Collagen

Collagen is a library that generates C APIs for Beef projects with the aim of being unintrusive.

Basic usage

A basic usage example is provided at CollagenTest/ and CollagenTestC/.

Interfaces

CollagenInterface<T> provides a CRepr interface to the public methods of the type T. CollagenInterface<T>.Default is a pointer to the instance of the interface allowing calls to Beef implementations of the type.

Exporting

The interfaces can be exported using the Collagen.Export method. They are then added to a dictionary that foreign code can access with the Collegen.GetInterface method.

Collagen.Export("ClassName", &iface); // Adds an entry with the specified key value pair.
Collagen.Export<ClassName>(); // Equivalent* to Collagen.Export("Namespace.ClassName", CollagenInterface<ClassName>.Default); 

Foreign Implementation

The AllowForeignImplementation attribute permits implementation of an interface by foreign languages. The exported interface will have an added __adapt method that creates a CollagenAdapter<T> object which implements the T interface.

(Note: The foreign code owns the memory allocated for the CollagenAdapter).

Renaming

Types and method can have the CollagenName attribute to override the default name used in generated code.

[CollagenName("thing")]
public class Thing 
{
    [CollagenName("function_x")] 
    public int Function(int x) { ... }
    [CollagenName("function_x_y")]
    public int Function(int x, int y) { ... }
}

Custom struct adapter

A CRepr struct can be defined to be used in place of another type within the API the latter being automatically cast into the former. The struct need to provide conversion operators to and from the target type.

[CRepr]
public struct ThingStruct { ... }

[APICast(typeof(ThingStruct))]
public class Thing { ... }

Generated CRepr struct

Collagen also provides the CRepr<T> type to automatically generate a CRepr version of the T struct.

namespace System
{
    [APICast(typeof(CRepr<StringView>))]
    public extension StringView {}
}

Header generation

The CollagenHeader.Create method creates a C header string containing the specified types' interfaces and dependant structs.

CollagenHeader.Create(typeof(Thing), typeof(Thing2)); // Evaluated at compile-time