Merge pull request #30 from tsandall/basic-indexing

Add basic indexing support

eval/hashmap.go

@@ -17,10 +17,33 @@ type hashEntry struct {
 
 type hashMap struct {
 	table map[int]*hashEntry
+	size  int
 }
 
 func newHashMap() *hashMap {
-	return &hashMap{make(map[int]*hashEntry)}
+	return &hashMap{make(map[int]*hashEntry), 0}
+}
+
+func (hm *hashMap) Copy() *hashMap {
+	cpy := newHashMap()
+	hm.Iter(func(k, v opalog.Value) bool {
+		cpy.Put(k, v)
+		return false
+	})
+	return cpy
+}
+
+func (hm *hashMap) Equal(other *hashMap) bool {
+	if hm.Len() != other.Len() {
+		return false
+	}
+	return !hm.Iter(func(k, v opalog.Value) bool {
+		ov := other.Get(k)
+		if ov == nil {
+			return true
+		}
+		return !v.Equal(ov)
+	})
 }
 
 func (hm *hashMap) Get(k opalog.Value) opalog.Value {
@@ -33,6 +56,15 @@ func (hm *hashMap) Get(k opalog.Value) opalog.Value {
 	return nil
 }
 
+func (hm *hashMap) Hash() int {
+	var hash int
+	hm.Iter(func(k, v opalog.Value) bool {
+		hash += k.Hash() + v.Hash()
+		return false
+	})
+	return hash
+}
+
 // Iter invokes the iter function for each element in the hashMap.
 // If the iter function returns true, iteration stops and the return value is true.
 // If the iter function never returns true, iteration proceeds through all elements
@@ -48,6 +80,10 @@ func (hm *hashMap) Iter(iter func(opalog.Value, opalog.Value) bool) bool {
 	return false
 }
 
+func (hm *hashMap) Len() int {
+	return hm.size
+}
+
 func (hm *hashMap) Put(k opalog.Value, v opalog.Value) {
 	hash := k.Hash()
 	head := hm.table[hash]
@@ -58,6 +94,7 @@ func (hm *hashMap) Put(k opalog.Value, v opalog.Value) {
 		}
 	}
 	hm.table[hash] = &hashEntry{k: k, v: v, next: head}
+	hm.size++
 }
 
 func (hm *hashMap) String() string {
@@ -68,3 +105,15 @@ func (hm *hashMap) String() string {
 	})
 	return "{" + strings.Join(buf, ", ") + "}"
 }
+
+// Update returns a new hashMap with elements from the other hashMap put into this hashMap.
+// If the other hashMap contains elements with the same key as this hashMap, the value
+// from the other hashMap overwrites the value from this hashMap.
+func (hm *hashMap) Update(other *hashMap) *hashMap {
+	updated := hm.Copy()
+	other.Iter(func(k, v opalog.Value) bool {
+		updated.Put(k, v)
+		return false
+	})
+	return updated
+}

eval/hashmap_test.go

@@ -24,7 +24,7 @@ func TestHashmapOverwrite(t *testing.T) {
 	}
 }
 
-func TestIter(t *testing.T) {
+func TestHashmapIter(t *testing.T) {
 	m := newHashMap()
 	keys := []opalog.Number{opalog.Number(1), opalog.Number(2), opalog.Number(1.4)}
 	value := opalog.Null{}
@@ -49,3 +49,36 @@ func TestIter(t *testing.T) {
 		t.Errorf("Expected %v but got %v", expected, results)
 	}
 }
+
+func TestHashmapCompare(t *testing.T) {
+	m := newHashMap()
+	n := newHashMap()
+	k1 := opalog.String("k1")
+	k2 := opalog.String("k2")
+	k3 := opalog.String("k3")
+	v1 := parseTerm(`[{"a": 1, "b": 2}, {"c": 3}]`).Value
+	v2 := parseTerm(`[{"a": 1, "b": 2}, {"c": 4}]`).Value
+	m.Put(k1, v1)
+	if m.Equal(n) {
+		t.Errorf("Expected hash maps of different size to be non-equal for %v and %v", m, n)
+		return
+	}
+	n.Put(k1, v1)
+	if m.Hash() != n.Hash() {
+		t.Errorf("Expected hashes to equal for %v and %v", m, n)
+		return
+	}
+	if !m.Equal(n) {
+		t.Errorf("Expected hash maps to be equal for %v and %v", m, n)
+		return
+	}
+	m.Put(k2, v2)
+	n.Put(k3, v2)
+	if m.Hash() == n.Hash() {
+		t.Errorf("Did not expect hashes to equal for %v and %v", m, n)
+		return
+	}
+	if m.Equal(n) {
+		t.Errorf("Did not expect hash maps to be equal for %v and %v", m, n)
+	}
+}