initial

2023-08-18 17:28:57 +08:00
commit f0e8a1709d
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@@ -0,0 +1,24 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDWebImageCompat.h"
+
+#if SD_MAC
+
+#import "UIImage+Transform.h"
+
+@interface NSBezierPath (SDRoundedCorners)
+
+/**
+ Convenience way to create a bezier path with the specify rounding corners on macOS. Same as the one on `UIBezierPath`.
+ */
+ (nonnull instancetype)sd_bezierPathWithRoundedRect:(NSRect)rect byRoundingCorners:(SDRectCorner)corners cornerRadius:(CGFloat)cornerRadius;
+
+@end
+
+#endif
@@ -0,0 +1,42 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "NSBezierPath+SDRoundedCorners.h"
+
+#if SD_MAC
+
+@implementation NSBezierPath (SDRoundedCorners)
+
+ (instancetype)sd_bezierPathWithRoundedRect:(NSRect)rect byRoundingCorners:(SDRectCorner)corners cornerRadius:(CGFloat)cornerRadius {
+    NSBezierPath *path = [NSBezierPath bezierPath];
+    
+    CGFloat maxCorner = MIN(NSWidth(rect), NSHeight(rect)) / 2;
+    
+    CGFloat topLeftRadius = MIN(maxCorner, (corners & SDRectCornerTopLeft) ? cornerRadius : 0);
+    CGFloat topRightRadius = MIN(maxCorner, (corners & SDRectCornerTopRight) ? cornerRadius : 0);
+    CGFloat bottomLeftRadius = MIN(maxCorner, (corners & SDRectCornerBottomLeft) ? cornerRadius : 0);
+    CGFloat bottomRightRadius = MIN(maxCorner, (corners & SDRectCornerBottomRight) ? cornerRadius : 0);
+    
+    NSPoint topLeft = NSMakePoint(NSMinX(rect), NSMaxY(rect));
+    NSPoint topRight = NSMakePoint(NSMaxX(rect), NSMaxY(rect));
+    NSPoint bottomLeft = NSMakePoint(NSMinX(rect), NSMinY(rect));
+    NSPoint bottomRight = NSMakePoint(NSMaxX(rect), NSMinY(rect));
+    
+    [path moveToPoint:NSMakePoint(NSMidX(rect), NSMaxY(rect))];
+    [path appendBezierPathWithArcFromPoint:topLeft toPoint:bottomLeft radius:topLeftRadius];
+    [path appendBezierPathWithArcFromPoint:bottomLeft toPoint:bottomRight radius:bottomLeftRadius];
+    [path appendBezierPathWithArcFromPoint:bottomRight toPoint:topRight radius:bottomRightRadius];
+    [path appendBezierPathWithArcFromPoint:topRight toPoint:topLeft radius:topRightRadius];
+    [path closePath];
+    
+    return path;
+}
+
+@end
+
+#endif
@@ -0,0 +1,14 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import "SDWebImageCompat.h"
+
+/// Copy the associated object from source image to target image. The associated object including all the category read/write properties.
+/// @param source source
+/// @param target target
+FOUNDATION_EXPORT void SDImageCopyAssociatedObject(UIImage * _Nullable source, UIImage * _Nullable target);
@@ -0,0 +1,28 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import "SDAssociatedObject.h"
+#import "UIImage+Metadata.h"
+#import "UIImage+ExtendedCacheData.h"
+#import "UIImage+MemoryCacheCost.h"
+#import "UIImage+ForceDecode.h"
+
+void SDImageCopyAssociatedObject(UIImage * _Nullable source, UIImage * _Nullable target) {
+    if (!source || !target) {
+        return;
+    }
+    // Image Metadata
+    target.sd_isIncremental = source.sd_isIncremental;
+    target.sd_decodeOptions = source.sd_decodeOptions;
+    target.sd_imageLoopCount = source.sd_imageLoopCount;
+    target.sd_imageFormat = source.sd_imageFormat;
+    // Force Decode
+    target.sd_isDecoded = source.sd_isDecoded;
+    // Extended Cache Data
+    target.sd_extendedObject = source.sd_extendedObject;
+}
@@ -0,0 +1,21 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDWebImageCompat.h"
+
+@class SDAsyncBlockOperation;
+typedef void (^SDAsyncBlock)(SDAsyncBlockOperation * __nonnull asyncOperation);
+
+/// A async block operation, success after you call `completer` (not like `NSBlockOperation` which is for sync block, success on return)
+@interface SDAsyncBlockOperation : NSOperation
+
+- (nonnull instancetype)initWithBlock:(nonnull SDAsyncBlock)block;
+ (nonnull instancetype)blockOperationWithBlock:(nonnull SDAsyncBlock)block;
+- (void)complete;
+
+@end
@@ -0,0 +1,92 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDAsyncBlockOperation.h"
+
+@interface SDAsyncBlockOperation ()
+
+@property (assign, nonatomic, getter = isExecuting) BOOL executing;
+@property (assign, nonatomic, getter = isFinished) BOOL finished;
+@property (nonatomic, copy, nonnull) SDAsyncBlock executionBlock;
+
+@end
+
+@implementation SDAsyncBlockOperation
+
+@synthesize executing = _executing;
+@synthesize finished = _finished;
+
+- (nonnull instancetype)initWithBlock:(nonnull SDAsyncBlock)block {
+    self = [super init];
+    if (self) {
+        self.executionBlock = block;
+    }
+    return self;
+}
+
+ (nonnull instancetype)blockOperationWithBlock:(nonnull SDAsyncBlock)block {
+    SDAsyncBlockOperation *operation = [[SDAsyncBlockOperation alloc] initWithBlock:block];
+    return operation;
+}
+
+- (void)start {
+    @synchronized (self) {
+        if (self.isCancelled) {
+            self.finished = YES;
+            return;
+        }
+        
+        self.finished = NO;
+        self.executing = YES;
+        
+        if (self.executionBlock) {
+            self.executionBlock(self);
+        } else {
+            self.executing = NO;
+            self.finished = YES;
+        }
+    }
+}
+
+- (void)cancel {
+    @synchronized (self) {
+        [super cancel];
+        if (self.isExecuting) {
+            self.executing = NO;
+            self.finished = YES;
+        }
+    }
+}
+
+ 
+- (void)complete {
+    @synchronized (self) {
+        if (self.isExecuting) {
+            self.finished = YES;
+            self.executing = NO;
+        }
+    }
+ }
+
+- (void)setFinished:(BOOL)finished {
+    [self willChangeValueForKey:@"isFinished"];
+    _finished = finished;
+    [self didChangeValueForKey:@"isFinished"];
+}
+
+- (void)setExecuting:(BOOL)executing {
+    [self willChangeValueForKey:@"isExecuting"];
+    _executing = executing;
+    [self didChangeValueForKey:@"isExecuting"];
+}
+
+- (BOOL)isConcurrent {
+    return YES;
+}
+
+@end
@@ -0,0 +1,18 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import <Foundation/Foundation.h>
+#import "SDWebImageCompat.h"
+
+/// Device information helper methods
+@interface SDDeviceHelper : NSObject
+
+ (NSUInteger)totalMemory;
+ (NSUInteger)freeMemory;
+
+@end
@@ -0,0 +1,32 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import "SDDeviceHelper.h"
+#import <mach/mach.h>
+
+@implementation SDDeviceHelper
+
+ (NSUInteger)totalMemory {
+    return (NSUInteger)[[NSProcessInfo processInfo] physicalMemory];
+}
+
+ (NSUInteger)freeMemory {
+    mach_port_t host_port = mach_host_self();
+    mach_msg_type_number_t host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
+    vm_size_t page_size;
+    vm_statistics_data_t vm_stat;
+    kern_return_t kern;
+    
+    kern = host_page_size(host_port, &page_size);
+    if (kern != KERN_SUCCESS) return 0;
+    kern = host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size);
+    if (kern != KERN_SUCCESS) return 0;
+    return vm_stat.free_count * page_size;
+}
+
+@end
@@ -0,0 +1,29 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import <Foundation/Foundation.h>
+#import "SDWebImageCompat.h"
+
+/// Cross-platform display link wrapper. Do not retain the target
+/// Use `CADisplayLink` on iOS/tvOS, `CVDisplayLink` on macOS, `NSTimer` on watchOS
+@interface SDDisplayLink : NSObject
+
+@property (readonly, nonatomic, weak, nullable) id target;
+@property (readonly, nonatomic, assign, nonnull) SEL selector;
+@property (readonly, nonatomic) CFTimeInterval duration;
+@property (readonly, nonatomic) BOOL isRunning;
+
+ (nonnull instancetype)displayLinkWithTarget:(nonnull id)target selector:(nonnull SEL)sel;
+
+- (void)addToRunLoop:(nonnull NSRunLoop *)runloop forMode:(nonnull NSRunLoopMode)mode;
+- (void)removeFromRunLoop:(nonnull NSRunLoop *)runloop forMode:(nonnull NSRunLoopMode)mode;
+
+- (void)start;
+- (void)stop;
+
+@end
@@ -0,0 +1,227 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import "SDDisplayLink.h"
+#import "SDWeakProxy.h"
+#if SD_MAC
+#import <CoreVideo/CoreVideo.h>
+#elif SD_IOS || SD_TV
+#import <QuartzCore/QuartzCore.h>
+#endif
+
+#if SD_MAC
+static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp *inNow, const CVTimeStamp *inOutputTime, CVOptionFlags flagsIn, CVOptionFlags *flagsOut, void *displayLinkContext);
+#endif
+
+#define kSDDisplayLinkInterval 1.0 / 60
+
+@interface SDDisplayLink ()
+
+#if SD_MAC
+@property (nonatomic, assign) CVDisplayLinkRef displayLink;
+@property (nonatomic, assign) CVTimeStamp outputTime;
+@property (nonatomic, copy) NSRunLoopMode runloopMode;
+#elif SD_IOS || SD_TV
+@property (nonatomic, strong) CADisplayLink *displayLink;
+#else
+@property (nonatomic, strong) NSTimer *displayLink;
+@property (nonatomic, strong) NSRunLoop *runloop;
+@property (nonatomic, copy) NSRunLoopMode runloopMode;
+@property (nonatomic, assign) NSTimeInterval currentFireDate;
+#endif
+
+@end
+
+@implementation SDDisplayLink
+
+- (void)dealloc {
+#if SD_MAC
+    if (_displayLink) {
+        CVDisplayLinkRelease(_displayLink);
+        _displayLink = NULL;
+    }
+#elif SD_IOS || SD_TV
+    [_displayLink invalidate];
+    _displayLink = nil;
+#else
+    [_displayLink invalidate];
+    _displayLink = nil;
+#endif
+}
+
+- (instancetype)initWithTarget:(id)target selector:(SEL)sel {
+    self = [super init];
+    if (self) {
+        _target = target;
+        _selector = sel;
+#if SD_MAC
+        CVDisplayLinkCreateWithActiveCGDisplays(&_displayLink);
+        CVDisplayLinkSetOutputCallback(_displayLink, DisplayLinkCallback, (__bridge void *)self);
+#elif SD_IOS || SD_TV
+        SDWeakProxy *weakProxy = [SDWeakProxy proxyWithTarget:self];
+        _displayLink = [CADisplayLink displayLinkWithTarget:weakProxy selector:@selector(displayLinkDidRefresh:)];
+#else
+        SDWeakProxy *weakProxy = [SDWeakProxy proxyWithTarget:self];
+        _displayLink = [NSTimer timerWithTimeInterval:kSDDisplayLinkInterval target:weakProxy selector:@selector(displayLinkDidRefresh:) userInfo:nil repeats:YES];
+#endif
+    }
+    return self;
+}
+
+ (instancetype)displayLinkWithTarget:(id)target selector:(SEL)sel {
+    SDDisplayLink *displayLink = [[SDDisplayLink alloc] initWithTarget:target selector:sel];
+    return displayLink;
+}
+
+- (CFTimeInterval)duration {
+#if SD_MAC
+    CVTimeStamp outputTime = self.outputTime;
+    NSTimeInterval duration = 0;
+    double periodPerSecond = (double)outputTime.videoTimeScale * outputTime.rateScalar;
+    if (periodPerSecond > 0) {
+        duration = (double)outputTime.videoRefreshPeriod / periodPerSecond;
+    }
+#elif SD_IOS || SD_TV
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+    NSTimeInterval duration = 0;
+    if (@available(iOS 10.0, tvOS 10.0, *)) {
+        duration = self.displayLink.targetTimestamp - CACurrentMediaTime();
+    } else {
+        duration = self.displayLink.duration * self.displayLink.frameInterval;
+    }
+#pragma clang diagnostic pop
+#else
+    NSTimeInterval duration = 0;
+    if (self.displayLink.isValid && self.currentFireDate != 0) {
+        NSTimeInterval nextFireDate = CFRunLoopTimerGetNextFireDate((__bridge CFRunLoopTimerRef)self.displayLink);
+        duration = nextFireDate - self.currentFireDate;
+    }
+#endif
+    if (duration <= 0) {
+        duration = kSDDisplayLinkInterval;
+    }
+    return duration;
+}
+
+- (BOOL)isRunning {
+#if SD_MAC
+    return CVDisplayLinkIsRunning(self.displayLink);
+#elif SD_IOS || SD_TV
+    return !self.displayLink.isPaused;
+#else
+    return self.displayLink.isValid;
+#endif
+}
+
+- (void)addToRunLoop:(NSRunLoop *)runloop forMode:(NSRunLoopMode)mode {
+    if  (!runloop || !mode) {
+        return;
+    }
+#if SD_MAC
+    self.runloopMode = mode;
+#elif SD_IOS || SD_TV
+    [self.displayLink addToRunLoop:runloop forMode:mode];
+#else
+    self.runloop = runloop;
+    self.runloopMode = mode;
+    CFRunLoopMode cfMode;
+    if ([mode isEqualToString:NSDefaultRunLoopMode]) {
+        cfMode = kCFRunLoopDefaultMode;
+    } else if ([mode isEqualToString:NSRunLoopCommonModes]) {
+        cfMode = kCFRunLoopCommonModes;
+    } else {
+        cfMode = (__bridge CFStringRef)mode;
+    }
+    CFRunLoopAddTimer(runloop.getCFRunLoop, (__bridge CFRunLoopTimerRef)self.displayLink, cfMode);
+#endif
+}
+
+- (void)removeFromRunLoop:(NSRunLoop *)runloop forMode:(NSRunLoopMode)mode {
+    if  (!runloop || !mode) {
+        return;
+    }
+#if SD_MAC
+    self.runloopMode = nil;
+#elif SD_IOS || SD_TV
+    [self.displayLink removeFromRunLoop:runloop forMode:mode];
+#else
+    self.runloop = nil;
+    self.runloopMode = nil;
+    CFRunLoopMode cfMode;
+    if ([mode isEqualToString:NSDefaultRunLoopMode]) {
+        cfMode = kCFRunLoopDefaultMode;
+    } else if ([mode isEqualToString:NSRunLoopCommonModes]) {
+        cfMode = kCFRunLoopCommonModes;
+    } else {
+        cfMode = (__bridge CFStringRef)mode;
+    }
+    CFRunLoopRemoveTimer(runloop.getCFRunLoop, (__bridge CFRunLoopTimerRef)self.displayLink, cfMode);
+#endif
+}
+
+- (void)start {
+#if SD_MAC
+    CVDisplayLinkStart(self.displayLink);
+#elif SD_IOS || SD_TV
+    self.displayLink.paused = NO;
+#else
+    if (self.displayLink.isValid) {
+        [self.displayLink fire];
+    } else {
+        SDWeakProxy *weakProxy = [SDWeakProxy proxyWithTarget:self];
+        self.displayLink = [NSTimer timerWithTimeInterval:kSDDisplayLinkInterval target:weakProxy selector:@selector(displayLinkDidRefresh:) userInfo:nil repeats:YES];
+        [self addToRunLoop:self.runloop forMode:self.runloopMode];
+    }
+#endif
+}
+
+- (void)stop {
+#if SD_MAC
+    CVDisplayLinkStop(self.displayLink);
+#elif SD_IOS || SD_TV
+    self.displayLink.paused = YES;
+#else
+    [self.displayLink invalidate];
+#endif
+}
+
+- (void)displayLinkDidRefresh:(id)displayLink {
+#if SD_MAC
+    // CVDisplayLink does not use runloop, but we can provide similar behavior for modes
+    // May use `default` runloop to avoid extra callback when in `eventTracking` (mouse drag, scroll) or `modalPanel` (modal panel)
+    NSString *runloopMode = self.runloopMode;
+    if (![runloopMode isEqualToString:NSRunLoopCommonModes] && ![runloopMode isEqualToString:NSRunLoop.mainRunLoop.currentMode]) {
+        return;
+    }
+#endif
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
+    [_target performSelector:_selector withObject:self];
+#pragma clang diagnostic pop
+#if SD_WATCH
+    self.currentFireDate = CFRunLoopTimerGetNextFireDate((__bridge CFRunLoopTimerRef)self.displayLink);
+#endif
+}
+
+@end
+
+#if SD_MAC
+static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp *inNow, const CVTimeStamp *inOutputTime, CVOptionFlags flagsIn, CVOptionFlags *flagsOut, void *displayLinkContext) {
+    // CVDisplayLink callback is not on main queue
+    SDDisplayLink *object = (__bridge SDDisplayLink *)displayLinkContext;
+    if (inOutputTime) {
+        object.outputTime = *inOutputTime;
+    }
+    __weak SDDisplayLink *weakObject = object;
+    dispatch_async(dispatch_get_main_queue(), ^{
+        [weakObject displayLinkDidRefresh:(__bridge id)(displayLink)];
+    });
+    return kCVReturnSuccess;
+}
+#endif
@@ -0,0 +1,19 @@
+//
+//  This file is from https://gist.github.com/zydeco/6292773
+//
+//  Created by Jesús A. Álvarez on 2008-12-17.
+//  Copyright 2008-2009 namedfork.net. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+/// File Extended Attribute (xattr) helper methods
+@interface SDFileAttributeHelper : NSObject
+
+ (nullable NSArray<NSString *> *)extendedAttributeNamesAtPath:(nonnull NSString *)path traverseLink:(BOOL)follow error:(NSError * _Nullable * _Nullable)err;
+ (BOOL)hasExtendedAttribute:(nonnull NSString *)name atPath:(nonnull NSString *)path traverseLink:(BOOL)follow error:(NSError * _Nullable * _Nullable)err;
+ (nullable NSData *)extendedAttribute:(nonnull NSString *)name atPath:(nonnull NSString *)path traverseLink:(BOOL)follow error:(NSError * _Nullable * _Nullable)err;
+ (BOOL)setExtendedAttribute:(nonnull NSString *)name value:(nonnull NSData *)value atPath:(nonnull NSString *)path traverseLink:(BOOL)follow overwrite:(BOOL)overwrite error:(NSError * _Nullable * _Nullable)err;
+ (BOOL)removeExtendedAttribute:(nonnull NSString *)name atPath:(nonnull NSString *)path traverseLink:(BOOL)follow error:(NSError * _Nullable * _Nullable)err;
+
+@end
@@ -0,0 +1,127 @@
+//
+//  This file is from https://gist.github.com/zydeco/6292773
+//
+//  Created by Jesús A. Álvarez on 2008-12-17.
+//  Copyright 2008-2009 namedfork.net. All rights reserved.
+//
+
+#import "SDFileAttributeHelper.h"
+#import <sys/xattr.h>
+
+@implementation SDFileAttributeHelper
+
+ (NSArray*)extendedAttributeNamesAtPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
+    int flags = follow? 0 : XATTR_NOFOLLOW;
+    
+    // get size of name list
+    ssize_t nameBuffLen = listxattr([path fileSystemRepresentation], NULL, 0, flags);
+    if (nameBuffLen == -1) {
+        if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
+                         @{
+                             @"error": [NSString stringWithUTF8String:strerror(errno)],
+                             @"function": @"listxattr",
+                             @":path": path,
+                             @":traverseLink": @(follow)
+                         }
+                         ];
+        return nil;
+    } else if (nameBuffLen == 0) return @[];
+    
+    // get name list
+    NSMutableData *nameBuff = [NSMutableData dataWithLength:nameBuffLen];
+    listxattr([path fileSystemRepresentation], [nameBuff mutableBytes], nameBuffLen, flags);
+    
+    // convert to array
+    NSMutableArray * names = [NSMutableArray arrayWithCapacity:5];
+    char *nextName, *endOfNames = [nameBuff mutableBytes] + nameBuffLen;
+    for(nextName = [nameBuff mutableBytes]; nextName < endOfNames; nextName += 1+strlen(nextName))
+        [names addObject:[NSString stringWithUTF8String:nextName]];
+    return names.copy;
+}
+
+ (BOOL)hasExtendedAttribute:(NSString *)name atPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
+    int flags = follow? 0 : XATTR_NOFOLLOW;
+    
+    // get size of name list
+    ssize_t nameBuffLen = listxattr([path fileSystemRepresentation], NULL, 0, flags);
+    if (nameBuffLen == -1) {
+        if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
+                         @{
+                             @"error": [NSString stringWithUTF8String:strerror(errno)],
+                             @"function": @"listxattr",
+                             @":path": path,
+                             @":traverseLink": @(follow)
+                         }
+                         ];
+        return NO;
+    } else if (nameBuffLen == 0) return NO;
+    
+    // get name list
+    NSMutableData *nameBuff = [NSMutableData dataWithLength:nameBuffLen];
+    listxattr([path fileSystemRepresentation], [nameBuff mutableBytes], nameBuffLen, flags);
+    
+    // find our name
+    char *nextName, *endOfNames = [nameBuff mutableBytes] + nameBuffLen;
+    for(nextName = [nameBuff mutableBytes]; nextName < endOfNames; nextName += 1+strlen(nextName))
+        if (strcmp(nextName, [name UTF8String]) == 0) return YES;
+    return NO;
+}
+
+ (NSData *)extendedAttribute:(NSString *)name atPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
+    int flags = follow? 0 : XATTR_NOFOLLOW;
+    // get length
+    ssize_t attrLen = getxattr([path fileSystemRepresentation], [name UTF8String], NULL, 0, 0, flags);
+    if (attrLen == -1) {
+        if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
+                         @{
+                             @"error": [NSString stringWithUTF8String:strerror(errno)],
+                             @"function": @"getxattr",
+                             @":name": name,
+                             @":path": path,
+                             @":traverseLink": @(follow)
+                         }
+                         ];
+        return nil;
+    }
+    
+    // get attribute data
+    NSMutableData *attrData = [NSMutableData dataWithLength:attrLen];
+    getxattr([path fileSystemRepresentation], [name UTF8String], [attrData mutableBytes], attrLen, 0, flags);
+    return attrData;
+}
+
+ (BOOL)setExtendedAttribute:(NSString *)name value:(NSData *)value atPath:(NSString *)path traverseLink:(BOOL)follow overwrite:(BOOL)overwrite error:(NSError **)err {
+    int flags = (follow? 0 : XATTR_NOFOLLOW) | (overwrite? 0 : XATTR_CREATE);
+    if (0 == setxattr([path fileSystemRepresentation], [name UTF8String], [value bytes], [value length], 0, flags)) return YES;
+    // error
+    if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
+                     @{
+                         @"error": [NSString stringWithUTF8String:strerror(errno)],
+                         @"function": @"setxattr",
+                         @":name": name,
+                         @":value.length": @(value.length),
+                         @":path": path,
+                         @":traverseLink": @(follow),
+                         @":overwrite": @(overwrite)
+                     }
+                     ];
+    return NO;
+}
+
+ (BOOL)removeExtendedAttribute:(NSString *)name atPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
+    int flags = (follow? 0 : XATTR_NOFOLLOW);
+    if (0 == removexattr([path fileSystemRepresentation], [name UTF8String], flags)) return YES;
+    // error
+    if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
+                     @{
+                         @"error": [NSString stringWithUTF8String:strerror(errno)],
+                         @"function": @"removexattr",
+                         @":name": name,
+                         @":path": path,
+                         @":traverseLink": @(follow)
+                     }
+                     ];
+    return NO;
+}
+
+@end
@@ -0,0 +1,23 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import <Foundation/Foundation.h>
+#import "SDWebImageCompat.h"
+
+/// A Image-Asset manager to work like UIKit/AppKit's image cache behavior
+/// Apple parse the Asset Catalog compiled file(`Assets.car`) by CoreUI.framework, however it's a private framework and there are no other ways to directly get the data. So we just process the normal bundle files :)
+@interface SDImageAssetManager : NSObject
+
+@property (nonatomic, strong, nonnull) NSMapTable<NSString *, UIImage *> *imageTable;
+
+ (nonnull instancetype)sharedAssetManager;
+- (nullable NSString *)getPathForName:(nonnull NSString *)name bundle:(nonnull NSBundle *)bundle preferredScale:(nonnull CGFloat *)scale;
+- (nullable UIImage *)imageForName:(nonnull NSString *)name;
+- (void)storeImage:(nonnull UIImage *)image forName:(nonnull NSString *)name;
+
+@end
@@ -0,0 +1,164 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDImageAssetManager.h"
+#import "SDInternalMacros.h"
+
+static NSArray *SDBundlePreferredScales() {
+    static NSArray *scales;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+#if SD_WATCH
+        CGFloat screenScale = [WKInterfaceDevice currentDevice].screenScale;
+#elif SD_UIKIT
+        CGFloat screenScale = [UIScreen mainScreen].scale;
+#elif SD_MAC
+      NSScreen *mainScreen = nil;
+      if (@available(macOS 10.12, *)) {
+          mainScreen = [NSScreen mainScreen];
+      } else {
+          mainScreen = [NSScreen screens].firstObject;
+      }
+      CGFloat screenScale = mainScreen.backingScaleFactor ?: 1.0f;
+#endif
+        if (screenScale <= 1) {
+            scales = @[@1,@2,@3];
+        } else if (screenScale <= 2) {
+            scales = @[@2,@3,@1];
+        } else {
+            scales = @[@3,@2,@1];
+        }
+    });
+    return scales;
+}
+
+@implementation SDImageAssetManager {
+    SD_LOCK_DECLARE(_lock);
+}
+
+ (instancetype)sharedAssetManager {
+    static dispatch_once_t onceToken;
+    static SDImageAssetManager *assetManager;
+    dispatch_once(&onceToken, ^{
+        assetManager = [[SDImageAssetManager alloc] init];
+    });
+    return assetManager;
+}
+
+- (instancetype)init {
+    self = [super init];
+    if (self) {
+        NSPointerFunctionsOptions valueOptions;
+#if SD_MAC
+        // Apple says that NSImage use a weak reference to value
+        valueOptions = NSPointerFunctionsWeakMemory;
+#else
+        // Apple says that UIImage use a strong reference to value
+        valueOptions = NSPointerFunctionsStrongMemory;
+#endif
+        _imageTable = [NSMapTable mapTableWithKeyOptions:NSPointerFunctionsCopyIn valueOptions:valueOptions];
+        SD_LOCK_INIT(_lock);
+#if SD_UIKIT
+        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didReceiveMemoryWarning:) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
+#endif
+    }
+    return self;
+}
+
+- (void)dealloc {
+#if SD_UIKIT
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
+#endif
+}
+
+- (void)didReceiveMemoryWarning:(NSNotification *)notification {
+    SD_LOCK(_lock);
+    [self.imageTable removeAllObjects];
+    SD_UNLOCK(_lock);
+}
+
+- (NSString *)getPathForName:(NSString *)name bundle:(NSBundle *)bundle preferredScale:(CGFloat *)scale {
+    NSParameterAssert(name);
+    NSParameterAssert(bundle);
+    NSString *path;
+    if (name.length == 0) {
+        return path;
+    }
+    if ([name hasSuffix:@"/"]) {
+        return path;
+    }
+    NSString *extension = name.pathExtension;
+    if (extension.length == 0) {
+        // If no extension, follow Apple's doc, check PNG format
+        extension = @"png";
+    }
+    name = [name stringByDeletingPathExtension];
+    
+    CGFloat providedScale = *scale;
+    NSArray *scales = SDBundlePreferredScales();
+    
+    // Check if file name contains scale
+    for (size_t i = 0; i < scales.count; i++) {
+        NSNumber *scaleValue = scales[i];
+        if ([name hasSuffix:[NSString stringWithFormat:@"@%@x", scaleValue]]) {
+            path = [bundle pathForResource:name ofType:extension];
+            if (path) {
+                *scale = scaleValue.doubleValue; // override
+                return path;
+            }
+        }
+    }
+    
+    // Search with provided scale first
+    if (providedScale != 0) {
+        NSString *scaledName = [name stringByAppendingFormat:@"@%@x", @(providedScale)];
+        path = [bundle pathForResource:scaledName ofType:extension];
+        if (path) {
+            return path;
+        }
+    }
+    
+    // Search with preferred scale
+    for (size_t i = 0; i < scales.count; i++) {
+        NSNumber *scaleValue = scales[i];
+        if (scaleValue.doubleValue == providedScale) {
+            // Ignore provided scale
+            continue;
+        }
+        NSString *scaledName = [name stringByAppendingFormat:@"@%@x", scaleValue];
+        path = [bundle pathForResource:scaledName ofType:extension];
+        if (path) {
+            *scale = scaleValue.doubleValue; // override
+            return path;
+        }
+    }
+    
+    // Search without scale
+    path = [bundle pathForResource:name ofType:extension];
+    
+    return path;
+}
+
+- (UIImage *)imageForName:(NSString *)name {
+    NSParameterAssert(name);
+    UIImage *image;
+    SD_LOCK(_lock);
+    image = [self.imageTable objectForKey:name];
+    SD_UNLOCK(_lock);
+    return image;
+}
+
+- (void)storeImage:(UIImage *)image forName:(NSString *)name {
+    NSParameterAssert(image);
+    NSParameterAssert(name);
+    SD_LOCK(_lock);
+    [self.imageTable setObject:image forKey:name];
+    SD_UNLOCK(_lock);
+}
+
+@end
@@ -0,0 +1,21 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import <Foundation/Foundation.h>
+#import "SDWebImageCompat.h"
+
+/// This is used for operation management, but not for operation queue execute
+@interface SDImageCachesManagerOperation : NSOperation
+
+@property (nonatomic, assign, readonly) NSUInteger pendingCount;
+
+- (void)beginWithTotalCount:(NSUInteger)totalCount;
+- (void)completeOne;
+- (void)done;
+
+@end
@@ -0,0 +1,83 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDImageCachesManagerOperation.h"
+#import "SDInternalMacros.h"
+
+@implementation SDImageCachesManagerOperation {
+    SD_LOCK_DECLARE(_pendingCountLock);
+}
+
+@synthesize executing = _executing;
+@synthesize finished = _finished;
+@synthesize cancelled = _cancelled;
+@synthesize pendingCount = _pendingCount;
+
+- (instancetype)init {
+    if (self = [super init]) {
+        SD_LOCK_INIT(_pendingCountLock);
+        _pendingCount = 0;
+    }
+    return self;
+}
+
+- (void)beginWithTotalCount:(NSUInteger)totalCount {
+    self.executing = YES;
+    self.finished = NO;
+    _pendingCount = totalCount;
+}
+
+- (NSUInteger)pendingCount {
+    SD_LOCK(_pendingCountLock);
+    NSUInteger pendingCount = _pendingCount;
+    SD_UNLOCK(_pendingCountLock);
+    return pendingCount;
+}
+
+- (void)completeOne {
+    SD_LOCK(_pendingCountLock);
+    _pendingCount = _pendingCount > 0 ? _pendingCount - 1 : 0;
+    SD_UNLOCK(_pendingCountLock);
+}
+
+- (void)cancel {
+    self.cancelled = YES;
+    [self reset];
+}
+
+- (void)done {
+    self.finished = YES;
+    self.executing = NO;
+    [self reset];
+}
+
+- (void)reset {
+    SD_LOCK(_pendingCountLock);
+    _pendingCount = 0;
+    SD_UNLOCK(_pendingCountLock);
+}
+
+- (void)setFinished:(BOOL)finished {
+    [self willChangeValueForKey:@"isFinished"];
+    _finished = finished;
+    [self didChangeValueForKey:@"isFinished"];
+}
+
+- (void)setExecuting:(BOOL)executing {
+    [self willChangeValueForKey:@"isExecuting"];
+    _executing = executing;
+    [self didChangeValueForKey:@"isExecuting"];
+}
+
+- (void)setCancelled:(BOOL)cancelled {
+    [self willChangeValueForKey:@"isCancelled"];
+    _cancelled = cancelled;
+    [self didChangeValueForKey:@"isCancelled"];
+}
+
+@end
@@ -0,0 +1,36 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import <Foundation/Foundation.h>
+#import "SDImageIOAnimatedCoder.h"
+
+// AVFileTypeHEIC/AVFileTypeHEIF is defined in AVFoundation via iOS 11, we use this without import AVFoundation
+#define kSDUTTypeHEIC  ((__bridge CFStringRef)@"public.heic")
+#define kSDUTTypeHEIF  ((__bridge CFStringRef)@"public.heif")
+// HEIC Sequence (Animated Image)
+#define kSDUTTypeHEICS ((__bridge CFStringRef)@"public.heics")
+// kSDUTTypeWebP seems not defined in public UTI framework, Apple use the hardcode string, we define them :)
+#define kSDUTTypeWebP  ((__bridge CFStringRef)@"org.webmproject.webp")
+
+#define kSDUTTypeImage ((__bridge CFStringRef)@"public.image")
+#define kSDUTTypeJPEG  ((__bridge CFStringRef)@"public.jpeg")
+#define kSDUTTypePNG   ((__bridge CFStringRef)@"public.png")
+#define kSDUTTypeTIFF  ((__bridge CFStringRef)@"public.tiff")
+#define kSDUTTypeSVG   ((__bridge CFStringRef)@"public.svg-image")
+#define kSDUTTypeGIF   ((__bridge CFStringRef)@"com.compuserve.gif")
+#define kSDUTTypePDF   ((__bridge CFStringRef)@"com.adobe.pdf")
+
+@interface SDImageIOAnimatedCoder ()
+
+ (NSTimeInterval)frameDurationAtIndex:(NSUInteger)index source:(nonnull CGImageSourceRef)source;
+ (NSUInteger)imageLoopCountWithSource:(nonnull CGImageSourceRef)source;
+ (nullable UIImage *)createFrameAtIndex:(NSUInteger)index source:(nonnull CGImageSourceRef)source scale:(CGFloat)scale preserveAspectRatio:(BOOL)preserveAspectRatio thumbnailSize:(CGSize)thumbnailSize options:(nullable NSDictionary *)options;
+ (BOOL)canEncodeToFormat:(SDImageFormat)format;
+ (BOOL)canDecodeFromFormat:(SDImageFormat)format;
+
+@end
@@ -0,0 +1,122 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import <Foundation/Foundation.h>
+#import <os/lock.h>
+#import <libkern/OSAtomic.h>
+#import "SDmetamacros.h"
+
+#define SD_USE_OS_UNFAIR_LOCK TARGET_OS_MACCATALYST ||\
+    (__IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_10_0) ||\
+    (__MAC_OS_X_VERSION_MIN_REQUIRED >= __MAC_10_12) ||\
+    (__TV_OS_VERSION_MIN_REQUIRED >= __TVOS_10_0) ||\
+    (__WATCH_OS_VERSION_MIN_REQUIRED >= __WATCHOS_3_0)
+
+#ifndef SD_LOCK_DECLARE
+#if SD_USE_OS_UNFAIR_LOCK
+#define SD_LOCK_DECLARE(lock) os_unfair_lock lock
+#else
+#define SD_LOCK_DECLARE(lock) os_unfair_lock lock API_AVAILABLE(ios(10.0), tvos(10), watchos(3), macos(10.12)); \
+OSSpinLock lock##_deprecated;
+#endif
+#endif
+
+#ifndef SD_LOCK_DECLARE_STATIC
+#if SD_USE_OS_UNFAIR_LOCK
+#define SD_LOCK_DECLARE_STATIC(lock) static os_unfair_lock lock
+#else
+#define SD_LOCK_DECLARE_STATIC(lock) static os_unfair_lock lock API_AVAILABLE(ios(10.0), tvos(10), watchos(3), macos(10.12)); \
+static OSSpinLock lock##_deprecated;
+#endif
+#endif
+
+#ifndef SD_LOCK_INIT
+#if SD_USE_OS_UNFAIR_LOCK
+#define SD_LOCK_INIT(lock) lock = OS_UNFAIR_LOCK_INIT
+#else
+#define SD_LOCK_INIT(lock) if (@available(iOS 10, tvOS 10, watchOS 3, macOS 10.12, *)) lock = OS_UNFAIR_LOCK_INIT; \
+else lock##_deprecated = OS_SPINLOCK_INIT;
+#endif
+#endif
+
+#ifndef SD_LOCK
+#if SD_USE_OS_UNFAIR_LOCK
+#define SD_LOCK(lock) os_unfair_lock_lock(&lock)
+#else
+#define SD_LOCK(lock) if (@available(iOS 10, tvOS 10, watchOS 3, macOS 10.12, *)) os_unfair_lock_lock(&lock); \
+else OSSpinLockLock(&lock##_deprecated);
+#endif
+#endif
+
+#ifndef SD_UNLOCK
+#if SD_USE_OS_UNFAIR_LOCK
+#define SD_UNLOCK(lock) os_unfair_lock_unlock(&lock)
+#else
+#define SD_UNLOCK(lock) if (@available(iOS 10, tvOS 10, watchOS 3, macOS 10.12, *)) os_unfair_lock_unlock(&lock); \
+else OSSpinLockUnlock(&lock##_deprecated);
+#endif
+#endif
+
+#ifndef SD_OPTIONS_CONTAINS
+#define SD_OPTIONS_CONTAINS(options, value) (((options) & (value)) == (value))
+#endif
+
+#ifndef SD_CSTRING
+#define SD_CSTRING(str) #str
+#endif
+
+#ifndef SD_NSSTRING
+#define SD_NSSTRING(str) @(SD_CSTRING(str))
+#endif
+
+#ifndef SD_SEL_SPI
+#define SD_SEL_SPI(name) NSSelectorFromString([NSString stringWithFormat:@"_%@", SD_NSSTRING(name)])
+#endif
+
+#ifndef weakify
+#define weakify(...) \
+sd_keywordify \
+metamacro_foreach_cxt(sd_weakify_,, __weak, __VA_ARGS__)
+#endif
+
+#ifndef strongify
+#define strongify(...) \
+sd_keywordify \
+_Pragma("clang diagnostic push") \
+_Pragma("clang diagnostic ignored \"-Wshadow\"") \
+metamacro_foreach(sd_strongify_,, __VA_ARGS__) \
+_Pragma("clang diagnostic pop")
+#endif
+
+#define sd_weakify_(INDEX, CONTEXT, VAR) \
+CONTEXT __typeof__(VAR) metamacro_concat(VAR, _weak_) = (VAR);
+
+#define sd_strongify_(INDEX, VAR) \
+__strong __typeof__(VAR) VAR = metamacro_concat(VAR, _weak_);
+
+#if DEBUG
+#define sd_keywordify autoreleasepool {}
+#else
+#define sd_keywordify try {} @catch (...) {}
+#endif
+
+#ifndef onExit
+#define onExit \
+sd_keywordify \
+__strong sd_cleanupBlock_t metamacro_concat(sd_exitBlock_, __LINE__) __attribute__((cleanup(sd_executeCleanupBlock), unused)) = ^
+#endif
+
+typedef void (^sd_cleanupBlock_t)(void);
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+    void sd_executeCleanupBlock (__strong sd_cleanupBlock_t *block);
+#if defined(__cplusplus)
+}
+#endif
@@ -0,0 +1,13 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDInternalMacros.h"
+
+void sd_executeCleanupBlock (__strong sd_cleanupBlock_t *block) {
+    (*block)();
+}
@@ -0,0 +1,20 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import <Foundation/Foundation.h>
+#import "SDWebImageCompat.h"
+
+/// A weak proxy which forward all the message to the target
+@interface SDWeakProxy : NSProxy
+
+@property (nonatomic, weak, readonly, nullable) id target;
+
+- (nonnull instancetype)initWithTarget:(nonnull id)target;
+ (nonnull instancetype)proxyWithTarget:(nonnull id)target;
+
+@end
@@ -0,0 +1,79 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDWeakProxy.h"
+
+@implementation SDWeakProxy
+
+- (instancetype)initWithTarget:(id)target {
+    _target = target;
+    return self;
+}
+
+ (instancetype)proxyWithTarget:(id)target {
+    return [[SDWeakProxy alloc] initWithTarget:target];
+}
+
+- (id)forwardingTargetForSelector:(SEL)selector {
+    return _target;
+}
+
+- (void)forwardInvocation:(NSInvocation *)invocation {
+    void *null = NULL;
+    [invocation setReturnValue:&null];
+}
+
+- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector {
+    return [NSObject instanceMethodSignatureForSelector:@selector(init)];
+}
+
+- (BOOL)respondsToSelector:(SEL)aSelector {
+    return [_target respondsToSelector:aSelector];
+}
+
+- (BOOL)isEqual:(id)object {
+    return [_target isEqual:object];
+}
+
+- (NSUInteger)hash {
+    return [_target hash];
+}
+
+- (Class)superclass {
+    return [_target superclass];
+}
+
+- (Class)class {
+    return [_target class];
+}
+
+- (BOOL)isKindOfClass:(Class)aClass {
+    return [_target isKindOfClass:aClass];
+}
+
+- (BOOL)isMemberOfClass:(Class)aClass {
+    return [_target isMemberOfClass:aClass];
+}
+
+- (BOOL)conformsToProtocol:(Protocol *)aProtocol {
+    return [_target conformsToProtocol:aProtocol];
+}
+
+- (BOOL)isProxy {
+    return YES;
+}
+
+- (NSString *)description {
+    return [_target description];
+}
+
+- (NSString *)debugDescription {
+    return [_target debugDescription];
+}
+
+@end
@@ -0,0 +1,19 @@
+/*
+* This file is part of the SDWebImage package.
+* (c) Olivier Poitrey <rs@dailymotion.com>
+*
+* For the full copyright and license information, please view the LICENSE
+* file that was distributed with this source code.
+*/
+
+#import "SDWebImageCompat.h"
+
+#if SD_MAC
+
+#import <QuartzCore/QuartzCore.h>
+
+/// Helper method for Core Animation transition
+FOUNDATION_EXPORT CAMediaTimingFunction * _Nullable SDTimingFunctionFromAnimationOptions(SDWebImageAnimationOptions options);
+FOUNDATION_EXPORT CATransition * _Nullable SDTransitionFromAnimationOptions(SDWebImageAnimationOptions options);
+
+#endif
@@ -0,0 +1,667 @@
+/**
+ * Macros for metaprogramming
+ * ExtendedC
+ *
+ * Copyright (C) 2012 Justin Spahr-Summers
+ * Released under the MIT license
+ */
+
+#ifndef EXTC_METAMACROS_H
+#define EXTC_METAMACROS_H
+
+
+/**
+ * Executes one or more expressions (which may have a void type, such as a call
+ * to a function that returns no value) and always returns true.
+ */
+#define metamacro_exprify(...) \
+    ((__VA_ARGS__), true)
+
+/**
+ * Returns a string representation of VALUE after full macro expansion.
+ */
+#define metamacro_stringify(VALUE) \
+        metamacro_stringify_(VALUE)
+
+/**
+ * Returns A and B concatenated after full macro expansion.
+ */
+#define metamacro_concat(A, B) \
+        metamacro_concat_(A, B)
+
+/**
+ * Returns the Nth variadic argument (starting from zero). At least
+ * N + 1 variadic arguments must be given. N must be between zero and twenty,
+ * inclusive.
+ */
+#define metamacro_at(N, ...) \
+        metamacro_concat(metamacro_at, N)(__VA_ARGS__)
+
+/**
+ * Returns the number of arguments (up to twenty) provided to the macro. At
+ * least one argument must be provided.
+ *
+ * Inspired by P99: http://p99.gforge.inria.fr
+ */
+#define metamacro_argcount(...) \
+        metamacro_at(20, __VA_ARGS__, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
+
+/**
+ * Identical to #metamacro_foreach_cxt, except that no CONTEXT argument is
+ * given. Only the index and current argument will thus be passed to MACRO.
+ */
+#define metamacro_foreach(MACRO, SEP, ...) \
+        metamacro_foreach_cxt(metamacro_foreach_iter, SEP, MACRO, __VA_ARGS__)
+
+/**
+ * For each consecutive variadic argument (up to twenty), MACRO is passed the
+ * zero-based index of the current argument, CONTEXT, and then the argument
+ * itself. The results of adjoining invocations of MACRO are then separated by
+ * SEP.
+ *
+ * Inspired by P99: http://p99.gforge.inria.fr
+ */
+#define metamacro_foreach_cxt(MACRO, SEP, CONTEXT, ...) \
+        metamacro_concat(metamacro_foreach_cxt, metamacro_argcount(__VA_ARGS__))(MACRO, SEP, CONTEXT, __VA_ARGS__)
+
+/**
+ * Identical to #metamacro_foreach_cxt. This can be used when the former would
+ * fail due to recursive macro expansion.
+ */
+#define metamacro_foreach_cxt_recursive(MACRO, SEP, CONTEXT, ...) \
+        metamacro_concat(metamacro_foreach_cxt_recursive, metamacro_argcount(__VA_ARGS__))(MACRO, SEP, CONTEXT, __VA_ARGS__)
+
+/**
+ * In consecutive order, appends each variadic argument (up to twenty) onto
+ * BASE. The resulting concatenations are then separated by SEP.
+ *
+ * This is primarily useful to manipulate a list of macro invocations into instead
+ * invoking a different, possibly related macro.
+ */
+#define metamacro_foreach_concat(BASE, SEP, ...) \
+        metamacro_foreach_cxt(metamacro_foreach_concat_iter, SEP, BASE, __VA_ARGS__)
+
+/**
+ * Iterates COUNT times, each time invoking MACRO with the current index
+ * (starting at zero) and CONTEXT. The results of adjoining invocations of MACRO
+ * are then separated by SEP.
+ *
+ * COUNT must be an integer between zero and twenty, inclusive.
+ */
+#define metamacro_for_cxt(COUNT, MACRO, SEP, CONTEXT) \
+        metamacro_concat(metamacro_for_cxt, COUNT)(MACRO, SEP, CONTEXT)
+
+/**
+ * Returns the first argument given. At least one argument must be provided.
+ *
+ * This is useful when implementing a variadic macro, where you may have only
+ * one variadic argument, but no way to retrieve it (for example, because \c ...
+ * always needs to match at least one argument).
+ *
+ * @code
+
+#define varmacro(...) \
+    metamacro_head(__VA_ARGS__)
+
+ * @endcode
+ */
+#define metamacro_head(...) \
+        metamacro_head_(__VA_ARGS__, 0)
+
+/**
+ * Returns every argument except the first. At least two arguments must be
+ * provided.
+ */
+#define metamacro_tail(...) \
+        metamacro_tail_(__VA_ARGS__)
+
+/**
+ * Returns the first N (up to twenty) variadic arguments as a new argument list.
+ * At least N variadic arguments must be provided.
+ */
+#define metamacro_take(N, ...) \
+        metamacro_concat(metamacro_take, N)(__VA_ARGS__)
+
+/**
+ * Removes the first N (up to twenty) variadic arguments from the given argument
+ * list. At least N variadic arguments must be provided.
+ */
+#define metamacro_drop(N, ...) \
+        metamacro_concat(metamacro_drop, N)(__VA_ARGS__)
+
+/**
+ * Decrements VAL, which must be a number between zero and twenty, inclusive.
+ *
+ * This is primarily useful when dealing with indexes and counts in
+ * metaprogramming.
+ */
+#define metamacro_dec(VAL) \
+        metamacro_at(VAL, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
+
+/**
+ * Increments VAL, which must be a number between zero and twenty, inclusive.
+ *
+ * This is primarily useful when dealing with indexes and counts in
+ * metaprogramming.
+ */
+#define metamacro_inc(VAL) \
+        metamacro_at(VAL, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
+
+/**
+ * If A is equal to B, the next argument list is expanded; otherwise, the
+ * argument list after that is expanded. A and B must be numbers between zero
+ * and twenty, inclusive. Additionally, B must be greater than or equal to A.
+ *
+ * @code
+
+// expands to true
+metamacro_if_eq(0, 0)(true)(false)
+
+// expands to false
+metamacro_if_eq(0, 1)(true)(false)
+
+ * @endcode
+ *
+ * This is primarily useful when dealing with indexes and counts in
+ * metaprogramming.
+ */
+#define metamacro_if_eq(A, B) \
+        metamacro_concat(metamacro_if_eq, A)(B)
+
+/**
+ * Identical to #metamacro_if_eq. This can be used when the former would fail
+ * due to recursive macro expansion.
+ */
+#define metamacro_if_eq_recursive(A, B) \
+        metamacro_concat(metamacro_if_eq_recursive, A)(B)
+
+/**
+ * Returns 1 if N is an even number, or 0 otherwise. N must be between zero and
+ * twenty, inclusive.
+ *
+ * For the purposes of this test, zero is considered even.
+ */
+#define metamacro_is_even(N) \
+        metamacro_at(N, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1)
+
+/**
+ * Returns the logical NOT of B, which must be the number zero or one.
+ */
+#define metamacro_not(B) \
+        metamacro_at(B, 1, 0)
+
+// IMPLEMENTATION DETAILS FOLLOW!
+// Do not write code that depends on anything below this line.
+#define metamacro_stringify_(VALUE) # VALUE
+#define metamacro_concat_(A, B) A ## B
+#define metamacro_foreach_iter(INDEX, MACRO, ARG) MACRO(INDEX, ARG)
+#define metamacro_head_(FIRST, ...) FIRST
+#define metamacro_tail_(FIRST, ...) __VA_ARGS__
+#define metamacro_consume_(...)
+#define metamacro_expand_(...) __VA_ARGS__
+
+// implemented from scratch so that metamacro_concat() doesn't end up nesting
+#define metamacro_foreach_concat_iter(INDEX, BASE, ARG) metamacro_foreach_concat_iter_(BASE, ARG)
+#define metamacro_foreach_concat_iter_(BASE, ARG) BASE ## ARG
+
+// metamacro_at expansions
+#define metamacro_at0(...) metamacro_head(__VA_ARGS__)
+#define metamacro_at1(_0, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at2(_0, _1, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at3(_0, _1, _2, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at4(_0, _1, _2, _3, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at5(_0, _1, _2, _3, _4, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at6(_0, _1, _2, _3, _4, _5, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at7(_0, _1, _2, _3, _4, _5, _6, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at8(_0, _1, _2, _3, _4, _5, _6, _7, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at9(_0, _1, _2, _3, _4, _5, _6, _7, _8, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at10(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at11(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at12(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at13(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at14(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at15(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at16(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at17(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at18(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at19(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, ...) metamacro_head(__VA_ARGS__)
+#define metamacro_at20(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, ...) metamacro_head(__VA_ARGS__)
+
+// metamacro_foreach_cxt expansions
+#define metamacro_foreach_cxt0(MACRO, SEP, CONTEXT)
+#define metamacro_foreach_cxt1(MACRO, SEP, CONTEXT, _0) MACRO(0, CONTEXT, _0)
+
+#define metamacro_foreach_cxt2(MACRO, SEP, CONTEXT, _0, _1) \
+    metamacro_foreach_cxt1(MACRO, SEP, CONTEXT, _0) \
+    SEP \
+    MACRO(1, CONTEXT, _1)
+
+#define metamacro_foreach_cxt3(MACRO, SEP, CONTEXT, _0, _1, _2) \
+    metamacro_foreach_cxt2(MACRO, SEP, CONTEXT, _0, _1) \
+    SEP \
+    MACRO(2, CONTEXT, _2)
+
+#define metamacro_foreach_cxt4(MACRO, SEP, CONTEXT, _0, _1, _2, _3) \
+    metamacro_foreach_cxt3(MACRO, SEP, CONTEXT, _0, _1, _2) \
+    SEP \
+    MACRO(3, CONTEXT, _3)
+
+#define metamacro_foreach_cxt5(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4) \
+    metamacro_foreach_cxt4(MACRO, SEP, CONTEXT, _0, _1, _2, _3) \
+    SEP \
+    MACRO(4, CONTEXT, _4)
+
+#define metamacro_foreach_cxt6(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5) \
+    metamacro_foreach_cxt5(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4) \
+    SEP \
+    MACRO(5, CONTEXT, _5)
+
+#define metamacro_foreach_cxt7(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6) \
+    metamacro_foreach_cxt6(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5) \
+    SEP \
+    MACRO(6, CONTEXT, _6)
+
+#define metamacro_foreach_cxt8(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7) \
+    metamacro_foreach_cxt7(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6) \
+    SEP \
+    MACRO(7, CONTEXT, _7)
+
+#define metamacro_foreach_cxt9(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8) \
+    metamacro_foreach_cxt8(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7) \
+    SEP \
+    MACRO(8, CONTEXT, _8)
+
+#define metamacro_foreach_cxt10(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9) \
+    metamacro_foreach_cxt9(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8) \
+    SEP \
+    MACRO(9, CONTEXT, _9)
+
+#define metamacro_foreach_cxt11(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10) \
+    metamacro_foreach_cxt10(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9) \
+    SEP \
+    MACRO(10, CONTEXT, _10)
+
+#define metamacro_foreach_cxt12(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11) \
+    metamacro_foreach_cxt11(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10) \
+    SEP \
+    MACRO(11, CONTEXT, _11)
+
+#define metamacro_foreach_cxt13(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12) \
+    metamacro_foreach_cxt12(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11) \
+    SEP \
+    MACRO(12, CONTEXT, _12)
+
+#define metamacro_foreach_cxt14(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13) \
+    metamacro_foreach_cxt13(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12) \
+    SEP \
+    MACRO(13, CONTEXT, _13)
+
+#define metamacro_foreach_cxt15(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14) \
+    metamacro_foreach_cxt14(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13) \
+    SEP \
+    MACRO(14, CONTEXT, _14)
+
+#define metamacro_foreach_cxt16(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15) \
+    metamacro_foreach_cxt15(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14) \
+    SEP \
+    MACRO(15, CONTEXT, _15)
+
+#define metamacro_foreach_cxt17(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16) \
+    metamacro_foreach_cxt16(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15) \
+    SEP \
+    MACRO(16, CONTEXT, _16)
+
+#define metamacro_foreach_cxt18(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17) \
+    metamacro_foreach_cxt17(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16) \
+    SEP \
+    MACRO(17, CONTEXT, _17)
+
+#define metamacro_foreach_cxt19(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18) \
+    metamacro_foreach_cxt18(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17) \
+    SEP \
+    MACRO(18, CONTEXT, _18)
+
+#define metamacro_foreach_cxt20(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19) \
+    metamacro_foreach_cxt19(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18) \
+    SEP \
+    MACRO(19, CONTEXT, _19)
+
+// metamacro_foreach_cxt_recursive expansions
+#define metamacro_foreach_cxt_recursive0(MACRO, SEP, CONTEXT)
+#define metamacro_foreach_cxt_recursive1(MACRO, SEP, CONTEXT, _0) MACRO(0, CONTEXT, _0)
+
+#define metamacro_foreach_cxt_recursive2(MACRO, SEP, CONTEXT, _0, _1) \
+    metamacro_foreach_cxt_recursive1(MACRO, SEP, CONTEXT, _0) \
+    SEP \
+    MACRO(1, CONTEXT, _1)
+
+#define metamacro_foreach_cxt_recursive3(MACRO, SEP, CONTEXT, _0, _1, _2) \
+    metamacro_foreach_cxt_recursive2(MACRO, SEP, CONTEXT, _0, _1) \
+    SEP \
+    MACRO(2, CONTEXT, _2)
+
+#define metamacro_foreach_cxt_recursive4(MACRO, SEP, CONTEXT, _0, _1, _2, _3) \
+    metamacro_foreach_cxt_recursive3(MACRO, SEP, CONTEXT, _0, _1, _2) \
+    SEP \
+    MACRO(3, CONTEXT, _3)
+
+#define metamacro_foreach_cxt_recursive5(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4) \
+    metamacro_foreach_cxt_recursive4(MACRO, SEP, CONTEXT, _0, _1, _2, _3) \
+    SEP \
+    MACRO(4, CONTEXT, _4)
+
+#define metamacro_foreach_cxt_recursive6(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5) \
+    metamacro_foreach_cxt_recursive5(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4) \
+    SEP \
+    MACRO(5, CONTEXT, _5)
+
+#define metamacro_foreach_cxt_recursive7(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6) \
+    metamacro_foreach_cxt_recursive6(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5) \
+    SEP \
+    MACRO(6, CONTEXT, _6)
+
+#define metamacro_foreach_cxt_recursive8(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7) \
+    metamacro_foreach_cxt_recursive7(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6) \
+    SEP \
+    MACRO(7, CONTEXT, _7)
+
+#define metamacro_foreach_cxt_recursive9(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8) \
+    metamacro_foreach_cxt_recursive8(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7) \
+    SEP \
+    MACRO(8, CONTEXT, _8)
+
+#define metamacro_foreach_cxt_recursive10(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9) \
+    metamacro_foreach_cxt_recursive9(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8) \
+    SEP \
+    MACRO(9, CONTEXT, _9)
+
+#define metamacro_foreach_cxt_recursive11(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10) \
+    metamacro_foreach_cxt_recursive10(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9) \
+    SEP \
+    MACRO(10, CONTEXT, _10)
+
+#define metamacro_foreach_cxt_recursive12(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11) \
+    metamacro_foreach_cxt_recursive11(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10) \
+    SEP \
+    MACRO(11, CONTEXT, _11)
+
+#define metamacro_foreach_cxt_recursive13(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12) \
+    metamacro_foreach_cxt_recursive12(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11) \
+    SEP \
+    MACRO(12, CONTEXT, _12)
+
+#define metamacro_foreach_cxt_recursive14(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13) \
+    metamacro_foreach_cxt_recursive13(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12) \
+    SEP \
+    MACRO(13, CONTEXT, _13)
+
+#define metamacro_foreach_cxt_recursive15(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14) \
+    metamacro_foreach_cxt_recursive14(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13) \
+    SEP \
+    MACRO(14, CONTEXT, _14)
+
+#define metamacro_foreach_cxt_recursive16(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15) \
+    metamacro_foreach_cxt_recursive15(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14) \
+    SEP \
+    MACRO(15, CONTEXT, _15)
+
+#define metamacro_foreach_cxt_recursive17(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16) \
+    metamacro_foreach_cxt_recursive16(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15) \
+    SEP \
+    MACRO(16, CONTEXT, _16)
+
+#define metamacro_foreach_cxt_recursive18(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17) \
+    metamacro_foreach_cxt_recursive17(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16) \
+    SEP \
+    MACRO(17, CONTEXT, _17)
+
+#define metamacro_foreach_cxt_recursive19(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18) \
+    metamacro_foreach_cxt_recursive18(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17) \
+    SEP \
+    MACRO(18, CONTEXT, _18)
+
+#define metamacro_foreach_cxt_recursive20(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19) \
+    metamacro_foreach_cxt_recursive19(MACRO, SEP, CONTEXT, _0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18) \
+    SEP \
+    MACRO(19, CONTEXT, _19)
+
+// metamacro_for_cxt expansions
+#define metamacro_for_cxt0(MACRO, SEP, CONTEXT)
+#define metamacro_for_cxt1(MACRO, SEP, CONTEXT) MACRO(0, CONTEXT)
+
+#define metamacro_for_cxt2(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt1(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(1, CONTEXT)
+
+#define metamacro_for_cxt3(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt2(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(2, CONTEXT)
+
+#define metamacro_for_cxt4(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt3(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(3, CONTEXT)
+
+#define metamacro_for_cxt5(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt4(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(4, CONTEXT)
+
+#define metamacro_for_cxt6(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt5(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(5, CONTEXT)
+
+#define metamacro_for_cxt7(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt6(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(6, CONTEXT)
+
+#define metamacro_for_cxt8(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt7(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(7, CONTEXT)
+
+#define metamacro_for_cxt9(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt8(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(8, CONTEXT)
+
+#define metamacro_for_cxt10(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt9(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(9, CONTEXT)
+
+#define metamacro_for_cxt11(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt10(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(10, CONTEXT)
+
+#define metamacro_for_cxt12(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt11(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(11, CONTEXT)
+
+#define metamacro_for_cxt13(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt12(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(12, CONTEXT)
+
+#define metamacro_for_cxt14(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt13(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(13, CONTEXT)
+
+#define metamacro_for_cxt15(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt14(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(14, CONTEXT)
+
+#define metamacro_for_cxt16(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt15(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(15, CONTEXT)
+
+#define metamacro_for_cxt17(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt16(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(16, CONTEXT)
+
+#define metamacro_for_cxt18(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt17(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(17, CONTEXT)
+
+#define metamacro_for_cxt19(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt18(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(18, CONTEXT)
+
+#define metamacro_for_cxt20(MACRO, SEP, CONTEXT) \
+    metamacro_for_cxt19(MACRO, SEP, CONTEXT) \
+    SEP \
+    MACRO(19, CONTEXT)
+
+// metamacro_if_eq expansions
+#define metamacro_if_eq0(VALUE) \
+    metamacro_concat(metamacro_if_eq0_, VALUE)
+
+#define metamacro_if_eq0_0(...) __VA_ARGS__ metamacro_consume_
+#define metamacro_if_eq0_1(...) metamacro_expand_
+#define metamacro_if_eq0_2(...) metamacro_expand_
+#define metamacro_if_eq0_3(...) metamacro_expand_
+#define metamacro_if_eq0_4(...) metamacro_expand_
+#define metamacro_if_eq0_5(...) metamacro_expand_
+#define metamacro_if_eq0_6(...) metamacro_expand_
+#define metamacro_if_eq0_7(...) metamacro_expand_
+#define metamacro_if_eq0_8(...) metamacro_expand_
+#define metamacro_if_eq0_9(...) metamacro_expand_
+#define metamacro_if_eq0_10(...) metamacro_expand_
+#define metamacro_if_eq0_11(...) metamacro_expand_
+#define metamacro_if_eq0_12(...) metamacro_expand_
+#define metamacro_if_eq0_13(...) metamacro_expand_
+#define metamacro_if_eq0_14(...) metamacro_expand_
+#define metamacro_if_eq0_15(...) metamacro_expand_
+#define metamacro_if_eq0_16(...) metamacro_expand_
+#define metamacro_if_eq0_17(...) metamacro_expand_
+#define metamacro_if_eq0_18(...) metamacro_expand_
+#define metamacro_if_eq0_19(...) metamacro_expand_
+#define metamacro_if_eq0_20(...) metamacro_expand_
+
+#define metamacro_if_eq1(VALUE) metamacro_if_eq0(metamacro_dec(VALUE))
+#define metamacro_if_eq2(VALUE) metamacro_if_eq1(metamacro_dec(VALUE))
+#define metamacro_if_eq3(VALUE) metamacro_if_eq2(metamacro_dec(VALUE))
+#define metamacro_if_eq4(VALUE) metamacro_if_eq3(metamacro_dec(VALUE))
+#define metamacro_if_eq5(VALUE) metamacro_if_eq4(metamacro_dec(VALUE))
+#define metamacro_if_eq6(VALUE) metamacro_if_eq5(metamacro_dec(VALUE))
+#define metamacro_if_eq7(VALUE) metamacro_if_eq6(metamacro_dec(VALUE))
+#define metamacro_if_eq8(VALUE) metamacro_if_eq7(metamacro_dec(VALUE))
+#define metamacro_if_eq9(VALUE) metamacro_if_eq8(metamacro_dec(VALUE))
+#define metamacro_if_eq10(VALUE) metamacro_if_eq9(metamacro_dec(VALUE))
+#define metamacro_if_eq11(VALUE) metamacro_if_eq10(metamacro_dec(VALUE))
+#define metamacro_if_eq12(VALUE) metamacro_if_eq11(metamacro_dec(VALUE))
+#define metamacro_if_eq13(VALUE) metamacro_if_eq12(metamacro_dec(VALUE))
+#define metamacro_if_eq14(VALUE) metamacro_if_eq13(metamacro_dec(VALUE))
+#define metamacro_if_eq15(VALUE) metamacro_if_eq14(metamacro_dec(VALUE))
+#define metamacro_if_eq16(VALUE) metamacro_if_eq15(metamacro_dec(VALUE))
+#define metamacro_if_eq17(VALUE) metamacro_if_eq16(metamacro_dec(VALUE))
+#define metamacro_if_eq18(VALUE) metamacro_if_eq17(metamacro_dec(VALUE))
+#define metamacro_if_eq19(VALUE) metamacro_if_eq18(metamacro_dec(VALUE))
+#define metamacro_if_eq20(VALUE) metamacro_if_eq19(metamacro_dec(VALUE))
+
+// metamacro_if_eq_recursive expansions
+#define metamacro_if_eq_recursive0(VALUE) \
+    metamacro_concat(metamacro_if_eq_recursive0_, VALUE)
+
+#define metamacro_if_eq_recursive0_0(...) __VA_ARGS__ metamacro_consume_
+#define metamacro_if_eq_recursive0_1(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_2(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_3(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_4(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_5(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_6(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_7(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_8(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_9(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_10(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_11(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_12(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_13(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_14(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_15(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_16(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_17(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_18(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_19(...) metamacro_expand_
+#define metamacro_if_eq_recursive0_20(...) metamacro_expand_
+
+#define metamacro_if_eq_recursive1(VALUE) metamacro_if_eq_recursive0(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive2(VALUE) metamacro_if_eq_recursive1(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive3(VALUE) metamacro_if_eq_recursive2(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive4(VALUE) metamacro_if_eq_recursive3(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive5(VALUE) metamacro_if_eq_recursive4(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive6(VALUE) metamacro_if_eq_recursive5(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive7(VALUE) metamacro_if_eq_recursive6(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive8(VALUE) metamacro_if_eq_recursive7(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive9(VALUE) metamacro_if_eq_recursive8(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive10(VALUE) metamacro_if_eq_recursive9(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive11(VALUE) metamacro_if_eq_recursive10(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive12(VALUE) metamacro_if_eq_recursive11(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive13(VALUE) metamacro_if_eq_recursive12(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive14(VALUE) metamacro_if_eq_recursive13(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive15(VALUE) metamacro_if_eq_recursive14(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive16(VALUE) metamacro_if_eq_recursive15(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive17(VALUE) metamacro_if_eq_recursive16(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive18(VALUE) metamacro_if_eq_recursive17(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive19(VALUE) metamacro_if_eq_recursive18(metamacro_dec(VALUE))
+#define metamacro_if_eq_recursive20(VALUE) metamacro_if_eq_recursive19(metamacro_dec(VALUE))
+
+// metamacro_take expansions
+#define metamacro_take0(...)
+#define metamacro_take1(...) metamacro_head(__VA_ARGS__)
+#define metamacro_take2(...) metamacro_head(__VA_ARGS__), metamacro_take1(metamacro_tail(__VA_ARGS__))
+#define metamacro_take3(...) metamacro_head(__VA_ARGS__), metamacro_take2(metamacro_tail(__VA_ARGS__))
+#define metamacro_take4(...) metamacro_head(__VA_ARGS__), metamacro_take3(metamacro_tail(__VA_ARGS__))
+#define metamacro_take5(...) metamacro_head(__VA_ARGS__), metamacro_take4(metamacro_tail(__VA_ARGS__))
+#define metamacro_take6(...) metamacro_head(__VA_ARGS__), metamacro_take5(metamacro_tail(__VA_ARGS__))
+#define metamacro_take7(...) metamacro_head(__VA_ARGS__), metamacro_take6(metamacro_tail(__VA_ARGS__))
+#define metamacro_take8(...) metamacro_head(__VA_ARGS__), metamacro_take7(metamacro_tail(__VA_ARGS__))
+#define metamacro_take9(...) metamacro_head(__VA_ARGS__), metamacro_take8(metamacro_tail(__VA_ARGS__))
+#define metamacro_take10(...) metamacro_head(__VA_ARGS__), metamacro_take9(metamacro_tail(__VA_ARGS__))
+#define metamacro_take11(...) metamacro_head(__VA_ARGS__), metamacro_take10(metamacro_tail(__VA_ARGS__))
+#define metamacro_take12(...) metamacro_head(__VA_ARGS__), metamacro_take11(metamacro_tail(__VA_ARGS__))
+#define metamacro_take13(...) metamacro_head(__VA_ARGS__), metamacro_take12(metamacro_tail(__VA_ARGS__))
+#define metamacro_take14(...) metamacro_head(__VA_ARGS__), metamacro_take13(metamacro_tail(__VA_ARGS__))
+#define metamacro_take15(...) metamacro_head(__VA_ARGS__), metamacro_take14(metamacro_tail(__VA_ARGS__))
+#define metamacro_take16(...) metamacro_head(__VA_ARGS__), metamacro_take15(metamacro_tail(__VA_ARGS__))
+#define metamacro_take17(...) metamacro_head(__VA_ARGS__), metamacro_take16(metamacro_tail(__VA_ARGS__))
+#define metamacro_take18(...) metamacro_head(__VA_ARGS__), metamacro_take17(metamacro_tail(__VA_ARGS__))
+#define metamacro_take19(...) metamacro_head(__VA_ARGS__), metamacro_take18(metamacro_tail(__VA_ARGS__))
+#define metamacro_take20(...) metamacro_head(__VA_ARGS__), metamacro_take19(metamacro_tail(__VA_ARGS__))
+
+// metamacro_drop expansions
+#define metamacro_drop0(...) __VA_ARGS__
+#define metamacro_drop1(...) metamacro_tail(__VA_ARGS__)
+#define metamacro_drop2(...) metamacro_drop1(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop3(...) metamacro_drop2(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop4(...) metamacro_drop3(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop5(...) metamacro_drop4(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop6(...) metamacro_drop5(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop7(...) metamacro_drop6(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop8(...) metamacro_drop7(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop9(...) metamacro_drop8(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop10(...) metamacro_drop9(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop11(...) metamacro_drop10(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop12(...) metamacro_drop11(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop13(...) metamacro_drop12(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop14(...) metamacro_drop13(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop15(...) metamacro_drop14(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop16(...) metamacro_drop15(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop17(...) metamacro_drop16(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop18(...) metamacro_drop17(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop19(...) metamacro_drop18(metamacro_tail(__VA_ARGS__))
+#define metamacro_drop20(...) metamacro_drop19(metamacro_tail(__VA_ARGS__))
+
+#endif
@@ -0,0 +1,18 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "SDWebImageCompat.h"
+
+@interface UIColor (SDHexString)
+
+/**
+ Convenience way to get hex string from color. The output should always be 32-bit RGBA hex string like `#00000000`.
+ */
+@property (nonatomic, copy, readonly, nonnull) NSString *sd_hexString;
+
+@end
@@ -0,0 +1,42 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) Olivier Poitrey <rs@dailymotion.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+#import "UIColor+SDHexString.h"
+
+@implementation UIColor (SDHexString)
+
+- (NSString *)sd_hexString {
+    CGFloat red, green, blue, alpha;
+#if SD_UIKIT
+    if (![self getRed:&red green:&green blue:&blue alpha:&alpha]) {
+        [self getWhite:&red alpha:&alpha];
+        green = red;
+        blue = red;
+    }
+#else
+    @try {
+        [self getRed:&red green:&green blue:&blue alpha:&alpha];
+    }
+    @catch (NSException *exception) {
+        [self getWhite:&red alpha:&alpha];
+        green = red;
+        blue = red;
+    }
+#endif
+    
+    red = roundf(red * 255.f);
+    green = roundf(green * 255.f);
+    blue = roundf(blue * 255.f);
+    alpha = roundf(alpha * 255.f);
+    
+    uint hex = ((uint)alpha << 24) | ((uint)red << 16) | ((uint)green << 8) | ((uint)blue);
+    
+    return [NSString stringWithFormat:@"#%08x", hex];
+}
+
+@end