Implement the next/previous editor commands and keybindings

src/Model/EditorGroup.re

@@ -61,16 +61,23 @@ let getOrCreateEditorForBuffer = (state, bufferId) => {
   };
 };
 
-// TODO: Just use List.find_opt?
 let rec _getIndexOfElement = elem =>
   fun
-  | [] => (-1)
-  | [hd, ...tl] => hd === elem ? 0 : _getIndexOfElement(elem, tl) + 1;
+  | [] => None
+  | [hd, ...tl] =>
+    hd === elem
+      ? Some(0)
+      : (
+        switch (_getIndexOfElement(elem, tl)) {
+        | None => None
+        | Some(i) => Some(i + 1)
+        }
+      );
 
 let _getAdjacentEditor = (editor: int, reverseTabOrder: list(int)) => {
   switch (_getIndexOfElement(editor, reverseTabOrder)) {
-  | (-1) => None
-  | idx =>
+  | None => None
+  | Some(idx) =>
     switch (
       List.nth_opt(reverseTabOrder, idx + 1),
       List.nth_opt(reverseTabOrder, max(idx - 1, 0)),
@@ -82,6 +89,48 @@ let _getAdjacentEditor = (editor: int, reverseTabOrder: list(int)) => {
   };
 };
 
+let setActiveEditorTo = (kind, model) =>
+  switch (model.reverseTabOrder) {
+  | []
+  | [_] => model
+  | _ =>
+    switch (model.activeEditorId) {
+    | Some(activeEditorId) =>
+      switch (_getIndexOfElement(activeEditorId, model.reverseTabOrder)) {
+      | None => model
+      | Some(idx) =>
+        // The diff amounts are inverted because the list is in reverse order
+        let newIndex =
+          switch (kind) {
+          | `Next => idx - 1
+          | `Previous => idx + 1
+          };
+
+        let count = List.length(model.reverseTabOrder);
+
+        let newIndex =
+          if (newIndex < 0) {
+            // Wrapping negative, go to end
+            count - 1;
+          } else if (newIndex >= count) {
+            0;
+            // If this is past the end, go to zero
+          } else {
+            newIndex;
+          };
+
+        {
+          ...model,
+          activeEditorId: List.nth_opt(model.reverseTabOrder, newIndex),
+        };
+      }
+    | None => model
+    }
+  };
+
+let nextEditor = setActiveEditorTo(`Next);
+let previousEditor = setActiveEditorTo(`Previous);
+
 let isEmpty = model => IntMap.is_empty(model.editors);
 
 let removeEditorById = (state, editorId) => {

src/Model/EditorGroup.rei

@@ -17,6 +17,8 @@ let getActiveEditor: t => option(Feature_Editor.Editor.t);
 let setActiveEditor: (t, int) => t;
 let getEditorById: (int, t) => option(Feature_Editor.Editor.t);
 let getOrCreateEditorForBuffer: (t, int) => (t, Feature_Editor.EditorId.t);
+let nextEditor: t => t;
+let previousEditor: t => t;
 let removeEditorById: (t, int) => t;
 
 let isEmpty: t => bool;

src/Model/EditorGroupReducer.re

@@ -24,6 +24,9 @@ let reduce = (v: EditorGroup.t, action: Actions.t) => {
     let (newState, activeEditorId) =
       EditorGroup.getOrCreateEditorForBuffer(v, id);
     {...newState, activeEditorId: Some(activeEditorId)};
+  | Command("workbench.action.nextEditor") => EditorGroup.nextEditor(v)
+  | Command("workbench.action.previousEditor") =>
+    EditorGroup.previousEditor(v)
   | ViewCloseEditor(id) => EditorGroup.removeEditorById(v, id)
   | ViewSetActiveEditor(id) =>
     switch (IntMap.find_opt(id, v.editors)) {

src/Store/CommandStoreConnector.re

@@ -45,6 +45,18 @@ let createDefaultCommands = getState => {
         ~action=Command("view.closeEditor"),
         (),
       ),
+      Command.create(
+        ~category=Some("View"),
+        ~name="Open Next Editor",
+        ~action=Command("workbench.action.nextEditor"),
+        (),
+      ),
+      Command.create(
+        ~category=Some("View"),
+        ~name="Open Previous Editor",
+        ~action=Command("workbench.action.previousEditor"),
+        (),
+      ),
       Command.create(
         ~category=Some("View"),
         ~name="Toggle Problems (Errors, Warnings)",

src/Store/KeyBindingsStoreConnector.re

@@ -204,6 +204,26 @@ let start = () => {
         command: "view.closeEditor",
         condition: WhenExpr.Value(True),
       },
+      {
+        key: "<C-PAGEDOWN>",
+        command: "workbench.action.nextEditor",
+        condition: WhenExpr.Value(True),
+      },
+      {
+        key: "<D-S-]>",
+        command: "workbench.action.nextEditor",
+        condition: WhenExpr.Value(True),
+      },
+      {
+        key: "<C-PAGEUP>",
+        command: "workbench.action.previousEditor",
+        condition: WhenExpr.Value(True),
+      },
+      {
+        key: "<D-S-[>",
+        command: "workbench.action.previousEditor",
+        condition: WhenExpr.Value(True),
+      },
     ];
 
   let reloadConfigOnWritePost = (~configPath, dispatch) => {

src/Store/VimStoreConnector.re

@@ -904,6 +904,14 @@ let start =
       )
     | ViewSetActiveEditor(_) => (state, synchronizeEditorEffect(state))
     | ViewCloseEditor(_) => (state, synchronizeEditorEffect(state))
+    | Command("workbench.action.nextEditor") => (
+        state,
+        synchronizeEditorEffect(state),
+      )
+    | Command("workbench.action.previousEditor") => (
+        state,
+        synchronizeEditorEffect(state),
+      )
     | KeyboardInput(s) => (state, inputEffect(s))
     | CopyActiveFilepathToClipboard => (
         state,