utils/dev.kindling.utils.state/KStateWithHistory

KStateWithHistory

class KStateWithHistory<T>(defaultValue: T, capacity: Int = 10)(source)

Holds a value and a capped history of past values, supporting undo/redo.

Port of the useStateWithHistory and useUndoRedo React hooks.

val history = StateWithHistory("hello", capacity = 10)

history.set("world")
history.set("!")

history.back()             // → "world"
history.forward()          // → "!"

println(history.canUndo)   // true
println(history.canRedo)   // false

// Observe reactively:
history.state.collect { v -> println(v) }

Parameters

defaultValue

Initial value pushed into history.

capacity

Maximum number of history entries retained. Default: 10.

Constructors

KStateWithHistory

constructor(defaultValue: T, capacity: Int = 10)

Properties

val canRedo: Boolean

true when there is at least one step to redo.

val canUndo: Boolean

true when there is at least one step to undo.

val currentPointer: Int

Index of the current entry within historySnapshot.

historySnapshot

val historySnapshot: List<T>

Snapshot of the history list (oldest → newest, up to capacity entries).

val state: StateFlow<T>

The current value as a StateFlow.

val value: T

The current value.

Functions

fun back()

Moves one step back in history. No-op if already at the oldest entry.

Moves one step forward in history. No-op if already at the newest entry.

fun go(index: Int)

Jumps to an arbitrary history index. No-op if out of bounds.

fun redo()

Alias for forward.

fun set(newValue: T)

Updates the value and records it in history. Any redo history ahead of the current pointer is discarded.

open override fun toString(): String

fun undo()

Alias for back.