diff options
Diffstat (limited to 'base/json_reader.cc')
| -rw-r--r-- | base/json_reader.cc | 126 |
1 files changed, 103 insertions, 23 deletions
diff --git a/base/json_reader.cc b/base/json_reader.cc index c0e019b..2cea239 100644 --- a/base/json_reader.cc +++ b/base/json_reader.cc @@ -71,66 +71,116 @@ bool ReadHexDigits(JSONReader::Token& token, int digits) { } // anonymous namespace +const char* JSONReader::kBadRootElementType = + "Root value must be an array or object."; +const char* JSONReader::kInvalidEscape = + "Invalid escape sequence."; +const char* JSONReader::kSyntaxError = + "Syntax error."; +const char* JSONReader::kTrailingComma = + "Trailing comma not allowed."; +const char* JSONReader::kTooMuchNesting = + "Too much nesting."; +const char* JSONReader::kUnexpectedDataAfterRoot = + "Unexpected data after root element."; +const char* JSONReader::kUnsupportedEncoding = + "Unsupported encoding. JSON must be UTF-8."; +const char* JSONReader::kUnquotedDictionaryKey = + "Dictionary keys must be quoted."; + /* static */ bool JSONReader::Read(const std::string& json, Value** root, bool allow_trailing_comma) { - return JsonToValue(json, root, true, allow_trailing_comma); + return ReadAndReturnError(json, root, allow_trailing_comma, NULL); +} + +/* static */ +bool JSONReader::ReadAndReturnError(const std::string& json, + Value** root, + bool allow_trailing_comma, + std::string *error_message_out) { + JSONReader reader = JSONReader(); + if (reader.JsonToValue(json, root, true, allow_trailing_comma)) { + return true; + } else { + if (error_message_out) + *error_message_out = reader.error_message(); + return false; + } } /* static */ -bool JSONReader::JsonToValue(const std::string& json, - Value** root, - bool check_root, - bool allow_trailing_comma) { +std::string JSONReader::FormatErrorMessage(int line, int column, + const char* description) { + return StringPrintf("Line: %i, column: %i, %s", + line, column, description); +} + +JSONReader::JSONReader() + : start_pos_(NULL), json_pos_(NULL), stack_depth_(0), + allow_trailing_comma_(false) {} + +bool JSONReader::JsonToValue(const std::string& json, Value** root, + bool check_root, bool allow_trailing_comma) { // The input must be in UTF-8. - if (!IsStringUTF8(json.c_str())) + if (!IsStringUTF8(json.c_str())) { + error_message_ = kUnsupportedEncoding; return false; + } + // The conversion from UTF8 to wstring removes null bytes for us // (a good thing). std::wstring json_wide(UTF8ToWide(json)); - const wchar_t* json_cstr = json_wide.c_str(); + start_pos_ = json_wide.c_str(); // When the input JSON string starts with a UTF-8 Byte-Order-Mark // (0xEF, 0xBB, 0xBF), the UTF8ToWide() function converts it to a Unicode // BOM (U+FEFF). To avoid the JSONReader::BuildValue() function from // mis-treating a Unicode BOM as an invalid character and returning false, // skip a converted Unicode BOM if it exists. - if (!json_wide.empty() && json_cstr[0] == 0xFEFF) { - ++json_cstr; + if (!json_wide.empty() && start_pos_[0] == 0xFEFF) { + ++start_pos_; } - JSONReader reader(json_cstr, allow_trailing_comma); + json_pos_ = start_pos_; + allow_trailing_comma_ = allow_trailing_comma; + stack_depth_ = 0; + error_message_.clear(); Value* temp_root = NULL; - bool success = reader.BuildValue(&temp_root, check_root); // Only modify root_ if we have valid JSON and nothing else. - if (success && reader.ParseToken().type == Token::END_OF_INPUT) { - *root = temp_root; - return true; + if (BuildValue(&temp_root, check_root)) { + if (ParseToken().type == Token::END_OF_INPUT) { + *root = temp_root; + return true; + } else { + SetErrorMessage(kUnexpectedDataAfterRoot, json_pos_); + } } + // Default to calling errors "syntax errors". + if (error_message_.empty()) + SetErrorMessage(kSyntaxError, json_pos_); + if (temp_root) delete temp_root; return false; } -JSONReader::JSONReader(const wchar_t* json_start_pos, - bool allow_trailing_comma) - : json_pos_(json_start_pos), - stack_depth_(0), - allow_trailing_comma_(allow_trailing_comma) {} - bool JSONReader::BuildValue(Value** node, bool is_root) { ++stack_depth_; - if (stack_depth_ > kStackLimit) + if (stack_depth_ > kStackLimit) { + SetErrorMessage(kTooMuchNesting, json_pos_); return false; + } Token token = ParseToken(); // The root token must be an array or an object. if (is_root && token.type != Token::OBJECT_BEGIN && token.type != Token::ARRAY_BEGIN) { + SetErrorMessage(kBadRootElementType, json_pos_); return false; } @@ -184,6 +234,7 @@ bool JSONReader::BuildValue(Value** node, bool is_root) { // consumers need the parsing leniency, so handle accordingly. if (token.type == Token::ARRAY_END) { if (!allow_trailing_comma_) { + SetErrorMessage(kTrailingComma, json_pos_); delete array; return false; } @@ -212,6 +263,7 @@ bool JSONReader::BuildValue(Value** node, bool is_root) { DictionaryValue* dict = new DictionaryValue; while (token.type != Token::OBJECT_END) { if (token.type != Token::STRING) { + SetErrorMessage(kUnquotedDictionaryKey, json_pos_); delete dict; return false; } @@ -252,6 +304,7 @@ bool JSONReader::BuildValue(Value** node, bool is_root) { // consumers need the parsing leniency, so handle accordingly. if (token.type == Token::OBJECT_END) { if (!allow_trailing_comma_) { + SetErrorMessage(kTrailingComma, json_pos_); delete dict; return false; } @@ -347,12 +400,16 @@ JSONReader::Token JSONReader::ParseStringToken() { // Make sure the escaped char is valid. switch (c) { case 'x': - if (!ReadHexDigits(token, 2)) + if (!ReadHexDigits(token, 2)) { + SetErrorMessage(kInvalidEscape, json_pos_ + token.length); return kInvalidToken; + } break; case 'u': - if (!ReadHexDigits(token, 4)) + if (!ReadHexDigits(token, 4)) { + SetErrorMessage(kInvalidEscape, json_pos_ + token.length); return kInvalidToken; + } break; case '\\': case '/': @@ -365,6 +422,7 @@ JSONReader::Token JSONReader::ParseStringToken() { case '"': break; default: + SetErrorMessage(kInvalidEscape, json_pos_ + token.length); return kInvalidToken; } } else if ('"' == c) { @@ -582,3 +640,25 @@ bool JSONReader::EatComment() { return true; } +void JSONReader::SetErrorMessage(const char* description, + const wchar_t* error_pos) { + int line_number = 1; + int column_number = 1; + + // Figure out the line and column the error occured at. + for (const wchar_t* pos = start_pos_; pos != error_pos; ++pos) { + if (*pos == '\0') { + NOTREACHED(); + return; + } + + if (*pos == '\n') { + ++line_number; + column_number = 1; + } else { + ++column_number; + } + } + + error_message_ = FormatErrorMessage(line_number, column_number, description); +} |