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Get appending at the end of the rope to work

This commit is contained in:
Savanni D'Gerinel 2024-05-13 10:15:28 -04:00
parent 02af9e4ea7
commit 77bc77cd20
1 changed files with 126 additions and 81 deletions
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201
editor-challenge/src/doc_rope.rs
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@ -2,7 +2,7 @@ use std::{mem, ops::Deref};
const CHUNK_SIZE: usize = 10;
#[derive(Clone, Copy)]
#[derive(Clone, Copy, Debug)]
struct NodeId(usize);
impl Deref for NodeId {
@ -12,14 +12,15 @@ impl Deref for NodeId {
}
}
#[derive(Debug)]
enum Node {
Interior {
// the number of characters to the left of this node
// the number of lines to the left of this node
char_count: usize,
left: NodeId,
right: NodeId,
left: Option<NodeId>,
right: Option<NodeId>,
},
Leaf(LeafNode),
}
@ -33,6 +34,7 @@ impl Node {
}
}
#[derive(Debug)]
struct LeafNode(String);
impl LeafNode {
@ -56,97 +58,55 @@ impl From<String> for LeafNode {
}
}
// a Rope is a regular tree which adds on some extra behavior for dealing with a continuous data
// structure.
/// A Rope is a regular tree which adds on some extra behavior for dealing with a continuous data
/// structure. In this case, the nodes all contain strings, and the rope is arranged such that a
/// depth-first traversal will yield the entire contents of the rope in proper order.
#[derive(Debug)]
pub struct Rope {
node_count: usize,
contents: Vec<Option<Node>>,
}
impl Rope {
/// Insert text at an index within the document. loc is the number of characters from the
/// beginning.
pub fn insert_at(&mut self, loc: usize, text: String) {
unimplemented!();
}
pub fn append(&mut self, text: String) {
if self.node_count == 0 {
match self.find_insertion_node_id(loc) {
None => {
let node = Node::Leaf(LeafNode::from(text));
self.node_count += 1;
self.contents.push(Some(node));
} else {
// Let's grab a node. If it's a leaf node, we need to convert it into a interior node.
// In doing so, we need to move the current leaf node into a left-hand child and create
// the right-hand child.
//
// If it's an interior node, we'll dig deeper. Not doing any tree rebalancing at the
// moment.
//
// First thing we need to know is what mode of node we have. That's going to determine
// which branch of operations we go into. We want to do this without borrowing the data
// for anything more than the match.
// let mut node = mem::replace(&mut self.contents[0], None);
match self.contents[0] {
Some(Node::Interior { ref left, ref right, .. }) => {
}
Some(Node::Leaf(_)) => {
let Some(Node::Leaf(mut ln)) = mem::replace(&mut self.contents[0], None) else {
panic!("Should never leave an empty space in the node list")
};
let contents = ln.take();
let lnode = Node::Leaf(LeafNode::from(contents));
let rnode = Node::Leaf(LeafNode::from(text));
let lnode_id = self.node_count;
let rnode_id = self.node_count + 1;
let interior_node = Node::Interior {
char_count: lnode.len(),
left: NodeId(lnode_id),
right: NodeId(rnode_id),
};
let _ = mem::replace(&mut self.contents[0], Some(interior_node));
self.node_count += 2;
self.contents.push(Some(lnode));
self.contents.push(Some(rnode));
Some(id) => {
self.insert_at_node(id, text);
}
None => panic!("Should never leave an empty space in the node list"),
}
/*
let mut node = &mut self.contents[0];
if let Node::Leaf(s) = node {
let contents = s.take();
let lnode = Node::Leaf(LeafNode::from(contents));
let rnode = Node::Leaf(LeafNode::from(text));
self.contents.push(lnode);
self.contents.push(rnode);
let lnode_id = self.node_count;
let rnode_id = self.node_count + 1;
self.node_count += 2;
*node = Node::Interior{
char_count: 0,
left: NodeId(lnode_id),
right: NodeId(rnode_id),
};
}
*/
}
}
/// Append text to the end of the document.
pub fn append(&mut self, text: String) {
self.insert_at(self.len(), text);
}
/// Convert the entire rope back to a continuous String.
pub fn to_string(&self) -> String {
if self.contents.is_empty() {
return "".to_owned();
}
let mut r = String::new();
let mut stack = vec![NodeId(0)];
while let Some(current_id) = stack.pop() {
let node = &self.contents[*current_id];
match node {
Some(Node::Interior{ left, right, .. }) => {
stack.push(*right);
stack.push(*left);
Some(Node::Interior { left, right, .. }) => {
if let Some(right_id) = *right {
stack.push(right_id);
}
if let Some(left_id) = *left {
stack.push(left_id);
}
}
Some(Node::Leaf(ln)) => r.push_str(ln.as_str()),
None => panic!("Should never leave an empty space in the node list"),
@ -156,6 +116,7 @@ impl Rope {
r
}
/// Calculate the length of the stored string.
pub fn len(&self) -> usize {
// This can be optimized later. Do a traversal of each right node. We already have
// character counts of each left tree. Only count the length of the final right leaf.
@ -177,6 +138,74 @@ impl Rope {
fn node_count(&self) -> usize {
self.node_count
}
// Find the node ID of the insertion point. This is not fully implemented, in that this
// function ignores the offset from the beginning. Because of that, it is also always inserting
// onto the right side, and never traversing down the left.
fn find_insertion_node_id(&self, _loc: usize) -> Option<NodeId> {
let mut current_id = NodeId(0);
loop {
match self.contents.get(*current_id) {
Some(Some(Node::Interior { ref right, .. })) => match right {
Some(id) => current_id = *id,
None => return Some(current_id),
},
Some(Some(Node::Leaf(_))) => return Some(current_id),
Some(None) => panic!("There should never be an empty node in the tree"),
// This only happens when the list is empty. Otherwise, we're detecting the None in
// advance.
None => return None,
}
}
}
// Insert text at a particular node location.
//
// This is not a self-balancing operation (yet). Once we know where text needs to be inserted,
// based on the offset from the beginning, we can grab that node and either replace it (if it
// is a Leaf node) or update it (if it is an Interior node).
//
// This function is currently naive, in that it will always assume that text needs to be added
// to the right side, which may not be correct.
fn insert_at_node(&mut self, id: NodeId, text: String) {
match self.contents[*id] {
Some(Node::Interior { ref mut right, .. }) => {
let new_node = Node::Leaf(LeafNode::from(text));
let new_node_id = NodeId(self.node_count + 1);
*right = Some(new_node_id);
self.contents.push(Some(new_node));
self.node_count += 1;
}
Some(Node::Leaf(_)) => {
let Some(Node::Leaf(mut ln)) = mem::replace(&mut self.contents[*id], None) else {
panic!("Should never leave an empty space in the node list")
};
let contents = ln.take();
let lnode = Node::Leaf(LeafNode::from(contents));
let rnode = Node::Leaf(LeafNode::from(text));
let lnode_id = self.node_count;
let rnode_id = self.node_count + 1;
let interior_node = Node::Interior {
char_count: lnode.len(),
left: Some(NodeId(lnode_id)),
right: Some(NodeId(rnode_id)),
};
let _ = mem::replace(&mut self.contents[*id], Some(interior_node));
self.node_count += 2;
self.contents.push(Some(lnode));
self.contents.push(Some(rnode));
}
None => panic!("Should never leave an empty space in the node list"),
}
}
}
impl Default for Rope {
@ -199,9 +228,9 @@ impl From<String> for Rope {
while lst.len() > CHUNK_SIZE {
(first, lst) = lst.split_at(CHUNK_SIZE);
println!("[{}] [{}]", first, lst);
rope.append(first.to_owned());
}
rope.append(lst.to_owned());
rope
}
}
@ -210,15 +239,31 @@ impl From<String> for Rope {
mod test {
use super::*;
struct TestCase {
content: String,
}
#[test]
fn it_creates_a_rope_from_a_string() {
let content =
let test_cases = vec![
TestCase{ content: "".to_owned() },
TestCase{ content: "This".to_owned() },
TestCase{ content: "This is some basic".to_owned() },
TestCase{ content: "This is some basic context which is much smaller".to_owned() },
TestCase{ content:
"This is some basic context which is much smaller than the rope is designed for."
.to_owned();
.to_owned()
},
];
let rope = Rope::from(content.clone());
for case in test_cases {
let rope = Rope::from(case.content.clone());
assert_eq!(rope.to_string(), content);
assert_eq!(rope.len(), content.len());
for (idx, node) in rope.contents.iter().enumerate() {
}
assert_eq!(rope.len(), case.content.len(), "{}", case.content);
assert_eq!(rope.to_string(), case.content, "{:?}", case.content);
}
}
}