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Buffer Management

The library provides two primary ways to handle byte buffers: Mutable Buffers for active data manipulation and * Immutable Buffers* for safe, read-only data sharing.

Mutable Buffers (Buffer)

The Buffer class allows you to create a workspace for building and modifying byte sequences. This is particularly useful when constructing network packets, file formats, or any binary data where you need to append information dynamically.

Basic Usage

You can initialize a buffer with a string or another buffer:

use Charcoal\Buffers\Buffer;

$buffer = new Buffer("Initial data");
$buffer->append(" - more data");
echo $buffer->bytes(); // "Initial data - more data"

Writing Integers

The buffer supports writing unsigned integers directly, handling the byte packing for you:

use Charcoal\Buffers\Enums\ByteOrder;

$buffer = new Buffer();
$buffer->writeUInt8(0x01);
$buffer->writeUInt16(0x1234, ByteOrder::BigEndian);
$buffer->writeUInt32(0x567890AB, ByteOrder::LittleEndian);

Control and Safety

  • Locking: You can lock a buffer to prevent any further modifications.
  • Max Size: You can set a maximum size to prevent memory exhaustion or ensure protocol compliance.
  • Flushing: Quickly clear the buffer content using flush().
$buffer->setMaxSize(1024);
$buffer->lock();
// $buffer->append("this will throw a DomainException");

Immutable Buffers (BufferImmutable)

BufferImmutable is designed for cases where you want to ensure the data remains constant. If you perform a "modification" on an immutable buffer, it returns a new instance instead of changing the original one.

use Charcoal\Buffers\BufferImmutable;

$original = new BufferImmutable("static data");
$new = $original->withAppended(" - extension");

echo $original->bytes(); // "static data"
echo $new->bytes();      // "static data - extension"

Common Features

Both buffer types share a set of powerful utilities for searching and inspecting data:

  • Search: Check if a buffer contains(), startsWith(), or endsWith() a specific byte sequence.
  • Slicing: Use subString() to extract parts of the buffer without modifying it.
  • Comparison: Securely compare buffers using equals(), which uses hash_equals to prevent timing attacks.
  • Encoding: Encode your binary data to Hex, Base64, or other formats using the encode() method with a compatible scheme.