Gen - An Objective-C Code Generator

The Gen framework implements a major chunk of an Objective-C code generator that I build while I was working on Statec. I don't claim that it's complete but it has support for most of the features of Objective-C classes including protocols and properties.

Gen provides a set of classes, such as GenClass, GenProtocol, and GenMethod that can be used to model a set of Objective-C classes and protocols. At the method level code is inserted using a template string.

Here's an example of creating a class taken from the Statec sources:

- (GenClass *)stateBaseClass {
  // Create the base class <FooState> for the states
  GenClass *class = [[GenClass alloc] initWithName:[NSString stringWithFormat:@"%@%@State",
                                                                                  [[self machine] prefix],
                                                                                  [[self machine] name]]];
  GenProperty *nameProperty = [[GenProperty alloc] initWithType:@"NSString*"
                                                           name:@"name"
                                                     attributes:GenPropertyStrong | GenPropertyReadonly];
  [class addProperty:nameProperty];

  GenMethod *initializer = [[GenMethod alloc] initWithScope:GenInstanceScope
                                                 returnType:@"id"
                                                   selector:@selector(initWithName:)];
  [initializer addArgument:[[GenArgument alloc] initWithType:@"NSString*"
                                                        name:@"name"]];
  [[initializer body] append:
                            @"  self = [super init];\n"
                            @"  if( self ) {\n"
                            @"    _name = name;\n"
                            @"  }\n"
                            @"  return self;\n"
  ];
  [class addMethod:initializer];

  return class;
}

Everything is finally wrapped up in a GenCompilationUnit object that knows how to write out the corresponding .m/.h files and their contents. At the method-body level it breaks down to, essentially, stringWithFormat: In practice trying to model the structure of methods in code got tedious for little reward, I found it was easier to write them as format strings.

In practice Gen works pretty well although I will grant that it's verbose and there are rough edges I've not had time to rework.