feat: add highlighter

src/Highlighter.php

@@ -0,0 +1,92 @@
+<?php
+
+namespace Ahc\CliSyntax;
+
+class Highlighter
+{
+    /** @var string The PHP code. */
+    protected $code;
+
+    /** @var bool Indicates if it has been already configured. */
+    protected static $configured;
+
+    public function __construct(string $code)
+    {
+        $this->code = $code;
+    }
+
+    public function __toString(): string
+    {
+        return $this->highlight();
+    }
+
+    public static function for(string $file): self
+    {
+        if (!\is_file($file)) {
+            throw new \InvalidArgumentException('The given file doesnot exist or is unreadable.');
+        }
+
+        return new static(\file_get_contents($file));
+    }
+
+    public function highlight(): string
+    {
+        static::configure();
+
+        $html = \highlight_string($this->code, true);
+        $html = \str_replace(['<br />', '<br/>', '<br>'], "\n", $html);
+
+        return $this->parse($html);
+    }
+
+    public function configure()
+    {
+        if (static::$configured) {
+            return;
+        }
+
+        foreach (['comment', 'default', 'html', 'keyword', 'string'] as $type) {
+            \ini_set("highlight.$type", \ini_get("highlight.$type") . \sprintf('" data-type="%s', $type));
+        }
+
+        static::$configured = true;
+    }
+
+    protected function parse(string $html): string
+    {
+        $str = '';
+        $dom = new \DOMDocument;
+
+        $dom->loadHTML($html);
+        foreach ($dom->getElementsByTagName('span') as $el) {
+            $str .= $this->visit($el);
+        }
+
+        return $str;
+    }
+
+    protected function visit(\DOMElement $el): string
+    {
+        if ('html' === $type = $el->getAttribute('data-type')) {
+            return '';
+        }
+
+        $text = $el->textContent;
+
+        $text = \str_replace(['&nbsp;', '&lt;', '&gt;'], [' ', '<', '>'], $text);
+
+        return $this->format($text, $type);
+    }
+
+    protected function format(string $text, string $type): string
+    {
+        static $formats = [
+            'comment' => "\033[1;30;40m%s\033[0m",
+            'default' => "\033[0;32;40m%s\033[0m",
+            'keyword' => "\033[0;36;40m%s\033[0m",
+            'string'  => "\033[0;33;40m%s\033[0m",
+        ];
+
+        return \sprintf($formats[$type] ?? '%s', $text);
+    }
+}