diffstore2: AnyLeaf initial implementation

client/diffstore2/any-leaf.go

@@ -0,0 +1,46 @@
+package diffstore2
+
+import (
+    "constraints"
+    "fmt"
+)
+
+func NewAnyStore[K constraints.Ordered, T any](equal func(a,b T) bool) *Store[K, *AnyLeaf[T]] {
+	return New[K](func() *AnyLeaf[T] { return NewAnyLeaf(equal) })
+}
+
+type AnyLeaf[T any] struct {
+    equal func(a,b T) bool
+    value T
+
+    hash uint64
+}
+
+func NewAnyLeaf[T any](equal func(a,b T) bool) *AnyLeaf[T] {
+	return &AnyLeaf[T]{equal: equal, hash: 1}
+}
+
+var _ Leaf = NewAnyLeaf(func(a,b string) bool { return a == b })
+
+func (l *AnyLeaf[T]) Reset() {
+}
+
+func (l *AnyLeaf[T]) Hash() uint64 {
+    return l.hash
+}
+
+func (l *AnyLeaf[T]) Get() T {
+    return l.value
+}
+
+func (l *AnyLeaf[T]) Set(v T) {
+    if !l.equal(l.value, v) {
+        l.hash++
+    }
+
+    l.value = v
+}
+
+func (l *AnyLeaf[T]) String() string {
+    return fmt.Sprintf("{%v}", l.value)
+}

client/diffstore2/any-leaf_test.go

@@ -0,0 +1,33 @@
+package diffstore2
+
+func ExampleAnyLeafStore() {
+	store := NewAnyStore[string](func(a, b string) bool { return a == b })
+
+	store.Get("a").Set("a1")
+	store.Done()
+	store.printDiff()
+
+	store.Reset()
+	store.Get("a").Set("a1")
+	store.Done()
+	store.printDiff()
+
+	store.Reset()
+	store.Get("a").Set("a2")
+	store.Done()
+	store.printDiff()
+
+	store.Reset()
+	store.Done()
+	store.printDiff()
+
+	// Output:
+	// -----
+	// C a => "{a1}"
+	// -----
+	// <same>
+	// -----
+	// U a => "{a2}"
+	// -----
+	// D a
+}

client/diffstore2/buffer-leaf.go

@@ -2,12 +2,13 @@ package diffstore2
 
 import (
 	"bytes"
+    "constraints"
 
 	"github.com/cespare/xxhash"
 )
 
-func NewBufferStore() *Store[string, *BufferLeaf] {
-	return New[string](NewBufferLeaf)
+func NewBufferStore[K constraints.Ordered]() *Store[K, *BufferLeaf] {
+	return New[K](NewBufferLeaf)
 }
 
 type BufferLeaf struct {

client/diffstore2/diffstore_test.go

@@ -6,38 +6,13 @@ import (
 )
 
 func ExampleStore() {
-	store := NewBufferStore()
-
-	printDiff := func() {
-		fmt.Println("-----")
-		hasChanges := false
-
-		for _, i := range store.Changed() {
-			hasChanges = true
-
-			s := "U"
-			if i.Created() {
-				s = "C"
-			}
-			fmt.Printf("%s %s => %q\n", s, i.Key(), i.Value())
-		}
-
-		for _, i := range store.Deleted() {
-			hasChanges = true
-
-			fmt.Printf("D %s\n", i.Key())
-		}
-
-		if !hasChanges {
-			fmt.Println("<same>")
-		}
-	}
+	store := NewBufferStore[string]()
 
 	{
 		fmt.Fprint(store.Get("a"), "hello a")
 
 		store.Done()
-		printDiff()
+		store.printDiff()
 	}
 
 	{
@@ -46,7 +21,7 @@ func ExampleStore() {
 		fmt.Fprint(store.Get("a"), "hello a")
 
 		store.Done()
-		printDiff()
+		store.printDiff()
 	}
 
 	{
@@ -56,7 +31,7 @@ func ExampleStore() {
 		fmt.Fprint(store.Get("b"), "hello b")
 
 		store.Done()
-		printDiff()
+		store.printDiff()
 	}
 
 	{
@@ -65,7 +40,7 @@ func ExampleStore() {
 		fmt.Fprint(store.Get("a"), "hi a")
 
 		store.Done()
-		printDiff()
+		store.printDiff()
 	}
 
 	{
@@ -74,14 +49,14 @@ func ExampleStore() {
 		fmt.Fprint(store.Get("b"), "hi b")
 
 		store.Done()
-		printDiff()
+		store.printDiff()
 	}
 
 	{
 		store.Reset()
 
 		store.Done()
-		printDiff()
+        store.printDiff()
 	}
 
 	// Output:

client/diffstore2/print.go

@@ -0,0 +1,30 @@
+package diffstore2
+
+import (
+    "fmt"
+)
+
+func (store *Store[K,V]) printDiff() {
+	fmt.Println("-----")
+	hasChanges := false
+
+	for _, i := range store.Changed() {
+		hasChanges = true
+
+		s := "U"
+		if i.Created() {
+			s = "C"
+		}
+		fmt.Printf("%s %v => %q\n", s, i.Key(), fmt.Sprint(i.Value()))
+	}
+
+	for _, i := range store.Deleted() {
+		hasChanges = true
+
+		fmt.Printf("D %v\n", i.Key())
+	}
+
+	if !hasChanges {
+		fmt.Println("<same>")
+	}
+}