An intuitive, small, and fast regular expression helper for PHP 8.3+ with clean result objects and a few ergonomic utilities around PCRE.

Package: liquidrazor/liquid-regex • License: MIT

• Fluent, tiny API for matching and replacing.
• Lazy, rewindable match results with Iterator, ArrayAccess, Countable, and JsonSerializable support.
• Deterministic result shapes via ResultTypes (numeric, associative, or both) and a STRICT filter.
• PCRE helpers to check version/JIT support and validate pattern syntax.
• Exceptions you can catch with informative messages bubbled from PCRE.

• PHP 8.3 or newer
• PCRE (bundled with PHP)

composer require liquidrazor/regex

The library is namespaced under LiquidRazor\Regex and PSR‑4 autoloaded per composer.json.

The Regex class is the main façade. It also memoizes compiled instances by pattern:

use LiquidRazor\Regex\Regex;

$re = Regex::compiled('/(?P<word>[a-z]+)/i');

From there you can match or replace (see examples below).

Choose how match arrays are exposed:

use LiquidRazor\Regex\Result\ResultTypes;

// Types
ResultTypes::INDEXED;      // numeric keys only (0, 1, 2, ...)
ResultTypes::ASSOCIATIVE;  // named keys only ('foo', 'bar', ...)
ResultTypes::BOTH;         // default: include both kinds

// Modifier
ResultTypes::STRICT;       // when used, filters to "pure" keys only:
//   - with INDEXED: keeps only truly integer keys (0,1,2...)
//   - with ASSOCIATIVE: keeps only truly string, non-numeric keys

This lets you request exactly the view you need (e.g., only named groups). You can bit‑OR flags:

$flags = ResultTypes::ASSOCIATIVE | ResultTypes::STRICT;

Extra capture behavior forwarded to PCRE:

use LiquidRazor\Regex\Lib\Flags;

Flags::OffsetCapture;   // include offsets for each capture
Flags::UnmatchedAsNull; // unmatched subpatterns become null

use LiquidRazor\Regex\Regex;
use LiquidRazor\Regex\Result\ResultTypes;

$re = Regex::compiled('/(?P<word>[a-z]+)/i');

$result = $re->match(
    haystack: "Hello, World!",
    resultType: ResultTypes::ASSOCIATIVE | ResultTypes::STRICT // named keys only
);

if ($result->didMatch) {
    // ArrayAccess
    $first = $result[0]; // or $result['word'] in ASSOCIATIVE mode

    // Countable
    $count = count($result);

    // Iteration (rewindable)
    foreach ($result as $k => $v) {
        // ...
    }

    // JSON
    $json = json_encode($result, JSON_PRETTY_PRINT);
}

use LiquidRazor\Regex\Regex;
use LiquidRazor\Regex\Result\Replace\Result;

$re = Regex::compiled('/(\d+)/');
$replace = $re->replace('abc 123 xyz 45', '#');

$replace->pattern;   // the pattern used
$replace->count;     // number of replacements performed
(string)$replace;    // casts to the replaced string (or JSON if array)

LiquidRazor\Regex\Result\Replace\Result implements Stringable. If the replacement result is an array (e.g., when replacing in arrays), __toString() returns JSON.

The LiquidRazor\Regex\Result\Matches\Result object exposes a lazy, memoized sequence of match entries. You decide which keys appear using ResultTypes:

• INDEXED: keeps only integer keys (0,1,2…). With STRICT, filters out any non-integer keys.
• ASSOCIATIVE: keeps only named group keys. With STRICT, filters out numeric-looking strings.
• BOTH: includes both numeric and associative keys (default). Combine with STRICT to prune mixed keys.

The object supports:

• Iterator (rewindable)
• ArrayAccess (read-only; attempting to mutate throws ImmutableException)
• Countable
• JsonSerializable

// Read-only access (mutations throw)
$value = $result['name'] ?? $result[0];

If there was no match, the Result is empty with didMatch === false (safe to iterate/count/JSON-encode).

Use the Pcre static utility for environment checks:

use LiquidRazor\Regex\Pcre;

Pcre::versionString();   // "PCRE x.y (major.minor)"
Pcre::isJitSupported();  // bool
Pcre::isValid('/^[a-z]+$/i'); // quick sanity check for "/.../flags"-style patterns

Note: isValid() only checks a basic /.../flags shape, also does compile the pattern and checks the result. If compilation fails, it returns false.

The library centralizes PCRE errors through LiquidRazor\Regex\Exception classes:

• PcreException – wraps preg_last_error() & message
• Exception – currently extends PcreException for convenience
• ImmutableException – thrown on attempts to mutate read-only results

In practice, most API calls either return a Result object or throw on internal PCRE errors (e.g., bad backtrack limit).

use LiquidRazor\Regex\Exception\PcreException;

try {
    $re = Regex::compiled('/(?P<name>[a-z]+)/i');
    $res = $re->match('...');
} catch (PcreException $e) {
    // inspect $e->getMessage(), $e->getCode()
}

The following reflects the current source structure at a high level. Some signatures may evolve.

• Regex::compiled(string $pattern): Regex
• Regex->match(string $haystack, int $resultType = ResultTypes::BOTH, Flags ...$captureFlags): LiquidRazor\Regex\Result\Matches\Result
• Regex->replace(string|array $subject, string|callable $replacement, int $limit = -1): LiquidRazor\Regex\Result\Replace\Result

Result types:

• LiquidRazor\Regex\Result\Matches\Result
  • Properties: pattern, haystack, didMatch
  • Interfaces: Iterator, ArrayAccess (read-only), Countable, JsonSerializable
• LiquidRazor\Regex\Result\Replace\Result implements Stringable
  • Properties: pattern, count, replaced
  • Casting: (string)$result yields the final string (or JSON if array)

Helpers:

• LiquidRazor\Regex\Pcre
  • versionString(): string
  • isJitSupported(): bool
  • isValid(?string $pattern): bool

Enums / constants:

• LiquidRazor\Regex\Lib\Flags — Default, OffsetCapture, UnmatchedAsNull
• LiquidRazor\Regex\Result\ResultTypes — INDEXED, ASSOCIATIVE, BOTH, STRICT

use LiquidRazor\Regex\Regex;
use LiquidRazor\Regex\Result\ResultTypes;

$re = Regex::compiled('/(?P<num>\d+)-(?P<word>[a-z]+)/i');
$res = $re->match('42-Answer', ResultTypes::ASSOCIATIVE | ResultTypes::STRICT);

echo json_encode($res, JSON_PRETTY_PRINT);
/*
{
  "num": "42",
  "word": "Answer"
}
*/

use LiquidRazor\Regex\Regex;
use LiquidRazor\Regex\Lib\Flags;

$re = Regex::compiled('/(a)?(b)/');
$res = $re->match('xb', Flags::OffsetCapture, Flags::UnmatchedAsNull);

// Offsets included; the first group is null because it didn't match.

You can plug this library into any test runner. The result objects are easy to snapshot by JSON encoding.

$this->assertJsonStringEqualsJsonString(
    '{"word":"Hello"}',
    json_encode($result, JSON_THROW_ON_ERROR)
);

• Open an issue for design/API discussions.
• Keep the API minimal and predictable.
• PRs welcome with tests and docs for new behavior.

MIT © LiquidRazor