Loop in string2 in normal case

src/tables.h

@@ -1,19 +1,48 @@
 #pragma once
 
 constexpr inline struct Tables {
+  enum StringByteMeaning {
+    INVALID,
+    NORMAL,
+    DUBQUOTE,
+    BACKSLASH,
+    TWO_BYTE_UTF8,
+    THREE_BYTE_UTF8,
+    FOUR_BYTE_UTF8,
+    CONTINUATION_BYTE,
+  };
+
   constexpr Tables() {
     whitespace[' '] = true;
     whitespace['\n'] = true;
     whitespace['\r'] = true;
     whitespace['\t'] = true;
 
-    for (int i = 0; i < 0x20; ++i) {
-      invalidStringByte[i] = true;
+    for (int i = 0; i < 256; ++i) {
+      if ((i & 0b11000000) == 0b10000000) {
+        stringByteMeaning[i] = CONTINUATION_BYTE;
+      }
+      if ((i & 0b11100000) == 0b11000000) {
+        stringByteMeaning[i] = TWO_BYTE_UTF8;
+      }
+      if ((i & 0b11110000) == 0b11100000) {
+        stringByteMeaning[i] = THREE_BYTE_UTF8;
+      }
+      if ((i & 0b11111000) == 0b11110000) {
+        stringByteMeaning[i] = FOUR_BYTE_UTF8;
+      }
     }
-    invalidStringByte[0xc0] = true;
-    invalidStringByte[0xc1] = true;
-    for (int i = 0xf5; i <= 0xff; ++i) {
-      invalidStringByte[i] = true;
+
+    for (int i = 0x20; i < 128; ++i) {
+      stringByteMeaning[i] = NORMAL;
+    }
+    stringByteMeaning['"'] = DUBQUOTE;
+    stringByteMeaning['\\'] = BACKSLASH;
+
+    stringByteMeaning[0xc0] = INVALID;
+    stringByteMeaning[0xc1] = INVALID;
+    for (int i = 0xF5; i < 0x100; ++i) {
+      stringByteMeaning[i] = INVALID;
     }
 
     unescape['n'] = '\n';
@@ -26,6 +55,6 @@ constexpr inline struct Tables {
     unescape['/'] = '/';
   }
   alignas(16) bool whitespace[256]{};
-  alignas(16) bool invalidStringByte[256]{};
+  alignas(16) StringByteMeaning stringByteMeaning[256]{};
   alignas(16) char unescape[256]{};
 } tables;