rippled/include/xrpl/json/json_reader.h

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#ifndef RIPPLE_JSON_JSON_READER_H_INCLUDED
#define RIPPLE_JSON_JSON_READER_H_INCLUDED

#define CPPTL_JSON_READER_H_INCLUDED

#include <xrpl/json/json_forwards.h>
#include <xrpl/json/json_value.h>

#include <boost/asio/buffer.hpp>

#include <stack>

namespace Json {

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

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

    /** \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.
     * \return \c true if the document was successfully parsed, \c false if an
     * error occurred.
     */
    bool
    parse(std::string const& document, Value& root);

    /** \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.
     * \return \c true if the document was successfully parsed, \c false if an
     * error occurred.
     */
    bool
    parse(char const* beginDoc, char const* endDoc, Value& root);

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

    /** \brief Read a Value from a <a HREF="http://www.json.org">JSON</a> buffer
     * sequence. \param root [out] Contains the root value of the document if it
     * was successfully parsed. \param UTF-8 encoded buffer sequence. \return \c
     * true if the buffer was successfully parsed, \c false if an error
     * occurred.
     */
    template <class BufferSequence>
    bool
    parse(Value& root, BufferSequence const& bs);

    /** \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;

    static constexpr unsigned nest_limit{25};

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

    class Token
    {
    public:
        explicit Token() = default;

        TokenType type_;
        Location start_;
        Location end_;
    };

    class ErrorInfo
    {
    public:
        explicit ErrorInfo() = default;

        Token token_;
        std::string message_;
        Location extra_;
    };

    using Errors = std::deque<ErrorInfo>;

    bool
    expectToken(TokenType type, Token& token, char const* message);
    bool
    readToken(Token& token);
    void
    skipSpaces();
    bool
    match(Location pattern, int patternLength);
    bool
    readComment();
    bool
    readCStyleComment();
    bool
    readCppStyleComment();
    bool
    readString();
    Reader::TokenType
    readNumber();
    bool
    readValue(unsigned depth);
    bool
    readObject(Token& token, unsigned depth);
    bool
    readArray(Token& token, unsigned depth);
    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(std::string const& message, Token& token, Location extra = 0);
    bool
    recoverFromError(TokenType skipUntilToken);
    bool
    addErrorAndRecover(
        std::string const& 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
    skipCommentTokens(Token& token);

    using Nodes = std::stack<Value*>;
    Nodes nodes_;
    Errors errors_;
    std::string document_;
    Location begin_;
    Location end_;
    Location current_;
    Location lastValueEnd_;
    Value* lastValue_;
};

template <class BufferSequence>
bool
Reader::parse(Value& root, BufferSequence const& bs)
{
    using namespace boost::asio;
    std::string s;
    s.reserve(buffer_size(bs));
    for (auto const& b : bs)
        s.append(static_cast<char const*>(b.data()), buffer_size(b));
    return parse(s, root);
}

/** \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