 91 | -0x17 this the extention has a length of 23 bits | ||
| 92 | -0x30b93c the extention 'ary' = 0x617279 that is shift left one bit. 'a' is 0x61 which | ||
| 93 | -is read 100001100 (little endian) The was first bit is was used to choose the branch (right) | ||
| 94 | -turns into 0x30 (110000) | ||
| 95 | -``` | ||
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