Pipe improvements, misc cleanup

* Pipe improvements; better filter code, pipeline etc.
* Moved commands in PDO plugin to dedicated namespace

src/Pipe/Pipeline.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace Spark\Pipe;
+
+use Spark\Pipe\Filters\FilterInterface;
+
+class Pipeline
+{
+    
+    private $fdin;
+
+    private $fdout;
+
+    private array $filters = [];
+
+    public function setInputFile(string $filename)
+    {
+        if (ctype_digit($filename) && !file_exists($filename)) {
+            $filename = "php://fd/" . $filename;
+        }
+        $this->fdin = fopen($filename, 'rb');
+    }
+
+    public function setOutputFile(string $filename)
+    {
+        if (ctype_digit($filename) && !file_exists($filename)) {
+            $filename = "php://fd/" . $filename;
+        }
+        $this->fdout = fopen($filename, 'wb');
+    }
+
+    public function addFilter(FilterInterface $filter)
+    {
+        $this->filters[] = $filter;
+    }
+
+    public function run()
+    {
+        while (!feof($this->fdin)) {
+            ob_start();
+            $buf = fread($this->fdin, 8192);
+            foreach ($this->filters as $filter) {
+                $buf = $filter->pipe($buf);
+            }
+            ob_end_clean();
+            fwrite($this->fdout, $buf);
+        }
+        ob_start();
+        foreach ($this->filters as $filter) {
+            $filter->pipe(null);
+        }
+        ob_end_clean();
+    }
+
+}