My first commit of codes

vendor/psy/psysh/src/Psy/Output/ProcOutputPager.php

@@ -0,0 +1,103 @@
+<?php
+
+/*
+ * This file is part of Psy Shell
+ *
+ * (c) 2012-2014 Justin Hileman
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Psy\Output;
+
+use Symfony\Component\Console\Output\StreamOutput;
+
+/**
+ * ProcOutputPager class.
+ *
+ * A ProcOutputPager instance wraps a regular StreamOutput's stream. Rather
+ * than writing directly to the stream, it shells out to a pager process and
+ * gives that process the stream as stdout. This means regular *nix commands
+ * like `less` and `more` can be used to page large amounts of output.
+ */
+class ProcOutputPager extends StreamOutput implements OutputPager
+{
+    private $proc;
+    private $pipe;
+    private $stream;
+    private $cmd;
+
+    /**
+     * Constructor.
+     *
+     * @param StreamOutput $output
+     * @param string       $cmd    Pager process command (default: 'less -R -S -F -X')
+     */
+    public function __construct(StreamOutput $output, $cmd = 'less -R -S -F -X')
+    {
+        $this->stream = $output->getStream();
+        $this->cmd    = $cmd;
+    }
+
+    /**
+     * Writes a message to the output.
+     *
+     * @param string  $message A message to write to the output
+     * @param Boolean $newline Whether to add a newline or not
+     *
+     * @throws \RuntimeException When unable to write output (should never happen)
+     */
+    public function doWrite($message, $newline)
+    {
+        $pipe = $this->getPipe();
+        if (false === @fwrite($pipe, $message . ($newline ? PHP_EOL : ''))) {
+            // @codeCoverageIgnoreStart
+            // should never happen
+            throw new \RuntimeException('Unable to write output.');
+            // @codeCoverageIgnoreEnd
+        }
+
+        fflush($pipe);
+    }
+
+    /**
+     * Close the current pager process.
+     */
+    public function close()
+    {
+        if (isset($this->pipe)) {
+            fclose($this->pipe);
+        }
+
+        if (isset($this->proc)) {
+            $exit = proc_close($this->proc);
+            if ($exit !== 0) {
+                throw new \RuntimeException('Error closing output stream');
+            }
+        }
+
+        unset($this->pipe, $this->proc);
+    }
+
+    /**
+     * Get a pipe for paging output.
+     *
+     * If no active pager process exists, fork one and return its input pipe.
+     */
+    private function getPipe()
+    {
+        if (!isset($this->pipe) || !isset($this->proc)) {
+            $desc = array(array('pipe', 'r'), $this->stream, fopen('php://stderr', 'w'));
+            $this->proc = proc_open($this->cmd, $desc, $pipes);
+
+            if (!is_resource($this->proc)) {
+                throw new \RuntimeException('Error opening output stream');
+            }
+
+            $this->pipe = $pipes[0];
+        }
+
+        return $this->pipe;
+    }
+}