Don't use std::isalnum for isBase64Char

Fixes #356

Signed-off-by: falkTX <[email protected]>

distrho/extra/Base64.hpp

@@ -1,6 +1,6 @@
 /*
  * DISTRHO Plugin Framework (DPF)
- * Copyright (C) 2012-2016 Filipe Coelho <[email protected]>
+ * Copyright (C) 2012-2024 Filipe Coelho <[email protected]>
  *
  * Permission to use, copy, modify, and/or distribute this software for any purpose with
  * or without fee is hereby granted, provided that the above copyright notice and this
@@ -19,7 +19,6 @@
 
 #include "../DistrhoUtils.hpp"
 
-#include <cctype>
 #include <vector>
 
 // -----------------------------------------------------------------------
@@ -55,15 +54,15 @@
 #ifndef DOXYGEN
 namespace DistrhoBase64Helpers {
 
-static const char* const kBase64Chars =
+static constexpr const char* const kBase64Chars =
     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
     "abcdefghijklmnopqrstuvwxyz"
     "0123456789+/";
 
 static inline
 uint8_t findBase64CharIndex(const char c)
 {
-    static const uint8_t kBase64CharsLen(static_cast<uint8_t>(std::strlen(kBase64Chars)));
+    static const uint8_t kBase64CharsLen = static_cast<uint8_t>(std::strlen(kBase64Chars));
 
     for (uint8_t i=0; i<kBase64CharsLen; ++i)
     {
@@ -75,10 +74,79 @@ uint8_t findBase64CharIndex(const char c)
     return 0;
 }
 
-static inline
+static constexpr inline
 bool isBase64Char(const char c)
 {
-    return (std::isalnum(c) || (c == '+') || (c == '/'));
+    switch (c)
+    {
+    case 'A':
+    case 'B':
+    case 'C':
+    case 'D':
+    case 'E':
+    case 'F':
+    case 'G':
+    case 'H':
+    case 'I':
+    case 'J':
+    case 'K':
+    case 'L':
+    case 'M':
+    case 'N':
+    case 'O':
+    case 'P':
+    case 'Q':
+    case 'R':
+    case 'S':
+    case 'T':
+    case 'U':
+    case 'V':
+    case 'W':
+    case 'X':
+    case 'Y':
+    case 'Z':
+    case 'a':
+    case 'b':
+    case 'c':
+    case 'd':
+    case 'e':
+    case 'f':
+    case 'g':
+    case 'h':
+    case 'i':
+    case 'j':
+    case 'k':
+    case 'l':
+    case 'm':
+    case 'n':
+    case 'o':
+    case 'p':
+    case 'q':
+    case 'r':
+    case 's':
+    case 't':
+    case 'u':
+    case 'v':
+    case 'w':
+    case 'x':
+    case 'y':
+    case 'z':
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9':
+    case '+':
+    case '/':
+        return true;
+    default:
+        return false;
+    }
 }
 
 } // namespace DistrhoBase64Helpers