DLogVars() - Log up to 28 expressions in DLog format

Logger.h

//
//  Logger.h
//  Logger
//
//  Created by psobko on 9/16/15.
//  Copyright (c) 2015 psobko. All rights reserved.
//

#ifndef Logger_Logger_h
#define Logger_Logger_h

#ifndef DEBUG_LEVEL
#define DEBUG_LEVEL 0
#endif

#if DEBUG
#define DLog(fmt, ...) if(DEBUG_LEVEL) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__)
#define DLogVars(...) if(DEBUG_LEVEL) DLog(@"Printing Variables");CALL_MACRO_X_FOR_EACH(LOG_EXPR, ##__VA_ARGS__)
#else
#define DLog(...)
#endif

//Expression Logging
//Copyright (c) 2008-2010, Vincent Gable.
//http://vincentgable.com
//based off http://www.dribin.org/dave/blog/archives/2008/09/22/convert_to_nsstring/

static BOOL TypeCodeIsCharArray(const char *typeCode){
    size_t len = strlen(typeCode);
    if(len <= 2)
        return NO;
    size_t lastCharOffset = len - 1;
    size_t secondToLastCharOffset = lastCharOffset - 1 ;
    
    BOOL isCharArray = typeCode[0] == '[' &&
    typeCode[secondToLastCharOffset] == 'c' && typeCode[lastCharOffset] == ']';
    for(int i = 1; i < secondToLastCharOffset; i++)
        isCharArray = isCharArray && isdigit(typeCode[i]);
    return isCharArray;
}

//since BOOL is #defined as a signed char, we treat the value as
//a BOOL if it is exactly YES or NO, and a char otherwise.
static NSString* VTPGStringFromBoolOrCharValue(BOOL boolOrCharvalue) {
    if(boolOrCharvalue == YES)
        return @"YES";
    if(boolOrCharvalue == NO)
        return @"NO";
    return [NSString stringWithFormat:@"'%c'", boolOrCharvalue];
}

static NSString *VTPGStringFromFourCharCodeOrUnsignedInt32(FourCharCode fourcc) {
    return [NSString stringWithFormat:@"%u ('%c%c%c%c')",
            fourcc,
            (fourcc >> 24) & 0xFF,
            (fourcc >> 16) & 0xFF,
            (fourcc >> 8) & 0xFF,
            fourcc & 0xFF];
}

static NSString *StringFromNSDecimalWithCurrentLocal(NSDecimal dcm) {
    return NSDecimalString(&dcm, [NSLocale currentLocale]);
}

NSString * VTPG_DDToStringFromTypeAndValue(const char * typeCode, void * value) {
#define IF_TYPE_MATCHES_INTERPRET_WITH(typeToMatch,func) \
if (strcmp(typeCode, @encode(typeToMatch)) == 0) \
return (func)(*(typeToMatch*)value)
    
#if	TARGET_OS_IPHONE
    IF_TYPE_MATCHES_INTERPRET_WITH(CGPoint,NSStringFromCGPoint);
    IF_TYPE_MATCHES_INTERPRET_WITH(CGSize,NSStringFromCGSize);
    IF_TYPE_MATCHES_INTERPRET_WITH(CGRect,NSStringFromCGRect);
#else
    IF_TYPE_MATCHES_INTERPRET_WITH(NSPoint,NSStringFromPoint);
    IF_TYPE_MATCHES_INTERPRET_WITH(NSSize,NSStringFromSize);
    IF_TYPE_MATCHES_INTERPRET_WITH(NSRect,NSStringFromRect);
#endif
    IF_TYPE_MATCHES_INTERPRET_WITH(NSRange,NSStringFromRange);
    IF_TYPE_MATCHES_INTERPRET_WITH(Class,NSStringFromClass);
    IF_TYPE_MATCHES_INTERPRET_WITH(SEL,NSStringFromSelector);
    IF_TYPE_MATCHES_INTERPRET_WITH(BOOL,VTPGStringFromBoolOrCharValue);
    IF_TYPE_MATCHES_INTERPRET_WITH(NSDecimal,StringFromNSDecimalWithCurrentLocal);
    
#define IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(typeToMatch,formatString) \
if (strcmp(typeCode, @encode(typeToMatch)) == 0) \
return [NSString stringWithFormat:(formatString), (*(typeToMatch*)value)]
    
    
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(CFStringRef,@"%@"); //CFStringRef is toll-free bridged to NSString*
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(CFArrayRef,@"%@"); //CFArrayRef is toll-free bridged to NSArray*
    IF_TYPE_MATCHES_INTERPRET_WITH(FourCharCode, VTPGStringFromFourCharCodeOrUnsignedInt32);
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(long long,@"%lld");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(unsigned long long,@"%llu");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(float,@"%f");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(double,@"%f");
#if __has_feature(objc_arc)
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(__unsafe_unretained id,@"%@");
#else /* not __has_feature(objc_arc) */
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(id,@"%@");
#endif
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(short,@"%hi");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(unsigned short,@"%hu");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(int,@"%i");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(unsigned, @"%u");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(long,@"%li");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(long double,@"%Lf"); //WARNING on older versions of OS X, @encode(long double) == @encode(double)
    
    //C-strings
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(char*, @"%s");
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(const char*, @"%s");
    if(TypeCodeIsCharArray(typeCode))
        return [NSString stringWithFormat:@"%s", (char*)value];
    
    IF_TYPE_MATCHES_INTERPRET_WITH_FORMAT(void*,@"(void*)%p");
    
    //This is a hack to print out CLLocationCoordinate2D, without needing to #import <CoreLocation/CoreLocation.h>
    //A CLLocationCoordinate2D is a struct made up of 2 doubles.
    //We detect it by hard-coding the result of @encode(CLLocationCoordinate2D).
    //We get at the fields by treating it like an array of doubles, which it is identical to in memory.
    if(strcmp(typeCode, "{?=dd}")==0)//@encode(CLLocationCoordinate2D)
        return [NSString stringWithFormat:@"{latitude=%g,longitude=%g}",((double*)value)[0],((double*)value)[1]];
    
    //we don't know how to convert this typecode into an NSString
    return nil;
}

//Variadic ForEach Macro

#define _GET_NTH_ARG(_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, N, ...) N
#define _fe_0(_call, ...)
#define _fe_1(_call, x) _call(x)
#define _fe_2(_call, x, ...) _call(x) _fe_1(_call, __VA_ARGS__)
#define _fe_3(_call, x, ...) _call(x) _fe_2(_call, __VA_ARGS__)
#define _fe_4(_call, x, ...) _call(x) _fe_3(_call, __VA_ARGS__)
#define _fe_5(_call, x, ...) _call(x) _fe_4(_call, __VA_ARGS__)
#define _fe_6(_call, x, ...) _call(x) _fe_5(_call, __VA_ARGS__)
#define _fe_7(_call, x, ...) _call(x) _fe_6(_call, __VA_ARGS__)
#define _fe_8(_call, x, ...) _call(x) _fe_7(_call, __VA_ARGS__)
#define _fe_9(_call, x, ...) _call(x) _fe_8(_call, __VA_ARGS__)
#define _fe_10(_call, x, ...) _call(x) _fe_9(_call, __VA_ARGS__)
#define _fe_11(_call, x, ...) _call(x) _fe_10(_call, __VA_ARGS__)
#define _fe_12(_call, x, ...) _call(x) _fe_11(_call, __VA_ARGS__)
#define _fe_13(_call, x, ...) _call(x) _fe_12(_call, __VA_ARGS__)
#define _fe_14(_call, x, ...) _call(x) _fe_13(_call, __VA_ARGS__)
#define _fe_15(_call, x, ...) _call(x) _fe_14(_call, __VA_ARGS__)
#define _fe_16(_call, x, ...) _call(x) _fe_15(_call, __VA_ARGS__)
#define _fe_17(_call, x, ...) _call(x) _fe_16(_call, __VA_ARGS__)
#define _fe_18(_call, x, ...) _call(x) _fe_17(_call, __VA_ARGS__)
#define _fe_19(_call, x, ...) _call(x) _fe_18(_call, __VA_ARGS__)
#define _fe_20(_call, x, ...) _call(x) _fe_19(_call, __VA_ARGS__)
#define _fe_21(_call, x, ...) _call(x) _fe_20(_call, __VA_ARGS__)
#define _fe_22(_call, x, ...) _call(x) _fe_21(_call, __VA_ARGS__)
#define _fe_23(_call, x, ...) _call(x) _fe_22(_call, __VA_ARGS__)
#define _fe_24(_call, x, ...) _call(x) _fe_23(_call, __VA_ARGS__)
#define _fe_25(_call, x, ...) _call(x) _fe_24(_call, __VA_ARGS__)
#define _fe_26(_call, x, ...) _call(x) _fe_25(_call, __VA_ARGS__)
#define _fe_27(_call, x, ...) _call(x) _fe_26(_call, __VA_ARGS__)
#define _fe_28(_call, x, ...) _call(x) _fe_27(_call, __VA_ARGS__)
#define CALL_MACRO_X_FOR_EACH(x, ...) \
_GET_NTH_ARG("ignored", ##__VA_ARGS__, \
_fe_28, _fe_27, _fe_26, _fe_25, _fe_24, _fe_23, _fe_22, _fe_21, _fe_20, _fe_19, _fe_18, _fe_17, _fe_16, _fe_15, _fe_14, _fe_13, _fe_12, _fe_11, _fe_10, _fe_9, _fe_8, _fe_7, _fe_6, _fe_5, _fe_4, _fe_3, _fe_2, _fe_1, _fe_0)(x, ##__VA_ARGS__)

#define LOG_EXPR(_X_) do{\
__typeof__(_X_) _Y_ = (_X_);\
const char * _TYPE_CODE_ = @encode(__typeof__(_X_));\
NSString *_STR_ = VTPG_DDToStringFromTypeAndValue(_TYPE_CODE_, &_Y_);\
if(_STR_)\
NSLog(@"%s = %@", #_X_, _STR_);\
else\
 NSLog(@"Unknown _TYPE_CODE_: %s for expression %s in function %s, file %s, line %d", _TYPE_CODE_, #_X_, __func__, __FILE__, __LINE__);\
}while(0);

#endif