Move the cursor

justfile

@@ -50,7 +50,7 @@ deno-test:
 # Create test coverage report with deno
 deno-coverage:
 	deno test --allow-all --coverage=.deno-cover
-	deno coverage --lcov .deno-cover
+	deno coverage --unstable-ffi .deno-cover
 
 # Run with deno
 deno-run:

src/common/editor/ansi.ts

@@ -9,7 +9,7 @@ export const Ansi = {
 	HideCursor: esc`?25l`,
 	ShowCursor: esc`?25h`,
 	moveCursor: function moveCursor(row: number, col: number): string {
-		return `\x1b${row};${col}H`;
+		return `\x1b[${row};${col}H`;
 	},
 };
 

src/common/editor/editor.ts

@@ -3,6 +3,7 @@ import Buffer from './buffer.ts';
 import {
 	ctrl_key,
 	importDefaultForRuntime,
+	IPoint,
 	ITerminalSize,
 	truncate,
 	VERSION,
@@ -10,14 +11,21 @@ import {
 
 export class Editor {
 	#buffer: Buffer;
-	#screenRows: number;
-	#screenCols: number;
+	#screen: ITerminalSize;
+	#cursor: IPoint;
 	constructor(terminalSize: ITerminalSize) {
 		this.#buffer = new Buffer();
-		this.#screenRows = terminalSize.rows;
-		this.#screenCols = terminalSize.cols;
+		this.#screen = terminalSize;
+		this.#cursor = {
+			x: 0,
+			y: 0,
+		};
 	}
 
+	// --------------------------------------------------------------------------
+	// Command/input mapping
+	// --------------------------------------------------------------------------
+
 	/**
 	 * Determine what to do based on input
 	 * @param input - the decoded chunk of stdin
@@ -28,14 +36,37 @@ export class Editor {
 				this.clearScreen().then(() => {});
 				return false;
 
-			default:
-				return true;
+			case 'w':
+			case 's':
+			case 'a':
+			case 'd':
+					this.moveCursor(input);
+					break;
+		}
+
+		return true;
+	}
+
+	private moveCursor(char: string): void {
+		switch (char) {
+			case 'a':
+				this.#cursor.x--;
+				break;
+			case 'd':
+				this.#cursor.x++;
+				break;
+			case 'w':
+				this.#cursor.y--;
+				break;
+			case 's':
+				this.#cursor.y++;
+				break;
 		}
 	}
 
-	// -------------------------------------------------------------------------------------------------------------------
+	// --------------------------------------------------------------------------
 	// Terminal Output / Drawing
-	// -------------------------------------------------------------------------------------------------------------------
+	// --------------------------------------------------------------------------
 
 	/**
 	 * Clear the screen and write out the buffer
@@ -44,6 +75,9 @@ export class Editor {
 		this.#buffer.append(Ansi.HideCursor);
 		this.#buffer.append(Ansi.ResetCursor);
 		this.drawRows();
+		this.#buffer.append(
+			Ansi.moveCursor(this.#cursor.y + 1, this.#cursor.x + 1),
+		);
 		this.#buffer.append(Ansi.ShowCursor);
 
 		await this.writeToScreen();
@@ -61,11 +95,13 @@ export class Editor {
 	}
 
 	private drawPlaceholderRows(): void {
-		for (let y = 0; y < this.#screenRows; y++) {
-			if (y === Math.trunc(this.#screenRows / 2)) {
+		for (let y = 0; y < this.#screen.rows; y++) {
+			if (y === Math.trunc(this.#screen.rows / 2)) {
 				const message = `Kilo editor -- version ${VERSION}`;
-				const messageLen = (message.length > this.#screenCols) ? this.#screenCols : message.length;
-				let padding = Math.trunc((this.#screenCols - messageLen) / 2);
+				const messageLen = (message.length > this.#screen.cols)
+					? this.#screen.cols
+					: message.length;
+				let padding = Math.trunc((this.#screen.cols - messageLen) / 2);
 				if (padding > 0) {
 					this.#buffer.append('~');
 					padding -= 1;
@@ -79,7 +115,7 @@ export class Editor {
 			}
 
 			this.#buffer.append(Ansi.ClearLine);
-			if (y < this.#screenRows - 1) {
+			if (y < this.#screen.rows - 1) {
 				this.#buffer.appendLine('');
 			}
 		}

src/common/types.ts

@@ -1,17 +1,15 @@
-/**
- * The shared test interface, so tests can be run by both runtimes
- */
-export interface ITestBase {
-	test(name: string, fn: () => void): void;
-	assertEquals(actual: unknown, expected: unknown): void;
-	assertNotEquals(actual: unknown, expected: unknown): void;
-	assertStrictEquals(actual: unknown, expected: unknown): void;
-	assertExists(actual: unknown): void;
-	assertInstanceOf(actual: unknown, expectedType: any): void;
-	assertTrue(actual: boolean): void;
-	assertFalse(actual: boolean): void;
+// ----------------------------------------------------------------------------
+// General types
+// ----------------------------------------------------------------------------
+
+export interface IPoint {
+	x: number;
+	y: number;
 }
 
+// ----------------------------------------------------------------------------
+// Runtime adapter interfaces
+// ----------------------------------------------------------------------------
 /**
  * The native functions for terminal settings
  */
@@ -69,3 +67,21 @@ export interface IRuntime {
 	 */
 	onExit(cb: () => void): void;
 }
+
+// ----------------------------------------------------------------------------
+// Testing
+// ----------------------------------------------------------------------------
+
+/**
+ * The shared test interface, so tests can be run by both runtimes
+ */
+export interface ITestBase {
+	test(name: string, fn: () => void): void;
+	assertEquals(actual: unknown, expected: unknown): void;
+	assertNotEquals(actual: unknown, expected: unknown): void;
+	assertStrictEquals(actual: unknown, expected: unknown): void;
+	assertExists(actual: unknown): void;
+	assertInstanceOf(actual: unknown, expectedType: any): void;
+	assertTrue(actual: boolean): void;
+	assertFalse(actual: boolean): void;
+}

src/common/utils.ts

@@ -1,6 +1,6 @@
-// ---------------------------------------------------------------------------------------------------------------------
+// ----------------------------------------------------------------------------
 // Strings
-// ---------------------------------------------------------------------------------------------------------------------
+// ----------------------------------------------------------------------------
 
 /**
  * Split a string by graphemes, not just bytes