Set up basic ascii parsing and display

deno.jsonc

@@ -1,11 +1,9 @@
 {
-	"imports": {
-		"std": "https://deno.land/std@0.204.0/",
-	},
+	"exclude": ["src/bun/**/*.ts"],
 	"lint": {
 		"include": ["src/"],
 		"rules": {
-			"tags": ["recommended"],
+			"tags": ["recommended"]
 		}
 	},
 	"fmt": {
@@ -13,7 +11,7 @@
 		"lineWidth": 80,
 		"indentWidth": 2,
 		"semiColons": true,
-		"singleQuote": true,
+		"singleQuote": true
 	},
-	"nodeModulesDir": true,
-}
+	"nodeModulesDir": true
+}

justfile

@@ -2,12 +2,17 @@
 default:
 	@just --list
 
-# Code linting with deno
+# Typescript checking
+check:
+	deno check --unstable  --all -c deno.jsonc ./src/deno/*.ts ./src/common/*.ts
+
+# Code linting
 deno-lint:
 	deno lint
 
-# Code linting with bun
-bun-lint:
+# Reformat the code
+fmt:
+	deno fmt
 
 # Run with bun
 bun-run:
@@ -15,4 +20,7 @@ bun-run:
 
 # Run with deno
 deno-run:
-	deno run --allow-all --allow-ffi --deny-net --deny-hrtime --unstable ./src/scroll.ts
+	deno run --allow-all --allow-ffi --deny-net --deny-hrtime --unstable ./src/scroll.ts
+
+deno-test:
+	deno test --allow-all

src/bun/index.ts

@@ -3,6 +3,7 @@
  */
 
 import { getTermios } from '../common/termios';
+import {ctrl_key, is_control} from "../common/strings";
 
 export async function main(): Promise<number> {
 	const t = await getTermios();
@@ -10,12 +11,19 @@ export async function main(): Promise<number> {
 
 	const decoder = new TextDecoder();
 	for await (const chunk of Bun.stdin.stream()) {
-		const char = String(decoder.decode(chunk)).trim();
+		const char = String(decoder.decode(chunk));
 
-		if (char === 'q') {
+		if (char === ctrl_key('q')) {
 			t.disableRawMode();
 			return 0;
 		}
+
+		if (is_control(char)) {
+			console.log(char.codePointAt(0) + '\r');
+		} else {
+			console.log(`${char} ('${char.codePointAt(0)}')\r`);
+		}
+
 	}
 
 	process.on('exit', (code) => {
@@ -24,4 +32,4 @@ export async function main(): Promise<number> {
 	});
 
 	return -1;
-}
+}

src/common/index.ts

@@ -1,9 +1,16 @@
+import { getTermios } from './termios.ts';
+
 export enum RunTime {
 	Bun = 'bun',
 	Deno = 'deno',
 	Unknown = 'common',
 }
 
+export function die(s: string): void {
+	getTermios().then((t) => t.disableRawMode());
+	console.error(s);
+}
+
 /**
  * Determine which Typescript runtime we are operating under
  */

src/common/strings.ts

@@ -0,0 +1,60 @@
+/**
+ * Split a string by graphemes, not just bytes
+ * @param s - the string to split into 'characters'
+ */
+export function chars(s: string): string[] {
+	return s.split(/(?:)/u);
+}
+
+/**
+ * Is the character part of ascii?
+ *
+ * @param char - a one character string to check
+ */
+export function is_ascii(char: string): boolean {
+	if (typeof char !== 'string') {
+		return false;
+	}
+
+	return chars(char).every((char) => {
+		const point = char.codePointAt(0);
+		if (typeof point === 'undefined') {
+			return false;
+		}
+
+		return point < 0x80;
+	});
+}
+
+/**
+ * Is the one char in the string an ascii control character?
+ *
+ * @param char - a one character string to check
+ */
+export function is_control(char: string): boolean {
+	const code = char.codePointAt(0);
+	if (code === undefined) {
+		return false;
+	}
+
+	return is_ascii(char) && (code === 0x7f || code < 0x20);
+}
+
+/**
+ * Get the key code for a ctrl chord
+ * @param char - a one character string
+ */
+export function ctrl_key(char: string): string {
+	// This is the normal use case, of course
+	if (is_ascii(char)) {
+		const point = char.codePointAt(0);
+		if (point === undefined) {
+			return char;
+		}
+
+		return String.fromCodePoint(point & 0x1f);
+	}
+
+	// If it's not ascii, just return the input key code
+	return char;
+}

src/common/strings_test.ts

@@ -0,0 +1,8 @@
+import { importForRuntime } from './index.ts';
+import { chars } from './strings.ts';
+
+const { test, assertEquals } = await importForRuntime('test_base');
+
+test('chars fn properly splits strings into unicode characters', () => {
+	assertEquals(chars('😺😸😹'), ['😺', '😸', '😹']);
+});

src/common/termios.ts

@@ -1,4 +1,4 @@
-import { importForRuntime } from './index.ts';
+import { die, importForRuntime } from './index.ts';
 
 export const STDIN_FILENO = 0;
 export const STOUT_FILENO = 1;
@@ -27,7 +27,13 @@ export interface ITermios {
 	disableRawMode(): void;
 }
 
+let termiosSingleton: ITermios | null = null;
+
 export const getTermios = async () => {
+	if (termiosSingleton !== null) {
+		return termiosSingleton;
+	}
+
 	// Get the runtime-specific ffi wrappers
 	const { tcgetattr, tcsetattr, cfmakeraw, getPointer } =
 		await importForRuntime('ffi');
@@ -81,18 +87,30 @@ export const getTermios = async () => {
 			}
 
 			// Get the current termios settings
-			tcgetattr(STDIN_FILENO, this.#ptr);
+			let res = tcgetattr(STDIN_FILENO, this.#ptr);
+			if (res === -1) {
+				die('Failed to get terminal settings');
+			}
 
 			// The #ptr property is pointing to the #termios TypedArray. As the pointer
 			// is manipulated, the TypedArray is as well. We will use this to save
 			// the original canonical/cooked terminal settings for disabling raw mode later.
 			this.#cookedTermios = new Uint8Array(this.#termios, 0, 60);
 
-			// Update termios struct with raw settings
-			cfmakeraw(this.#ptr);
+			// Update termios struct with (most of the) raw settings
+			res = cfmakeraw(this.#ptr);
+			if (res === -1) {
+				die('Failed to call cfmakeraw');
+			}
+
+			// @TODO: Tweak a few more terminal settings
 
 			// Actually set the new termios settings
-			tcsetattr(STDIN_FILENO, TCSANOW, this.#ptr);
+			res = tcsetattr(STDIN_FILENO, TCSANOW, this.#ptr);
+			if (res === -1) {
+				die('Failed to update terminal settings. Can\'t enter raw mode');
+			}
+
 			this.#inRawMode = true;
 		}
 
@@ -104,11 +122,16 @@ export const getTermios = async () => {
 			}
 
 			const oldTermiosPtr = getPointer(this.#cookedTermios);
-			tcsetattr(STDIN_FILENO, TCSANOW, oldTermiosPtr);
+			let res = tcsetattr(STDIN_FILENO, TCSANOW, oldTermiosPtr);
+			if (res === -1) {
+				die('Failed to restore canonical mode.');
+			}
 
 			this.#inRawMode = false;
 		}
 	}
 
-	return new Termios();
+	termiosSingleton = new Termios();
+
+	return termiosSingleton;
 };

src/deno/index.ts

@@ -2,6 +2,7 @@
  * The main entrypoint when using Deno as the runtime
  */
 import { getTermios } from '../common/termios.ts';
+import { ctrl_key, is_control } from '../common/strings.ts';
 
 export async function main(): Promise<number> {
 	const t = await getTermios();
@@ -9,12 +10,18 @@ export async function main(): Promise<number> {
 
 	const decoder = new TextDecoder();
 	for await (const chunk of Deno.stdin.readable) {
-		const char = String(decoder.decode(chunk)).trim();
+		const char = String(decoder.decode(chunk));
 
-		if (char === 'q') {
+		if (char === ctrl_key('q')) {
 			t.disableRawMode();
 			return 0;
 		}
+
+		if (is_control(char)) {
+			console.log(char.codePointAt(0) + '\r');
+		} else {
+			console.log(`${char} ('${char.codePointAt(0)}')\r`);
+		}
 	}
 
 	return -1;

src/deno/test_base.ts

@@ -0,0 +1,7 @@
+export const test = Deno.test;
+export {
+	assert,
+	assertEquals,
+	assertNotEquals,
+	assertStrictEquals,
+} from 'https://deno.land/std/assert/mod.ts';