$handler
$handler
Creates a composed Guzzle handler function by stacking middlewares on top of an HTTP handler function.
create(?callable $handler = null) : self
Creates a default handler stack that can be used by clients.
The returned handler will wrap the provided handler or use the most appropriate default handler for your system. The returned HandlerStack has support for cookies, redirects, HTTP error exceptions, and preparing a body before sending.
The returned handler stack can be passed to a client in the "handler" option.
| ?callable | $handler |
__invoke(\Psr\Http\Message\RequestInterface $request, array $options) : \Psr\Http\Message\ResponseInterface|\GuzzleHttp\Promise\PromiseInterface
Invokes the handler stack as a composed handler
| \Psr\Http\Message\RequestInterface | $request | |
| array | $options |
<?php
namespace GuzzleHttp;
use GuzzleHttp\Promise\PromiseInterface;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;
/**
* Creates a composed Guzzle handler function by stacking middlewares on top of
* an HTTP handler function.
*
* @final
*/
class HandlerStack
{
/**
* @var null|callable(RequestInterface, array): PromiseInterface
*/
private $handler;
/**
* @var array{(callable(callable(RequestInterface, array): PromiseInterface): callable), (string|null)}[]
*/
private $stack = [];
/**
* @var null|callable(RequestInterface, array): PromiseInterface
*/
private $cached;
/**
* Creates a default handler stack that can be used by clients.
*
* The returned handler will wrap the provided handler or use the most
* appropriate default handler for your system. The returned HandlerStack has
* support for cookies, redirects, HTTP error exceptions, and preparing a body
* before sending.
*
* The returned handler stack can be passed to a client in the "handler"
* option.
*
* @param null|callable(RequestInterface, array): PromiseInterface $handler HTTP handler function to use with the stack. If no
* handler is provided, the best handler for your
* system will be utilized.
*/
public static function create(?callable $handler = null): self
{
$stack = new self($handler ?: Utils::chooseHandler());
$stack->push(Middleware::httpErrors(), 'http_errors');
$stack->push(Middleware::redirect(), 'allow_redirects');
$stack->push(Middleware::cookies(), 'cookies');
$stack->push(Middleware::prepareBody(), 'prepare_body');
return $stack;
}
/**
* @param null|callable(RequestInterface, array): PromiseInterface $handler Underlying HTTP handler.
*/
public function __construct(callable $handler = null)
{
$this->handler = $handler;
}
/**
* Invokes the handler stack as a composed handler
*
* @return ResponseInterface|PromiseInterface
*/
public function __invoke(RequestInterface $request, array $options)
{
$handler = $this->resolve();
return $handler($request, $options);
}
/**
* Dumps a string representation of the stack.
*
* @return string
*/
public function __toString()
{
$depth = 0;
$stack = [];
if ($this->handler !== null) {
$stack[] = "0) Handler: " . $this->debugCallable($this->handler);
}
$result = '';
foreach (\array_reverse($this->stack) as $tuple) {
$depth++;
$str = "{$depth}) Name: '{$tuple[1]}', ";
$str .= "Function: " . $this->debugCallable($tuple[0]);
$result = "> {$str}\n{$result}";
$stack[] = $str;
}
foreach (\array_keys($stack) as $k) {
$result .= "< {$stack[$k]}\n";
}
return $result;
}
/**
* Set the HTTP handler that actually returns a promise.
*
* @param callable(RequestInterface, array): PromiseInterface $handler Accepts a request and array of options and
* returns a Promise.
*/
public function setHandler(callable $handler): void
{
$this->handler = $handler;
$this->cached = null;
}
/**
* Returns true if the builder has a handler.
*/
public function hasHandler(): bool
{
return $this->handler !== null ;
}
/**
* Unshift a middleware to the bottom of the stack.
*
* @param callable(callable): callable $middleware Middleware function
* @param string $name Name to register for this middleware.
*/
public function unshift(callable $middleware, ?string $name = null): void
{
\array_unshift($this->stack, [$middleware, $name]);
$this->cached = null;
}
/**
* Push a middleware to the top of the stack.
*
* @param callable(callable): callable $middleware Middleware function
* @param string $name Name to register for this middleware.
*/
public function push(callable $middleware, string $name = ''): void
{
$this->stack[] = [$middleware, $name];
$this->cached = null;
}
/**
* Add a middleware before another middleware by name.
*
* @param string $findName Middleware to find
* @param callable(callable): callable $middleware Middleware function
* @param string $withName Name to register for this middleware.
*/
public function before(string $findName, callable $middleware, string $withName = ''): void
{
$this->splice($findName, $withName, $middleware, true);
}
/**
* Add a middleware after another middleware by name.
*
* @param string $findName Middleware to find
* @param callable(callable): callable $middleware Middleware function
* @param string $withName Name to register for this middleware.
*/
public function after(string $findName, callable $middleware, string $withName = ''): void
{
$this->splice($findName, $withName, $middleware, false);
}
/**
* Remove a middleware by instance or name from the stack.
*
* @param callable|string $remove Middleware to remove by instance or name.
*/
public function remove($remove): void
{
$this->cached = null;
$idx = \is_callable($remove) ? 0 : 1;
$this->stack = \array_values(\array_filter(
$this->stack,
static function ($tuple) use ($idx, $remove) {
return $tuple[$idx] !== $remove;
}
));
}
/**
* Compose the middleware and handler into a single callable function.
*
* @return callable(RequestInterface, array): PromiseInterface
*/
public function resolve(): callable
{
if ($this->cached === null) {
if (($prev = $this->handler) === null) {
throw new \LogicException('No handler has been specified');
}
foreach (\array_reverse($this->stack) as $fn) {
/** @var callable(RequestInterface, array): PromiseInterface $prev */
$prev = $fn[0]($prev);
}
$this->cached = $prev;
}
return $this->cached;
}
private function findByName(string $name): int
{
foreach ($this->stack as $k => $v) {
if ($v[1] === $name) {
return $k;
}
}
throw new \InvalidArgumentException("Middleware not found: $name");
}
/**
* Splices a function into the middleware list at a specific position.
*/
private function splice(string $findName, string $withName, callable $middleware, bool $before): void
{
$this->cached = null;
$idx = $this->findByName($findName);
$tuple = [$middleware, $withName];
if ($before) {
if ($idx === 0) {
\array_unshift($this->stack, $tuple);
} else {
$replacement = [$tuple, $this->stack[$idx]];
\array_splice($this->stack, $idx, 1, $replacement);
}
} elseif ($idx === \count($this->stack) - 1) {
$this->stack[] = $tuple;
} else {
$replacement = [$this->stack[$idx], $tuple];
\array_splice($this->stack, $idx, 1, $replacement);
}
}
/**
* Provides a debug string for a given callable.
*
* @param callable $fn Function to write as a string.
*/
private function debugCallable($fn): string
{
if (\is_string($fn)) {
return "callable({$fn})";
}
if (\is_array($fn)) {
return \is_string($fn[0])
? "callable({$fn[0]}::{$fn[1]})"
: "callable(['" . \get_class($fn[0]) . "', '{$fn[1]}'])";
}
/** @var object $fn */
return 'callable(' . \spl_object_hash($fn) . ')';
}
}