Alto Language Detector

A blazing-fast, pluggable PHP library to identify the programming language of a code snippet using a smart heuristic engine.

Lightweight, extensible, and battle-tested for 12 of the most popular languages today.

Features

• High-precision detection with confidence scoring
• Heuristics-based engine using language-specific markers, keywords & patterns
• PHP-optimized: Uses the native tokenizer for unmatched accuracy
• Extensible: Add your own languages in seconds
• Zero dependencies, ultra-light footprint

🧠 How It Works

The detector computes a score for each supported language based on:

• Markers: Unique syntax signatures (e.g., fn main() in Rust)
• Keywords: Common language-specific tokens (e.g., let, function)
• Regex patterns: Structural indicators (e.g., arrow functions, tag formats)
• Negative markers: Penalize false positives (e.g., class in procedural snippets)
• PHP tokenizer: Leveraged when <?php is found for definitive detection

Each snippet is scored and the most likely language is returned with a confidence value between 0 and 1.

✅ Supported Languages

css, go, html, java, javascript, php, python, ruby, svg, twig, typescript, xml

Want more? Add your own with just one file.

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📦 Installation

composer require alto/language-detector

---

🧪 Usage

use Alto\LanguageDetector\LanguageDetector;

$detector = new LanguageDetector();
$code = '<?php echo "Hello!";';

$result = $detector->detect($code);

if ($result->getLanguage()) {
    echo "Language: {$result->getLanguage()} ({$result->getConfidence()})";
} else {
    echo "Could not confidently detect language.";
}

---

🔍 Example Output

Code Sample	Detected Language	Confidence
<?php echo "Hi";	php	0.98
console.log("Hello")	javascript	0.87
public class Hello {}	java	0.94
fn main() {}	go	0.81
??? (ambiguous snippet)	none	< 0.25

---

🛠 Adding a Language

Just drop a file in data/language/yourlang.php:

return [
    'rust' => [
        'markers' => [ 'fn main()' => 10 ],
        'keywords' => [ 'let ' => 2, 'impl ' => 3 ],
        'patterns' => [ '/fn\\s+\\w+\\s*\\(.*\\)/' => 4 ],
        'negative_keywords' => [ 'function(' => -5 ],
    ]
];

The detector will load it automatically. No extra config needed.

---

🔧 Custom Profiles

Use your own language definitions:

$detector = new LanguageDetector('/my/custom/profiles.php');
// or a directory of profile files
$detector = new LanguageDetector('/profiles/');

📘 API Reference

LanguageDetector

• __construct(?string $profilesPath = null)
• detect(string $code): DetectionResult

DetectionResult

• getLanguage(): ?string
• getConfidence(): float
• isDefinitive(): bool

🏎 Performance Tips

• ✅ Larger snippets = better results
• ✅ PHP detection uses tokenizer, not heuristics
• ✅ Profiles are cached in memory
• ❌ Avoid mixing multiple languages in one snippet

🧱 Limitations

• Not designed for multi-language files (e.g., HTML+JS)
• May confuse dialects (e.g., Java vs. C#)
• Template engines (like Twig) are heuristically supported, not parsed

🤝 Contributing

Issues, improvements, and new profiles are welcome via pull requests.

🪪 License

MIT — see LICENSE.

Made with ❤️ by the Alto project team.