Setup basic terminal output for Deno

src/common/ansi.ts

@@ -1,2 +1,15 @@
-export enum Ansi {
+function escape(suffix: string): string {
+	return `\x1b[${suffix}`;
 }
+
+function moveCursor(row: number, col: number): string {
+	return escape(`${row};${col}H`);
+}
+
+export const Ansi = {
+	ClearScreen: escape('2J'),
+	ResetCursor: escape('H'),
+	moveCursor,
+};
+
+export default Ansi;

src/common/editor.ts

@@ -1,6 +1,60 @@
-export class Editor {
+import { Ansi } from './ansi.ts';
+import { importForRuntime } from './runtime.ts';
+import { ctrl_key } from './strings.ts';
+
+class Buffer {
+	#b = '';
+
 	constructor() {
 	}
-	public processKeyPress(): void {
+
+	append(s: string): void {
+		this.#b += s;
+	}
+
+	clear(): void {
+		this.#b = '';
+	}
+
+	getBuffer(): string {
+		return this.#b;
+	}
+}
+
+export class Editor {
+	#buffer: Buffer;
+	constructor() {
+		this.#buffer = new Buffer();
+	}
+
+	/**
+	 * Determine what to do based on input
+	 * @param input - the decoded chunk of stdin
+	 */
+	public processKeyPress(input: string): boolean {
+		switch (input) {
+			case ctrl_key('q'):
+				this.clearScreen();
+				return false;
+
+			default:
+				return true;
+		}
+	}
+
+	/**
+	 * Clear the screen and write out the buffer
+	 */
+	public async refreshScreen(): Promise<void> {
+		const { write } = await importForRuntime('terminal_io');
+
+		this.clearScreen();
+		await write(this.#buffer.getBuffer());
+		this.#buffer.clear();
+	}
+
+	private clearScreen(): void {
+		this.#buffer.append(Ansi.ClearScreen);
+		this.#buffer.append(Ansi.ResetCursor);
 	}
 }

src/common/mod.ts

@@ -1,5 +1,5 @@
-import { importForRuntime } from "./runtime";
-import { ctrl_key, is_control } from "./strings";
+import { importForRuntime } from './runtime.ts';
+import { Editor } from './editor.ts';
 
 export * from './runtime.ts';
 export * from './strings.ts';
@@ -8,32 +8,29 @@ export type { ITestBase } from './test_base.ts';
 
 const decoder = new TextDecoder();
 
-export function readKey(chunk): string {
-	const char = String(decoder.decode(chunk))
-
-	return char;
-}
-
 export async function main() {
 	const { inputLoop, init } = await importForRuntime('mod.ts');
 
 	// Set up handlers to enable/disable raw mode for each runtime
 	await init();
 
+	// Create the editor itself
+	const editor = new Editor();
+
 	// The main event loop
 	for await (const chunk of inputLoop()) {
-		const char = readKey(chunk);
+		const char = String(decoder.decode(chunk));
 
-		if (char === ctrl_key('q')) {
+		// Clear the screen for output
+		await editor.refreshScreen();
+
+		// Process input
+		const shouldLoop = editor.processKeyPress(char);
+
+		if (!shouldLoop) {
 			return 0;
 		}
-
-		if (is_control(char)) {
-			console.log(char.codePointAt(0) + '\r');
-		} else {
-			console.log(`${char} ('${char.codePointAt(0)}')\r`);
-		}
 	}
 
 	return -1;
-}
+}

src/deno/mod.ts

@@ -1,7 +1,7 @@
 /**
  * The main entrypoint when using Deno as the runtime
  */
-import { getTermios } from "../common/mod.ts";
+import { getTermios } from '../common/mod.ts';
 
 export * from './terminal_io.ts';
 

src/deno/terminal_io.ts

@@ -6,3 +6,11 @@ export async function* inputLoop() {
 		yield chunk;
 	}
 }
+
+export async function write(s: string): Promise<void> {
+	const buffer = new TextEncoder().encode(s);
+
+	const stdout = Deno.stdout.writable.getWriter();
+	await stdout.write(buffer);
+	stdout.releaseLock();
+}