Function NewComparer

immutable.go:2365–2380

NewComparer returns the built-in comparer for a given key type. Note that only int-ish and string-ish types are supported, despite the 'comparable' constraint. Attempts to use other types will result in a panic - users should define their own Comparers for these cases.

(key K)

// Note that only int-ish and string-ish types are supported, despite the 'comparable' constraint.
// Attempts to use other types will result in a panic - users should define their own Comparers for these cases.
func NewComparer[K any](key K) Comparer[K] {
	// Attempt to use non-reflection based comparer first.
	switch (any(key)).(type) {
	case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, string:
		return &defaultComparer[K]{}
	}
	// Fallback to reflection-based comparer otherwise.
	// This is used when caller wraps a type around a primitive type.
	switch reflect.TypeOf(key).Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.String:
		return &reflectComparer[K]{}
	}
	// If no comparers match then panic.
	// This is a compile time issue so it should not return an error.
	panic(fmt.Sprintf("immutable.NewComparer: must set comparer for %T type", key))
}

// defaultComparer compares two values (int-ish and string-ish types are supported). Implements Comparer.
type defaultComparer[K any] struct{}