example and neccessary fixes

examples/producer.rs

@@ -0,0 +1,219 @@
+extern crate zcash_mmr as mmr;
+
+use mmr::{NodeData, Tree, EntryLink, Entry};
+
+fn prepare_tree(vec: Vec<NodeData>) -> (Tree, EntryLink) {
+
+    assert!(vec.len() > 0);
+
+    // integer log2 of (vec.len()+1), -1
+    let mut h = (32 - ((vec.len()+1) as u32).leading_zeros() - 1)-1;
+    let mut peak_pos = (1 << (h+1)) - 1;
+
+    let mut nodes = Vec::new();
+    let mut root_peak: Entry = vec[peak_pos-1].clone().into();
+
+    root_peak.update_siblings(
+        EntryLink::Stored((peak_pos - (1<<h) - 1) as u32),
+        EntryLink::Stored((peak_pos - 2) as u32),
+    );
+    nodes.push(((peak_pos-1) as u32, root_peak));
+
+    // + 2^(h+1)-1
+    peak_pos = peak_pos + (1 << (h+1)) - 1;
+
+    loop {
+
+        if peak_pos > vec.len() {
+            // left child, -2^h
+            peak_pos = peak_pos - (1<<h);
+            h = h - 1;
+        }
+
+        if peak_pos <= vec.len() {
+            let mut peak: Entry = vec[peak_pos-1].clone().into();
+            if h != 0 {
+                peak.update_siblings(
+                    EntryLink::Stored((peak_pos - (1<<h) - 1) as u32),
+                    EntryLink::Stored((peak_pos - 2) as u32),
+                );
+            }
+            nodes.push(((peak_pos-1) as u32, peak));
+
+            // right sibling
+            peak_pos = peak_pos + (1 << (h+1)) - 1;
+        }
+
+        if h == 0 {
+            break;
+        }
+    }
+
+    Tree::new(vec.len() as u32, nodes, vec![])
+}
+
+fn main() {
+
+    let mut initial_tree_vec = vec![
+
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 10,
+            end_time: 20,
+            start_target: 100,
+            end_target: 110,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 1,
+            end_height: 1,
+            shielded_tx: 5,
+        },
+
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 21,
+            end_time: 30,
+            start_target: 110,
+            end_target: 120,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 2,
+            end_height: 2,
+            shielded_tx: 4,
+        },
+    ];
+
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[0], &initial_tree_vec[1]));
+
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 31,
+            end_time: 40,
+            start_target: 120,
+            end_target: 130,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 3,
+            end_height: 3,
+            shielded_tx: 6,
+        },
+    );
+
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 41,
+            end_time: 50,
+            start_target: 130,
+            end_target: 140,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 4,
+            end_height: 4,
+            shielded_tx: 7,
+        },
+    );
+
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[3], &initial_tree_vec[4]));
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[2], &initial_tree_vec[5]));
+
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 51,
+            end_time: 60,
+            start_target: 140,
+            end_target: 150,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 5,
+            end_height: 5,
+            shielded_tx: 8,
+        },
+    );
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 61,
+            end_time: 70,
+            start_target: 150,
+            end_target: 160,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 6,
+            end_height: 6,
+            shielded_tx: 9,
+        },
+    );
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[7], &initial_tree_vec[8]));
+
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 71,
+            end_time: 80,
+            start_target: 160,
+            end_target: 170,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 7,
+            end_height: 7,
+            shielded_tx: 10,
+        },
+    );
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 81,
+            end_time: 90,
+            start_target: 170,
+            end_target: 180,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 8,
+            end_height: 8,
+            shielded_tx: 11,
+        },
+    );
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[10], &initial_tree_vec[11]));
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[9], &initial_tree_vec[12]));
+    initial_tree_vec.push(NodeData::combine(&initial_tree_vec[6], &initial_tree_vec[13]));
+
+    initial_tree_vec.push(
+        NodeData {
+            consensus_branch_id: 0,
+            subtree_commitment: [0u8; 32],
+            start_time: 91,
+            end_time: 100,
+            start_target: 180,
+            end_target: 190,
+            start_sapling_root: [0u8; 32],
+            end_sapling_root: [0u8; 32],
+            subtree_total_work: Default::default(),
+            start_height: 9,
+            end_height: 9,
+            shielded_tx: 12,
+        },
+    );
+
+    let (_tree, root) = prepare_tree(initial_tree_vec);
+    println!("root: {}", root);
+
+}

src/lib.rs

@@ -45,12 +45,17 @@ pub enum EntryKind {
     Node(EntryLink, EntryLink),
 }
 
+#[derive(Debug)]
 pub struct Entry {
     kind: EntryKind,
     data: NodeData,
 }
 
 impl Entry {
+    pub fn update_siblings(&mut self, left: EntryLink, right: EntryLink) {
+        self.kind = EntryKind::Node(left, right);
+    }
+
     pub fn complete(&self) -> bool {
         let leaves = self.leaf_count();
         leaves & (leaves - 1) == 0

src/node_data.rs

@@ -4,7 +4,7 @@ use blake2::blake2b::Blake2b;
 
 /// Node metadata.
 #[repr(C)]
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct NodeData {
     pub consensus_branch_id: u32,
     pub subtree_commitment: [u8; 32],

src/tree.rs

@@ -88,23 +88,28 @@ impl Tree {
 
     pub fn new(
         length: u32,
-        stored: Vec<(u32, Entry)>,
+        peaks: Vec<(u32, Entry)>,
-        generated: Vec<Entry>,
+        extra: Vec<(u32, Entry)>,
-    ) -> Self {
+    ) -> (Self, EntryLink) {
         let mut result = Tree::default();
         result.stored_count = length;
 
-        for (idx, node) in stored.into_iter() {
+        let mut gen = 0;
+        let mut root = EntryLink::Stored(peaks[0].0);
+        for (idx, node) in peaks.into_iter() {
             result.stored.insert(idx, node);
+            if gen != 0 {
+                let next_generated =
+                    combine_nodes(result.
+                        resolve_link(root).expect("Inserted before, cannot fail; qed"),
+                      result.resolve_link(EntryLink::Stored(idx)).expect("Inserted before, cannot fail; qed")
+                    );
+                root = result.push_generated(next_generated);
+            }
+            gen += 1;
         }
 
-        result.generated_count = generated.len() as u32;
+        (result, root)
-
-        for (idx, node) in generated.into_iter().enumerate() {
-            result.generated.insert(idx as u32, node);
-        }
-
-        result
     }
 
     fn get_peaks(&self, root: EntryLink, target: &mut Vec<EntryLink>) -> Result<(), Error> {