Remove RwLock for registers

Registers are stored inside `Editor` and accessed without `RwLock`.
To work around ownership, I added a sister method to `Editor::current`:
`Editor::current_with_context`. I tried to modify `Editor::current`
directly but it's used at a lot of places so I reverted into this for
now at least.

5 files changed, 161 insertions, 86 deletions

diff --git a/helix-core/src/register.rs b/helix-core/src/register.rs
index 0176d23e..cc881a17 100644
--- a/helix-core/src/register.rs
+++ b/helix-core/src/register.rs
@@ -1,20 +1,63 @@
-use crate::Tendril;
-use once_cell::sync::Lazy;
-use std::{collections::HashMap, sync::RwLock};
-
-// TODO: could be an instance on Editor
-static REGISTRY: Lazy<RwLock<HashMap<char, Vec<String>>>> =
-    Lazy::new(|| RwLock::new(HashMap::new()));
-
-/// Read register values.
-pub fn get(register_name: char) -> Option<Vec<String>> {
-    let registry = REGISTRY.read().unwrap();
-    registry.get(&register_name).cloned() // TODO: no cloning
+use std::collections::HashMap;
+
+#[derive(Debug)]
+pub struct Register {
+    name: char,
+    values: Vec<String>,
+}
+
+impl Register {
+    pub fn new(name: char) -> Self {
+        Self {
+            name,
+            values: Vec::new(),
+        }
+    }
+
+    pub fn new_with_values(name: char, values: Vec<String>) -> Self {
+        Self { name, values }
+    }
+
+    pub fn name(&self) -> char {
+        self.name
+    }
+
+    pub fn read(&self) -> &Vec<String> {
+        &self.values
+    }
+
+    pub fn write(&mut self, values: Vec<String>) {
+        self.values = values;
+    }
 }
 
-/// Read register values.
-// restoring: bool
-pub fn set(register_name: char, values: Vec<String>) {
-    let mut registry = REGISTRY.write().unwrap();
-    registry.insert(register_name, values);
+/// Currently just wraps a `HashMap` of `Register`s
+#[derive(Debug, Default)]
+pub struct Registers {
+    inner: HashMap<char, Register>,
+}
+
+impl Registers {
+    pub fn get(&self, name: char) -> Option<&Register> {
+        self.inner.get(&name)
+    }
+
+    pub fn get_mut(&mut self, name: char) -> Option<&mut Register> {
+        self.inner.get_mut(&name)
+    }
+
+    pub fn get_or_insert(&mut self, name: char) -> &mut Register {
+        self.inner
+            .entry(name)
+            .or_insert_with(|| Register::new(name))
+    }
+
+    pub fn write(&mut self, name: char, values: Vec<String>) {
+        self.inner
+            .insert(name, Register::new_with_values(name, values));
+    }
+
+    pub fn read(&self, name: char) -> Option<&Vec<String>> {
+        self.get(name).map(|reg| reg.read())
+    }
 }
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 382137d1..c80716d4 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -4,8 +4,9 @@ use helix_core::{
     movement::{self, Direction},
     object, pos_at_coords,
     regex::{self, Regex},
-    register, search, selection, Change, ChangeSet, Position, Range, Rope, RopeSlice, Selection,
-    SmallVec, Tendril, Transaction,
+    register::{self, Register, Registers},
+    search, selection, Change, ChangeSet, Position, Range, Rope, RopeSlice, Selection, SmallVec,
+    Tendril, Transaction,
 };
 
 use helix_view::{
@@ -39,7 +40,7 @@ use crossterm::event::{KeyCode, KeyEvent};
 use once_cell::sync::Lazy;
 
 pub struct Context<'a> {
-    pub register: helix_view::RegisterSelection,
+    pub selected_register: helix_view::RegisterSelection,
     pub count: Option<std::num::NonZeroUsize>,
     pub editor: &'a mut Editor,
 
@@ -65,6 +66,11 @@ impl<'a> Context<'a> {
         self.editor.current()
     }
 
+    #[inline]
+    pub fn current_with_registers(&mut self) -> (&mut View, &mut Document, &mut Registers) {
+        self.editor.current_with_registers()
+    }
+
     /// Push a new component onto the compositor.
     pub fn push_layer(&mut self, mut component: Box<dyn Component>) {
         self.callback = Some(Box::new(|compositor: &mut Compositor| {
@@ -631,7 +637,7 @@ pub fn select_all(cx: &mut Context) {
 }
 
 pub fn select_regex(cx: &mut Context) {
-    let prompt = ui::regex_prompt(cx, "select:".to_string(), move |view, doc, regex| {
+    let prompt = ui::regex_prompt(cx, "select:".to_string(), move |view, doc, _, regex| {
         let text = doc.text().slice(..);
         if let Some(selection) = selection::select_on_matches(text, doc.selection(view.id), &regex)
         {
@@ -643,7 +649,7 @@ pub fn select_regex(cx: &mut Context) {
 }
 
 pub fn split_selection(cx: &mut Context) {
-    let prompt = ui::regex_prompt(cx, "split:".to_string(), move |view, doc, regex| {
+    let prompt = ui::regex_prompt(cx, "split:".to_string(), move |view, doc, _, regex| {
         let text = doc.text().slice(..);
         let selection = selection::split_on_matches(text, doc.selection(view.id), &regex);
         doc.set_selection(view.id, selection);
@@ -714,20 +720,24 @@ pub fn search(cx: &mut Context) {
     let contents = doc.text().slice(..).to_string();
 
     let view_id = view.id;
-    let prompt = ui::regex_prompt(cx, "search:".to_string(), move |view, doc, regex| {
-        search_impl(doc, view, &contents, &regex, false);
-        // TODO: only store on enter (accept), not update
-        register::set('\\', vec![regex.as_str().to_string()]);
-    });
+    let prompt = ui::regex_prompt(
+        cx,
+        "search:".to_string(),
+        move |view, doc, registers, regex| {
+            search_impl(doc, view, &contents, &regex, false);
+            // TODO: only store on enter (accept), not update
+            registers.write('\\', vec![regex.as_str().to_string()]);
+        },
+    );
 
     cx.push_layer(Box::new(prompt));
 }
 // can't search next for ""compose"" for some reason
 
 pub fn search_next_impl(cx: &mut Context, extend: bool) {
-    if let Some(query) = register::get('\\') {
+    let (view, doc, registers) = cx.current_with_registers();
+    if let Some(query) = registers.read('\\') {
         let query = query.first().unwrap();
-        let (view, doc) = cx.current();
         let contents = doc.text().slice(..).to_string();
         let regex = Regex::new(query).unwrap();
         search_impl(doc, view, &contents, &regex, extend);
@@ -747,7 +757,7 @@ pub fn search_selection(cx: &mut Context) {
     let contents = doc.text().slice(..);
     let query = doc.selection(view.id).primary().fragment(contents);
     let regex = regex::escape(&query);
-    register::set('\\', vec![regex]);
+    cx.editor.registers.write('\\', vec![regex]);
     search_next(cx);
 }
 
@@ -794,7 +804,7 @@ pub fn extend_line(cx: &mut Context) {
 
 // heuristic: append changes to history after each command, unless we're in insert mode
 
-fn delete_selection_impl(reg: char, doc: &mut Document, view_id: ViewId) {
+fn delete_selection_impl(reg: &mut Register, doc: &mut Document, view_id: ViewId) {
     // first yank the selection
     let values: Vec<String> = doc
         .selection(view_id)
@@ -802,7 +812,7 @@ fn delete_selection_impl(reg: char, doc: &mut Document, view_id: ViewId) {
         .map(Cow::into_owned)
         .collect();
 
-    register::set(reg, values);
+    reg.write(values);
 
     // then delete
     let transaction =
@@ -815,8 +825,9 @@ fn delete_selection_impl(reg: char, doc: &mut Document, view_id: ViewId) {
 }
 
 pub fn delete_selection(cx: &mut Context) {
-    let reg = cx.register.name();
-    let (view, doc) = cx.current();
+    let reg_name = cx.selected_register.name();
+    let (view, doc, registers) = cx.current_with_registers();
+    let reg = registers.get_or_insert(reg_name);
     delete_selection_impl(reg, doc, view.id);
 
     doc.append_changes_to_history(view.id);
@@ -826,8 +837,9 @@ pub fn delete_selection(cx: &mut Context) {
 }
 
 pub fn change_selection(cx: &mut Context) {
-    let reg = cx.register.name();
-    let (view, doc) = cx.current();
+    let reg_name = cx.selected_register.name();
+    let (view, doc, registers) = cx.current_with_registers();
+    let reg = registers.get_or_insert(reg_name);
     delete_selection_impl(reg, doc, view.id);
     enter_insert_mode(doc);
 }
@@ -2227,10 +2239,12 @@ pub fn yank(cx: &mut Context) {
     let msg = format!(
         "yanked {} selection(s) to register {}",
         values.len(),
-        cx.register.name()
+        cx.selected_register.name()
     );
 
-    register::set(cx.register.name(), values);
+    cx.editor
+        .registers
+        .write(cx.selected_register.name(), values);
 
     cx.editor.set_status(msg)
 }
@@ -2241,47 +2255,48 @@ enum Paste {
     After,
 }
 
-fn paste_impl(reg: char, doc: &mut Document, view: &View, action: Paste) -> Option<Transaction> {
-    if let Some(values) = register::get(reg) {
-        let repeat = std::iter::repeat(
-            values
-                .last()
-                .map(|value| Tendril::from_slice(value))
-                .unwrap(),
-        );
+fn paste_impl(
+    values: &[String],
+    doc: &mut Document,
+    view: &View,
+    action: Paste,
+) -> Option<Transaction> {
+    let repeat = std::iter::repeat(
+        values
+            .last()
+            .map(|value| Tendril::from_slice(value))
+            .unwrap(),
+    );
 
-        // if any of values ends \n it's linewise paste
-        let linewise = values.iter().any(|value| value.ends_with('\n'));
+    // if any of values ends \n it's linewise paste
+    let linewise = values.iter().any(|value| value.ends_with('\n'));
 
-        let mut values = values.into_iter().map(Tendril::from).chain(repeat);
+    let mut values = values.iter().cloned().map(Tendril::from).chain(repeat);
 
-        let text = doc.text();
+    let text = doc.text();
 
-        let transaction =
-            Transaction::change_by_selection(doc.text(), doc.selection(view.id), |range| {
-                let pos = match (action, linewise) {
-                    // paste linewise before
-                    (Paste::Before, true) => text.line_to_char(text.char_to_line(range.from())),
-                    // paste linewise after
-                    (Paste::After, true) => text.line_to_char(text.char_to_line(range.to()) + 1),
-                    // paste insert
-                    (Paste::Before, false) => range.from(),
-                    // paste append
-                    (Paste::After, false) => range.to() + 1,
-                };
-                (pos, pos, Some(values.next().unwrap()))
-            });
-        return Some(transaction);
-    }
-    None
+    let transaction = Transaction::change_by_selection(text, doc.selection(view.id), |range| {
+        let pos = match (action, linewise) {
+            // paste linewise before
+            (Paste::Before, true) => text.line_to_char(text.char_to_line(range.from())),
+            // paste linewise after
+            (Paste::After, true) => text.line_to_char(text.char_to_line(range.to()) + 1),
+            // paste insert
+            (Paste::Before, false) => range.from(),
+            // paste append
+            (Paste::After, false) => range.to() + 1,
+        };
+        (pos, pos, Some(values.next().unwrap()))
+    });
+
+    Some(transaction)
 }
 
 pub fn replace_with_yanked(cx: &mut Context) {
-    let reg = cx.register.name();
-
-    if let Some(values) = register::get(reg) {
-        let (view, doc) = cx.current();
+    let reg_name = cx.selected_register.name();
+    let (view, doc, registers) = cx.current_with_registers();
 
+    if let Some(values) = registers.read(reg_name) {
         if let Some(yank) = values.first() {
             let transaction =
                 Transaction::change_by_selection(doc.text(), doc.selection(view.id), |range| {
@@ -2307,20 +2322,26 @@ pub fn replace_with_yanked(cx: &mut Context) {
 // default insert
 
 pub fn paste_after(cx: &mut Context) {
-    let reg = cx.register.name();
-    let (view, doc) = cx.current();
+    let reg_name = cx.selected_register.name();
+    let (view, doc, registers) = cx.current_with_registers();
 
-    if let Some(transaction) = paste_impl(reg, doc, view, Paste::After) {
+    if let Some(transaction) = registers
+        .read(reg_name)
+        .and_then(|values| paste_impl(values, doc, view, Paste::After))
+    {
         doc.apply(&transaction, view.id);
         doc.append_changes_to_history(view.id);
     }
 }
 
 pub fn paste_before(cx: &mut Context) {
-    let reg = cx.register.name();
-    let (view, doc) = cx.current();
+    let reg_name = cx.selected_register.name();
+    let (view, doc, registers) = cx.current_with_registers();
 
-    if let Some(transaction) = paste_impl(reg, doc, view, Paste::Before) {
+    if let Some(transaction) = registers
+        .read(reg_name)
+        .and_then(|values| paste_impl(values, doc, view, Paste::Before))
+    {
         doc.apply(&transaction, view.id);
         doc.append_changes_to_history(view.id);
     }
@@ -2494,7 +2515,7 @@ pub fn join_selections(cx: &mut Context) {
 
 pub fn keep_selections(cx: &mut Context) {
     // keep selections matching regex
-    let prompt = ui::regex_prompt(cx, "keep:".to_string(), move |view, doc, regex| {
+    let prompt = ui::regex_prompt(cx, "keep:".to_string(), move |view, doc, _, regex| {
         let text = doc.text().slice(..);
 
         if let Some(selection) = selection::keep_matches(text, doc.selection(view.id), &regex) {
@@ -2788,7 +2809,7 @@ pub fn select_register(cx: &mut Context) {
             ..
         } = event
         {
-            cx.editor.register.select(ch);
+            cx.editor.selected_register.select(ch);
         }
     })
 }
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 4b4b9fb2..5913df29 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -570,7 +570,7 @@ impl EditorView {
                 // debug_assert!(cxt.count != 0);
 
                 // set the register
-                cxt.register = cxt.editor.register.take();
+                cxt.selected_register = cxt.editor.selected_register.take();
 
                 if let Some(command) = self.keymap[&mode].get(&event) {
                     command(cxt);
@@ -610,7 +610,7 @@ impl Component for EditorView {
                 let mode = doc.mode();
 
                 let mut cxt = commands::Context {
-                    register: helix_view::RegisterSelection::default(),
+                    selected_register: helix_view::RegisterSelection::default(),
                     editor: &mut cx.editor,
                     count: None,
                     callback: None,
diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index 7e4464bc..77e53690 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -20,6 +20,7 @@ pub use tui::layout::Rect;
 pub use tui::style::{Color, Modifier, Style};
 
 use helix_core::regex::Regex;
+use helix_core::register::Registers;
 use helix_view::{Document, Editor, View};
 
 use std::path::{Path, PathBuf};
@@ -27,7 +28,7 @@ use std::path::{Path, PathBuf};
 pub fn regex_prompt(
     cx: &mut crate::commands::Context,
     prompt: String,
-    fun: impl Fn(&mut View, &mut Document, Regex) + 'static,
+    fun: impl Fn(&mut View, &mut Document, &mut Registers, Regex) + 'static,
 ) -> Prompt {
     let view_id = cx.view().id;
     let snapshot = cx.doc().selection(view_id).clone();
@@ -53,13 +54,13 @@ pub fn regex_prompt(
 
                     match Regex::new(input) {
                         Ok(regex) => {
-                            let (view, doc) = editor.current();
+                            let (view, doc, registers) = editor.current_with_registers();
 
                             // revert state to what it was before the last update
                             // TODO: also revert text
                             doc.set_selection(view.id, snapshot.clone());
 
-                            fun(view, doc, regex);
+                            fun(view, doc, registers, regex);
 
                             view.ensure_cursor_in_view(doc);
                         }
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index ef0d8213..2fd01817 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -8,13 +8,15 @@ use slotmap::SlotMap;
 use anyhow::Error;
 
 pub use helix_core::diagnostic::Severity;
+pub use helix_core::register::Registers;
 
 #[derive(Debug)]
 pub struct Editor {
     pub tree: Tree,
     pub documents: SlotMap<DocumentId, Document>,
     pub count: Option<std::num::NonZeroUsize>,
-    pub register: RegisterSelection,
+    pub selected_register: RegisterSelection,
+    pub registers: Registers,
     pub theme: Theme,
     pub language_servers: helix_lsp::Registry,
 
@@ -59,9 +61,10 @@ impl Editor {
             tree: Tree::new(area),
             documents: SlotMap::with_key(),
             count: None,
-            register: RegisterSelection::default(),
+            selected_register: RegisterSelection::default(),
             theme,
             language_servers,
+            registers: Registers::default(),
             status_msg: None,
         }
     }
@@ -239,6 +242,13 @@ impl Editor {
         (view, doc)
     }
 
+    pub fn current_with_registers(&mut self) -> (&mut View, &mut Document, &mut Registers) {
+        let view = self.tree.get_mut(self.tree.focus);
+        let doc = &mut self.documents[view.doc];
+        let registers = &mut self.registers;
+        (view, doc, registers)
+    }
+
     pub fn view(&self) -> &View {
         self.tree.get(self.tree.focus)
     }