org.apache.jackrabbit.oak.plugins.memory

Class EmptyNodeState

java.lang.Object

org.apache.jackrabbit.oak.plugins.memory.EmptyNodeState

All Implemented Interfaces:

NodeState

public final class EmptyNodeState
extends java.lang.Object
implements NodeState

Singleton instances of empty and non-existent node states, i.e. ones with neither properties nor child nodes.

Field Summary

Fields

Modifier and Type	Field and Description
static NodeState	EMPTY_NODE
static NodeState	MISSING_NODE

Fields inherited from interface org.apache.jackrabbit.oak.spi.state.NodeState

EXISTS

Method Summary

Modifier and Type	Method and Description
@NotNull NodeBuilder	builder() Returns a builder for constructing a new node state based on this state, i.e.
boolean	compareAgainstBaseState(NodeState base, NodeStateDiff diff) Compares this node state against the given base state.
static boolean	compareAgainstEmptyState(NodeState state, NodeStateDiff diff)
boolean	equals(java.lang.Object object)
boolean	exists() Checks whether this node exists.
boolean	getBoolean(@NotNull java.lang.String name) Returns the boolean value of the named property.
@NotNull NodeState	getChildNode(@NotNull java.lang.String name) Returns the named, possibly non-existent, child node.
long	getChildNodeCount(long max) Returns the number of iterable child nodes of this node.
@NotNull java.lang.Iterable<? extends ChildNodeEntry>	getChildNodeEntries() Returns the iterable child node entries of this instance.
java.lang.Iterable<java.lang.String>	getChildNodeNames() Returns the names of all iterable child nodes.
long	getLong(java.lang.String name) Returns the long value of the named property.
@Nullable java.lang.String	getName(@NotNull java.lang.String name) Returns the name value of the named property.
@NotNull java.lang.Iterable<java.lang.String>	getNames(@NotNull java.lang.String name) Returns the name values of the named property.
@NotNull java.lang.Iterable<? extends PropertyState>	getProperties() Returns an iterable of the properties of this node.
@Nullable PropertyState	getProperty(@NotNull java.lang.String name) Returns the named property, or null if no such property exists.
long	getPropertyCount() Returns the number of properties of this node.
java.lang.String	getString(java.lang.String name) Returns the string value of the named property.
@NotNull java.lang.Iterable<java.lang.String>	getStrings(@NotNull java.lang.String name) Returns the string values of the named property.
boolean	hasChildNode(@NotNull java.lang.String name) Checks whether the named child node exists.
int	hashCode()
boolean	hasProperty(@NotNull java.lang.String name) Checks whether the named property exists.
static boolean	isEmptyState(NodeState state)
java.lang.String	toString()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

EMPTY_NODE

public static final NodeState EMPTY_NODE

MISSING_NODE

public static final NodeState MISSING_NODE

Method Detail

exists

public boolean exists()

Description copied from interface: NodeState

Checks whether this node exists. See the above discussion about the existence of node states.

Specified by:

exists in interface NodeState

Returns:

true if this node exists, false if not

getPropertyCount

public long getPropertyCount()

Description copied from interface: NodeState

Returns the number of properties of this node.

Specified by:

getPropertyCount in interface NodeState

Returns:

number of properties

hasProperty

public boolean hasProperty(@NotNull
                           @NotNull java.lang.String name)

Description copied from interface: NodeState

Checks whether the named property exists. The implementation is equivalent to getProperty(name) != null, but may be optimized to avoid having to load the property value.

Specified by:

hasProperty in interface NodeState

Parameters:

name - property name

Returns:

true if the named property exists, false otherwise

getProperty

@Nullable
public @Nullable PropertyState getProperty(@NotNull
                                                     @NotNull java.lang.String name)

Description copied from interface: NodeState

Returns the named property, or null if no such property exists.

Specified by:

getProperty in interface NodeState

Parameters:

name - name of the property to return

Returns:

named property, or null if not found

getBoolean

public boolean getBoolean(@NotNull
                          @NotNull java.lang.String name)

Description copied from interface: NodeState

Returns the boolean value of the named property. The implementation is equivalent to the following code, but may be optimized.

 
 PropertyState property = state.getProperty(name);
 return property != null
     && property.getType() == Type.BOOLEAN
     && property.getValue(Type.BOOLEAN);
 
 

Specified by:

getBoolean in interface NodeState

Parameters:

name - property name

Returns:

boolean value of the named property, or false

getLong

public long getLong(java.lang.String name)

Description copied from interface: NodeState

Returns the long value of the named property. The implementation is equivalent to the following code, but may be optimized.

 
 PropertyState property = state.getProperty(name);
 if (property != null && property.getType() == Type.LONG) {
     return property.getValue(Type.LONG);
 } else {
     return 0;
 }
 
 

Specified by:

getLong in interface NodeState

Parameters:

name - property name

Returns:

long value of the named property, or zero

getString

public java.lang.String getString(java.lang.String name)

Description copied from interface: NodeState

Returns the string value of the named property. The implementation is equivalent to the following code, but may be optimized.

 
 PropertyState property = state.getProperty(name);
 if (property != null && property.getType() == Type.STRING) {
     return property.getValue(Type.STRING);
 } else {
     return null;
 }
 
 

Specified by:

getString in interface NodeState

Parameters:

name - property name

Returns:

string value of the named property, or null

getStrings

@NotNull
public @NotNull java.lang.Iterable<java.lang.String> getStrings(@NotNull
                                                                         @NotNull java.lang.String name)

Description copied from interface: NodeState

Returns the string values of the named property. The implementation is equivalent to the following code, but may be optimized.

 
 PropertyState property = state.getProperty(name);
 if (property != null && property.getType() == Type.STRINGS) {
     return property.getValue(Type.STRINGS);
 } else {
     return Collections.emptyList();
 }
 
 

Specified by:

getStrings in interface NodeState

Parameters:

name - property name

Returns:

string values of the named property, or an empty collection

getName

@Nullable
public @Nullable java.lang.String getName(@NotNull
                                                    @NotNull java.lang.String name)

Description copied from interface: NodeState

Returns the name value of the named property. The implementation is equivalent to the following code, but may be optimized.

 
 PropertyState property = state.getProperty(name);
 if (property != null && property.getType() == Type.NAME) {
     return property.getValue(Type.NAME);
 } else {
     return null;
 }
 
 

Specified by:

getName in interface NodeState

Parameters:

name - property name

Returns:

name value of the named property, or null

getNames

@NotNull
public @NotNull java.lang.Iterable<java.lang.String> getNames(@NotNull
                                                                       @NotNull java.lang.String name)

Description copied from interface: NodeState

Returns the name values of the named property. The implementation is equivalent to the following code, but may be optimized.

 
 PropertyState property = state.getProperty(name);
 if (property != null && property.getType() == Type.NAMES) {
     return property.getValue(Type.NAMES);
 } else {
     return Collections.emptyList();
 }
 
 

Specified by:

getNames in interface NodeState

Parameters:

name - property name

Returns:

name values of the named property, or an empty collection

getProperties

@NotNull
public @NotNull java.lang.Iterable<? extends PropertyState> getProperties()

Description copied from interface: NodeState

Returns an iterable of the properties of this node. Multiple iterations are guaranteed to return the properties in the same order, but the specific order used is implementation-dependent and may change across different states of the same node.

Specified by:

getProperties in interface NodeState

Returns:

properties in some stable order

getChildNodeCount

public long getChildNodeCount(long max)

Description copied from interface: NodeState

Returns the number of iterable child nodes of this node.

If an implementation knows the exact value, it returns it (even if the value is higher than max). If the implementation does not know the exact value, and the child node count is higher than max, it may return Long.MAX_VALUE. The cost of the operation is at most O(max).

Specified by:

getChildNodeCount in interface NodeState

Parameters:

max - the maximum number of entries to traverse

Returns:

number of iterable child nodes

hasChildNode

public boolean hasChildNode(@NotNull
                            @NotNull java.lang.String name)

Description copied from interface: NodeState

Checks whether the named child node exists. The implementation is equivalent to getChildNode(name).exists(), except that passing an invalid name as argument will result in a false return value instead of an IllegalArgumentException.

Specified by:

hasChildNode in interface NodeState

Parameters:

name - name of the child node

Returns:

true if the named child node exists, false otherwise

getChildNode

@NotNull
public @NotNull NodeState getChildNode(@NotNull
                                                @NotNull java.lang.String name)

Description copied from interface: NodeState

Returns the named, possibly non-existent, child node. Use the NodeState.exists() method on the returned child node to determine whether the node exists or not.

Specified by:

getChildNode in interface NodeState

Parameters:

name - name of the child node to return

Returns:

named child node

getChildNodeNames

public java.lang.Iterable<java.lang.String> getChildNodeNames()

Description copied from interface: NodeState

Returns the names of all iterable child nodes.

Specified by:

getChildNodeNames in interface NodeState

Returns:

child node names in some stable order

getChildNodeEntries

@NotNull
public @NotNull java.lang.Iterable<? extends ChildNodeEntry> getChildNodeEntries()

Description copied from interface: NodeState

Returns the iterable child node entries of this instance. Multiple iterations are guaranteed to return the child nodes in the same order, but the specific order used is implementation dependent and may change across different states of the same node.

Note on cost and performance: while it is possible to iterate over all child NodeStates with the two methods NodeState.getChildNodeNames() and NodeState.getChildNode(String), this method is considered more efficient because an implementation can potentially perform the retrieval of the name and NodeState in one call. This results in O(n) vs. O(n log n) when iterating over the child node names and then look up the NodeState by name.

Specified by:

getChildNodeEntries in interface NodeState

Returns:

child node entries in some stable order

builder

@NotNull
public @NotNull NodeBuilder builder()

Description copied from interface: NodeState

Returns a builder for constructing a new node state based on this state, i.e. starting with all the properties and child nodes of this state.

Specified by:

builder in interface NodeState

Returns:

node builder based on this state

compareAgainstBaseState

public boolean compareAgainstBaseState(NodeState base,
                                       NodeStateDiff diff)

Description copied from interface: NodeState

Compares this node state against the given base state. Any differences are reported by calling the relevant added/changed/deleted methods of the given handler.

TODO: Define the behavior of this method with regards to iterability/existence of child nodes.

Specified by:

compareAgainstBaseState in interface NodeState

Parameters:

base - base state

diff - handler of node state differences

Returns:

true if the full diff was performed, or false if it was aborted as requested by the handler (see the NodeStateDiff contract for more details)

compareAgainstEmptyState

public static boolean compareAgainstEmptyState(NodeState state,
                                               NodeStateDiff diff)

isEmptyState

public static boolean isEmptyState(NodeState state)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object object)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object