k-kinzal / lemon-parser

dev-main 2026-09-28 02:32 UTC

Requires

• php: ^8.1

Requires (Dev)

• behat/behat: ^3.14
• brianium/paratest: ^7.3
• deptrac/deptrac: ^3.0
• friendsofphp/php-cs-fixer: ^3.95.25
• k-kinzal/php-ai-toolkit: dev-main
• phpbench/phpbench: ^1.4
• phpcompatibility/php-compatibility: ^10.0.0-alpha2
• phpstan/phpstan: ^2.1
• phpstan/phpstan-strict-rules: ^2.0
• phpunit/phpunit: ^10.5
• squizlabs/php_codesniffer: ^4.0.4

MIT

Published on Packagist.org on 2026-09-28 02:32 UTC

README

Lemon Parser reads grammar files of the Lemon parser generator into a syntax tree that keeps everything the file says, with the position of each part. It reads the language the Lemon manual defines, so a file Lemon accepts is read as Lemon reads it and a file Lemon rejects raises an error with Lemon's message. The manual is the specification, and spec/features states it clause by clause as scenarios that run the parser.

It reads grammars; it does not generate parsers. The tree is for tools that analyse, transform, document or generate from Lemon grammars.

Requirements

• PHP 8.1+

Installation

composer require k-kinzal/lemon-parser

Usage

%ifdef regions are settled with the names passed to parse(), as Lemon's -D option does.

use LemonParser\Parser;

$file = (new Parser())->parse(file_get_contents('parse.y'), ['SQLITE_OMIT_WINDOWFUNC']);

foreach ($file->rules() as $rule) {
    echo $rule->lhs->name, ' ::=';
    foreach ($rule->items as $item) {
        echo ' ', implode('|', array_map(fn ($symbol) => $symbol->name, $item->symbols));
    }
    echo $rule->precedence === null ? '' : " [{$rule->precedence->name}]", "\n";
}
foreach ($file->declarations() as $declaration) {
    echo $declaration::class, ' at ', $declaration->location(), "\n";
}

A tree prints back as a grammar file, and printing is stable, which is how a tree can be checked:

use LemonParser\Printer\Printer;

$text = (new Printer())->print($file);

Every node of the tree is described in the API documentation.

License

MIT License. See LICENSE for details.