v0.1.0 initial commit

internal/filter/pin.go

@@ -0,0 +1,64 @@
+package filter
+
+import "slices"
+
+// PinSet is the pin buffer: record indices the user marked. It is owned by the
+// app and outlives every filter change, which is the point — pins are
+// assembled across successive filters. Not registered: it has no meaningful
+// construction from a string argument.
+type PinSet struct{ m map[int32]struct{} }
+
+// NewPinSet returns an empty pin buffer.
+func NewPinSet() *PinSet { return &PinSet{m: make(map[int32]struct{})} }
+
+// Has reports whether record i is pinned.
+func (p *PinSet) Has(i int32) bool { _, ok := p.m[i]; return ok }
+
+// Toggle flips record i, returning its new state.
+func (p *PinSet) Toggle(i int32) bool {
+	if _, ok := p.m[i]; ok {
+		delete(p.m, i)
+		return false
+	}
+	p.m[i] = struct{}{}
+	return true
+}
+
+// Clear empties the buffer.
+func (p *PinSet) Clear() { clear(p.m) }
+
+// Len returns the pin count.
+func (p *PinSet) Len() int { return len(p.m) }
+
+// Sorted returns the pinned record indices in file order.
+func (p *PinSet) Sorted() []int32 {
+	out := make([]int32, 0, len(p.m))
+	for i := range p.m {
+		out = append(out, i)
+	}
+	slices.Sort(out)
+	return out
+}
+
+// Pinned restricts the view to the pin buffer.
+type Pinned struct {
+	Set *PinSet
+	On  bool
+}
+
+// NewPinned wraps a pin buffer as a filter.
+func NewPinned(s *PinSet) *Pinned { return &Pinned{Set: s} }
+
+func (f *Pinned) Kind() string { return "pin" }
+func (f *Pinned) Needs() Need  { return 0 }
+
+func (f *Pinned) Match(c *Ctx) bool {
+	return !f.On || f.Set.Has(int32(c.I))
+}
+
+func (f *Pinned) Label() string {
+	if !f.On {
+		return ""
+	}
+	return "pinned-only"
+}