Added `Set(index, value)` method to all Lists (closes #86)

Added tests

lists/arraylist/arraylist.go

@@ -11,9 +11,10 @@ package arraylist
 
 import (
 	"fmt"
+	"strings"
+
 	"github.com/emirpasic/gods/lists"
 	"github.com/emirpasic/gods/utils"
-	"strings"
 )
 
 func assertListImplementation() {
@@ -162,6 +163,22 @@ func (list *List) Insert(index int, values ...interface{}) {
 	copy(list.elements[index:], values)
 }
 
+// Set the value at specified index
+// Does not do anything if position is negative or bigger than list's size
+// Note: position equal to list's size is valid, i.e. append.
+func (list *List) Set(index int, value interface{}) {
+
+	if !list.withinRange(index) {
+		// Append
+		if index == list.size {
+			list.Add(value)
+		}
+		return
+	}
+
+	list.elements[index] = value
+}
+
 // String returns a string representation of container
 func (list *List) String() string {
 	str := "ArrayList\n"

lists/arraylist/arraylist_test.go

@@ -178,6 +178,27 @@ func TestListInsert(t *testing.T) {
 	}
 }
 
+func TestListSet(t *testing.T) {
+	list := New()
+	list.Set(0, "a")
+	list.Set(1, "b")
+	if actualValue := list.Size(); actualValue != 2 {
+		t.Errorf("Got %v expected %v", actualValue, 2)
+	}
+	list.Set(2, "c") // append
+	if actualValue := list.Size(); actualValue != 3 {
+		t.Errorf("Got %v expected %v", actualValue, 3)
+	}
+	list.Set(4, "d") // ignore
+	list.Set(1, "bb") // update
+	if actualValue := list.Size(); actualValue != 3 {
+		t.Errorf("Got %v expected %v", actualValue, 3)
+	}
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s", list.Values()...), "abbc"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+}
+
 func TestListEach(t *testing.T) {
 	list := New()
 	list.Add("a", "b", "c")

lists/doublylinkedlist/doublylinkedlist.go

@@ -11,9 +11,10 @@ package doublylinkedlist
 
 import (
 	"fmt"
+	"strings"
+
 	"github.com/emirpasic/gods/lists"
 	"github.com/emirpasic/gods/utils"
-	"strings"
 )
 
 func assertListImplementation() {
@@ -292,6 +293,37 @@ func (list *List) Insert(index int, values ...interface{}) {
 	}
 }
 
+// Sets value at specified index position
+// Does not do anything if position is negative or bigger than list's size
+// Note: position equal to list's size is valid, i.e. append.
+func (list *List) Set(index int, value interface{}) {
+
+	if !list.withinRange(index) {
+		// Append
+		if index == list.size {
+			list.Add(value)
+		}
+		return
+	}
+
+	var foundElement *element
+	// determine traversal direction, last to first or first to last
+	if list.size-index < index {
+		foundElement = list.last
+		for e := list.size - 1; e != index; {
+			fmt.Println("Set last", index, value, foundElement, foundElement.prev)
+			e, foundElement = e-1, foundElement.prev
+		}
+	} else {
+		foundElement = list.first
+		for e := 0; e != index; {
+			e, foundElement = e+1, foundElement.next
+		}
+	}
+
+	foundElement.value = value
+}
+
 // String returns a string representation of container
 func (list *List) String() string {
 	str := "DoublyLinkedList\n"

lists/doublylinkedlist/doublylinkedlist_test.go

@@ -6,8 +6,9 @@ package doublylinkedlist
 
 import (
 	"fmt"
-	"github.com/emirpasic/gods/utils"
 	"testing"
+
+	"github.com/emirpasic/gods/utils"
 )
 
 func TestListAdd(t *testing.T) {
@@ -177,6 +178,32 @@ func TestListInsert(t *testing.T) {
 	}
 }
 
+func TestListSet(t *testing.T) {
+	list := New()
+	list.Set(0, "a")
+	list.Set(1, "b")
+	if actualValue := list.Size(); actualValue != 2 {
+		t.Errorf("Got %v expected %v", actualValue, 2)
+	}
+	list.Set(2, "c") // append
+	if actualValue := list.Size(); actualValue != 3 {
+		t.Errorf("Got %v expected %v", actualValue, 3)
+	}
+	list.Set(4, "d")  // ignore
+	list.Set(1, "bb") // update
+	if actualValue := list.Size(); actualValue != 3 {
+		t.Errorf("Got %v expected %v", actualValue, 3)
+	}
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s", list.Values()...), "abbc"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+	list.Set(2, "cc") // last to first traversal
+	list.Set(0, "aa") // first to last traversal
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s", list.Values()...), "aabbcc"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+}
+
 func TestListEach(t *testing.T) {
 	list := New()
 	list.Add("a", "b", "c")

lists/lists.go

@@ -23,6 +23,7 @@ type List interface {
 	Sort(comparator utils.Comparator)
 	Swap(index1, index2 int)
 	Insert(index int, values ...interface{})
+	Set(index int, value interface{})
 
 	containers.Container
 	// Empty() bool

lists/singlylinkedlist/singlylinkedlist.go

@@ -11,9 +11,10 @@ package singlylinkedlist
 
 import (
 	"fmt"
+	"strings"
+
 	"github.com/emirpasic/gods/lists"
 	"github.com/emirpasic/gods/utils"
-	"strings"
 )
 
 func assertListImplementation() {
@@ -260,6 +261,26 @@ func (list *List) Insert(index int, values ...interface{}) {
 	}
 }
 
+// Sets value at specified index
+// Does not do anything if position is negative or bigger than list's size
+// Note: position equal to list's size is valid, i.e. append.
+func (list *List) Set(index int, value interface{}) {
+
+	if !list.withinRange(index) {
+		// Append
+		if index == list.size {
+			list.Add(value)
+		}
+		return
+	}
+
+	foundElement := list.first
+	for e := 0; e != index; {
+		e, foundElement = e+1, foundElement.next
+	}
+	foundElement.value = value
+}
+
 // String returns a string representation of container
 func (list *List) String() string {
 	str := "SinglyLinkedList\n"

lists/singlylinkedlist/singlylinkedlist_test.go

@@ -6,8 +6,9 @@ package singlylinkedlist
 
 import (
 	"fmt"
-	"github.com/emirpasic/gods/utils"
 	"testing"
+
+	"github.com/emirpasic/gods/utils"
 )
 
 func TestListAdd(t *testing.T) {
@@ -177,6 +178,27 @@ func TestListInsert(t *testing.T) {
 	}
 }
 
+func TestListSet(t *testing.T) {
+	list := New()
+	list.Set(0, "a")
+	list.Set(1, "b")
+	if actualValue := list.Size(); actualValue != 2 {
+		t.Errorf("Got %v expected %v", actualValue, 2)
+	}
+	list.Set(2, "c") // append
+	if actualValue := list.Size(); actualValue != 3 {
+		t.Errorf("Got %v expected %v", actualValue, 3)
+	}
+	list.Set(4, "d")  // ignore
+	list.Set(1, "bb") // update
+	if actualValue := list.Size(); actualValue != 3 {
+		t.Errorf("Got %v expected %v", actualValue, 3)
+	}
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s", list.Values()...), "abbc"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+}
+
 func TestListEach(t *testing.T) {
 	list := New()
 	list.Add("a", "b", "c")