Module handler 

Hierarchical Input Handling System

This module provides a tree-based input dispatch system where input events flow through a hierarchy of handlers. The design follows these principles:

1. Leaf-first, bubble up: Input is dispatched to the deepest focused element first. If not consumed, it bubbles up to parents.

2. Explicit consumption: Handlers return InputResult::Consumed to stop propagation or InputResult::Ignored to let parents try.

3. Modals consume by default: Modal dialogs (Settings, Prompts) should return Consumed for unhandled keys to prevent input leakage.

4. No capture phase: Unlike DOM events, there’s no capture phase. This keeps the model simple and predictable.

Example

impl InputHandler for MyPanel {
    fn handle_input(&mut self, event: &KeyEvent, ctx: &mut InputContext) -> InputResult {
        // Let focused child try first
        if let Some(child) = self.focused_child_mut() {
            if child.handle_input(event, ctx) == InputResult::Consumed {
                return InputResult::Consumed;
            }
        }

        // Handle at this level
        match event.code {
            KeyCode::Up => { self.move_up(); InputResult::Consumed }
            KeyCode::Down => { self.move_down(); InputResult::Consumed }
            _ => InputResult::Ignored // Let parent handle
        }
    }
}

Structs

InputContext

Context passed to input handlers, providing access to shared state.

Enums

DeferredAction

Actions that need to be executed after input handling completes. These are operations that require mutable access to Editor.

InputResult

Result of handling an input event.

TerminalMouseButton

Mouse buttons for terminal forwarding.

TerminalMouseEventKind

Mouse event kinds for terminal forwarding. Simplified from crossterm’s MouseEventKind to capture what we need.

Traits

InputHandler

Trait for elements that can handle input events.

Functions

is_key

Helper to check for common key combinations.

is_key_with_alt

is_key_with_ctrl

is_key_with_shift