Use official JSON encoding for stream

runtime/platform/text_buffer.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/text_buffer.h"
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "platform/utils.h"
 #include "vm/os.h"
+#include "vm/unicode.h"
 
 namespace dart {
 
 TextBuffer::TextBuffer(intptr_t buf_size) {
   ASSERT(buf_size > 0);
   buf_ = reinterpret_cast<char*>(malloc(buf_size));
   buf_size_ = buf_size;
   Clear();
 }
 
@@ skipping 50 matching lines @@
     va_start(args2, format);
     intptr_t len2 = OS::VSNPrint(buf_ + msg_len_, remaining, format, args2);
     va_end(args2);
     ASSERT(len == len2);
   }
   msg_len_ += len;
   buf_[msg_len_] = '\0';
   return len;
 }
 
-
-// Write a UTF-16 code unit so it can be read by a JSON parser in a string
-// literal. Use escape sequences for characters other than printable ASCII.
+// Write a UTF-32 code unit so it can be read by a JSON parser in a string
+// literal. Use official encoding from JSON specification. http://json.org/
 void TextBuffer::EscapeAndAddCodeUnit(uint32_t codeunit) {

[rmacnak, 2016/06/21 16:56:56]

Perhaps this should be split into EscapeAndAddUTF16CodeUnit (with the old
behavior, for encoding Dart strings) and EscapeAndAddCodePoint (with your new
behavior), see below.

[cbernaschina, 2016/06/21 21:24:43]

Done.

   switch (codeunit) {
     case '"':
       Printf("%s", "\\\"");
       break;
     case '\\':
       Printf("%s", "\\\\");
       break;
     case '/':
       Printf("%s", "\\/");
       break;
     case '\b':
       Printf("%s", "\\b");
       break;
     case '\f':
       Printf("%s", "\\f");
       break;
     case '\n':
       Printf("%s", "\\n");
       break;
     case '\r':
       Printf("%s", "\\r");
       break;
     case '\t':
       Printf("%s", "\\t");
       break;
     default:
-      if (codeunit < 0x20) {
-        // Encode character as \u00HH.
-        uint32_t digit2 = (codeunit >> 4) & 0xf;
-        uint32_t digit3 = (codeunit & 0xf);
-        Printf("\\u00%c%c",
-               digit2 > 9 ? 'A' + (digit2 - 10) : '0' + digit2,
-               digit3 > 9 ? 'A' + (digit3 - 10) : '0' + digit3);
-      } else if (codeunit > 127) {
-        // Encode character as \uHHHH.
-        uint32_t digit0 = (codeunit >> 12) & 0xf;
-        uint32_t digit1 = (codeunit >> 8) & 0xf;
-        uint32_t digit2 = (codeunit >> 4) & 0xf;
-        uint32_t digit3 = (codeunit & 0xf);
-        Printf("\\u%c%c%c%c",
-               digit0 > 9 ? 'A' + (digit0 - 10) : '0' + digit0,
-               digit1 > 9 ? 'A' + (digit1 - 10) : '0' + digit1,
-               digit2 > 9 ? 'A' + (digit2 - 10) : '0' + digit2,
-               digit3 > 9 ? 'A' + (digit3 - 10) : '0' + digit3);
-      } else {
-        AddChar(codeunit);
-      }
+      char encoded[6];
+      intptr_t length = Utf8::Length(codeunit);
+      Utf8::Encode(codeunit, encoded);
+      AddRaw(reinterpret_cast<uint8_t*>(encoded), length);
   }
 }
 
 
 void TextBuffer::AddString(const char* s) {
   Printf("%s", s);
 }
 
 
 void TextBuffer::AddEscapedString(const char* s) {
@@ skipping 14 matching lines @@
     // the debugger front-end.
     intptr_t new_size = buf_size_ + len + kBufferSpareCapacity;
     char* new_buf = reinterpret_cast<char*>(realloc(buf_, new_size));
     ASSERT(new_buf != NULL);
     buf_ = new_buf;
     buf_size_ = new_size;
   }
 }
 
 }  // namespace dart