constexpr Base64EncodingBufferSize for C++23

libi2pd/Base.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2013-2025, The PurpleI2P Project
+* Copyright (c) 2013-2026, The PurpleI2P Project
 *
 * This file is part of Purple i2pd project and licensed under BSD3
 *
@@ -14,9 +14,9 @@
 #include <string_view>
 #include <cstdlib>
 
-namespace i2p 
+namespace i2p
 {
-namespace data 
+namespace data
 {
 	std::string ByteStreamToBase64 (const uint8_t * InBuffer, size_t InCount);
 	size_t Base64ToByteStream (std::string_view base64Str, uint8_t * OutBuffer, size_t len);
@@ -26,26 +26,30 @@ namespace data
 	constexpr bool IsBase64 (char ch)
 	{
 		return (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9') || ch == '-' || ch == '~';
-	}	
+	}
 
 	size_t Base32ToByteStream (std::string_view base32Str, uint8_t * outBuf, size_t outLen);
-	std::string ByteStreamToBase32 (const uint8_t * inBuf, size_t len);	
+	std::string ByteStreamToBase32 (const uint8_t * inBuf, size_t len);
 	constexpr bool IsBase32 (char ch)
 	{
 		return (ch >= 'a' && ch <= 'z') || (ch >= '2' && ch <= '7');
-	}	
+	}
 
 	/**
 	 * Compute the size for a buffer to contain encoded base64 given that the size of the input is input_size bytes
 	 */
+#if __cplusplus >= 202302L // C++23
+	constexpr size_t Base64EncodingBufferSize(size_t input_size)
+#else
 	inline size_t Base64EncodingBufferSize(size_t input_size)
+#endif
 	{
 		auto d = std::div (input_size, 3);
 		if (d.rem) d.quot++;
 		return 4 * d.quot;
-	}	
+	}
+
 
-	
 } // data
 } // i2p