base/json/string_escape.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This file defines utility functions for escaping strings suitable for JSON.
   6
   7 #ifndef BASE_JSON_STRING_ESCAPE_H_
   8 #define BASE_JSON_STRING_ESCAPE_H_
   9
  10 #include <string>
  11
  12 #include "base/base_export.h"
  13 #include "base/strings/string_piece.h"
  14
  15 namespace base {
  16
  17 // Appends to |dest| an escaped version of |str|. Valid UTF-8 code units will
  18 // pass through from the input to the output. Invalid code units will be
  19 // replaced with the U+FFFD replacement character. This function returns true
  20 // if no replacement was necessary and false if there was a lossy replacement.
  21 // On return, |dest| will contain a valid UTF-8 JSON string.
  22 //
  23 // Non-printing control characters will be escaped as \uXXXX sequences for
  24 // readability.
  25 //
  26 // If |put_in_quotes| is true, then a leading and trailing double-quote mark
  27 // will be appended to |dest| as well.
  28 BASE_EXPORT bool EscapeJSONString(const StringPiece& str,
  29                                   bool put_in_quotes,
  30                                   std::string* dest);
  31
  32 // Performs a similar function to the UTF-8 StringPiece version above,
  33 // converting UTF-16 code units to UTF-8 code units and escaping non-printing
  34 // control characters. On return, |dest| will contain a valid UTF-8 JSON string.
  35 BASE_EXPORT bool EscapeJSONString(const StringPiece16& str,
  36                                   bool put_in_quotes,
  37                                   std::string* dest);
  38
  39 // Helper functions that wrap the above two functions but return the value
  40 // instead of appending. |put_in_quotes| is always true.
  41 BASE_EXPORT std::string GetQuotedJSONString(const StringPiece& str);
  42 BASE_EXPORT std::string GetQuotedJSONString(const StringPiece16& str);
  43
  44 // Given an arbitrary byte string |str|, this will escape all non-ASCII bytes
  45 // as \uXXXX escape sequences. This function is *NOT* meant to be used with
  46 // Unicode strings and does not validate |str| as one.
  47 //
  48 // CAVEAT CALLER: The output of this function may not be valid JSON, since
  49 // JSON requires escape sequences to be valid UTF-16 code units. This output
  50 // will be mangled if passed to to the base::JSONReader, since the reader will
  51 // interpret it as UTF-16 and convert it to UTF-8.
  52 //
  53 // The output of this function takes the *appearance* of JSON but is not in
  54 // fact valid according to RFC 4627.
  55 BASE_EXPORT std::string EscapeBytesAsInvalidJSONString(const StringPiece& str,
  56                                                        bool put_in_quotes);
  57
  58 }  // namespace base
  59
  60 #endif  // BASE_JSON_STRING_ESCAPE_H_