SelectionController

Interface

projects/core/utils/selection-controller.ts

Info
API

Import#

import { SelectionController } from '@cngx/core/utils'

Description#

Signal-based selection engine. Reads + writes an external WritableSignal<T[]> — does not own the values.

Memoizes per-value isSelected / isIndeterminate signals by key so template diff stays stable and consumers can pass the handle into child components without identity churn.

Index#

Properties

hasSelection isEmpty selected selectedCount

Methods

clear deselect destroy isIndeterminate isSelected select set toggle toggleAll

Instance Properties#

hasSelection#Signal

Readonly

true when at least one value is selected.

isEmpty#Signal

Readonly

true when nothing is selected.

selected#Signal

Readonly

Snapshot of currently selected values (structural-equality computed).

selectedCount#Signal

Readonly

Current selection size.

Methods#

clear#void

Clear selection.

deselect#void

deselect(value: T)

Remove from selection. No-op if not selected.

@paramvalueT

destroy#void

Release retained per-value signal caches. Post-destroy isSelected(v) / isIndeterminate(v) return a shared Signal<false> no-op (identity-stable across all calls) so existing bindings keep working without further memory retention. Writes (select, deselect, toggle, toggleAll, clear, set) still mutate values but do not repopulate the caches. Idempotent.

isIndeterminate#Signal

isIndeterminate(value: T)

Reactive indeterminate state. With childrenFn: true iff SOME but not ALL descendants are selected. Without: always returns a shared constant Signal<false>.

@paramvalueT

isSelected#Signal

isSelected(value: T)

Reactive membership for a single value. Same value (by keyFn) always returns the SAME Signal instance — safe to pass into OnPush children or compare with ===.

@paramvalueT

select#void

select(value: T)

Idempotent add. No-op if already selected.

@paramvalueT

set#void

set(values: unknown)

Replace selection with the given values (copied).

@paramvaluesunknown

toggle#void

toggle(value: T)

Toggle a single value.

@paramvalueT

toggleAll#void

toggleAll(values: unknown)

Toggle-all semantics over a group: if every value in values is already selected, remove them all; otherwise add the missing ones.

@paramvaluesunknown