Get raw mode working in Deno

deno.jsonc

@@ -1,7 +1,6 @@
 {
 	"imports": {
 		"std": "https://deno.land/std@0.204.0/",
-		// "/": "./src/",
 	},
 	"lint": {
 		"include": ["src/"],

src/common/index.ts

@@ -0,0 +1,44 @@
+export enum RunTime {
+	Bun = 'bun',
+	Deno = 'deno',
+	Unknown = 'common',
+}
+
+/**
+ * Determine which Typescript runtime we are operating under
+ */
+export const getRuntime = (): RunTime => {
+	let runtime = RunTime.Unknown;
+
+	if ('Deno' in globalThis) {
+		runtime = RunTime.Deno;
+	}
+	if ('Bun' in globalThis) {
+		runtime = RunTime.Bun;
+	}
+
+	return runtime;
+};
+
+/**
+ * Import a runtime-specific module
+ *
+ * eg. to load "src/bun/index.ts", if the runtime is bun,
+ * you can use like so `await importForRuntime('index')`;
+ *
+ * @param path - the path within the runtime module
+ */
+export const importForRuntime = async (path: string) => {
+	const runtime = getRuntime();
+	const suffix = (runtime === RunTime.Deno) ? '.ts' : '';
+	const base = `../${runtime}/`;
+
+	const pathParts = path.split('/')
+		.filter((part) => part !== '' && part !== '.' && part !== suffix)
+		.map((part) => part.replace(suffix, ''));
+
+	const cleanedPath = pathParts.join('/');
+	const importPath = base + cleanedPath + suffix;
+
+	return await import(importPath);
+}

src/deno/ffi.ts

@@ -0,0 +1,41 @@
+// Deno-specific ffi code
+
+// Determine library extension based on
+// your OS.
+// import { termiosStruct } from "../common/termios.ts";
+
+let libSuffix = '';
+switch (Deno.build.os) {
+	case 'windows':
+		libSuffix = 'dll';
+		break;
+	case 'darwin':
+		libSuffix = 'dylib';
+		break;
+	default:
+		libSuffix = 'so.6';
+		break;
+}
+
+const cSharedLib = `libc.${libSuffix}`;
+const cStdLib = Deno.dlopen(
+	cSharedLib,
+	{
+		tcgetattr: {
+			parameters: ['i32', 'pointer'],
+			result: 'i32',
+		},
+		tcsetattr: {
+			parameters: ['i32', 'i32', 'pointer'],
+			result: 'i32',
+		},
+		cfmakeraw: {
+			parameters: ['pointer'],
+			result: 'void',
+		},
+	} as const,
+);
+
+export const { tcgetattr, tcsetattr, cfmakeraw} = cStdLib.symbols;
+
+export const getPointer = Deno.UnsafePointer.of;

src/deno/index.ts

@@ -1,12 +1,18 @@
 /**
  * The main entrypoint when using Deno as the runtime
  */
+import { Termios } from './termios.ts'
+
 export async function main(): Promise<number> {
+	const t = new Termios();
+	t.enableRawMode();
+
 	const decoder = new TextDecoder();
 	for await (const chunk of Deno.stdin.readable) {
 		const char = String(decoder.decode(chunk)).trim();
 
 		if (char === 'q') {
+			t.disableRawMode();
 			return 0;
 		}
 	}

src/deno/termios.ts

@@ -1,42 +1,81 @@
-// Deno-specific ffi code
+import { STDIN_FILENO, TCSANOW, ITermios, TERMIOS_SIZE } from "../common/termios.ts";
+import { cfmakeraw, tcgetattr, tcsetattr, getPointer } from "./ffi.ts";
 
-// Determine library extension based on
-// your OS.
-// import { termiosStruct } from "../common/termios.ts";
+/**
+ * Implementation to toggle raw mode with Deno runtime
+ */
+export class Termios implements ITermios {
+	/**
+	 * Are we in raw mode?
+	 * @private
+	 */
+	#inRawMode:boolean;
 
-let libSuffix = '';
-switch (Deno.build.os) {
-	case 'windows':
-		libSuffix = 'dll';
-		break;
-	case 'darwin':
-		libSuffix = 'dylib';
-		break;
-	default:
-		libSuffix = 'so.6';
-		break;
+	/**
+	 * The saved version of the termios struct for cooked/canonical mode
+	 * @private
+	 */
+	#cookedTermios: Uint8Array;
+
+	/**
+	 * The data for the termios struct we are manipulating
+	 * @private
+	 */
+	#termios: Uint8Array;
+
+	/**
+	 * The pointer to the termios struct
+	 * @private
+	 */
+	#ptr: any;
+
+	constructor() {
+		this.#inRawMode = false;
+
+		// These are the TypedArrays linked to the raw pointer data
+		this.#cookedTermios = new Uint8Array(TERMIOS_SIZE);
+		this.#termios = new Uint8Array(TERMIOS_SIZE);
+
+		// The current pointer for C
+		this.#ptr = getPointer(this.#termios);
+	}
+
+	get inRawMode() {
+		return this.#inRawMode;
+	}
+
+	enableRawMode() {
+		if (this.#inRawMode) {
+			throw new Error('Can not enable raw mode when in raw mode');
+		}
+
+		// Get the current termios settings
+		tcgetattr(STDIN_FILENO, this.#ptr);
+
+		// 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);
+
+		// Actually set the new termios settings
+		tcsetattr(STDIN_FILENO, TCSANOW, this.#ptr);
+		this.#inRawMode = true;
+	}
+
+	disableRawMode() {
+		// Don't even bother throwing an error if we try to disable raw mode
+		// and aren't in raw mode. It just doesn't really matter.
+		if (!this.#inRawMode) {
+			return;
+		}
+
+		const oldTermiosPtr = getPointer(this.#cookedTermios);
+		tcsetattr(STDIN_FILENO, TCSANOW, oldTermiosPtr);
+
+		this.#inRawMode = false;
+	}
 }
 
-const cSharedLib = `libc.${libSuffix}`;
-const cStdLib = Deno.dlopen(
-	cSharedLib,
-	{
-	tcgetattr: {
-		parameters: ['i32', 'pointer'],
-		result: 'i32',
-	},
-	tcsetattr: {
-		parameters: ['i32', 'i32', 'pointer'],
-		result: 'i32',
-	},
-	cfmakeraw: {
-		parameters: ['pointer'],
-		result: 'void',
-	},
-} as const,
-);
-
-export default cStdLib.symbols;
-export const tcgetattr = cStdLib.symbols.tcgetattr;
-export const tcsetattr = cStdLib.symbols.tcsetattr;
-export const cfmakeraw = cStdLib.symbols.cfmakeraw;

src/scroll.ts

@@ -8,18 +8,12 @@ export enum RunTime {
 	Unknown = 'common',
 }
 
+import { importForRuntime } from "./common/index.ts";
+
 /**
  * Determine the runtime strategy, and go!
  */
 (async () => {
-	let RUNTIME = RunTime.Unknown;
-	if ('Deno' in globalThis) {
-		RUNTIME = RunTime.Deno;
-	}
-	if ('Bun' in globalThis) {
-		RUNTIME = RunTime.Bun;
-	}
-
-	const { main } = await import(`./${RUNTIME}/index.ts`);
+	const { main } = await importForRuntime('./index.ts');
 	await main();
 })();