Scan string directly in n_value

src/parser3.h

@@ -780,6 +780,31 @@ inline PRESERVE_NONE WeaselJsonStatus n_number(Parser3 *self, char *buf,
   MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
 }
 
+// Advance buf until double quote, backslash, invalid utf8, or codepoint <
+// 0x20
+inline PRESERVE_NONE WeaselJsonStatus n_scan_string(Parser3 *self, char *&buf,
+                                                    char *bufEnd) {
+  const auto before = buf;
+
+  buf = (char *)self->strDfa.scan(buf, bufEnd);
+
+  int len = buf - before;
+  if (self->writeBuf != before) {
+    memmove(self->writeBuf, before, len);
+  }
+  self->writeBuf += len;
+
+  if (buf == bufEnd) {
+    self->flushString(false);
+    return WeaselJson_AGAIN;
+  }
+
+  if (!self->strDfa.accept()) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
+  return WeaselJson_OK;
+}
+
 inline PRESERVE_NONE WeaselJsonStatus n_value(Parser3 *self, char *buf,
                                               char *bufEnd) {
   assert(bufEnd - buf != 0);
@@ -811,10 +836,30 @@ inline PRESERVE_NONE WeaselJsonStatus n_value(Parser3 *self, char *buf,
     self->dataBegin = self->writeBuf = buf;
     self->pop();
     self->strDfa.reset();
-    if (auto s = self->push({N_STRING2})) {
+    if (auto s = n_scan_string(self, buf, bufEnd)) {
+      if (s == WeaselJson_AGAIN) {
+        if (auto s2 = self->push({N_STRING2})) {
+          return s2;
+        }
+      }
       return s;
     }
-    break;
+    {
+      switch (*buf) {
+      case '"':
+        self->flushString(true);
+        ++buf;
+        MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
+      case '\\':
+        ++buf;
+        if (auto s = self->push({N_STRING_FOLLOWING_ESCAPE})) {
+          return s;
+        }
+        MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
+      default:
+        return WeaselJson_REJECT;
+      }
+    }
   case '0':
   case '1':
   case '2':
@@ -1027,25 +1072,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_string(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_string2(Parser3 *self, char *buf,
                                                 char *bufEnd) {
-  const auto before = buf;
+  if (auto s = n_scan_string(self, buf, bufEnd)) {
-
+    return s;
-  // Advance buf until double quote, backslash, invalid utf8, or codepoint <
-  // 0x20
-  buf = (char *)self->strDfa.scan(buf, bufEnd);
-
-  int len = buf - before;
-  memmove(self->writeBuf, before, len);
-  self->writeBuf += len;
-
-  if (buf == bufEnd) {
-    self->flushString(false);
-    return WeaselJson_AGAIN;
   }
-
-  if (!self->strDfa.accept()) [[unlikely]] {
-    return WeaselJson_REJECT;
-  }
-
   switch (*buf) {
   case '"':
     self->flushString(true);