Fix: V3 Escape control chars when stringifing JSON (Netflix#492)

Properly handle UTF-16

hollow/src/main/java/com/netflix/hollow/tools/stringifier/HollowRecordJsonStringifier.java

@@ -409,70 +409,67 @@ private void appendFieldStringify(Writer writer, HollowDataAccess dataAccess, in
         }
     }
 
-    private final static int CHARS2DETECT =
-        ('"' << (2*9)) |    // " DQ
-        ('\\' << 9) |       // \ RS
-         0x1f;              // < 0x20 (non-print)
-    private final static int CAT_DQ = 1 << (3*9 - 1);
-    private final static int CAT_RS = 1 << (2*9 - 1);
-    private final static int CAT_NP = 1 << (9 - 1);
-    private final static int CATEGORY_BITS_MASK = CAT_DQ | CAT_RS | CAT_NP;
-    private final static int DETECT_MASK = ~CHARS2DETECT & ~CATEGORY_BITS_MASK;
-    private final static int DUP3TIMES_WITH_CAT_BIT= 0x40201;
-    private final static int CAUSE_CARRY = 0x40220;
+    private final static long CHARS2DETECT =
+            (0x22L << (2*17)) |     // " DQ
+            (0x5cL << 17) |         // \ RS
+            0x1fL;                  // < 0x20 (non-print)
+    private final static long CAT_DQ = 1L << (3*17 - 1);
+    private final static long CAT_RS = 1L << (2*17 - 1);
+    private final static long CAT_NP = 1L << (17 - 1);
+    private final static long CATEGORY_BITS_MASK = CAT_DQ | CAT_RS | CAT_NP;
+    private final static long DETECT_MASK = ~CHARS2DETECT & ~CATEGORY_BITS_MASK;
+    private final static long DUP3TIMES_WITH_CAT_BIT= 1 | (1 << 17) | (1L << (17*2));
+    private final static long CAUSE_CARRY = 0x20 | (1 << 17) | (1L << (17*2));
 
     /**
      * Returns the category (CAT_*) of ch8 - non-carry bits are garbage
      *
-     * Works by making 3 copies of the character every 9 bits leaving a "carry" bit
+     * Works by making 3 copies of the character every 17 bits leaving a "carry" bit
      * to hold the category in front of each copy.  When detecting a specific char,
      * the xor mask is the 1's complement of the char to detect, which will set the
-     * test char to 0xff when it matches.  Adding 1 to the 0xff will clear 0xff to 0,
+     * test char to 0xffff when it matches.  Adding 1 to the 0xffff will clear 0xffff to 0,
      * and "carry" over into the category bit recording the test character was detected.
-     * (e.g, 0x5c ^ 0xa3 + 1 = 0x100).  Detecting < 0x20 is detecting just the upper
-     * 3 bits are 0 so, 0x20 is added instead of 1 (e.g., 0x0a ^ e0 + 0x20 = 0x10a).
+     * (e.g, 0x5c ^ 0xffa3 + 1 = 0x10000).  Detecting < 0x20 is detecting just the upper
+     * 11 bits are 0 so, 0x20 is added instead of 1 (e.g., 0x0a ^ ffe0 + 0x20 = 0x1000a).
      */
-    private int categorize(char ch8) {
-        int ch = 0xff & ch8;
-        int cat = ch * DUP3TIMES_WITH_CAT_BIT;
+    private static long categorize(char ch) {
+        long cat = ch * DUP3TIMES_WITH_CAT_BIT;
 
         cat ^= DETECT_MASK;
         cat += CAUSE_CARRY;
 
         return cat;
-    }
+}
 
     /**
      * Returns the categories found in str (or of CAT_*)
      */
-    private int categorize(String str) {
-        int len = str.length();
-        int cat = 0;
-        int i;
+    private static long categorize(String string) {
+        int len = string.length();
+        long cat = 0;
 
-        for(i = 0; i < len ; i = i++) {
-            cat = cat | categorize(str.charAt(i));
+        for(int i = 0; i < len ; i++) {
+                cat = cat | categorize(string.charAt(i));
         }
         return cat & CATEGORY_BITS_MASK;
-    }
+}
 
     /**
-     * Escapes the NP characters in str (eg. NUL becomes \u0000)
+     * Escapes the NP characters in str (eg. \n becomes \u000a)
      */
     private String escapeNP(String str) {
-        char c = 0;
         int len = str.length();
         StringBuilder sb = new StringBuilder(2*len);
 
         for (int i = 0; i < len; i += 1) {
-            c = str.charAt(i);
-            if (c < 0x10) {
+            char c = str.charAt(i);
+
+            if (c < 0x10)
                 sb.append("\\u000" + Integer.toHexString(c));
-            } else if (c < 0x20 ) {
+            else if (c < 0x20)
                 sb.append("\\u00" + Integer.toHexString(c));
-            } else {
+            else
                 sb.append(c);
-            }
         }
         return sb.toString();
     }
@@ -483,7 +480,7 @@ private String escapeNP(String str) {
      * escaping the characters based on the categories recorded.
      */
     private String escapeString(String str) {
-        int cat = categorize(str);
+        long cat = categorize(str);
 
         if (cat == 0) {
             return str;