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Merge pull request #10 from kemitix/return-optionals

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Return Optionals rather than nulls
This commit is contained in:
Paul Campbell 2016-05-26 13:28:31 +01:00
commit 801178381e
3 changed files with 113 additions and 90 deletions
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14
src/main/java/net/kemitix/node/Node.java
View file

@ -32,9 +32,10 @@ public interface Node<T> {
/**
* Fetch the data held within the node.
*
* @return the node's data
* @return an Optional containing the node's data, or empty if the node has
* none
*/
T getData();
Optional<T> getData();
/**
* Set the data held within the node.
@ -52,13 +53,10 @@ public interface Node<T> {
/**
* Fetch the parent node.
* <p>
* If the node is a root node, i.e. has no parent, then this will return
* null.
*
* @return the parent node
* @return an Optional contain the parent node, or empty if a root node
*/
Node<T> getParent();
Optional<Node<T>> getParent();
/**
* Make the current node a direct child of the parent.
@ -182,6 +180,8 @@ public interface Node<T> {
* @param name the name of the child
*
* @return the node
*
* @throws NodeException if the node is not found
*/
Node<T> getChildByName(String name);

20
src/main/java/net/kemitix/node/NodeItem.java
View file

@ -124,8 +124,8 @@ public class NodeItem<T> implements Node<T> {
}
@Override
public T getData() {
return data;
public Optional<T> getData() {
return Optional.ofNullable(data);
}
@Override
@ -139,8 +139,8 @@ public class NodeItem<T> implements Node<T> {
}
@Override
public Node<T> getParent() {
return parent;
public Optional<Node<T>> getParent() {
return Optional.ofNullable(parent);
}
@Override
@ -170,7 +170,12 @@ public class NodeItem<T> implements Node<T> {
}
}
children.add(child);
if (child.getParent() == null || !child.getParent().equals(this)) {
// update the child's parent if they don't have one or it is not this
Optional<Node<T>> childParent = child.getParent();
boolean isOrphan = !childParent.isPresent();
boolean hasDifferentParent = !isOrphan && !childParent.get()
.equals(this);
if (isOrphan || hasDifferentParent) {
child.setParent(this);
}
}
@ -244,7 +249,8 @@ public class NodeItem<T> implements Node<T> {
throw new NullPointerException("child");
}
return children.stream()
.filter((Node<T> t) -> t.getData().equals(child))
.filter(n -> !n.isEmpty())
.filter(n -> n.getData().get().equals(child))
.findAny();
}
@ -333,7 +339,7 @@ public class NodeItem<T> implements Node<T> {
throw new NodeException("A non-empty node named '" + nodeName
+ "' already exists here");
} else {
existing.setData(nodeItem.getData());
nodeItem.getData().ifPresent(existing::setData);
}
return;
}

169
src/test/java/net/kemitix/node/NodeItemTest.java
View file

@ -36,7 +36,7 @@ public class NodeItemTest {
node = new NodeItem<>(data);
//then
assertThat(node.getData()).as("can get the data from a node").
isSameAs(data);
contains(data);
}
@Test
@ -55,9 +55,10 @@ public class NodeItemTest {
//given
node = new NodeItem<>(null, n -> "root name supplier");
//when
val child = new NodeItem<>(null, n -> "overridden", node);
val child = new NodeItem<String>(null, n -> "overridden", node);
//then
assertThat(child.getName()).isEqualTo("overridden");
assertThat(child.getParent()).contains(node);
}
@Test
@ -76,10 +77,10 @@ public class NodeItemTest {
@Test
public void shouldHaveNullForDefaultParent() {
//given
node = new NodeItem<>("data", Node::getData);
node = new NodeItem<>("data");
//then
assertThat(node.getParent()).as(
"node created without a parent has null as parent").isNull();
"node created without a parent has no parent").isEmpty();
}
/**
@ -88,13 +89,13 @@ public class NodeItemTest {
@Test
public void shouldReturnNodeParent() {
//given
val parent = new NodeItem<String>("parent", Node::getData);
val parent = new NodeItem<String>("parent");
//when
node = new NodeItem<>("subject", parent);
//then
assertThat(node.getParent()).as(
"node created with a parent can return the parent")
.isSameAs(parent);
.contains(parent);
}
/**
@ -104,7 +105,7 @@ public class NodeItemTest {
@Test
public void setParentShouldThrowNodeExceptionWhenParentIsAChild() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val child = new NodeItem<String>("child", node);
exception.expect(NodeException.class);
exception.expectMessage("Parent is a descendant");
@ -120,7 +121,7 @@ public class NodeItemTest {
@SuppressWarnings("unchecked")
public void shouldAddNewNodeAsChildToParent() {
//given
val parent = new NodeItem<String>("parent", Node::getData);
val parent = new NodeItem<String>("parent");
//when
node = new NodeItem<>("subject", parent);
//then
@ -135,14 +136,14 @@ public class NodeItemTest {
@Test
public void shouldReturnSetParent() {
//given
node = new NodeItem<>("subject", Node::getData);
val parent = new NodeItem<String>("parent", Node::getData);
node = new NodeItem<>("subject");
val parent = new NodeItem<String>("parent");
//when
node.setParent(parent);
//then
assertThat(node.getParent()).as(
"when a node is assigned a new parent that parent can be "
+ "returned").isSameAs(parent);
+ "returned").contains(parent);
}
/**
@ -151,7 +152,7 @@ public class NodeItemTest {
@Test
public void shouldThrowNPEWhenSetParentNull() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NullPointerException.class);
exception.expectMessage("parent");
//when
@ -165,7 +166,7 @@ public class NodeItemTest {
@Test
public void setParentShouldThrowNodeExceptionWhenParentIsSelf() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NodeException.class);
exception.expectMessage("Parent is a descendant");
//when
@ -179,15 +180,15 @@ public class NodeItemTest {
@Test
public void shouldUpdateOldParentWhenNodeSetToNewParent() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val child = node.createChild("child");
val newParent = new NodeItem<String>("newParent", Node::getData);
val newParent = new NodeItem<String>("newParent");
//when
child.setParent(newParent);
//then
assertThat(child.getParent()).as(
"when a node is assigned a new parent, the old parent is "
+ "replaced").isSameAs(newParent);
+ "replaced").contains(newParent);
assertThat(node.findChild("child").isPresent()).as(
"when a node is assigned a new parent, the old parent no "
+ "longer has the node among it's children").isFalse();
@ -200,16 +201,16 @@ public class NodeItemTest {
@Test
public void shouldRemoveNodeFromOldParentWhenAddedAsChildToNewParent() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val child = node.createChild("child");
val newParent = new NodeItem<String>("newParent", Node::getData);
val newParent = new NodeItem<String>("newParent");
//when
newParent.addChild(child);
//then
assertThat(child.getParent()).as(
"when a node with an existing parent is added as a child "
+ "to another node, then the old parent is replaced")
.isSameAs(newParent);
.contains(newParent);
assertThat(node.findChild("child").isPresent()).as(
"when a node with an existing parent is added as a child to "
+ "another node, then the old parent no longer has "
@ -222,7 +223,7 @@ public class NodeItemTest {
@Test
public void shouldThrowNPEWhenAddingNullAsChild() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NullPointerException.class);
exception.expectMessage("child");
//when
@ -236,8 +237,8 @@ public class NodeItemTest {
@SuppressWarnings("unchecked")
public void shouldReturnAddedChild() {
//given
node = new NodeItem<>("subject", Node::getData);
val child = new NodeItem<String>("child", Node::getData);
node = new NodeItem<>("subject");
val child = new NodeItem<String>("child");
//when
node.addChild(child);
//then
@ -252,7 +253,7 @@ public class NodeItemTest {
@Test
public void addChildShouldThrowNodeExceptionWhenAddingANodeAsOwnChild() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NodeException.class);
exception.expectMessage("Child is an ancestor");
//then
@ -265,7 +266,7 @@ public class NodeItemTest {
@Test
public void addChildShouldThrowNodeExceptionWhenAddingSelfAsChild() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NodeException.class);
exception.expectMessage("Child is an ancestor");
//when
@ -279,7 +280,7 @@ public class NodeItemTest {
@Test
public void addChildShouldThrowNodeExceptionWhenChildIsParent() {
//given
val parent = new NodeItem<String>("parent", Node::getData);
val parent = new NodeItem<String>("parent");
node = new NodeItem<>("subject", parent);
exception.expect(NodeException.class);
exception.expectMessage("Child is an ancestor");
@ -294,7 +295,7 @@ public class NodeItemTest {
@Test
public void addChildShouldThrowNodeExceptionWhenAddingGrandParentAsChild() {
//given
val grandParent = new NodeItem<String>("grandparent", Node::getData);
val grandParent = new NodeItem<String>("grandparent");
val parent = new NodeItem<String>("parent", grandParent);
node = new NodeItem<>("subject", parent);
exception.expect(NodeException.class);
@ -309,14 +310,14 @@ public class NodeItemTest {
@Test
public void shouldSetParentOnChildWhenAddedAsChild() {
//given
val child = new NodeItem<String>("child", Node::getData);
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val child = new NodeItem<String>("child");
//when
node.addChild(child);
//then
assertThat(child.getParent()).as(
"when a node is added as a child, the child has the node as "
+ "its parent").isSameAs(node);
+ "its parent").contains(node);
}
/**
@ -326,7 +327,7 @@ public class NodeItemTest {
public void shouldWalkTreeToNode() {
//given
val grandparent = "grandparent";
val grandParentNode = new NodeItem<String>(grandparent, Node::getData);
val grandParentNode = new NodeItem<String>(grandparent);
val parent = "parent";
val parentNode = new NodeItem<String>(parent, grandParentNode);
val subject = "subject";
@ -351,7 +352,7 @@ public class NodeItemTest {
public void shouldNotFindNonExistentChildNode() {
//given
val parent = "parent";
val parentNode = new NodeItem<String>(parent, Node::getData);
val parentNode = new NodeItem<String>(parent);
val subject = "subject";
node = new NodeItem<>(subject, parentNode);
//when
@ -368,7 +369,7 @@ public class NodeItemTest {
@Test
public void shouldThrowNEWhenWalkTreeNull() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NullPointerException.class);
exception.expectMessage("path");
//when
@ -382,7 +383,7 @@ public class NodeItemTest {
@Test
public void shouldReturnEmptyForEmptyWalkTreePath() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
//when
val result = node.findInPath(Collections.emptyList());
//then
@ -395,7 +396,7 @@ public class NodeItemTest {
@Test
public void shouldCreateDescendantNodes() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val alphaData = "alpha";
val betaData = "beta";
val gammaData = "gamma";
@ -411,7 +412,7 @@ public class NodeItemTest {
val alpha = alphaOptional.get();
assertThat(alpha.getParent()).as(
"when creating a descendant line, the first element has "
+ "the current node as its parent").isSameAs(node);
+ "the current node as its parent").contains(node);
val betaOptional = alpha.findChild(betaData);
assertThat(betaOptional.isPresent()).as(
"when creating a descendant line, the second element is "
@ -421,7 +422,7 @@ public class NodeItemTest {
assertThat(beta.getParent()).as(
"when creating a descendant line, the second element "
+ "has the first as its parent")
.isSameAs(alpha);
.contains(alpha);
val gammaOptional = beta.findChild(gammaData);
assertThat(gammaOptional.isPresent()).as(
"when creating a descendant line, the third element "
@ -431,7 +432,7 @@ public class NodeItemTest {
assertThat(gamma.getParent()).as(
"when creating a descendant line, the third "
+ "element has the second as its parent")
.isSameAs(beta);
.contains(beta);
}
}
}
@ -444,7 +445,7 @@ public class NodeItemTest {
@Test
public void createDescendantLineShouldThrowNPEWhenDescendantsAreNull() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NullPointerException.class);
exception.expectMessage("descendants");
//when
@ -457,7 +458,7 @@ public class NodeItemTest {
@Test
public void shouldChangeNothingWhenCreateDescendantEmpty() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
//when
node.createDescendantLine(Collections.emptyList());
//then
@ -472,7 +473,7 @@ public class NodeItemTest {
@Test
public void shouldFindExistingChildNode() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val childData = "child";
val child = new NodeItem<String>(childData, node);
//when
@ -489,14 +490,14 @@ public class NodeItemTest {
@Test
public void shouldFindCreateNewChildNode() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val childData = "child";
//when
val found = node.findOrCreateChild(childData);
//then
assertThat(found.getData()).as(
"when searching for a child by data, a new node is created")
.isSameAs(childData);
"when searching for a non-existent child by data, a new node "
+ "is created").contains(childData);
}
/**
@ -505,7 +506,7 @@ public class NodeItemTest {
@Test
public void findOrCreateChildShouldThrowNPEFWhenChildIsNull() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NullPointerException.class);
exception.expectMessage("child");
//when
@ -518,9 +519,9 @@ public class NodeItemTest {
@Test
public void shouldGetChild() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val childData = "child";
val child = new NodeItem<String>(childData, Node::getData);
val child = new NodeItem<String>(childData);
node.addChild(child);
//when
val found = node.findChild(childData);
@ -540,7 +541,7 @@ public class NodeItemTest {
@Test
public void getChildShouldThrowNPEWhenThereIsNoChild() {
//given
node = new NodeItem<>("data", Node::getData);
node = new NodeItem<>("data");
exception.expect(NullPointerException.class);
exception.expectMessage("child");
//when
@ -554,14 +555,14 @@ public class NodeItemTest {
@Test
public void shouldCreateChild() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
val childData = "child";
//when
val child = node.createChild(childData);
//then
assertThat(child.getParent()).as(
"when creating a child node, the child has the current node "
+ "as its parent").isSameAs(node);
+ "as its parent").contains(node);
val foundChild = node.findChild(childData);
assertThat(foundChild.isPresent()).as(
"when creating a child node, the child can be found by its "
@ -579,7 +580,7 @@ public class NodeItemTest {
@Test
public void createChildShouldThrowNPEWhenChildIsNull() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject");
exception.expect(NullPointerException.class);
exception.expectMessage("child");
//when
@ -589,7 +590,7 @@ public class NodeItemTest {
@Test
public void getNameShouldBeCorrect() {
//given
node = new NodeItem<>("subject", Node::getData);
node = new NodeItem<>("subject", n -> n.getData().get());
//then
assertThat(node.getName()).isEqualTo("subject");
}
@ -597,7 +598,7 @@ public class NodeItemTest {
@Test
public void getNameShouldUseParentNameSupplier() {
//given
val root = new NodeItem<String>("root", Node::getData);
val root = new NodeItem<String>("root", n -> n.getData().get());
node = new NodeItem<>("child", root);
//then
assertThat(node.getName()).isEqualTo("child");
@ -605,15 +606,20 @@ public class NodeItemTest {
@Test
public void getNameShouldReturnNameForNonStringData() {
val root = new NodeItem<LocalDate>(LocalDate.parse("2016-05-23"),
n -> n.getData().format(DateTimeFormatter.BASIC_ISO_DATE));
val root = new NodeItem<LocalDate>(LocalDate.parse("2016-05-23"), n -> {
if (n.isEmpty()) {
return null;
}
return n.getData().get().format(DateTimeFormatter.BASIC_ISO_DATE);
});
//then
assertThat(root.getName()).isEqualTo("20160523");
}
@Test
public void getNameShouldUseClosestNameSupplier() {
node = new NodeItem<>("root", Node::getData);
node = new NodeItem<>("root", n -> n.getData().get());
val child = new NodeItem<String>("child", Object::toString);
node.addChild(child);
val grandChild = new NodeItem<>("grandchild", child);
@ -635,13 +641,13 @@ public class NodeItemTest {
@Test
public void canCreateRootNodeWithoutData() {
node = new NodeItem<>(null, "empty");
assertThat(node.getData()).isNull();
assertThat(node.getData()).isEmpty();
}
@Test
public void canCreateRootNodeWithoutDataButWithNameSupplier() {
node = new NodeItem<>(null, Node::getData);
assertThat(node.getData()).isNull();
node = new NodeItem<>(null);
assertThat(node.getData()).isEmpty();
}
@Test
@ -693,14 +699,14 @@ public class NodeItemTest {
//when
node.insertInPath(four, "one", "two", "three");
//then
val three = four.getParent();
val three = four.getParent().get();
assertThat(four.getParent()).as("add node to a tree").isNotNull();
assertThat(three.getName()).isEqualTo("three");
val two = three.getParent();
val two = three.getParent().get();
assertThat(two.getName()).isEqualTo("two");
val one = two.getParent();
val one = two.getParent().get();
assertThat(one.getName()).isEqualTo("one");
assertThat(one.getParent()).isSameAs(node);
assertThat(one.getParent().get()).isSameAs(node);
assertThat(node.getChildByName("one")
.getChildByName("two")
.getChildByName("three")
@ -736,7 +742,7 @@ public class NodeItemTest {
node.insertInPath(child);
//then
assertThat(node.getChildByName("child").getData()).as("data in tree")
.isSameAs(
.contains(
"child data");
assertThat(
node.getChildByName("child").getChildByName("grandchild")).as(
@ -755,11 +761,12 @@ public class NodeItemTest {
public void removingParentFromNodeWithParentRemovesParent() {
//given
node = new NodeItem<>(null);
NodeItem<String> child = new NodeItem<>(null, node);
val child = new NodeItem<String>(null, node);
//when
child.removeParent();
//then
assertThat(child.getParent()).isNull();
assertThat(child.getParent()).isEmpty();
assertThat(node.getChildren()).isEmpty();
}
@Test
@ -800,7 +807,7 @@ public class NodeItemTest {
node.addChild(child);
child.addChild(target);
final NodeItem<String> addMe = new NodeItem<>("I'm new", "target");
assertThat(addMe.getParent()).isNull();
assertThat(addMe.getParent()).isEmpty();
assertThat(child.getChildByName("target").isEmpty()).as(
"target starts empty").isTrue();
//when
@ -808,7 +815,7 @@ public class NodeItemTest {
node.insertInPath(addMe, "child");
//then
assertThat(child.getChildByName("target").getData()).as(
"target now contains data").isEqualTo("I'm new");
"target now contains data").contains("I'm new");
}
@Test
@ -850,7 +857,7 @@ public class NodeItemTest {
// once a node has it's parent removed it should provide a default name
// provider
//given
node = new NodeItem<>("data", Node::getData); // name provider: getData
node = new NodeItem<>("data", n -> n.getData().get());
final NodeItem<String> child = new NodeItem<>("other", node);
assertThat(node.getName()).as("initial root name").isEqualTo("data");
assertThat(child.getName()).as("initial child name").isEqualTo("other");
@ -872,6 +879,7 @@ public class NodeItemTest {
node.removeChild(child);
//then
assertThat(node.getChildren()).isEmpty();
assertThat(child.getParent()).isEmpty();
}
@Test
@ -903,7 +911,7 @@ public class NodeItemTest {
//when
node.setData("updated");
//then
assertThat(node.getData()).isEqualTo("updated");
assertThat(node.getData()).contains("updated");
}
@Test
@ -915,7 +923,7 @@ public class NodeItemTest {
Node<String> child = node.createChild("child data", "child name");
//then
assertThat(child.getName()).isEqualTo("child name");
assertThat(child.getParent()).isSameAs(node);
assertThat(child.getParent()).contains(node);
assertThat(node.getChildren()).containsExactly(child);
}
@ -946,9 +954,9 @@ public class NodeItemTest {
//given
node = new NodeItem<>(null);
//when
NodeItem<String> child = new NodeItem<>(null, Node::getData, node);
NodeItem<String> child = new NodeItem<>(null, node);
//then
assertThat(child.getParent()).isSameAs(node);
assertThat(child.getParent()).contains(node);
assertThat(node.getChildren()).containsExactly(child);
}
@ -1019,11 +1027,11 @@ public class NodeItemTest {
public void canUseNameSupplierToBuildFullPath() {
//given
final Function<Node<String>, String> pathNameSupplier = node -> {
Node<String> parent = node.getParent();
if (parent == null) {
return "";
Optional<Node<String>> parent = node.getParent();
if (parent.isPresent()) {
return parent.get().getName() + "/" + node.getData().get();
}
return parent.getName() + "/" + node.getData();
return "";
};
node = new NodeItem<>(null, pathNameSupplier);
val child = new NodeItem<String>("child", node);
@ -1031,4 +1039,13 @@ public class NodeItemTest {
//then
assertThat(grandchild.getName()).isEqualTo("/child/grandchild");
}
@Test
public void canSafelyHandleFindChildWhenAChildHasNoData() {
//given
node = new NodeItem<>(null);
new NodeItem<>(null, node);
//when
node.findChild("data");
}
}