Remove PoolClient, simplify parser

This also drops support for header lines delimited with \n instead of \r\n.

lib/Client.php

@@ -22,4 +22,15 @@ public function request(
         Request $request,
         CancellationToken $cancellation = null
     ): Promise;
+
+    /**
+     * Adds a network interceptor.
+     *
+     * Whether the given network interceptor will be respected for currently running requests is undefined.
+     *
+     * Any new requests have to take the new interceptor into account.
+     *
+     * @param NetworkInterceptor $networkInterceptor
+     */
+    public function addNetworkInterceptor(NetworkInterceptor $networkInterceptor): void;
 }

lib/ClientBuilder.php

@@ -3,7 +3,6 @@
 namespace Amp\Http\Client;
 
 use Amp\Http\Client\Internal\ApplicationInterceptorClient;
-use Amp\Http\Client\Internal\PoolClient;
 use Amp\Socket\SocketPool;
 use Amp\Socket\UnlimitedSocketPool;
 
@@ -34,7 +33,10 @@ public function addApplicationInterceptor(ApplicationInterceptor $applicationInt
 
     public function build(): Client
     {
-        $client = new PoolClient($this->socketPool, ...$this->networkInterceptors);
+        $client = new SocketClient($this->socketPool);
+        foreach ($this->networkInterceptors as $networkInterceptor) {
+            $client->addNetworkInterceptor($networkInterceptor);
+        }
 
         $applicationInterceptors = $this->applicationInterceptors;
         while ($applicationInterceptor = \array_pop($applicationInterceptors)) {

lib/Internal/ApplicationInterceptorClient.php

@@ -5,6 +5,7 @@
 use Amp\CancellationToken;
 use Amp\Http\Client\ApplicationInterceptor;
 use Amp\Http\Client\Client;
+use Amp\Http\Client\NetworkInterceptor;
 use Amp\Http\Client\Request;
 use Amp\NullCancellationToken;
 use Amp\Promise;
@@ -31,4 +32,9 @@ public function request(Request $request, CancellationToken $cancellation = null
 
         return $this->interceptor->interceptApplicationRequest($request, $cancellation, $this->client);
     }
+
+    public function addNetworkInterceptor(NetworkInterceptor $networkInterceptor): void
+    {
+        throw new \RuntimeException('Operation not supported');
+    }
 }

lib/Internal/CallableNetworkClient.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Amp\Http\Client\Internal;
+
+use Amp\CancellationToken;
+use Amp\Failure;
+use Amp\Http\Client\Client;
+use Amp\Http\Client\HttpException;
+use Amp\Http\Client\NetworkInterceptor;
+use Amp\Http\Client\Request;
+use Amp\Promise;
+use function Amp\call;
+
+class CallableNetworkClient implements Client
+{
+    private $callable;
+
+    public function __construct(callable $callable)
+    {
+        $this->callable = $callable;
+    }
+
+    public function request(Request $request, CancellationToken $cancellation = null): Promise
+    {
+        $callable = $this->callable;
+        $this->callable = null;
+
+        if ($callable === null) {
+            return new Failure(new HttpException(__METHOD__ . ' may only be invoked once per instance. '
+                . 'If you need to implement retries or otherwise issue multiple requests, register an ApplicationInterceptor to do so.'));
+        }
+
+        return call($callable);
+    }
+
+    public function addNetworkInterceptor(NetworkInterceptor $networkInterceptor): void
+    {
+        throw new \RuntimeException('Operation not supported');
+    }
+}

lib/Internal/NetworkInterceptorClient.php

@@ -43,4 +43,9 @@ public function request(Request $request, CancellationToken $cancellation = null
 
         return $interceptor->interceptNetworkRequest($request, $cancellation, $this->connectionInfo, $next);
     }
+
+    public function addNetworkInterceptor(NetworkInterceptor $networkInterceptor): void
+    {
+        throw new \RuntimeException('Operation not supported');
+    }
 }