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Core interfaces and utilities for Blueprints
package com.tinkerpop.blueprints.util;
import com.tinkerpop.blueprints.Edge;
import com.tinkerpop.blueprints.Element;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public class ElementHelper {
/**
* Determines whether the property key/value for the specified element can be legally set.
* This is typically used as a pre-condition check prior to setting a property.
*
* @param element the element for the property to be set
* @param key the key of the property
* @param value the value of the property
* @throws IllegalArgumentException whether the triple is legal and if not, a clear reason message is provided
*/
public static final void validateProperty(final Element element, final String key, final Object value) throws IllegalArgumentException {
if (null == value)
throw ExceptionFactory.propertyValueCanNotBeNull();
if (null == key)
throw ExceptionFactory.propertyKeyCanNotBeNull();
if (key.equals(StringFactory.ID))
throw ExceptionFactory.propertyKeyIdIsReserved();
if (element instanceof Edge && key.equals(StringFactory.LABEL))
throw ExceptionFactory.propertyKeyLabelIsReservedForEdges();
if (key.isEmpty())
throw ExceptionFactory.propertyKeyCanNotBeEmpty();
}
/**
* Copy the properties (key and value) from one element to another.
* The properties are preserved on the from element.
* ElementPropertiesRule that share the same key on the to element are overwritten.
*
* @param from the element to copy properties from
* @param to the element to copy properties to
*/
public static void copyProperties(final Element from, final Element to) {
for (final String key : from.getPropertyKeys()) {
to.setProperty(key, from.getProperty(key));
}
}
/**
* Clear all the properties from an iterable of elements.
*
* @param elements the elements to remove properties from
*/
public static void removeProperties(final Iterable elements) {
for (final Element element : elements) {
final List keys = new ArrayList();
keys.addAll(element.getPropertyKeys());
for (final String key : keys) {
element.removeProperty(key);
}
}
}
/**
* Remove a property from all elements in the provided iterable.
*
* @param key the property to remove by key
* @param elements the elements to remove the property from
*/
public static void removeProperty(final String key, final Iterable elements) {
for (final Element element : elements) {
element.removeProperty(key);
}
}
/**
* Renames a property by removing the old key and adding the stored value to the new key.
* If property does not exist, nothing occurs.
*
* @param oldKey the key to rename
* @param newKey the key to rename to
* @param elements the elements to rename
*/
public static void renameProperty(final String oldKey, final String newKey, final Iterable elements) {
for (final Element element : elements) {
Object value = element.removeProperty(oldKey);
if (null != value)
element.setProperty(newKey, value);
}
}
/**
* Typecasts a property value. This only works for casting to a class that has a constructor of the for new X(String).
* If no such constructor exists, a RuntimeException is thrown and the original element property is left unchanged.
*
* @param key the key for the property value to typecast
* @param classCast the class to typecast to
* @param elements the elements to have their property typecasted
*/
public static void typecastProperty(final String key, final Class classCast, final Iterable elements) {
for (final Element element : elements) {
final Object value = element.removeProperty(key);
if (null != value) {
try {
element.setProperty(key, classCast.getConstructor(String.class).newInstance(value.toString()));
} catch (Exception e) {
element.setProperty(key, value);
throw new RuntimeException(e.getMessage(), e);
}
}
}
}
/**
* Determines whether two elements have the same properties.
* To be true, both must have the same property keys and respective values must be equals().
*
* @param a an element
* @param b an element
* @return whether the two elements have equal properties
*/
public static boolean haveEqualProperties(final Element a, final Element b) {
final Set aKeys = a.getPropertyKeys();
final Set bKeys = b.getPropertyKeys();
if (aKeys.containsAll(bKeys) && bKeys.containsAll(aKeys)) {
for (String key : aKeys) {
if (!a.getProperty(key).equals(b.getProperty(key)))
return false;
}
return true;
} else {
return false;
}
}
/**
* Get a clone of the properties of the provided element.
* In other words, a HashMap is created and filled with the key/values of the element's properties.
*
* @param element the element to get the properties of
* @return a clone of the properties of the element
*/
public static Map getProperties(final Element element) {
final Map properties = new HashMap();
for (final String key : element.getPropertyKeys()) {
properties.put(key, element.getProperty(key));
}
return properties;
}
/**
* Set the properties of the provided element using the provided map.
*
* @param element the element to set the properties of
* @param properties the properties to set as a Map
*/
public static void setProperties(final Element element, final Map properties) {
for (Map.Entry property : properties.entrySet()) {
element.setProperty(property.getKey(), property.getValue());
}
}
/**
* Set the properties of the provided element using the provided key value pairs.
* The var args of Objects must be divisible by 2. All odd elements in the array must be a String key.
*
* @param element the element to set the properties of
* @param keysValues the key value pairs of the properties
*/
public static void setProperties(final Element element, final Object... keysValues) {
if (keysValues.length % 2 != 0)
throw new IllegalArgumentException("The object var args must be divisible by 2");
for (int i = 0; i < keysValues.length; i = i + 2) {
element.setProperty((String) keysValues[i], keysValues[i + 1]);
}
}
/**
* A standard method for determining if two elements are equal.
* This method should be used by any Element.equals() implementation to ensure consistent behavior.
*
* @param a The first element
* @param b The second element (as an object)
* @return Whether the two elements are equal
*/
public static boolean areEqual(final Element a, final Object b) {
if (a == b)
return true;
if (null == b)
return false;
if (!a.getClass().equals(b.getClass()))
return false;
return a.getId().equals(((Element) b).getId());
}
}
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