Template Format Used by SunLicense for Key Generation: Complete Guide

SunLicense uses a pattern-based template format where alphabetic characters (A-Z, a-z) represent random letters, digits (0-9) represent random numbers, and any other characters (like hyphens) are inserted verbatim as separators.

The msbatal/php-license-key-generator repository implements this template system in the SunLicense class to generate structured license keys. The template format used by SunLicense for key generation acts as a blueprint that defines both the length and the visual structure of every generated key, including where random alphanumeric characters appear and where static separators divide the segments.

Understanding the SunLicense Template Syntax

SunLicense interprets templates using three distinct symbol categories. Each character in the template string maps to a specific generation rule:

• Alphabetic characters (A-Z or a-z) — Generate a random letter. The case of the generated letter follows the $case property, which defaults to upper but can be set to lower.
• Digit characters (0-9) — Generate a random numeric digit from 0 to 9.
• Any other character — Inserted exactly as written. Hyphens (-) are commonly used here to create visual separators between key segments.

Default Template Structure

In SunLicense.php at line 31, the class declares a default template that produces a standard 25-character key divided into four groups:

private $template = 'X9XX99-XX99-9X9X-99XX9X';

This template generates keys matching the pattern XXXXXX-XXXX-XXXX-XXXXXX, where each X represents a random letter and each 9 represents a random digit. For example, a generated key might look like AB7CD9-EF12-3GH4-56IJ7K.

How SunLicense Generates Keys from Templates

The generation logic resides in the license() method (lines 84–96 of SunLicense.php). This method iterates over every character in the template string and applies conditional logic based on regular expression matching:

1. Letter detection — If the character matches /[a-zA-Z]/, the method generates a random letter using chr(rand(65,90)) for uppercase or chr(rand(97,122)) for lowercase.
2. Digit detection — If the character matches /\d/, the method generates a random digit using rand(0,9).
3. Separator preservation — Any character that fails both checks (such as hyphens) is appended to the key unchanged.

This approach ensures that the template format used by SunLicense for key generation is both flexible and deterministic—you control the exact length and visual grouping of keys while the randomness fills in the alphanumeric placeholders.

Practical Code Examples

Generate a Single Key with the Default Template

The following example uses the default uppercase template defined in SunLicense.php:

require 'SunLicense.php';

$generator = new SunLicense();
$key = $generator->generate();
echo $key;  // Output: AB7CD9-EF12-3GH4-56IJ7K

Create Lowercase Keys with a Custom Template

To generate lowercase keys with a specific pattern, pass a custom template and set the case parameter to lower:

require 'SunLicense.php';

$customTemplate = 'xx-99-XX-999';
$generator = new SunLicense(null, $customTemplate, 'lower', 5);
$keys = $generator->generate();
print_r($keys);
// Output: Array containing 5 keys like "ab-12-cd-345"

Add a Product Prefix to Generated Keys

You can prepend a static product code to every generated key by passing a prefix as the first constructor argument:

require 'SunLicense.php';

$generator = new SunLicense('PROD');
$key = $generator->generate();
echo $key;  // Output: PROD-AB7CD9-EF12-3GH4-56IJ7K

Summary

• SunLicense uses a template string to define the structure of generated license keys, where alphabetic characters represent random letters, digits represent random numbers, and all other characters appear as literal separators.
• The default template 'X9XX99-XX99-9X9X-99XX9X' produces a 25-character key divided into four hyphen-separated groups.
• The license() method in SunLicense.php (lines 84–96) implements the generation logic using regular expressions to distinguish between letters (/[a-zA-Z]/), digits (/\d/), and separator characters.
• Developers can customize the template format, change the letter case (upper or lower), add prefixes, and generate multiple keys in a single call.

Frequently Asked Questions

What characters can I use in a SunLicense template?

You can use any combination of alphabetic characters (A-Z, a-z), digits (0-9), and special characters in your template. Letters generate random alphabetic characters, digits generate random numbers, and any other character (such as hyphens, dots, or underscores) is inserted exactly as written to serve as a separator or delimiter.

How do I create lowercase license keys with SunLicense?

To generate lowercase keys, instantiate the SunLicense class with the third parameter set to 'lower'. The constructor signature is SunLicense($prefix, $template, $case, $count), so you would call new SunLicense(null, 'XXXX-XXXX', 'lower', 1). When the case is set to lower, alphabetic template characters produce random lowercase letters using chr(rand(97,122)) instead of the default uppercase chr(rand(65,90)).

Can I use custom separators in the template format?

Yes, the template format used by SunLicense for key generation supports any non-alphanumeric character as a custom separator. While hyphens (-) are the most common choice for readability, you can use dots (.), underscores (_), slashes (/), or any other symbol. These characters are preserved verbatim in the final output, allowing you to create keys formatted like XXXX.XXXX.XXXX or XX_XX_XX_XX depending on your requirements.

Where is the license generation logic implemented in the source code?

The core generation logic is implemented in the license() method located at lines 84–96 of SunLicense.php. This method iterates over each character of the template string, applies regular expression checks to determine if the character is a letter (/[a-zA-Z]/) or digit (/\d/), and generates the corresponding random character using chr() and rand() functions. The default template itself is defined as a private property at line 31 of the same file.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}