Index: src/OFCharacterSet.h
==================================================================
--- src/OFCharacterSet.h
+++ src/OFCharacterSet.h
@@ -24,10 +24,14 @@
  * @class OFCharacterSet OFCharacterSet.h ObjFW/OFCharacterSet.h
  *
  * @brief A class cluster representing a character set.
  */
 @interface OFCharacterSet: OFObject
+#ifdef OF_HAVE_CLASS_PROPERTIES
+@property (class, readonly, nonatomic) OFCharacterSet *whitespaceCharacterSet;
+#endif
+
 /*!
  * @brief The inverted set, containing only the characters that do not exist in
  *	  the receiver.
  */
 @property (readonly, nonatomic) OFCharacterSet *invertedSet;
@@ -48,10 +52,16 @@
  * @param range The range of characters for the character set
  * @return A new OFCharacterSet
  */
 + (instancetype)characterSetWithRange: (of_range_t)range;
 
+/*!
+ * @brief A character set containing all Unicode characters in the category
+ *	  `Zs` plus CHARACTER TABULATION (U+0009).
+ */
++ (OFCharacterSet *)whitespaceCharacterSet;
+
 /*!
  * @brief Initializes an already allocated character set with the characters of
  *	  the specified string.
  *
  * @param characters The characters for the character set

Index: src/OFCharacterSet.m
==================================================================
--- src/OFCharacterSet.m
+++ src/OFCharacterSet.m
@@ -23,13 +23,19 @@
 #import "OFCharacterSet_range.h"
 
 static struct {
 	Class isa;
 } placeholder;
+
+static OFCharacterSet *whitespaceCharacterSet = nil;
 
 @interface OFCharacterSet_placeholder: OFCharacterSet
 @end
+
+@interface OFCharacterSet_whitespace: OFCharacterSet
+- (instancetype)of_init;
+@end
 
 @implementation OFCharacterSet_placeholder
 - (instancetype)init
 {
 	return (id)[[OFCharacterSet_bitset alloc] init];
@@ -91,10 +97,15 @@
 
 + (instancetype)characterSetWithRange: (of_range_t)range
 {
 	return [[[self alloc] initWithRange: range] autorelease];
 }
+
++ (OFCharacterSet *)whitespaceCharacterSet
+{
+	return [OFCharacterSet_whitespace whitespaceCharacterSet];
+}
 
 - (instancetype)init
 {
 	if ([self isMemberOfClass: [OFCharacterSet class]]) {
 		@try {
@@ -127,7 +138,78 @@
 
 - (OFCharacterSet *)invertedSet
 {
 	return [[[OFCharacterSet_invertedSet alloc]
 	    of_initWithCharacterSet: self] autorelease];
+}
+@end
+
+@implementation OFCharacterSet_whitespace
++ (void)initialize
+{
+	if (self != [OFCharacterSet_whitespace class])
+		return;
+
+	whitespaceCharacterSet = [[OFCharacterSet_whitespace alloc] of_init];
+}
+
++ (OFCharacterSet *)whitespaceCharacterSet
+{
+	return whitespaceCharacterSet;
+}
+
+- (instancetype)init
+{
+	OF_INVALID_INIT_METHOD
+}
+
+- (instancetype)of_init
+{
+	return [super init];
+}
+
+- (instancetype)autorelease
+{
+	return self;
+}
+
+- (instancetype)retain
+{
+	return self;
+}
+
+- (void)release
+{
+}
+
+- (unsigned int)retainCount
+{
+	return OF_RETAIN_COUNT_MAX;
+}
+
+- (bool)characterIsMember: (of_unichar_t)character
+{
+	switch (character) {
+	case 0x0009:
+	case 0x0020:
+	case 0x00A0:
+	case 0x1680:
+	case 0x2000:
+	case 0x2001:
+	case 0x2002:
+	case 0x2003:
+	case 0x2004:
+	case 0x2005:
+	case 0x2006:
+	case 0x2007:
+	case 0x2008:
+	case 0x2009:
+	case 0x200A:
+	case 0x202F:
+	case 0x205F:
+	case 0x3000:
+		return true;
+	default:
+		return false;
+	}
 }
 @end