Revert "Using table throughout."

This reverts commit 5050bdc.

src/unicode.cpp

@@ -293,6 +293,11 @@ static_assert(unicode::is_alnum_plus('1'));
 static_assert(unicode::is_alnum_plus('a'));
 static_assert(unicode::is_alnum_plus('b'));
 
+ada_really_inline constexpr bool is_ascii_hex_digit(const char c) noexcept {
+  return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') ||
+         (c >= 'a' && c <= 'f');
+}
+
 ada_really_inline constexpr bool is_c0_control_or_space(const char c) noexcept {
   return (unsigned char)c <= ' ';
 }
@@ -363,29 +368,12 @@ ada_really_inline constexpr bool is_lowercase_hex(const char c) noexcept {
   return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f');
 }
 
-constexpr static char hex_to_binary_table[256] = {
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0,  1,  2,  3,  4,  5,  6,  7,  8,
-    9,  -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-    -1, -1, -1, -1, -1, -1, -1, -1, -1};
-
-ada_really_inline constexpr bool is_ascii_hex_digit(const char c) noexcept {
-  return hex_to_binary_table[(unsigned char)c] != -1;
-}
-
-ada_really_inline unsigned constexpr convert_hex_to_binary(
-    const char c) noexcept {
-  return hex_to_binary_table[(unsigned char)c];
+constexpr static char hex_to_binary_table[] = {
+    0,  1,  2,  3,  4, 5, 6, 7, 8, 9, 0, 0,  0,  0,  0,  0,  0, 10, 11,
+    12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0,  0,  0,  0,  0,  0, 0,  0,
+    0,  0,  0,  0,  0, 0, 0, 0, 0, 0, 0, 10, 11, 12, 13, 14, 15};
+unsigned constexpr convert_hex_to_binary(const char c) noexcept {
+  return hex_to_binary_table[c - '0'];
 }
 
 std::string percent_decode(const std::string_view input, size_t first_percent) {