Sets & maps append-multi. Also docs and a fix for SortedSets

README.md

@@ -2,7 +2,7 @@ Immutable ![release](https://img.shields.io/github/release/benbjohnson/immutable
 =========
 
 This repository contains *generic* immutable collection types for Go. It includes
-`List`, `Map`, and `SortedMap` implementations. Immutable collections can
+`List`, `Map`, `SortedMap`, `Set` and `SortedSet` implementations. Immutable collections can
 provide efficient, lock free sharing of data by requiring that edits to the
 collections return new collections.
 
@@ -284,6 +284,29 @@ type Comparer[K comparable] interface {
 
 Please see the internal `defaultComparer` for an example, bearing in mind that it works for several types.
 
+## Set
+
+The `Set` represents a collection of unique values. It uses a `map[T]struct{}`, so it carries over some characteristics from the built-in Go `map` type.
+Values neeed to be `comparable`.
+
+Like Maps, Sets require a `Hasher` to hash keys and check for equality. There are built-in
+hasher implementations for most primitive types such as `int`, `uint`, and
+`string` keys. You may pass in a `nil` hasher to `NewMap()` if you are using
+one of these key types.
+
+
+## Sorted Set
+
+The `SortedSet` represents a sorted collection of unique values.
+Unlike the `Set`, however, keys can be iterated over in-order. It is implemented
+as a B+tree.
+
+Sorted sets require a `Comparer` to sort values and check for equality. There are
+built-in comparer implementations for `int`, `uint`, and `string` keys. You may
+pass a `nil` comparer to `NewSortedSet()` if you are using one of these key
+types.
+
+The API is identical to the `Set` implementation.
 
 
 ## Contributing

immutable.go

@@ -707,6 +707,20 @@ func NewMap[K comparable, V any](hasher Hasher[K]) *Map[K, V] {
 	}
 }
 
+// NewMapOf returns a new instance of Map, containing a map of provided entries.
+//
+// If hasher is nil, a default hasher implementation will automatically be chosen based on the first key added.
+// Default hasher implementations only exist for int, string, and byte slice types.
+func NewMapOf[K comparable, V any](hasher Hasher[K], entries map[K]V) *Map[K, V] {
+	m := &Map[K, V]{
+		hasher: hasher,
+	}
+	for k, v := range entries {
+		m.set(k, v, true)
+	}
+	return m
+}
+
 // Len returns the number of elements in the map.
 func (m *Map[K, V]) Len() int {
 	return m.size
@@ -738,6 +752,18 @@ func (m *Map[K, V]) Set(key K, value V) *Map[K, V] {
 	return m.set(key, value, false)
 }
 
+// SetMany returns a map with the keys set to the new values. nil values are allowed.
+//
+// This function will return a new map even if the updated value is the same as
+// the existing value because Map does not track value equality.
+func (m *Map[K, V]) SetMany(entries map[K]V) *Map[K, V] {
+	n := m.clone()
+	for k, v := range entries {
+		n.set(k, v, true)
+	}
+	return n
+}
+
 func (m *Map[K, V]) set(key K, value V, mutable bool) *Map[K, V] {
 	// Set a hasher on the first value if one does not already exist.
 	hasher := m.hasher
@@ -1582,6 +1608,20 @@ func NewSortedMap[K comparable, V any](comparer Comparer[K]) *SortedMap[K, V] {
 	}
 }
 
+// NewSortedMapOf returns a new instance of SortedMap, containing a map of provided entries.
+//
+// If comparer is nil then a default comparer is set after the first key is inserted. Default comparers
+// exist for int, string, and byte slice keys.
+func NewSortedMapOf[K comparable, V any](comparer Comparer[K], entries map[K]V) *SortedMap[K, V] {
+	m := &SortedMap[K, V]{
+		comparer: comparer,
+	}
+	for k, v := range entries {
+		m.set(k, v, true)
+	}
+	return m
+}
+
 // Len returns the number of elements in the sorted map.
 func (m *SortedMap[K, V]) Len() int {
 	return m.size
@@ -1602,6 +1642,15 @@ func (m *SortedMap[K, V]) Set(key K, value V) *SortedMap[K, V] {
 	return m.set(key, value, false)
 }
 
+// SetMany returns a map with the keys set to the new values.
+func (m *SortedMap[K, V]) SetMany(entries map[K]V) *SortedMap[K, V] {
+	n := m.clone()
+	for k, v := range entries {
+		n.set(k, v, true)
+	}
+	return n
+}
+
 func (m *SortedMap[K, V]) set(key K, value V, mutable bool) *SortedMap[K, V] {
 	// Set a comparer on the first value if one does not already exist.
 	comparer := m.comparer

immutable_test.go

@@ -200,8 +200,10 @@ func TestList(t *testing.T) {
 					t.Fatal("Failed to find leaf node due to nil child")
 				}
 				return findLeaf(n.children[0])
-			case *listLeafNode[*int]: return n
-			default: panic("Unexpected case")
+			case *listLeafNode[*int]:
+				return n
+			default:
+				panic("Unexpected case")
 			}
 		}
 
@@ -959,6 +961,22 @@ func TestMap_Set(t *testing.T) {
 		}
 	})
 
+	t.Run("Multi", func(t *testing.T) {
+		m := NewMapOf(nil, map[int]string{1: "foo"})
+		itr := m.Iterator()
+		if itr.Done() {
+			t.Fatal("MapIterator.Done()=false, expected true")
+		}
+		if k, v, ok := itr.Next(); !ok {
+			t.Fatalf("MapIterator.Next()!=ok, expected ok")
+		} else if k != 1 || v != "foo" {
+			t.Fatalf("MapIterator.Next()=<%v,%v>, expected <1, \"foo\">", k, v)
+		}
+		if k, v, ok := itr.Next(); ok {
+			t.Fatalf("MapIterator.Next()=<%v,%v>, expected nil", k, v)
+		}
+	})
+
 	t.Run("VerySmall", func(t *testing.T) {
 		const n = 6
 		m := NewMap[int, int](nil)
@@ -1070,6 +1088,16 @@ func TestMap_Overwrite(t *testing.T) {
 			t.Fatalf("Get(%d)=<%v,%v>", i, v, ok)
 		}
 	}
+
+	t.Run("Simple", func(t *testing.T) {
+		m := NewMap[int, string](nil)
+		itr := m.Iterator()
+		if !itr.Done() {
+			t.Fatal("MapIterator.Done()=true, expected false")
+		} else if k, v, ok := itr.Next(); ok {
+			t.Fatalf("MapIterator.Next()=<%v,%v>, expected nil", k, v)
+		}
+	})
 }
 
 func TestMap_Delete(t *testing.T) {

sets.go

@@ -1,54 +1,98 @@
 package immutable
 
+// Set represents a collection of unique values. The set uses a Hasher
+// to generate hashes and check for equality of key values.
+//
+// Internally, the Set stores values as keys of a Map[T,struct{}]
 type Set[T comparable] struct {
 	m *Map[T, struct{}]
 }
 
-func NewSet[T comparable](hasher Hasher[T]) Set[T] {
-	return Set[T]{
+// NewSet returns a new instance of Set.
+//
+// If hasher is nil, a default hasher implementation will automatically be chosen based on the first key added.
+// Default hasher implementations only exist for int, string, and byte slice types.
+// NewSet can also take some initial values as varargs.
+func NewSet[T comparable](hasher Hasher[T], values ...T) Set[T] {
+	s := Set[T]{
 		m: NewMap[T, struct{}](hasher),
 	}
+	for _, value := range values {
+		s.m.set(value, struct{}{}, true)
+	}
+	return s
 }
 
-func (s Set[T]) Set(val T) Set[T] {
-	return Set[T]{
-		m: s.m.Set(val, struct{}{}),
+// Set returns a set containing the new value.
+//
+// This function will return a new set even if the set already contains the value.
+func (s Set[T]) Set(values ...T) Set[T] {
+	n := Set[T]{
+		m: s.m.clone(),
+	}
+	for _, value := range values {
+		n.m.set(value, struct{}{}, true)
 	}
+	return n
 }
 
-func (s Set[T]) Delete(val T) Set[T] {
-	return Set[T]{
-		m: s.m.Delete(val),
+// Delete returns a set with the given key removed.
+func (s Set[T]) Delete(values ...T) Set[T] {
+	n := Set[T]{
+		m: s.m.clone(),
+	}
+	for _, value := range values {
+		n.m.delete(value, true)
 	}
+	return n
 }
 
+// Has returns true when the set contains the given value
 func (s Set[T]) Has(val T) bool {
 	_, ok := s.m.Get(val)
 	return ok
 }
 
+// Len returns the number of elements in the underlying map.
 func (s Set[K]) Len() int {
 	return s.m.Len()
 }
 
+// Items returns a slice of the items inside the set
+func (s Set[T]) Items() []T {
+	r := make([]T, 0, s.Len())
+	itr := s.Iterator()
+	for !itr.Done() {
+		v, _ := itr.Next()
+		r = append(r, v)
+	}
+	return r
+}
+
+// Iterator returns a new iterator for this set positioned at the first value.
 func (s Set[T]) Iterator() *SetIterator[T] {
 	itr := &SetIterator[T]{mi: s.m.Iterator()}
 	itr.mi.First()
 	return itr
 }
 
+// SetIterator represents an iterator over a set.
+// Iteration can occur in natural or reverse order based on use of Next() or Prev().
 type SetIterator[T comparable] struct {
 	mi *MapIterator[T, struct{}]
 }
 
+// Done returns true if no more values remain in the iterator.
 func (itr *SetIterator[T]) Done() bool {
 	return itr.mi.Done()
 }
 
+// First moves the iterator to the first value.
 func (itr *SetIterator[T]) First() {
 	itr.mi.First()
 }
 
+// Next moves the iterator to the next value.
 func (itr *SetIterator[T]) Next() (val T, ok bool) {
 	val, _, ok = itr.mi.Next()
 	return
@@ -82,65 +126,112 @@ type SortedSet[T comparable] struct {
 	m *SortedMap[T, struct{}]
 }
 
-func NewSortedSet[T comparable](comparer Comparer[T]) SortedSet[T] {
-	return SortedSet[T]{
+// NewSortedSet returns a new instance of SortedSet.
+//
+// If comparer is nil then
+// a default comparer is set after the first key is inserted. Default comparers
+// exist for int, string, and byte slice keys.
+// NewSortedSet can also take some initial values as varargs.
+func NewSortedSet[T comparable](comparer Comparer[T], values ...T) SortedSet[T] {
+	s := SortedSet[T]{
 		m: NewSortedMap[T, struct{}](comparer),
 	}
+	for _, value := range values {
+		s.m.set(value, struct{}{}, true)
+	}
+	return s
 }
 
-func (s SortedSet[T]) Put(val T) SortedSet[T] {
-	return SortedSet[T]{
-		m: s.m.Set(val, struct{}{}),
+// Set returns a set containing the new value.
+//
+// This function will return a new set even if the set already contains the value.
+func (s SortedSet[T]) Set(values ...T) SortedSet[T] {
+	n := SortedSet[T]{
+		m: s.m.clone(),
+	}
+	for _, value := range values {
+		n.m.set(value, struct{}{}, true)
 	}
+	return n
 }
 
-func (s SortedSet[T]) Delete(val T) SortedSet[T] {
-	return SortedSet[T]{
-		m: s.m.Delete(val),
+// Delete returns a set with the given key removed.
+func (s SortedSet[T]) Delete(values ...T) SortedSet[T] {
+	n := SortedSet[T]{
+		m: s.m.clone(),
+	}
+	for _, value := range values {
+		n.m.delete(value, true)
 	}
+	return n
 }
 
+// Has returns true when the set contains the given value
 func (s SortedSet[T]) Has(val T) bool {
 	_, ok := s.m.Get(val)
 	return ok
 }
 
+// Len returns the number of elements in the underlying map.
 func (s SortedSet[K]) Len() int {
 	return s.m.Len()
 }
 
+// Items returns a slice of the items inside the set
+func (s SortedSet[T]) Items() []T {
+	r := make([]T, 0, s.Len())
+	itr := s.Iterator()
+	for !itr.Done() {
+		v, _ := itr.Next()
+		r = append(r, v)
+	}
+	return r
+}
+
+// Iterator returns a new iterator for this set positioned at the first value.
 func (s SortedSet[T]) Iterator() *SortedSetIterator[T] {
 	itr := &SortedSetIterator[T]{mi: s.m.Iterator()}
 	itr.mi.First()
 	return itr
 }
 
+// SortedSetIterator represents an iterator over a sorted set.
+// Iteration can occur in natural or reverse order based on use of Next() or Prev().
 type SortedSetIterator[T comparable] struct {
 	mi *SortedMapIterator[T, struct{}]
 }
 
+// Done returns true if no more values remain in the iterator.
 func (itr *SortedSetIterator[T]) Done() bool {
 	return itr.mi.Done()
 }
 
+// First moves the iterator to the first value.
 func (itr *SortedSetIterator[T]) First() {
 	itr.mi.First()
 }
 
+// Last moves the iterator to the last value.
 func (itr *SortedSetIterator[T]) Last() {
 	itr.mi.Last()
 }
 
+// Next moves the iterator to the next value.
 func (itr *SortedSetIterator[T]) Next() (val T, ok bool) {
 	val, _, ok = itr.mi.Next()
 	return
 }
 
+// Next moves the iterator to the previous value.
 func (itr *SortedSetIterator[T]) Prev() (val T, ok bool) {
 	val, _, ok = itr.mi.Prev()
 	return
 }
 
+// Next moves the iterator to the given value.
+//
+// If the value does not exist then the next value is used. If no more keys exist
+// then the iterator is marked as done.
 func (itr *SortedSetIterator[T]) Seek(val T) {
 	itr.mi.Seek(val)
 }