Add 'zcash_history/' from commit 'e2c131fdc308265adcab774e54d4d5804c23b368'

git-subtree-dir: zcash_history
git-subtree-mainline: be0ee9eb82
git-subtree-split: e2c131fdc3

zcash_history/examples/lib/main.rs

@@ -0,0 +1,4 @@
+// dummy example
+pub fn main() {
+
+}

zcash_history/examples/lib/shared.rs

@@ -0,0 +1,78 @@
+use zcash_mmr:: {NodeData, Tree, Entry, EntryLink};
+
+pub struct NodeDataIterator {
+    return_stack: Vec<NodeData>,
+    tree: Tree,
+    cursor: usize,
+    leaf_cursor: usize,
+}
+
+impl Iterator for NodeDataIterator {
+    type Item = NodeData;
+
+    fn next(&mut self) -> Option<NodeData> {
+        let result = if self.cursor == 1 {
+            self.leaf_cursor = 2;
+            Some(leaf(1))
+        } else if self.cursor == 2 {
+            self.leaf_cursor = 3;
+            Some(leaf(2))
+        } else if self.cursor == 3 {
+            Some(self.tree.root_node().expect("always exists").data().clone())
+        } else if self.return_stack.len() > 0 {
+            self.return_stack.pop()
+        } else {
+            for n_append in
+                self.tree.append_leaf(leaf(self.leaf_cursor as u32))
+                    .expect("full tree cannot fail").into_iter().rev()
+            {
+                self.return_stack.push(self.tree.resolve_link(n_append).expect("just pushed").data().clone())
+            }
+            self.leaf_cursor += 1;
+            self.return_stack.pop()
+        };
+
+        self.cursor += 1;
+        result
+    }
+}
+
+impl NodeDataIterator {
+    pub fn new() -> Self {
+        let root = Entry::new(
+            NodeData::combine(&leaf(1), &leaf(2)),
+            EntryLink::Stored(0),
+            EntryLink::Stored(1)
+        );
+        let tree =
+            Tree::new(
+                3,
+                vec![(2, root)],
+                vec![(0, leaf(1).into()), (1, leaf(2).into())]
+            );
+
+        NodeDataIterator {
+            return_stack: Vec::new(),
+            tree,
+            cursor: 1,
+            leaf_cursor: 1,
+        }
+    }
+}
+
+fn leaf(height: u32) -> NodeData {
+    NodeData {
+        consensus_branch_id: 0,
+        subtree_commitment: [0u8; 32],
+        start_time: height*10+1,
+        end_time: (height+1)*10,
+        start_target: 100 + height*10,
+        end_target: 100 + (height+1)*10,
+        start_sapling_root: [0u8; 32],
+        end_sapling_root: [0u8; 32],
+        subtree_total_work: 0.into(),
+        start_height: height as u64,
+        end_height: height as u64,
+        shielded_tx: 5 + height as u64,
+    }
+}