Use a faster stack impl

Cargo.lock

@@ -20,15 +20,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "archery"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0a8da9bc4c4053ee067669762bcaeea6e241841295a2b6c948312dad6ef4cc02"
-dependencies = [
- "static_assertions",
-]
-
 [[package]]
 name = "atty"
 version = "0.2.14"
@@ -204,7 +195,6 @@ dependencies = [
  "radix-heap",
  "rayon",
  "regex",
- "rpds",
  "rustc-hash",
  "strsim",
  "term_size",
@@ -535,15 +525,6 @@ version = "0.6.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49b3de9ec5dc0a3417da371aab17d729997c15010e7fd24ff707773a33bddb64"
 
-[[package]]
-name = "rpds"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "054e417ded02a19ae192c8c89412eaec7d1c2cdd826aa412565761d86ca6315e"
-dependencies = [
- "archery",
-]
-
 [[package]]
 name = "rustc-hash"
 version = "1.1.0"
@@ -579,12 +560,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
-[[package]]
-name = "static_assertions"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
-
 [[package]]
 name = "strsim"
 version = "0.10.0"

Cargo.toml

@@ -42,7 +42,6 @@ walkdir = "2.3.2"
 terminal_size = "0.2.1"
 const_format = "0.2.22"
 owo-colors = "3.3.0"
-rpds = "0.10.0"
 wu-diff = "0.1.2"
 rayon = "1.5.2"
 tree_magic_mini = "3.0.3"

src/diff/graph.rs

@@ -1,7 +1,6 @@
 //! A graph representation for computing tree diffs.
 
 use bumpalo::Bump;
-use rpds::Stack;
 use rustc_hash::FxHashMap;
 use std::{
     cell::RefCell,
@@ -12,7 +11,10 @@ use std::{
 use strsim::normalized_levenshtein;
 
 use crate::{
-    diff::changes::{insert_deep_unchanged, ChangeKind, ChangeMap},
+    diff::{
+        changes::{insert_deep_unchanged, ChangeKind, ChangeMap},
+        stack::Stack,
+    },
     parse::syntax::{AtomKind, Syntax, SyntaxId},
 };
 use Edge::*;

src/diff/mod.rs

@@ -3,4 +3,5 @@ pub mod dijkstra;
 mod graph;
 pub mod myers_diff;
 pub mod sliders;
+mod stack;
 pub mod unchanged;

src/diff/stack.rs

@@ -0,0 +1,48 @@
+use std::rc::Rc;
+
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+struct Node<T> {
+    val: T,
+    next: Option<Rc<Node<T>>>,
+}
+
+#[derive(Debug, Clone, Default, PartialEq, Eq)]
+pub struct Stack<T> {
+    head: Option<Rc<Node<T>>>,
+    len: usize,
+}
+
+impl<T> Stack<T> {
+    pub fn new() -> Self {
+        Self { head: None, len: 0 }
+    }
+
+    pub fn peek(&self) -> Option<&T> {
+        self.head.as_deref().map(|n| &n.val)
+    }
+
+    pub fn pop(&self) -> Option<Stack<T>> {
+        self.head.as_deref().map(|n| Self {
+            head: n.next.clone(),
+            len: self.len - 1,
+        })
+    }
+
+    pub fn push(&self, v: T) -> Stack<T> {
+        Self {
+            head: Some(Rc::new(Node {
+                val: v,
+                next: self.head.clone(),
+            })),
+            len: self.len + 1,
+        }
+    }
+
+    pub fn size(&self) -> usize {
+        self.len
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.len == 0
+    }
+}