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Merged
pyramation merged 1 commit into from
Dec 25, 2025
Merged

revert(inquirerer): simplify keypress to per-instance model #32

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28 changes: 28 additions & 0 deletions packages/inquirerer/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,34 @@ close(): void
exit(): void
```

#### Managing Multiple Instances

When working with multiple `Inquirerer` instances that share the same input stream (typically `process.stdin`), only one instance should be actively prompting at a time. Each instance attaches its own keyboard listener, so having multiple active instances will cause duplicate or unexpected keypress behavior.

**Best practices:**

1. **Reuse a single instance** - Create one `Inquirerer` instance and reuse it for all prompts:
```typescript
const prompter = new Inquirerer();

// Use the same instance for multiple prompt sessions
const answers1 = await prompter.prompt({}, questions1);
const answers2 = await prompter.prompt({}, questions2);

prompter.close(); // Clean up when done
```

2. **Close before creating another** - If you need separate instances, close the first before using the second:
```typescript
const prompter1 = new Inquirerer();
const answers1 = await prompter1.prompt({}, questions1);
prompter1.close(); // Important: close before creating another

const prompter2 = new Inquirerer();
const answers2 = await prompter2.prompt({}, questions2);
prompter2.close();
```

### Question Types

#### Text Question
Expand Down
166 changes: 34 additions & 132 deletions packages/inquirerer/src/keypress.ts
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Expand Up @@ -22,79 +22,24 @@ export const KEY_CODES = {
BACKSPACE_LEGACY: '\x08' // For compatibility with some systems
};

interface SharedInputState {
dataHandler: (key: string) => void;
instances: Set<TerminalKeypress>;
activeStack: TerminalKeypress[]; // Stack of active instances, top is current owner
rawModeSet: boolean;
}

const sharedInputStates = new WeakMap<Readable, SharedInputState>();

function getOrCreateSharedState(input: Readable): SharedInputState {
let state = sharedInputStates.get(input);
if (!state) {
const dataHandler = (key: string) => {
const currentState = sharedInputStates.get(input);
if (!currentState) return;

// Only dispatch to the top of the active stack (current owner)
const owner = currentState.activeStack[currentState.activeStack.length - 1];
if (owner) {
owner.handleKey(key);

// Handle Ctrl+C via the current owner's process wrapper
if (key === KEY_CODES.CTRL_C) {
owner.exitProcess(0);
}
}
};

state = {
dataHandler,
instances: new Set(),
activeStack: [],
rawModeSet: false
};

sharedInputStates.set(input, state);
input.on('data', dataHandler);
}
return state;
}

function removeFromSharedState(input: Readable, instance: TerminalKeypress): void {
const state = sharedInputStates.get(input);
if (!state) return;

state.instances.delete(instance);

// Remove from active stack as well
const stackIndex = state.activeStack.indexOf(instance);
if (stackIndex !== -1) {
state.activeStack.splice(stackIndex, 1);
}

// If stack is now empty, disable raw mode
if (state.activeStack.length === 0 && state.rawModeSet) {
if (typeof (input as any).setRawMode === 'function') {
(input as any).setRawMode(false);
}
state.rawModeSet = false;
}

if (state.instances.size === 0) {
input.removeListener('data', state.dataHandler);
sharedInputStates.delete(input);
}
}

/**
* Handles keyboard input for interactive prompts.
*
* **Important**: Only one TerminalKeypress instance should be actively listening
* on a given input stream at a time. If you need multiple Inquirerer instances,
* call `close()` on the first instance before using the second, or reuse a single
* instance for all prompts.
*
* Multiple instances sharing the same input stream (e.g., process.stdin) will
* each receive all keypresses, which can cause duplicate or unexpected behavior.
*/
export class TerminalKeypress {
private listeners: Record<string, KeyHandler[]> = {};
private active: boolean = true;
private noTty: boolean;
private input: Readable;
private proc: ProcessWrapper;
private destroyed: boolean = false;
private dataHandler: ((key: string) => void) | null = null;

constructor(
noTty: boolean = false,
Expand All @@ -109,34 +54,23 @@ export class TerminalKeypress {
this.input.resume();
this.input.setEncoding('utf8');
}
this.registerWithSharedState();
}

private registerWithSharedState(): void {
const state = getOrCreateSharedState(this.input);
state.instances.add(this);
this.setupListeners();
}

isTTY() {
return !this.noTty;
}

isActive(): boolean {
if (this.destroyed) return false;
const state = sharedInputStates.get(this.input);
if (!state) return false;
// Active only if this instance is the current owner (top of stack)
return state.activeStack[state.activeStack.length - 1] === this;
}

exitProcess(code?: number): void {
this.proc.exit(code);
}

handleKey(key: string): void {
if (this.destroyed) return;
const handlers = this.listeners[key];
handlers?.forEach(handler => handler());
private setupListeners(): void {
this.dataHandler = (key: string) => {
if (!this.active) return;
const handlers = this.listeners[key];
handlers?.forEach(handler => handler());
if (key === KEY_CODES.CTRL_C) {
this.proc.exit(0);
}
};
this.input.on('data', this.dataHandler);
}

on(key: string, callback: KeyHandler): void {
Expand All @@ -160,57 +94,25 @@ export class TerminalKeypress {
}

pause(): void {
const state = sharedInputStates.get(this.input);
if (!state) return;

// Remove from active stack (from anywhere, not just top)
const stackIndex = state.activeStack.indexOf(this);
if (stackIndex !== -1) {
state.activeStack.splice(stackIndex, 1);
}

// If stack is now empty, disable raw mode
if (state.activeStack.length === 0 && state.rawModeSet) {
if (this.isTTY() && typeof (this.input as any).setRawMode === 'function') {
(this.input as any).setRawMode(false);
}
state.rawModeSet = false;
}
this.active = false;
this.clearHandlers();
}

resume(): void {
if (this.destroyed) return;

const state = sharedInputStates.get(this.input);
if (!state) return;

// Move-to-top semantics: remove from anywhere in stack, then push to top
const existingIndex = state.activeStack.indexOf(this);
if (existingIndex !== -1) {
state.activeStack.splice(existingIndex, 1);
}
state.activeStack.push(this);

// Enable raw mode if TTY
this.active = true;
if (this.isTTY() && typeof (this.input as any).setRawMode === 'function') {
(this.input as any).setRawMode(true);
state.rawModeSet = true;
}
}

destroy(): void {
if (this.destroyed) return;
this.destroyed = true;
this.clearHandlers();

removeFromSharedState(this.input, this);

const state = sharedInputStates.get(this.input);
if (!state || state.instances.size === 0) {
if (typeof (this.input as any).setRawMode === 'function') {
(this.input as any).setRawMode(false);
}
this.input.pause();
if (typeof (this.input as any).setRawMode === 'function') {
(this.input as any).setRawMode(false);
}
this.input.pause();
if (this.dataHandler) {
this.input.removeListener('data', this.dataHandler);
this.dataHandler = null;
}
}
}