PHP实现一个轻量级容器

/**
* Describes the interface of a container that exposes methods to read its entries.
*/
interface ContainerInterface
{
/**
* Finds an entry of the container by its identifier and returns it.
*
* @param string $id Identifier of the entry to look for.
*
* @throws NotFoundExceptionInterface  No entry was found for **this** identifier.
* @throws ContainerExceptionInterface Error while retrieving the entry.
*
* @return mixed Entry.
*/
public function get($id);/**
* Returns true if the container can return an entry for the given identifier.
* Returns false otherwise.
*
* `has($id)` returning true does not mean that `get($id)` will not throw an exception.
* It does however mean that `get($id)` will not throw a `NotFoundExceptionInterface`.
*
* @param string $id Identifier of the entry to look for.
*
* @return bool
*/
public function has($id);
}

abstract class AbstractContainer implements ContainerInterface
{protected $resolvedEntries = [];/**
* @var array
*/
protected $definitions = [];public function __construct($definitions = [])
{
foreach ($definitions as $id => $definition) {
$this->injection($id, $definition);
}
}public function get($id)
{if (!$this->has($id)) {
throw new NotFoundException("No entry or class found for {$id}");
}$instance = $this->make($id);return $instance;
}public function has($id)
{
return isset($this->definitions[$id]);
}

public function make($name)
{
if (!is_string($name)) {
throw new \InvalidArgumentException(sprintf(
'The name parameter must be of type string, %s given',
is_object($name) ? get_class($name) : gettype($name)
));
}if (isset($this->resolvedEntries[$name])) {
return $this->resolvedEntries[$name];
}if (!$this->has($name)) {
throw new NotFoundException("No entry or class found for {$name}");
}$definition = $this->definitions[$name];
$params = [];
if (is_array($definition) && isset($definition['class'])) {
$params = $definition;
$definition = $definition['class'];
unset($params['class']);
}$object = $this->reflector($definition, $params);return $this->resolvedEntries[$name] = $object;
}public function reflector($concrete, array $params = [])
{
if ($concrete instanceof \Closure) {
return $concrete($params);
} elseif (is_string($concrete)) {
$reflection = new \ReflectionClass($concrete);
$dependencies = $this->getDependencies($reflection);
foreach ($params as $index => $value) {
$dependencies[$index] = $value;
}
return $reflection->newInstanceArgs($dependencies);
} elseif (is_object($concrete)) {
return $concrete;
}
}/**
* @param \ReflectionClass $reflection
* @return array
*/
private function getDependencies($reflection)
{
$dependencies = [];
$constructor = $reflection->getConstructor();
if ($constructor !== null) {
$parameters = $constructor->getParameters();
$dependencies = $this->getParametersByDependencies($parameters);
}return $dependencies;
}/**
*
* 获取构造类相关参数的依赖
* @param array $dependencies
* @return array $parameters
* */
private function getParametersByDependencies(array $dependencies)
{
$parameters = [];
foreach ($dependencies as $param) {
if ($param->getClass()) {
$paramName = $param->getClass()->name;
$paramObject = $this->reflector($paramName);
$parameters[] = $paramObject;
} elseif ($param->isArray()) {
if ($param->isDefaultValueAvailable()) {
$parameters[] = $param->getDefaultValue();
} else {
$parameters[] = [];
}
} elseif ($param->isCallable()) {
if ($param->isDefaultValueAvailable()) {
$parameters[] = $param->getDefaultValue();
} else {
$parameters[] = function ($arg) {
};
}
} else {
if ($param->isDefaultValueAvailable()) {
$parameters[] = $param->getDefaultValue();
} else {
if ($param->allowsNull()) {
$parameters[] = null;
} else {
$parameters[] = false;
}
}
}
}
return $parameters;
}

/**
* @param string $id
* @param string | array | callable $concrete
* @throws ContainerException
*/
public function injection($id, $concrete)
{
if (is_array($concrete) && !isset($concrete['class'])) {
throw new ContainerException('数组必须包含类定义');
}$this->definitions[$id] = $concrete;
}

class Container extends AbstractContainer implements \ArrayAccess
{public function offsetExists($offset)
{
return $this->has($offset);
}public function offsetGet($offset)
{
return $this->get($offset);
}public function offsetSet($offset, $value)
{
return $this->injection($offset, $value);
}public function offsetUnset($offset)
{
unset($this->resolvedEntries[$offset]);
unset($this->definitions[$offset]);
}
}