Basic unescaping

src/parser3.h

@@ -79,7 +79,7 @@ struct Parser3 {
 
   [[nodiscard]] Status parse(char *buf, int len) {
     complete = len == 0;
-    this->buf = this->dataBegin = buf;
+    this->buf = this->dataBegin = this->writeBuf = buf;
     this->bufEnd = buf + len;
     return keepGoing(this);
   }
@@ -92,7 +92,7 @@ struct Parser3 {
   }
 
   void flushString() {
-    int len = buf - dataBegin;
+    int len = writeBuf - dataBegin;
     if (len > 0) {
       callbacks->on_string_data(data, dataBegin, len);
     }
@@ -127,10 +127,14 @@ struct Parser3 {
   constexpr static int kMaxStackSize = 1024;
 
   [[maybe_unused]] void debugPrint();
+  // Pointer to the next byte in the input to consume
   char *buf = nullptr;
+  // Pointer past the end of the last byte available to consume
   char *bufEnd = nullptr;
   // Used for flushing pending data with on_*_data callbacks
   char *dataBegin;
+  // Used for unescaping string data in place
+  char *writeBuf;
   const Callbacks *const callbacks;
   void *const data;
   Symbol stack[kMaxStackSize];
@@ -368,9 +372,9 @@ inline Status n_string2(Parser3 *self) {
     // one byte utf-8 encoding
     switch (*self->buf) {
     case '"':
-      self->flushString();
       ++self->buf;
       self->pop();
+      self->flushString();
       self->callbacks->on_end_string(self->data);
       MUSTTAIL return Parser3::keepGoing(self);
     case '\\':
@@ -389,6 +393,7 @@ inline Status n_string2(Parser3 *self) {
     self->utf8Codepoint = *self->buf & 0b00011111;
     self->minCodepoint = 0x80;
     ++self->buf;
+    ++self->writeBuf;
     self->pop();
     if (auto s = self->push({T_UTF8_LAST_CONTINUATION_BYTE, N_STRING2})) {
       return s;
@@ -400,6 +405,7 @@ inline Status n_string2(Parser3 *self) {
     self->utf8Codepoint = *self->buf & 0b00001111;
     self->minCodepoint = 0x800;
     ++self->buf;
+    ++self->writeBuf;
     self->pop();
     if (auto s = self->push({T_UTF8_CONTINUATION_BYTE,
                              T_UTF8_LAST_CONTINUATION_BYTE, N_STRING2})) {
@@ -411,6 +417,7 @@ inline Status n_string2(Parser3 *self) {
     self->utf8Codepoint = *self->buf & 0b00000111;
     self->minCodepoint = 0x10000;
     ++self->buf;
+    ++self->writeBuf;
     self->pop();
     if (auto s = self->push({T_UTF8_CONTINUATION_BYTE, T_UTF8_CONTINUATION_BYTE,
                              T_UTF8_LAST_CONTINUATION_BYTE, N_STRING2})) {
@@ -434,7 +441,7 @@ inline Status n_string_following_escape(Parser3 *self) {
   case 'n':
   case 'r':
   case 't':
-    ++self->buf;
+    *self->writeBuf++ = tables.unescape[*self->buf++];
     self->pop();
     if (auto s = self->push({N_STRING2})) {
       return s;
@@ -442,6 +449,7 @@ inline Status n_string_following_escape(Parser3 *self) {
     MUSTTAIL return Parser3::keepGoing(self);
   case 'u':
     ++self->buf;
+    // TODO unescape
     self->pop();
     if (auto s = self->push({T_HEX, T_HEX, T_HEX, T_HEX, N_STRING2})) {
       return s;
@@ -463,6 +471,7 @@ inline Status t_utf8_continuation_byte(Parser3 *self) {
     self->utf8Codepoint <<= 6;
     self->utf8Codepoint |= *self->buf & 0b00111111;
     ++self->buf;
+    ++self->writeBuf;
     self->pop();
     MUSTTAIL return Parser3::keepGoing(self);
   }
@@ -486,6 +495,7 @@ inline Status t_utf8_last_continuation_byte(Parser3 *self) {
     }
     // TODO tell valgrind utf8Codepoint and minCodepoint are uninitialized
     ++self->buf;
+    ++self->writeBuf;
     self->pop();
     MUSTTAIL return Parser3::keepGoing(self);
   }
@@ -524,6 +534,7 @@ inline Status t_hex(Parser3 *self) {
       ('a' <= *self->buf && *self->buf <= 'f') ||
       ('A' <= *self->buf && *self->buf <= 'F')) {
     ++self->buf;
+    ++self->writeBuf;
     self->pop();
     MUSTTAIL return Parser3::keepGoing(self);
   }