@@ -12,19 +12,22 @@
  * Alternatively, it may be distributed under the terms of the GNU General
  * Public License, either version 2 or 3, which can be found in the file
  * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
  * file.
  */
+
+#ifndef OBJFW_OF_STRING_H
+#define OBJFW_OF_STRING_H
 
 #ifndef __STDC_LIMIT_MACROS
 # define __STDC_LIMIT_MACROS
 #endif
 #ifndef __STDC_CONSTANT_MACROS
 # define __STDC_CONSTANT_MACROS
 #endif
 
-#import "objfw-defs.h"
+#include "objfw-defs.h"
 
 #ifdef OF_HAVE_SYS_TYPES_H
 # include <sys/types.h>
 #endif
 
@@ -32,20 +35,27 @@
 #include <stdint.h>
 #ifdef OF_HAVE_INTTYPES_H
 # include <inttypes.h>
 #endif
 
-#import "OFObject.h"
-#import "OFSerialization.h"
-#import "OFJSONRepresentation.h"
-#import "OFMessagePackRepresentation.h"
+#include "OFObject.h"
+#ifdef __OBJC__
+# import "OFSerialization.h"
+# import "OFJSONRepresentation.h"
+# import "OFMessagePackRepresentation.h"
+#endif
 
 OF_ASSUME_NONNULL_BEGIN
 
 /*! @file */
 
+#ifdef __OBJC__
 @class OFConstantString;
+@class OFString;
+#else
+typedef void OFString;
+#endif
 
 #if defined(__cplusplus) && __cplusplus >= 201103L
 typedef char16_t of_char16_t;
 typedef char32_t of_char32_t;
 #else
@@ -108,10 +118,11 @@
  *	       enumeration
  */
 typedef void (^of_string_line_enumeration_block_t)(OFString *line, bool *stop);
 #endif
 
+#ifdef __OBJC__
 @class OFArray OF_GENERIC(ObjectType);
 @class OFCharacterSet;
 @class OFURL;
 
 /*!
@@ -262,11 +273,11 @@
 /*!
  * @brief The string with leading and trailing whitespaces deleted.
  */
 @property (readonly, nonatomic) OFString *stringByDeletingEnclosingWhitespaces;
 
-#ifdef OF_HAVE_UNICODE_TABLES
+# ifdef OF_HAVE_UNICODE_TABLES
 /*!
  * @brief The string in Unicode Normalization Form D (NFD).
  */
 @property (readonly, nonatomic) OFString *decomposedStringWithCanonicalMapping;
 
@@ -273,11 +284,11 @@
 /*!
  * @brief The string in Unicode Normalization Form KD (NFKD).
  */
 @property (readonly, nonatomic)
     OFString *decomposedStringWithCompatibilityMapping;
-#endif
+# endif
 
 /*!
  * @brief Creates a new OFString.
  *
  * @return A new, autoreleased OFString
@@ -489,11 +500,11 @@
  * @param format A string used as format to initialize the OFString
  * @return A new autoreleased OFString
  */
 + (instancetype)stringWithFormat: (OFConstantString *)format, ...;
 
-#ifdef OF_HAVE_FILES
+# ifdef OF_HAVE_FILES
 /*!
  * @brief Creates a new OFString with the contents of the specified UTF-8
  *	  encoded file.
  *
  * @param path The path to the file
@@ -509,13 +520,13 @@
  * @param encoding The encoding of the file
  * @return A new autoreleased OFString
  */
 + (instancetype)stringWithContentsOfFile: (OFString *)path
 				encoding: (of_string_encoding_t)encoding;
-#endif
+# endif
 
-#if defined(OF_HAVE_FILES) || defined(OF_HAVE_SOCKETS)
+# if defined(OF_HAVE_FILES) || defined(OF_HAVE_SOCKETS)
 /*!
  * @brief Creates a new OFString with the contents of the specified URL.
  *
  * If the URL's scheme is file, it tries UTF-8 encoding.
  *
@@ -536,11 +547,11 @@
  * @param encoding The encoding to assume
  * @return A new autoreleased OFString
  */
 + (instancetype)stringWithContentsOfURL: (OFURL *)URL
 			       encoding: (of_string_encoding_t)encoding;
-#endif
+# endif
 
 /*!
  * @brief Initializes an already allocated OFString from a UTF-8 encoded C
  *	  string.
  *
@@ -763,11 +774,11 @@
  * @return An initialized OFString
  */
 - (instancetype)initWithFormat: (OFConstantString *)format
 		     arguments: (va_list)arguments;
 
-#ifdef OF_HAVE_FILES
+# ifdef OF_HAVE_FILES
 /*!
  * @brief Initializes an already allocated OFString with the contents of the
  *	  specified file in the specified encoding.
  *
  * @param path The path to the file
@@ -783,11 +794,11 @@
  * @param encoding The encoding of the file
  * @return An initialized OFString
  */
 - (instancetype)initWithContentsOfFile: (OFString *)path
 			      encoding: (of_string_encoding_t)encoding;
-#endif
+# endif
 
 /*!
  * @brief Initializes an already allocated OFString with the contents of the
  *	  specified URL.
  *
@@ -1168,11 +1179,11 @@
  * @param encoding The encoding to use for the returned OFData
  * @return The string as OFData with the specified encoding
  */
 - (OFData *)dataWithEncoding: (of_string_encoding_t)encoding;
 
-#ifdef OF_HAVE_FILES
+# ifdef OF_HAVE_FILES
 /*!
  * @brief Writes the string into the specified file using UTF-8 encoding.
  *
  * @param path The path of the file to write to
  */
@@ -1185,11 +1196,11 @@
  * @param path The path of the file to write to
  * @param encoding The encoding to use to write the string into the file
  */
 - (void)writeToFile: (OFString *)path
 	   encoding: (of_string_encoding_t)encoding;
-#endif
+# endif
 
 /*!
  * @brief Writes the string to the specified URL using UTF-8 encoding.
  *
  * @param URL The URL to write to
@@ -1203,19 +1214,20 @@
  * @param encoding The encoding to use to write the string to the URL
  */
 - (void)writeToURL: (OFURL *)URL
 	  encoding: (of_string_encoding_t)encoding;
 
-#ifdef OF_HAVE_BLOCKS
+# ifdef OF_HAVE_BLOCKS
 /*!
  * Enumerates all lines in the receiver using the specified block.
  *
  * @brief block The block to call for each line
  */
 - (void)enumerateLinesUsingBlock: (of_string_line_enumeration_block_t)block;
-#endif
+# endif
 @end
+#endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 extern of_string_encoding_t of_string_parse_encoding(OFString *);
@@ -1228,24 +1240,26 @@
 }
 #endif
 
 OF_ASSUME_NONNULL_END
 
-#import "OFConstantString.h"
-#import "OFMutableString.h"
-#import "OFString+CryptoHashing.h"
-#import "OFString+JSONValue.h"
-#ifdef OF_HAVE_FILES
-# import "OFString+PathAdditions.h"
-#endif
-#import "OFString+PropertyListValue.h"
-#import "OFString+Serialization.h"
-#import "OFString+URLEncoding.h"
-#import "OFString+XMLEscaping.h"
-#import "OFString+XMLUnescaping.h"
-
-#if !defined(NSINTEGER_DEFINED) && !__has_feature(modules)
+#include "OFConstantString.h"
+#include "OFMutableString.h"
+#ifdef __OBJC__
+# import "OFString+CryptoHashing.h"
+# import "OFString+JSONValue.h"
+# ifdef OF_HAVE_FILES
+#  import "OFString+PathAdditions.h"
+# endif
+# import "OFString+PropertyListValue.h"
+# import "OFString+Serialization.h"
+# import "OFString+URLEncoding.h"
+# import "OFString+XMLEscaping.h"
+# import "OFString+XMLUnescaping.h"
+#endif
+
+#if defined(__OBJC__) && !defined(NSINTEGER_DEFINED) && !__has_feature(modules)
 /*
  * Very *ugly* hack required for string boxing literals to work.
  *
  * This hack is needed in order to work with `@class NSString` from Apple's
  * objc/NSString.h - which is included when using modules - as
@@ -1256,6 +1270,8 @@
  *
  * TODO: Submit a patch for Clang that makes the boxing classes configurable!
  */
 @interface NSString: OFString
 @end
+#endif
+
 #endif