PageMonitor

Location: backend/navigation/pagemonitor.h / backend/navigation/pagemonitor.cpp

PageMonitor tracks path history for simple undo semantics.

Purpose

• Keep ordered route history.
• Provide undo() behavior by removing latest entry.
• Expose current path and undo availability.

Properties

• history: stringList
• count: int
• current: string
• canUndo: bool

Methods

• record(path): void
• undo(): string
• clear(): void

Behavior

record(path):

• trims incoming path,
• ignores empty value,
• appends only when different from current tail.

undo():

• if history size <= 1, returns current without mutation,
• otherwise removes last entry and returns new current.

clear():

• no-op when already empty,
• otherwise clears history and emits change.

Signal

• historyChanged()

Usage Example

import LVRS 1.0 as LV

function onRouteChanged(path) {
    LV.PageMonitor.record(path)
}

function goBackIfPossible() {
    if (!LV.PageMonitor.canUndo)
        return
    const target = LV.PageMonitor.undo()
    LV.Navigator.replace(target)
}

Integration Pattern with Router

A common pattern is to mirror PageRouter.navigated into PageMonitor.record. This keeps route history external to UI stack and enables independent undo UI controls.

Edge Cases

• Duplicate consecutive routes are ignored by design.
• Empty or whitespace-only input is ignored.
• undo() on a single-entry history is idempotent.

FAQ

Q. Does PageMonitor automatically sync with PageRouter?
A. No. Sync is explicit; route changes must call record() from integration layer.