1 files changed, 39 insertions, 0 deletions
diff --git a/include/jau/base_codec.hpp b/include/jau/base_codec.hpp
index 62e74c9..d5d9e3c 100644
--- a/include/jau/base_codec.hpp
+++ b/include/jau/base_codec.hpp
@@ -256,6 +256,45 @@ namespace jau::codec::base {
     };
 
     /**
+     * Safe base 38 alphabet with ASCII code-point sorting order.
+     *
+     * - Value: `-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_`
+     * - Padding: `=`
+     *
+     * ### Properties
+     * - 7-bit ASCII
+     * - Code page 437 compatible
+     * - Safe URL and filename use
+     * - Excludes forbidden [v]fat chars: `<>:"/\|?*`
+     * - Only using upper-case letters for unique filename under vfat
+     * - Excludes quoting chars: "'$ and space
+     * - Supporting ASCII code-point sorting.
+     * - Order: `-` < `0` < `A` < `a` < `z`
+     */
+    class ascii38_alphabet : public alphabet {
+        private:
+            static inline constexpr const std::string_view data = "-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_";
+
+            static int s_code_point(const char c) noexcept {
+                if ('0' <= c && c <= '9') {
+                    return c - '0' + 1;
+                } else if ('A' <= c && c <= 'Z') {
+                    return c - 'A' + 11;
+                } else if ('-' == c) {
+                    return 0;
+                } else if ('_' == c) {
+                    return 37;
+                } else {
+                    return -1;
+                }
+            }
+
+        public:
+            ascii38_alphabet() noexcept
+            : alphabet("ascii38", 38, data, '=', s_code_point) {}
+    };
+
+    /**
      * Safe base 64 alphabet with ASCII code-point sorting order.
      *
      * - Value: `-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz`