foundationdb/fdbclient/json_spirit/json_spirit_reader_template.h

#ifndef JSON_SPIRIT_READER_TEMPLATE
#define JSON_SPIRIT_READER_TEMPLATE

//          Copyright John W. Wilkinson 2007 - 2014
// Distributed under the MIT License, see accompanying file LICENSE-OSS

// json spirit version 4.08

#if defined(_MSC_VER) && (_MSC_VER >= 1020)
#pragma once
#endif

#include "json_spirit_value.h"
#include "json_spirit_error_position.h"

//#define BOOST_SPIRIT_THREADSAFE  // uncomment for multithreaded use, requires linking to boost.thread

#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/version.hpp>

#if BOOST_VERSION >= 103800
#include <boost/spirit/include/classic_core.hpp>
#include <boost/spirit/include/classic_confix.hpp>
#include <boost/spirit/include/classic_escape_char.hpp>
#include <boost/spirit/include/classic_multi_pass.hpp>
#include <boost/spirit/include/classic_position_iterator.hpp>
#define spirit_namespace boost::spirit::classic
#else
#include <boost/spirit/core.hpp>
#include <boost/spirit/utility/confix.hpp>
#include <boost/spirit/utility/escape_char.hpp>
#include <boost/spirit/iterator/multi_pass.hpp>
#include <boost/spirit/iterator/position_iterator.hpp>
#define spirit_namespace boost::spirit
#endif

namespace json_spirit {
const spirit_namespace::int_parser<int64_t> int64_p = spirit_namespace::int_parser<int64_t>();
const spirit_namespace::uint_parser<uint64_t> uint64_p = spirit_namespace::uint_parser<uint64_t>();

template <class Iter_type>
bool is_eq(Iter_type first, Iter_type last, const char* c_str) {
	for (Iter_type i = first; i != last; ++i, ++c_str) {
		if (*c_str == 0)
			return false;

		if (*i != *c_str)
			return false;
	}

	return true;
}

template <class Char_type>
Char_type hex_to_num(const Char_type c) {
	if ((c >= '0') && (c <= '9'))
		return c - '0';
	if ((c >= 'a') && (c <= 'f'))
		return c - 'a' + 10;
	if ((c >= 'A') && (c <= 'F'))
		return c - 'A' + 10;
	return 0;
}

template <class Char_type, class Iter_type>
Char_type hex_str_to_char(Iter_type& begin) {
	const Char_type c1(*(++begin));
	const Char_type c2(*(++begin));

	return (hex_to_num(c1) << 4) + hex_to_num(c2);
}

template <class Char_type, class Iter_type>
Char_type unicode_str_to_char(Iter_type& begin) {
	const Char_type c1(*(++begin));
	const Char_type c2(*(++begin));
	const Char_type c3(*(++begin));
	const Char_type c4(*(++begin));

	return (hex_to_num(c1) << 12) + (hex_to_num(c2) << 8) + (hex_to_num(c3) << 4) + hex_to_num(c4);
}

template <class String_type>
void append_esc_char_and_incr_iter(String_type& s,
                                   typename String_type::const_iterator& begin,
                                   typename String_type::const_iterator end) {
	typedef typename String_type::value_type Char_type;

	const Char_type c2(*begin);

	switch (c2) {
	case 't':
		s += '\t';
		break;
	case 'b':
		s += '\b';
		break;
	case 'f':
		s += '\f';
		break;
	case 'n':
		s += '\n';
		break;
	case 'r':
		s += '\r';
		break;
	case '\\':
		s += '\\';
		break;
	case '/':
		s += '/';
		break;
	case '"':
		s += '"';
		break;
	case 'x': {
		if (end - begin >= 3) //  expecting "xHH..."
		{
			s += hex_str_to_char<Char_type>(begin);
		}
		break;
	}
	case 'u': {
		if (end - begin >= 5) //  expecting "uHHHH..."
		{
			s += unicode_str_to_char<Char_type>(begin);
		}
		break;
	}
	}
}

template <class String_type>
String_type substitute_esc_chars(typename String_type::const_iterator begin, typename String_type::const_iterator end) {
	typedef typename String_type::const_iterator Iter_type;

	if (end - begin < 2)
		return String_type(begin, end);

	String_type result;

	result.reserve(end - begin);

	const Iter_type end_minus_1(end - 1);

	Iter_type substr_start = begin;
	Iter_type i = begin;

	for (; i < end_minus_1; ++i) {
		if (*i == '\\') {
			result.append(substr_start, i);

			++i; // skip the '\'

			append_esc_char_and_incr_iter(result, i, end);

			substr_start = i + 1;
		}
	}

	result.append(substr_start, end);

	return result;
}

template <class String_type>
String_type get_str_(typename String_type::const_iterator begin, typename String_type::const_iterator end) {
	assert(end - begin >= 2);

	typedef typename String_type::const_iterator Iter_type;

	Iter_type str_without_quotes(++begin);
	Iter_type end_without_quotes(--end);

	return substitute_esc_chars<String_type>(str_without_quotes, end_without_quotes);
}

inline std::string get_str(std::string::const_iterator begin, std::string::const_iterator end) {
	return get_str_<std::string>(begin, end);
}

inline std::wstring get_str(std::wstring::const_iterator begin, std::wstring::const_iterator end) {
	return get_str_<std::wstring>(begin, end);
}

template <class String_type, class Iter_type>
String_type get_str(Iter_type begin, Iter_type end) {
	const String_type tmp(begin, end); // convert multipass iterators to string iterators

	return get_str(tmp.begin(), tmp.end());
}

// this class's methods get called by the spirit parse resulting
// in the creation of a JSON object or array
//
// NB Iter_type could be a std::string iterator, wstring iterator, a position iterator or a multipass iterator
//
template <class Value_type, class Iter_type>
class Semantic_actions {
public:
	typedef typename Value_type::Config_type Config_type;
	typedef typename Config_type::String_type String_type;
	typedef typename Config_type::Object_type Object_type;
	typedef typename Config_type::Array_type Array_type;
	typedef typename String_type::value_type Char_type;

	Semantic_actions(Value_type& value) : value_(value), current_p_(0) {}

	void begin_obj(Char_type c) {
		assert(c == '{');

		begin_compound<Object_type>();
	}

	void end_obj(Char_type c) {
		assert(c == '}');

		end_compound();
	}

	void begin_array(Char_type c) {
		assert(c == '[');

		begin_compound<Array_type>();
	}

	void end_array(Char_type c) {
		assert(c == ']');

		end_compound();
	}

	void new_name(Iter_type begin, Iter_type end) {
		assert(current_p_->type() == obj_type);

		name_ = get_str<String_type>(begin, end);
	}

	void new_str(Iter_type begin, Iter_type end) { add_to_current(get_str<String_type>(begin, end)); }

	void new_true(Iter_type begin, Iter_type end) {
		assert(is_eq(begin, end, "true"));

		add_to_current(true);
	}

	void new_false(Iter_type begin, Iter_type end) {
		assert(is_eq(begin, end, "false"));

		add_to_current(false);
	}

	void new_null(Iter_type begin, Iter_type end) {
		assert(is_eq(begin, end, "null"));

		add_to_current(Value_type());
	}

	void new_int(int64_t i) { add_to_current(i); }

	void new_uint64(uint64_t ui) { add_to_current(ui); }

	void new_real(double d) { add_to_current(d); }

private:
	Semantic_actions& operator=(const Semantic_actions&);
	// to prevent "assignment operator could not be generated" warning

	Value_type* add_first(const Value_type& value) {
		assert(current_p_ == 0);

		value_ = value;
		current_p_ = &value_;
		return current_p_;
	}

	template <class Array_or_obj>
	void begin_compound() {
		if (current_p_ == 0) {
			add_first(Array_or_obj());
		} else {
			stack_.push_back(current_p_);

			Array_or_obj new_array_or_obj; // avoid copy by building new array or object in place

			current_p_ = add_to_current(new_array_or_obj);
		}
	}

	void end_compound() {
		if (current_p_ != &value_) {
			current_p_ = stack_.back();

			stack_.pop_back();
		}
	}

	Value_type* add_to_current(const Value_type& value) {
		if (current_p_ == 0) {
			return add_first(value);
		} else if (current_p_->type() == array_type) {
			current_p_->get_array().push_back(value);

			return &current_p_->get_array().back();
		}

		assert(current_p_->type() == obj_type);

		return &Config_type::add(current_p_->get_obj(), name_, value);
	}

	Value_type& value_; // this is the object or array that is being created
	Value_type* current_p_; // the child object or array that is currently being constructed

	std::vector<Value_type*> stack_; // previous child objects and arrays

	String_type name_; // of current name/value pair
};

template <typename Iter_type>
void throw_error(spirit_namespace::position_iterator<Iter_type> i, const std::string& reason) {
	throw Error_position(i.get_position().line, i.get_position().column, reason);
}

template <typename Iter_type>
void throw_error(Iter_type i, const std::string& reason) {
	throw reason;
}

// the spirit grammer
//
template <class Value_type, class Iter_type>
class Json_grammer : public spirit_namespace::grammar<Json_grammer<Value_type, Iter_type>> {
public:
	typedef Semantic_actions<Value_type, Iter_type> Semantic_actions_t;

	Json_grammer(Semantic_actions_t& semantic_actions) : actions_(semantic_actions) {}

	static void throw_not_value(Iter_type begin, Iter_type end) { throw_error(begin, "not a value"); }

	static void throw_not_array(Iter_type begin, Iter_type end) { throw_error(begin, "not an array"); }

	static void throw_not_object(Iter_type begin, Iter_type end) { throw_error(begin, "not an object"); }

	static void throw_not_pair(Iter_type begin, Iter_type end) { throw_error(begin, "not a pair"); }

	static void throw_not_colon(Iter_type begin, Iter_type end) { throw_error(begin, "no colon in pair"); }

	static void throw_not_string(Iter_type begin, Iter_type end) { throw_error(begin, "not a string"); }

	template <typename ScannerT>
	class definition {
	public:
		definition(const Json_grammer& self) {
			using namespace spirit_namespace;

			typedef typename Value_type::String_type::value_type Char_type;

			// first we convert the semantic action class methods to functors with the
			// parameter signature expected by spirit

			typedef boost::function<void(Char_type)> Char_action;
			typedef boost::function<void(Iter_type, Iter_type)> Str_action;
			typedef boost::function<void(double)> Real_action;
			typedef boost::function<void(boost::int64_t)> Int_action;
			typedef boost::function<void(boost::uint64_t)> Uint64_action;

			Char_action begin_obj(boost::bind(&Semantic_actions_t::begin_obj, &self.actions_, _1));
			Char_action end_obj(boost::bind(&Semantic_actions_t::end_obj, &self.actions_, _1));
			Char_action begin_array(boost::bind(&Semantic_actions_t::begin_array, &self.actions_, _1));
			Char_action end_array(boost::bind(&Semantic_actions_t::end_array, &self.actions_, _1));
			Str_action new_name(boost::bind(&Semantic_actions_t::new_name, &self.actions_, _1, _2));
			Str_action new_str(boost::bind(&Semantic_actions_t::new_str, &self.actions_, _1, _2));
			Str_action new_true(boost::bind(&Semantic_actions_t::new_true, &self.actions_, _1, _2));
			Str_action new_false(boost::bind(&Semantic_actions_t::new_false, &self.actions_, _1, _2));
			Str_action new_null(boost::bind(&Semantic_actions_t::new_null, &self.actions_, _1, _2));
			Real_action new_real(boost::bind(&Semantic_actions_t::new_real, &self.actions_, _1));
			Int_action new_int(boost::bind(&Semantic_actions_t::new_int, &self.actions_, _1));
			Uint64_action new_uint64(boost::bind(&Semantic_actions_t::new_uint64, &self.actions_, _1));

			// actual grammer

			json_ = value_ | eps_p[&throw_not_value];

			value_ = string_[new_str] | number_ | object_ | array_ | str_p("true")[new_true] |
			         str_p("false")[new_false] | str_p("null")[new_null];

			object_ = ch_p('{')[begin_obj] >> !members_ >> (ch_p('}')[end_obj] | eps_p[&throw_not_object]);

			members_ = pair_ >> *(',' >> pair_);

			pair_ = string_[new_name] >> (':' | eps_p[&throw_not_colon]) >> (value_ | eps_p[&throw_not_value]);

			array_ = ch_p('[')[begin_array] >> !elements_ >> (ch_p(']')[end_array] | eps_p[&throw_not_array]);

			elements_ = value_ >> *(',' >> value_);

			string_ =
			    lexeme_d // this causes white space and what would appear to be comments inside a string to be retained
			        [confix_p('"', *lex_escape_ch_p, '"')];

			number_ = strict_real_p[new_real] | int64_p[new_int] | uint64_p[new_uint64];
		}

		spirit_namespace::rule<ScannerT> json_, object_, members_, pair_, array_, elements_, value_, string_, number_;

		const spirit_namespace::rule<ScannerT>& start() const { return json_; }
	};

private:
	Json_grammer& operator=(const Json_grammer&); // to prevent "assignment operator could not be generated" warning

	Semantic_actions_t& actions_;
};

template <class Iter_type, class Value_type>
void add_posn_iter_and_read_range_or_throw(Iter_type begin, Iter_type end, Value_type& value) {
	typedef spirit_namespace::position_iterator<Iter_type> Posn_iter_t;

	const Posn_iter_t posn_begin(begin, end);
	const Posn_iter_t posn_end(end, end);

	read_range_or_throw(posn_begin, posn_end, value);
}

template <class Istream_type>
struct Multi_pass_iters {
	typedef typename Istream_type::char_type Char_type;
	typedef std::istream_iterator<Char_type, Char_type> istream_iter;
	typedef spirit_namespace::multi_pass<istream_iter> Mp_iter;

	Multi_pass_iters(Istream_type& is) {
		is.unsetf(std::ios::skipws);

		begin_ = spirit_namespace::make_multi_pass(istream_iter(is));
		end_ = spirit_namespace::make_multi_pass(istream_iter());
	}

	Mp_iter begin_;
	Mp_iter end_;
};

// reads a JSON Value from a pair of input iterators throwing an exception on invalid input, e.g.
//
// string::const_iterator start = str.begin();
// const string::const_iterator next = read_range_or_throw( str.begin(), str.end(), value );
//
// The iterator 'next' will point to the character past the
// last one read.
//
template <class Iter_type, class Value_type>
Iter_type read_range_or_throw(Iter_type begin, Iter_type end, Value_type& value) {
	Semantic_actions<Value_type, Iter_type> semantic_actions(value);

	const spirit_namespace::parse_info<Iter_type> info = spirit_namespace::parse(
	    begin,
	    end,
	    Json_grammer<Value_type, Iter_type>(semantic_actions),
	    spirit_namespace::space_p | spirit_namespace::comment_p("//") | spirit_namespace::comment_p("/*", "*/"));

	if (!info.hit) {
		assert(false); // in theory exception should already have been thrown
		throw_error(info.stop, "error");
	}

	return info.stop;
}

// reads a JSON Value from a pair of input iterators, e.g.
//
// string::const_iterator start = str.begin();
// const bool success = read_string( start, str.end(), value );
//
// The iterator 'start' will point to the character past the
// last one read.
//
template <class Iter_type, class Value_type>
bool read_range(Iter_type& begin, Iter_type end, Value_type& value) {
	try {
		begin = read_range_or_throw(begin, end, value);

		return true;
	} catch (...) {
		return false;
	}
}

// reads a JSON Value from a string, e.g.
//
// const bool success = read_string( str, value );
//
template <class String_type, class Value_type>
bool read_string(const String_type& s, Value_type& value) {
	typename String_type::const_iterator begin = s.begin();

	return read_range(begin, s.end(), value);
}

// reads a JSON Value from a string throwing an exception on invalid input, e.g.
//
// read_string_or_throw( is, value );
//
template <class String_type, class Value_type>
void read_string_or_throw(const String_type& s, Value_type& value) {
	add_posn_iter_and_read_range_or_throw(s.begin(), s.end(), value);
}

// reads a JSON Value from a stream, e.g.
//
// const bool success = read_stream( is, value );
//
template <class Istream_type, class Value_type>
bool read_stream(Istream_type& is, Value_type& value) {
	Multi_pass_iters<Istream_type> mp_iters(is);

	return read_range(mp_iters.begin_, mp_iters.end_, value);
}

// reads a JSON Value from a stream throwing an exception on invalid input, e.g.
//
// read_stream_or_throw( is, value );
//
template <class Istream_type, class Value_type>
void read_stream_or_throw(Istream_type& is, Value_type& value) {
	const Multi_pass_iters<Istream_type> mp_iters(is);

	add_posn_iter_and_read_range_or_throw(mp_iters.begin_, mp_iters.end_, value);
}
} // namespace json_spirit

#endif