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
15namespace 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.
28BASE_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.
35BASE_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.
41BASE_EXPORT std::string GetQuotedJSONString(const StringPiece& str);
42BASE_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.
55BASE_EXPORT std::string EscapeBytesAsInvalidJSONString(const StringPiece& str,
56                                                       bool put_in_quotes);
57
58}  // namespace base
59
60#endif  // BASE_JSON_STRING_ESCAPE_H_
61