add quick2

3 files changed, 54 insertions, 5 deletions

diff --git a/ds/elem.go b/ds/elem.go
index 0589e81..22bc9d9 100644
--- a/ds/elem.go
+++ b/ds/elem.go
@@ -1,10 +1,12 @@
 package ds
 
 type Elem interface {
-	Equal(a Elem) bool
-	Lower(a Elem) bool
-	LowerEqual(a Elem) bool
-	Higher(a Elem) bool
-	HigherEqual(a Elem) bool
+	Equal(e Elem) bool
+	Lower(e Elem) bool
+	LowerEqual(e Elem) bool
+	Higher(e Elem) bool
+	HigherEqual(e Elem) bool
+	Compare(e Elem) int
+	CompareCB(e Elem, lowerCB, higherCB, equalsCB func())
 	Int() int
 }
diff --git a/ds/integer.go b/ds/integer.go
index 4abb349..296e5bb 100644
--- a/ds/integer.go
+++ b/ds/integer.go
@@ -62,3 +62,26 @@ func (i Integer) Higher(j Elem) bool {
 func (i Integer) HigherEqual(j Elem) bool {
 	return i.Val >= j.Int()
 }
+
+func (i Integer) Compare(j Elem) int {
+    jVal := j.Int()
+    switch {
+      case i.Val < jVal:
+      return -1
+      case i.Val > jVal:
+      return 1
+    }
+	return 0
+}
+
+func (i Integer) CompareCB(j Elem, lowerCB, higherCB, equalsCB func()) {
+    jVal := j.Int()
+    switch {
+      case i.Val < jVal:
+        lowerCB()
+      case i.Val > jVal:
+        higherCB()
+      default:
+        equalsCB()
+    }
+}
diff --git a/ds/integer_test.go b/ds/integer_test.go
new file mode 100644
index 0000000..9be55eb
--- /dev/null
+++ b/ds/integer_test.go
@@ -0,0 +1,24 @@
+package ds
+
+import "testing"
+
+func TestCompare(t *testing.T) {
+	i := Integer{1}
+	j := Integer{10}
+	res := i.Compare(j)
+	if res != -1 {
+		t.Errorf("%v must be lower than %v, but got %v", i, j, res)
+	}
+
+	res = j.Compare(i)
+	if res != 1 {
+		t.Errorf("%v must be higher than %v, but got %v", j, i, res)
+	}
+
+	i = Integer{2}
+	j = Integer{2}
+	res = i.Compare(j)
+	if res != 0 {
+		t.Errorf("%v must be equal to %v, but got %v", i, j, res)
+	}
+}