Function IgnoreMapEntries

cmp/cmpopts/ignore.go:183–206

IgnoreMapEntries returns an [cmp.Option] that ignores entries of map[K]V. The discard function must be of the form "func(T, R) bool" which is used to ignore map entries of type K and V, where K and V are assignable to T and R. Entries are ignored if the function reports true.

(discardFunc interface{})

// ignore map entries of type K and V, where K and V are assignable to T and R.
// Entries are ignored if the function reports true.
func IgnoreMapEntries(discardFunc interface{}) cmp.Option {
	vf := reflect.ValueOf(discardFunc)
	if !function.IsType(vf.Type(), function.KeyValuePredicate) || vf.IsNil() {
		panic(fmt.Sprintf("invalid discard function: %T", discardFunc))
	}
	return cmp.FilterPath(func(p cmp.Path) bool {
		mi, ok := p.Index(-1).(cmp.MapIndex)
		if !ok {
			return false
		}
		if !mi.Key().Type().AssignableTo(vf.Type().In(0)) || !mi.Type().AssignableTo(vf.Type().In(1)) {
			return false
		}
		k := mi.Key()
		vx, vy := mi.Values()
		if vx.IsValid() && vf.Call([]reflect.Value{k, vx})[0].Bool() {
			return true
		}
		if vy.IsValid() && vf.Call([]reflect.Value{k, vy})[0].Bool() {
			return true
		}
		return false
	}, cmp.Ignore())
}