Patch line cursor

Ensure cursor loops back as well as forward.
Remove stack connection positions.

Author: microbit-robert

src/line_cursor_patch.ts

@@ -0,0 +1,129 @@
+/**
+ * @license
+ * Copyright 2021 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as Blockly from 'blockly/core';
+
+export const applyLineCursorPatch = () => {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  (Blockly.LineCursor.prototype as any).getLastNode = function (
+    isValid: (p1: Blockly.ASTNode | null) => boolean,
+  ): Blockly.ASTNode | null {
+    // Loop back to last block if it exists.
+    const topBlocks = this.workspace.getTopBlocks(true);
+    if (!topBlocks.length) return null;
+
+    // Find the last stack.
+    const lastTopBlockNode = Blockly.ASTNode.createStackNode(
+      topBlocks[topBlocks.length - 1],
+    );
+    let prevNode = lastTopBlockNode;
+    let nextNode: Blockly.ASTNode | null = lastTopBlockNode;
+    // Iterate until you fall off the end of the stack.
+    while (nextNode) {
+      prevNode = nextNode;
+      nextNode = this.getNextNode(prevNode, isValid, false);
+    }
+    return prevNode;
+  };
+
+  Blockly.LineCursor.prototype.prev = function (): Blockly.ASTNode | null {
+    const curNode = this.getCurNode();
+    if (!curNode) {
+      return null;
+    }
+    const newNode = this.getPreviousNode(
+      curNode,
+      // @ts-expect-error accessing private method
+      this.validLineNode.bind(this),
+      true,
+    );
+    if (newNode) {
+      this.setCurNode(newNode);
+    }
+    return newNode;
+  };
+
+  Blockly.LineCursor.prototype.out = function (): Blockly.ASTNode | null {
+    const curNode = this.getCurNode();
+    if (!curNode) {
+      return null;
+    }
+    const newNode = this.getPreviousNode(
+      curNode,
+      // @ts-expect-error accessing private method
+      this.validInLineNode.bind(this),
+      true,
+    );
+
+    if (newNode) {
+      this.setCurNode(newNode);
+    }
+    return newNode;
+  };
+
+  Blockly.LineCursor.prototype.getPreviousNode = function (
+    node: Blockly.ASTNode | null,
+    isValid: (p1: Blockly.ASTNode | null) => boolean,
+    loop: boolean,
+  ): Blockly.ASTNode | null {
+    if (!node) return null;
+    // @ts-expect-error accessing private method
+    const potential = this.getPreviousNodeImpl(node, isValid);
+    if (potential || !loop) return potential;
+    // Loop back.
+    // @ts-expect-error passing unexpected arg
+    const lastNode = this.getLastNode(isValid);
+    if (isValid(lastNode)) return lastNode;
+    // @ts-expect-error accessing private method
+    return this.getPreviousNodeImpl(lastNode, isValid);
+  };
+
+  // @ts-expect-error accessing protected method
+  Blockly.LineCursor.prototype.validLineNode = function (
+    node: Blockly.ASTNode | null,
+  ): boolean {
+    if (!node) return false;
+    const location = node.getLocation();
+    const type = node && node.getType();
+    switch (type) {
+      case Blockly.ASTNode.types.BLOCK:
+        return !(location as Blockly.Block).outputConnection?.isConnected();
+      default:
+        return false;
+    }
+  };
+
+  // @ts-expect-error accessing protected method
+  Blockly.LineCursor.prototype.validInLineNode = function (
+    node: Blockly.ASTNode | null,
+  ): boolean {
+    if (!node) return false;
+    // @ts-expect-error accessing private method
+    if (this.validLineNode(node)) return true;
+    const location = node.getLocation();
+    const type = node && node.getType();
+    switch (type) {
+      case Blockly.ASTNode.types.BLOCK:
+        return true;
+      case Blockly.ASTNode.types.INPUT: {
+        const connection = location as Blockly.Connection;
+        return (
+          connection.type !== Blockly.ConnectionType.NEXT_STATEMENT &&
+          connection.type !== Blockly.ConnectionType.PREVIOUS_STATEMENT &&
+          !connection.isConnected()
+        );
+      }
+      case Blockly.ASTNode.types.FIELD: {
+        const field = node.getLocation() as Blockly.Field;
+        return !(
+          field.getSourceBlock()?.isSimpleReporter() && field.isFullBlockField()
+        );
+      }
+      default:
+        return false;
+    }
+  };
+};

src/navigation_controller.ts

@@ -37,6 +37,9 @@ import {ActionMenu} from './actions/action_menu';
 import {MoveActions} from './actions/move';
 import {Mover} from './actions/mover';
 import {UndoRedoAction} from './actions/undo_redo';
+import {applyLineCursorPatch} from './line_cursor_patch';
+
+applyLineCursorPatch();
 
 const KeyCodes = BlocklyUtils.KeyCodes;