rippled/modules/ripple_basics/json/json_reader.h

//------------------------------------------------------------------------------
/*
    Copyright (c) 2011-2013, OpenCoin, Inc.
*/
//==============================================================================

#ifndef CPPTL_JSON_READER_H_INCLUDED
# define CPPTL_JSON_READER_H_INCLUDED

namespace Json
{

/** \brief Unserialize a <a HREF="http://www.json.org">JSON</a> document into a Value.
 *
 */
class JSON_API Reader
{
public:
    typedef char Char;
    typedef const Char* Location;

    /** \brief Constructs a Reader allowing all features
     * for parsing.
     */
    Reader ();

    /** \brief Constructs a Reader allowing the specified feature set
     * for parsing.
     */
    Reader ( const Features& features );

    /** \brief Read a Value from a <a HREF="http://www.json.org">JSON</a> document.
     * \param document UTF-8 encoded string containing the document to read.
     * \param root [out] Contains the root value of the document if it was
     *             successfully parsed.
     * \param collectComments \c true to collect comment and allow writing them back during
     *                        serialization, \c false to discard comments.
     *                        This parameter is ignored if Features::allowComments_
     *                        is \c false.
     * \return \c true if the document was successfully parsed, \c false if an error occurred.
     */
    bool parse ( const std::string& document,
                 Value& root,
                 bool collectComments = true );

    /** \brief Read a Value from a <a HREF="http://www.json.org">JSON</a> document.
     * \param document UTF-8 encoded string containing the document to read.
     * \param root [out] Contains the root value of the document if it was
     *             successfully parsed.
     * \param collectComments \c true to collect comment and allow writing them back during
     *                        serialization, \c false to discard comments.
     *                        This parameter is ignored if Features::allowComments_
     *                        is \c false.
     * \return \c true if the document was successfully parsed, \c false if an error occurred.
     */
    bool parse ( const char* beginDoc, const char* endDoc,
                 Value& root,
                 bool collectComments = true );

    /// \brief Parse from input stream.
    /// \see Json::operator>>(std::istream&, Json::Value&).
    bool parse ( std::istream& is,
                 Value& root,
                 bool collectComments = true );

    /** \brief Returns a user friendly string that list errors in the parsed document.
     * \return Formatted error message with the list of errors with their location in
     *         the parsed document. An empty string is returned if no error occurred
     *         during parsing.
     */
    std::string getFormatedErrorMessages () const;

private:
    enum TokenType
    {
        tokenEndOfStream = 0,
        tokenObjectBegin,
        tokenObjectEnd,
        tokenArrayBegin,
        tokenArrayEnd,
        tokenString,
        tokenNumber,
        tokenTrue,
        tokenFalse,
        tokenNull,
        tokenArraySeparator,
        tokenMemberSeparator,
        tokenComment,
        tokenError
    };

    class Token
    {
    public:
        TokenType type_;
        Location start_;
        Location end_;
    };

    class ErrorInfo
    {
    public:
        Token token_;
        std::string message_;
        Location extra_;
    };

    typedef std::deque<ErrorInfo> Errors;

    bool expectToken ( TokenType type, Token& token, const char* message );
    bool readToken ( Token& token );
    void skipSpaces ();
    bool match ( Location pattern,
                 int patternLength );
    bool readComment ();
    bool readCStyleComment ();
    bool readCppStyleComment ();
    bool readString ();
    void readNumber ();
    bool readValue ();
    bool readObject ( Token& token );
    bool readArray ( Token& token );
    bool decodeNumber ( Token& token );
    bool decodeString ( Token& token );
    bool decodeString ( Token& token, std::string& decoded );
    bool decodeDouble ( Token& token );
    bool decodeUnicodeCodePoint ( Token& token,
                                  Location& current,
                                  Location end,
                                  unsigned int& unicode );
    bool decodeUnicodeEscapeSequence ( Token& token,
                                       Location& current,
                                       Location end,
                                       unsigned int& unicode );
    bool addError ( const std::string& message,
                    Token& token,
                    Location extra = 0 );
    bool recoverFromError ( TokenType skipUntilToken );
    bool addErrorAndRecover ( const std::string& message,
                              Token& token,
                              TokenType skipUntilToken );
    void skipUntilSpace ();
    Value& currentValue ();
    Char getNextChar ();
    void getLocationLineAndColumn ( Location location,
                                    int& line,
                                    int& column ) const;
    std::string getLocationLineAndColumn ( Location location ) const;
    void addComment ( Location begin,
                      Location end,
                      CommentPlacement placement );
    void skipCommentTokens ( Token& token );

    typedef std::stack<Value*> Nodes;
    Nodes nodes_;
    Errors errors_;
    std::string document_;
    Location begin_;
    Location end_;
    Location current_;
    Location lastValueEnd_;
    Value* lastValue_;
    std::string commentsBefore_;
    Features features_;
    bool collectComments_;
};

/** \brief Read from 'sin' into 'root'.

 Always keep comments from the input JSON.

 This can be used to read a file into a particular sub-object.
 For example:
 \code
 Json::Value root;
 cin >> root["dir"]["file"];
 cout << root;
 \endcode
 Result:
 \verbatim
 {
"dir": {
    "file": {
 // The input stream JSON would be nested here.
    }
}
 }
 \endverbatim
 \throw std::exception on parse error.
 \see Json::operator<<()
*/
std::istream& operator>> ( std::istream&, Value& );

} // namespace Json

#endif // CPPTL_JSON_READER_H_INCLUDED