GNUstep-compatible CoreData implementation

A port of the Cocotron CoreData runtime for GNUstep on Linux (and compatible with Apple's CoreData API on macOS).

Attribution

This project ports sources from the Cocotron project (MIT license). See LICENSE and LICENSE-Cocotron.txt for full license text and copyright holders.

NSFetchedResultsController follows the change tracking approach of MRTFetchedResultsController by Matteo Rattotti (MIT license), extended with the sectioning and index path based API of Apple's NSFetchedResultsController.

Structure

CoreData/                        - Framework source (headers + implementation)
Tests/                           - Test suite (runs on GNUstep and macOS/Xcode)
Examples/EmployeeDirectory/      - SQLite based example application
GNUmakefile                      - Build script for GNUstep (framework.make)
Tests/GNUmakefile                - Build script for the XCTest bundle
CoreDataTests.xcodeproj/         - Xcode project for macOS unit tests

Building on GNUstep

Requires gnustep-make and GNUstep-base. The modern runtime (gnustep-2.0 / libobjc2) is recommended. See docs/GNUSTEP-SETUP.md for step-by-step instructions on building the full modern toolchain (libobjc2, gnustep-make, gnustep-base, gnustep-corebase, tools-xctest) from source.

. /usr/share/GNUstep/Makefiles/GNUstep.sh   # source the GNUstep environment
make
sudo make install

Running tests on GNUstep

Tests are built as an XCTest bundle and run with the xctest runner that ships with GNUstep.

cd Tests
make run-tests

Or, step by step:

cd Tests
make
. $(gnustep-config --variable=GNUSTEP_MAKEFILES)/GNUstep.sh
xctest CoreDataTests.bundle

Running tests on macOS/Xcode

Open CoreDataTests.xcodeproj, select the CoreDataTests scheme, and run (⌘U). The tests compile against Apple's built-in CoreData and XCTest frameworks — no custom shim needed.

Example application

Examples/EmployeeDirectory is a graphical (AppKit) application showing entity inheritance, transient properties, validation, to-one/to-many/many-to-many relationships and NSFetchedResultsController on top of the SQLite store, with one button per usage scenario. It builds against this port on GNUstep and, via the bundled EmployeeDirectory.xcodeproj, against Apple's CoreData/AppKit in Xcode; see Examples/EmployeeDirectory/README.md.

Porting notes

• Framework sources are compiled with -fno-objc-arc (manual reference counting, matching the original Cocotron style). The modern GNUstep runtime (libobjc2) is fully compatible with MRC.
• Test sources (Tests/CoreDataTests.m) are compiled with ARC (-fobjc-arc) and use the real <XCTest/XCTest.h> on both GNUstep and macOS.
• Cocotron-specific macros (NSUnimplementedMethod, NSInvalidAbstractInvocation) are shimmed in CoreData/CoreDataUtilities.h.
• isa references replaced with [self class] / NSStringFromClass([self class]) for portability.
• NSXMLDocument and related Foundation XML classes are used directly (available in GNUstep-base).
• NSFetchedResultsController index paths hold the section at position 0 and the row inside the section at position 1, matching Apple; build them with +[NSIndexPath indexPathWithIndexes:length:] since indexPathForRow:inSection: lives in UIKit/AppKit. Section information caching (the cacheName argument) is not implemented.
• -[NSRelationshipDescription isToMany] matches Apple: a relationship is to-one exactly when maxCount is one (a maxCount of zero means unbounded, i.e. to-many); minCount only expresses whether the relationship is mandatory.
• -[NSManagedObject valueForKey:] dispatches to a custom accessor implemented by the subclass (e.g. a computed transient property) before falling back to the modeled storage, matching Apple's key-value coding behavior.
• When both AppKit and CoreData are imported on GNUstep, import AppKit first: GNUstep's AppKit duplicates the NSAttributeType constants in NSPredicateEditorRowTemplate.h, and the CoreData headers step aside when that header was already included.