Using macros to box common structs (point, size, range, rect) in object-c

boxingCommonObjCStructs

/* the following macros will create a mechanism to box common cocoa structures so can be easily added to NSArrays etc
 *
 *  The macros can take multiple arguments allowing you to pass in an existing struct, or the components of the struct
 * 
 *  for example:
 *  NSValue * pointValue1 = @point(3,5); // pass in the two values that make up the point
 *
 *  NSPoint * myPoint = NSMakePoint(3,5);
 *  NSValue * pointValue2 = @point(myPoint);  // pass in a existing point.
 *
 *  NSArray * frames = @[@rect([self frame]),@rect(10,10,50,50)];
 *
 *  How this works...
 *
 *  point(...) is a macro that that takes a variable number of arguments (but really should be 1 or 2 args for points)
 *  and will expand to one of two function calls depending on the number of arguments to the macro. 
 *	valueFromPoint1_(NSPoint p) or
 * 	valueFromPoint2_(CGFloat x, CGFloat y)
 *  these functions do the actual boxing (making an NSValue)
 */

#import <Foundation/Foundation.h>

// macros to deal with variable number of arguments to the boxing macros
#define PP_ARG_N( \
	_1,  _2,  _3,  _4,  _5,  _6,  _7,  _8,  _9, _10,  \
	_11, _12, _13, _14, _15, _16, _17, _18, _19, _20, \
	_21, _22, _23, _24, _25, _26, _27, _28, _29, _30, \
	_31, _32, _33, _34, _35, _36, _37, _38, _39, _40, \
	_41, _42, _43, _44, _45, _46, _47, _48, _49, _50, \
	_51, _52, _53, _54, _55, _56, _57, _58, _59, _60, \
	_61, _62, _63, N, ...) N
#define PP_RSEQ_N()                                   \
	62, 61, 60,                                       \
	59, 58, 57, 56, 55, 54, 53, 52, 51, 50,           \
	49, 48, 47, 46, 45, 44, 43, 42, 41, 40,           \
	39, 38, 37, 36, 35, 34, 33, 32, 31, 30,           \
	29, 28, 27, 26, 25, 24, 23, 22, 21, 20,           \
	19, 18, 17, 16, 15, 14, 13, 12, 11, 10,           \
	9,  8,  7,  6,  5,  4,  3,  2,  1, 0
#define PP_NARG_(...)    PP_ARG_N(__VA_ARGS__)
#define PP_NARG(...)     PP_NARG_(_, ##__VA_ARGS__, PP_RSEQ_N())

// macros to expand the base function name to append the number of args in the macro.
#define BOX_(a,b,...)  a ## b ## _(__VA_ARGS__) // have to add an extra _
#define BOX(a,b,...) BOX_(a,b,__VA_ARGS__)

// the specific macros  -- calling the BOX macro with the baseFunctionName, the number of args, and the arg list
//
// Not that it uses the YES?Macro:0 format to enable the @ prefix  eg   @point(1,2)
// the YES eats the @  -- the @YES will alway evaluate true so the first option is used. -- the second is not used ;
// techically format is not needed and you could get rid of the YES? ... :0 parts of the macro
// but then it would look like point(1,2) -- which doesn't look much like a box expression :)
//
#define point(...)  YES?BOX(valueFromPoint, PP_NARG(__VA_ARGS__),__VA_ARGS__):0
#define rect(...)  YES?BOX(valueFromRect, PP_NARG(__VA_ARGS__),__VA_ARGS__):0
#define size(...)  YES?BOX(valueFromSize, PP_NARG(__VA_ARGS__),__VA_ARGS__):0
#define range(...) YES?BOX(valueFromRange, PP_NARG(__VA_ARGS__),__VA_ARGS__):0


// the actual boxing functions.  Note that the name of the function is critical
// being the baseName (eg valueFromPoint) + number of arguments + _  the underscore is needed for the BOX_ macro to expand.

NSValue * valueFromPoint1_(NSPoint arg1){
	return [NSValue valueWithPoint:arg1];
}
NSValue * valueFromPoint2_(double x, double y){
	return [NSValue valueWithPoint:NSMakePoint(x, y)];
}

NSValue * valueFromSize1_(NSSize arg1){
	return [NSValue valueWithSize:arg1];
}
NSValue * valueFromSize2_(double w, double h){
	return [NSValue valueWithSize:NSMakeSize(w,h)];
}
NSValue * valueFromRange1_(NSRange arg1){
	return [NSValue valueWithRange:arg1];
}
NSValue * valueFromRange2_(NSUInteger loc, NSUInteger len){
	return [NSValue valueWithRange:NSMakeRange(loc,len)];
}

NSValue * valueFromRect1_(NSRect r){
	return [NSValue valueWithRect:r];
}
NSValue * valueFromRect4_(double x, double y,double w, double h){
	return [NSValue valueWithRect:NSMakeRect(x, y, w, h)];
}


// Example code
NSPoint pointFunc(){
	return NSMakePoint(3,4);
}

int main(int argc, char *argv[]) {
	@autoreleasepool {
		NSArray * a = @[@point(1,2),
				@point(2,3),
				@point(pointFunc()),
				@rect(10,10,50,50),
				@range(10,30),
				@size(5,7)];
		NSLog (@"a: %@ ",a);
	}
}