This is an adaptation of Merkle Trees for a github commit-like implementation.
Yes, I was bored
Merkle trees are a type of binary tree that compute a hash to verify the integrity of a sequence.
In this project, each Tree contains branches made of nodes.
Branches are a HasmMap<String, Rc<RefCell>> (this is a smart pointer in Rust, don't be scared). The node linked
is always the head of the branch.
A node contains some data that can be a string, a float or an int. The node also knows its hash and its children if it has any.
If a node has any children, it will compute its hash according to their data. Else, it will compute from its own data.
The following code
// Creating 4 nodes
let first_node = Node::new(Data::new(String::from("My age"), DataType::Integer(21)), String::from("Added my age."));
let second_node = Node::new(Data::new(String::from("A float"), DataType::Float(3.14)), String::from("Defined PI."));
let third_node = Node::new(Data::new(String::from("This is a"), DataType::String(String::from("Working tree."))), String::from("Commented line"));
let fourth_node = Node::new(Data::new(String::from("Random number"), DataType::Integer(21)), String::from("New branch!"));
// Create the tree with the first node as the 'master' head
let mut merkle_tree = Tree::new(first_node);
merkle_tree.push(second_node, String::from("master"));
merkle_tree.push(third_node, String::from("master")); // At this point, the third node is the 'master' head
// Error because the dev branch doesn't exist [1]
let error = merkle_tree.push(fourth_node.clone(), String::from("dev"));
println!("{}", error);
// Last used branch was 'master' so the 'dev' branch will be set from the 'master' branch
merkle_tree.new_branch(fourth_node, String::from("dev"));
// Display the 'dev' branch [2]
merkle_tree.print_all_data(String::from("dev"));
// Any commit with this hash will be removed.
// All parent commits will recompute their hash !
merkle_tree.remove(String::from("3c59dc048e8850243be8079a5c74d079"));
// Since commits are branch dependents, the removed commit from master is not
// removed from the 'dev' branch. Note how all the hashes haved changed!
// You can see that our tree now has 2 heads! [3]
merkle_tree.print_all_data(String::from("master"));
merkle_tree.print_all_data(String::from("dev"));
Will output:
[1]
[error] branch does not exist
[2]
Branch dev
|-[HEAD] Commit 'New branch!'
|-- Data name: 'Random number' Held information -> 21 hash: c9db9322d5885099119e7f35f6166c25
|-Commit 'Commented line'
|-- Data name: 'This is a' Held information -> Working tree. hash: 5864ecaeb40a56fe627fc36da2945b7b
|-Commit 'Defined PI.'
|-- Data name: 'A float' Held information -> 3.14 hash: 84d415275baf9261771b8f12d3f4617f
|-[LEAF] Commit 'Added my age.'
|-- Data name: 'My age' Held information -> 21 hash: 6727efa2c4e2e02eae4410a0ab82156f
[3]
Branch master
|-[HEAD] Commit 'Commented line'
|-- Data name: 'This is a' Held information -> Working tree. hash: 6f2f27ec205a1fb26a3fe0574a20e261
|-Commit 'Defined PI.'
|-- Data name: 'A float' Held information -> 3.14 hash: cf670ae90f73a914cdb447627421af2b
|-[LEAF] Commit 'Added my age.'
|-- Data name: 'My age' Held information -> 21 hash: 03f8faa47a2e9614453e50aaf8d7f278
Branch dev
|-[HEAD] Commit 'New branch!'
|-- Data name: 'Random number' Held information -> 21 hash: c9db9322d5885099119e7f35f6166c25
|-Commit 'Commented line'
|-- Data name: 'This is a' Held information -> Working tree. hash: 5864ecaeb40a56fe627fc36da2945b7b
|-Commit 'Defined PI.'
|-- Data name: 'A float' Held information -> 3.14 hash: 84d415275baf9261771b8f12d3f4617f
|-[LEAF] Commit 'Added my age.'
|-- Data name: 'My age' Held information -> 21 hash: 6727efa2c4e2e02eae4410a0ab82156f