Use a HashSet in MultiMap

Also, rename NewMap to NewHashMap

Signed-off-by: Elazar Gershuni <[email protected]>

README.md

@@ -15,7 +15,7 @@ A collection of Golang packages with models for cartesian products and network r
     * `Triple` - A simple generic triple
     * `HashMap` - A generic map for mapping any Hashable key to any Comparable.
     * `HashSet` - A generic `Set` for storing any Hashable.
-    * `MultiMap` - A map for mapping any Hashable key to a set of Comparable values.
+    * `MultiMap` - A map for mapping any Hashable key to a set of Hashable values.
     * `ProductLeft` - A `Product` of two sets, implemented using a map where each key-values pair represents the cartesian product of the two sets.
     * `LeftTripleSet`, RightTripleSet, OuterTripleSet - `TripleSet` implementations.
     * `DisjointSum` - A sum type for two tagged sets.

pkg/ds/hashmap.go

@@ -11,8 +11,8 @@ type HashMap[K Hashable[K], V Comparable[V]] struct {
 	m map[int][]Pair[K, V]
 }
 
-// NewMap creates a new empty hash map.
-func NewMap[K Hashable[K], V Comparable[V]]() *HashMap[K, V] {
+// NewHashMap creates a new empty hash map.
+func NewHashMap[K Hashable[K], V Comparable[V]]() *HashMap[K, V] {
 	return &HashMap[K, V]{m: map[int][]Pair[K, V]{}}
 }
 
@@ -53,7 +53,7 @@ func (m *HashMap[K, V]) Insert(k K, v V) {
 
 // Copy returns a deep copy of the map.
 func (m *HashMap[K, V]) Copy() *HashMap[K, V] {
-	res := NewMap[K, V]()
+	res := NewHashMap[K, V]()
 	for _, p := range m.Pairs() {
 		res.Insert(p.Left, p.Right)
 	}

pkg/ds/hashmap_test.go

@@ -26,7 +26,7 @@ func less(p1, p2 ds.Pair[Int, Int]) bool {
 func assertMapEmpty(t *testing.T, m *Map) {
 	t.Helper()
 	assertEmpty(t, m)
-	require.True(t, m.Equal(ds.NewMap[Int, Int]()))
+	require.True(t, m.Equal(ds.NewHashMap[Int, Int]()))
 	_, ok := m.At(Int{1})
 	require.False(t, ok)
 
@@ -65,7 +65,7 @@ func assertMapSingle(t *testing.T, m *Map, key, value int) {
 		require.True(t, values[0].int == value)
 	}
 
-	m1 := ds.NewMap[Int, Int]()
+	m1 := ds.NewHashMap[Int, Int]()
 	assertNotEqual(t, m, m1)
 
 	m1.Insert(Int{key}, Int{value})
@@ -135,7 +135,7 @@ func assertMapDouble(t *testing.T, m *Map, key1, value1, key2, value2 int) {
 		require.True(t, values[1].int == v2)
 	}
 
-	m1 := ds.NewMap[Int, Int]()
+	m1 := ds.NewHashMap[Int, Int]()
 	assertNotEqual(t, m, m1)
 
 	m1.Insert(Int{key2}, Int{value2})
@@ -157,7 +157,7 @@ func assertMapDouble(t *testing.T, m *Map, key1, value1, key2, value2 int) {
 func TestMap(t *testing.T) {
 	var m, dupl *Map
 
-	m = ds.NewMap[Int, Int]()
+	m = ds.NewHashMap[Int, Int]()
 	assertMapEmpty(t, m)
 	m.Delete(Int{1})
 	assertMapEmpty(t, m)

pkg/ds/product_left.go

@@ -16,7 +16,7 @@ type ProductLeft[K Set[K], V Set[V]] struct {
 // NewProductLeft with parameters [K, V] creates an empty Product[K, V] object,
 // implemented using K sets are keys and V sets as values.
 func NewProductLeft[K Set[K], V Set[V]]() *ProductLeft[K, V] {
-	return &ProductLeft[K, V]{m: NewMap[K, V]()}
+	return &ProductLeft[K, V]{m: NewHashMap[K, V]()}
 }
 
 // CartesianPairLeft returns a new Product object holding the cartesian product of the input sets k x v.
@@ -128,7 +128,7 @@ func (m *ProductLeft[K, V]) Union(other Product[K, V]) Product[K, V] {
 	if other.IsEmpty() {
 		return m.Copy()
 	}
-	remainingFromSelf := NewMap[K, K]()
+	remainingFromSelf := NewHashMap[K, K]()
 	for _, k := range m.m.Keys() {
 		remainingFromSelf.Insert(k, k)
 	}
@@ -221,17 +221,17 @@ func (m *ProductLeft[K, V]) canonicalize() {
 			m.m.Delete(k)
 		}
 	}
-	newM := NewMap[K, V]()
+	newM := NewHashMap[K, V]()
 	for _, p := range InverseMap(m.m).MultiPairs() {
-		items := p.Value.Items()
+		items := p.Right.Items()
 		if len(items) == 0 {
 			continue
 		}
 		newKey := items[0]
 		for _, v := range items[1:] {
 			newKey = newKey.Union(v)
 		}
-		newM.Insert(newKey, p.Key)
+		newM.Insert(newKey, p.Left)
 	}
 	m.m = newM
 }