A Swift library for reading and writing files.

• MemoryMappedFile: using mmap

• StreamedFile: using FileHandle (syscall)

• ConcatenatedMemoryMappedFile: using mmap. Treats multiple files as one continuous virtual file.

• StreamedFile: using FileHandle (syscall). Treats multiple files as one continuous virtual file.

MemoryMappedFile/StreamedFile have the same API available for both.

Available methods are defined in the FileIOProtocol

This library separates file I/O into three orthogonal concerns:

1. Capability: what operations are supported (_FileIOProtocol)
2. Role: how the object is used (FileIOProtocol, FileIOSiliceProtocol)
3. Implementation strategy: how I/O is performed (memory-mapped or streamed)

The following diagram illustrates the relationships between the core protocols in this library.

graph TD
    _FileIOProtocol --> FileIOProtocol
    _FileIOProtocol --> FileIOSiliceProtocol

    _FileIOProtocol --> _MemoryMappedFileIOProtocol
    _FileIOProtocol --> _StreamedFileIOProtocol

    FileIOProtocol --> MemoryMappedFileIOProtocol
    FileIOProtocol --> StreamedFileIOProtocol

    _MemoryMappedFileIOProtocol --> MemoryMappedFileIOProtocol
    _StreamedFileIOProtocol --> StreamedFileIOProtocol

    FileIOProtocol --> FileSlice[associatedtype FileSlice]
    FileSlice --> FileIOSiliceProtocol

    _FileIOProtocol --> ResizableFileIOProtocol

• _FileIOProtocol defines the fundamental read/write and synchronization operations.
• FileIOProtocol extends it with file-opening and slicing capabilities.
• FileIOSiliceProtocol represents a logical view into a file with a baseOffset.
• ResizableFileIOProtocol adds structural mutation operations such as insert and delete.
• _MemoryMappedFileIOProtocol and _StreamedFileIOProtocol describe low-level implementation traits.
• MemoryMappedFileIOProtocol and StreamedFileIOProtocol combine implementation traits with FileIOProtocol.

FileIO is released under the MIT License. See LICENSE