--- /dev/null
+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the MIT license. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\Common\Collections;
+
+use Closure;
+
+/**
+ * Lazy collection that is backed by a concrete collection
+ *
+ * @author Michaƫl Gallego <mic.gallego@gmail.com>
+ * @since 1.2
+ */
+abstract class AbstractLazyCollection implements Collection
+{
+ /**
+ * The backed collection to use
+ *
+ * @var Collection
+ */
+ protected $collection;
+
+ /**
+ * @var boolean
+ */
+ protected $initialized = false;
+
+ /**
+ * {@inheritDoc}
+ */
+ public function count()
+ {
+ $this->initialize();
+ return $this->collection->count();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function add($element)
+ {
+ $this->initialize();
+ return $this->collection->add($element);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function clear()
+ {
+ $this->initialize();
+ $this->collection->clear();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function contains($element)
+ {
+ $this->initialize();
+ return $this->collection->contains($element);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function isEmpty()
+ {
+ $this->initialize();
+ return $this->collection->isEmpty();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function remove($key)
+ {
+ $this->initialize();
+ return $this->collection->remove($key);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function removeElement($element)
+ {
+ $this->initialize();
+ return $this->collection->removeElement($element);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function containsKey($key)
+ {
+ $this->initialize();
+ return $this->collection->containsKey($key);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function get($key)
+ {
+ $this->initialize();
+ return $this->collection->get($key);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function getKeys()
+ {
+ $this->initialize();
+ return $this->collection->getKeys();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function getValues()
+ {
+ $this->initialize();
+ return $this->collection->getValues();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function set($key, $value)
+ {
+ $this->initialize();
+ $this->collection->set($key, $value);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function toArray()
+ {
+ $this->initialize();
+ return $this->collection->toArray();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function first()
+ {
+ $this->initialize();
+ return $this->collection->first();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function last()
+ {
+ $this->initialize();
+ return $this->collection->last();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function key()
+ {
+ $this->initialize();
+ return $this->collection->key();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function current()
+ {
+ $this->initialize();
+ return $this->collection->current();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function next()
+ {
+ $this->initialize();
+ return $this->collection->next();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function exists(Closure $p)
+ {
+ $this->initialize();
+ return $this->collection->exists($p);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function filter(Closure $p)
+ {
+ $this->initialize();
+ return $this->collection->filter($p);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function forAll(Closure $p)
+ {
+ $this->initialize();
+ return $this->collection->forAll($p);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function map(Closure $func)
+ {
+ $this->initialize();
+ return $this->collection->map($func);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function partition(Closure $p)
+ {
+ $this->initialize();
+ return $this->collection->partition($p);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function indexOf($element)
+ {
+ $this->initialize();
+ return $this->collection->indexOf($element);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function slice($offset, $length = null)
+ {
+ $this->initialize();
+ return $this->collection->slice($offset, $length);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function getIterator()
+ {
+ $this->initialize();
+ return $this->collection->getIterator();
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function offsetExists($offset)
+ {
+ $this->initialize();
+ return $this->collection->offsetExists($offset);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function offsetGet($offset)
+ {
+ $this->initialize();
+ return $this->collection->offsetGet($offset);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function offsetSet($offset, $value)
+ {
+ $this->initialize();
+ $this->collection->offsetSet($offset, $value);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ public function offsetUnset($offset)
+ {
+ $this->initialize();
+ $this->collection->offsetUnset($offset);
+ }
+
+ /**
+ * Is the lazy collection already initialized?
+ *
+ * @return bool
+ */
+ public function isInitialized()
+ {
+ return $this->initialized;
+ }
+
+ /**
+ * Initialize the collection
+ *
+ * @return void
+ */
+ protected function initialize()
+ {
+ if ( ! $this->initialized) {
+ $this->doInitialize();
+ $this->initialized = true;
+ }
+ }
+
+ /**
+ * Do the initialization logic
+ *
+ * @return void
+ */
+ abstract protected function doInitialize();
+}