Implement methods to get current console size

src/bun/terminal_io.ts

@@ -1,7 +1,7 @@
 /**
  * Wrap the runtime-specific hook into stdin
  */
-import { ITerminalIO } from '../common/mod.ts';
+import { ITerminalIO, ITerminalSize } from '../common/mod.ts';
 
 export async function* inputLoop() {
 	for await (const chunk of Bun.stdin.stream()) {
@@ -15,8 +15,20 @@ export async function write(s: string): Promise<void> {
 	await Bun.write(Bun.stdout, buffer);
 }
 
+export function getSize(): ITerminalSize {
+	// @TODO implement
+	// Check for tput
+	// If has tput, use it to get terminal size
+	// If not, try FFI fallback
+	// Otherwise, return 80x25 as a last resort
+	const fallback: ITerminalSize = { rows: 25, cols: 80 };
+
+	return fallback;
+}
+
 const BunTerminalIO: ITerminalIO = {
 	inputLoop,
+	getSize,
 	write,
 };
 

src/common/ansi.ts

@@ -1,15 +1,13 @@
-function escape(suffix: string): string {
-	return `\x1b[${suffix}`;
-}
-
-function moveCursor(row: number, col: number): string {
-	return escape(`${row};${col}H`);
+function esc(pieces: TemplateStringsArray): string {
+	return '\x1b[' + pieces[0];
 }
 
 export const Ansi = {
-	ClearScreen: escape('2J'),
-	ResetCursor: escape('H'),
-	moveCursor,
+	ClearScreen: esc`2J`,
+	ResetCursor: esc`H`,
+	moveCursor: function moveCursor(row: number, col: number): string {
+		return `\x1b${row};${col}H`;
+	},
 };
 
 export default Ansi;

src/common/editor.ts

@@ -12,6 +12,10 @@ class Buffer {
 		this.#b += s;
 	}
 
+	appendLine(s: string): void {
+		this.#b += s + '\r\n';
+	}
+
 	clear(): void {
 		this.#b = '';
 	}
@@ -49,10 +53,18 @@ export class Editor {
 		const { write } = await importForRuntime('terminal_io');
 
 		this.clearScreen();
+		this.drawRows();
+
 		await write(this.#buffer.getBuffer());
 		this.#buffer.clear();
 	}
 
+	private drawRows(): void {
+		for (let y = 0; y <= 24; y++) {
+			this.#buffer.appendLine('~');
+		}
+	}
+
 	private clearScreen(): void {
 		this.#buffer.append(Ansi.ClearScreen);
 		this.#buffer.append(Ansi.ResetCursor);

src/common/mod.ts

@@ -1,41 +1,3 @@
-import { importForRuntime } from './runtime.ts';
-import { Editor } from './editor.ts';
-import { getTermios } from './termios.ts';
-
 export * from './runtime.ts';
 export * from './strings.ts';
 export type * from './types.ts';
-
-const decoder = new TextDecoder();
-
-export async function main() {
-	const { inputLoop, onExit } = await importForRuntime('mod.ts');
-
-	// Setup raw mode, and tear down on error or normal exit
-	const t = await getTermios();
-	t.enableRawMode();
-	onExit(() => {
-		console.info('Exit handler called, disabling raw mode');
-		t.disableRawMode();
-	});
-
-	// Create the editor itself
-	const editor = new Editor();
-
-	// The main event loop
-	for await (const chunk of inputLoop()) {
-		const char = String(decoder.decode(chunk));
-
-		// Clear the screen for output
-		await editor.refreshScreen();
-
-		// Process input
-		const shouldLoop = editor.processKeyPress(char);
-
-		if (!shouldLoop) {
-			return 0;
-		}
-	}
-
-	return -1;
-}

src/common/types.ts

@@ -37,6 +37,11 @@ export interface IFFI {
 	getPointer(ta: any): unknown;
 }
 
+export interface ITerminalSize {
+	rows: number;
+	cols: number;
+}
+
 /**
  * Runtime-specific IO streams
  */
@@ -46,6 +51,11 @@ export interface ITerminalIO {
 	 */
 	inputLoop(): AsyncGenerator<Uint8Array, void, unknown>;
 
+	/**
+	 * Get the size of the terminal
+	 */
+	getSize(): ITerminalSize;
+
 	/**
 	 * Pipe a string to stdout
 	 */

src/deno/terminal_io.ts

@@ -1,4 +1,4 @@
-import { ITerminalIO } from '../common/types.ts';
+import { ITerminalIO, ITerminalSize } from '../common/types.ts';
 
 /**
  * Wrap the runtime-specific hook into stdin
@@ -17,8 +17,18 @@ export async function write(s: string): Promise<void> {
 	stdout.releaseLock();
 }
 
+export function getSize(): ITerminalSize {
+	const size: { rows: number; columns: number } = Deno.consoleSize();
+
+	return {
+		rows: size.rows,
+		cols: size.columns,
+	};
+}
+
 const DenoTerminalIO: ITerminalIO = {
 	inputLoop,
+	getSize,
 	write,
 };
 

src/scroll.ts

@@ -1,7 +1,43 @@
 /**
  * The starting point for running scroll
  */
-import { main } from './common/mod.ts';
+import { importForRuntime } from './common/mod.ts';
+import { getTermios } from './common/termios.ts';
+import { Editor } from './common/editor.ts';
+
+const decoder = new TextDecoder();
+
+export async function main() {
+	const { inputLoop, onExit } = await importForRuntime('mod.ts');
+
+	// Setup raw mode, and tear down on error or normal exit
+	const t = await getTermios();
+	t.enableRawMode();
+	onExit(() => {
+		console.info('Exit handler called, disabling raw mode');
+		t.disableRawMode();
+	});
+
+	// Create the editor itself
+	const editor = new Editor();
+
+	// The main event loop
+	for await (const chunk of inputLoop()) {
+		const char = String(decoder.decode(chunk));
+
+		// Clear the screen for output
+		await editor.refreshScreen();
+
+		// Process input
+		const shouldLoop = editor.processKeyPress(char);
+
+		if (!shouldLoop) {
+			return 0;
+		}
+	}
+
+	return -1;
+}
 
 /**
  * Start the event loop