//

// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)

//

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//

// Official repository: https://github.com/boostorg/json

//

//[example_validate

/*

This example verifies that a file contains valid JSON.

*/

#include <boost/json.hpp>

// This file must be manually included when

// using basic_parser to implement a parser.

#include <boost/json/basic_parser_impl.hpp>

#include <iomanip>

#include <iostream>

#include "file.hpp"

using namespace boost::json;

// The null parser discards all the data

class null_parser

{

struct handler

{

constexpr static std::size_t max_object_size = std::size_t(-1);

constexpr static std::size_t max_array_size = std::size_t(-1);

constexpr static std::size_t max_key_size = std::size_t(-1);

constexpr static std::size_t max_string_size = std::size_t(-1);

bool on_document_begin( boost::system::error_code& ) { return true; }

bool on_document_end( boost::system::error_code& ) { return true; }

bool on_object_begin( boost::system::error_code& ) { return true; }

bool on_object_end( std::size_t, boost::system::error_code& ) { return true; }

bool on_array_begin( boost::system::error_code& ) { return true; }

bool on_array_end( std::size_t, boost::system::error_code& ) { return true; }

bool on_key_part( string_view, std::size_t, boost::system::error_code& ) { return true; }

bool on_key( string_view, std::size_t, boost::system::error_code& ) { return true; }

bool on_string_part( string_view, std::size_t, boost::system::error_code& ) { return true; }

bool on_string( string_view, std::size_t, boost::system::error_code& ) { return true; }

bool on_number_part( string_view, boost::system::error_code& ) { return true; }

bool on_int64( std::int64_t, string_view, boost::system::error_code& ) { return true; }

bool on_uint64( std::uint64_t, string_view, boost::system::error_code& ) { return true; }

bool on_double( double, string_view, boost::system::error_code& ) { return true; }

bool on_bool( bool, boost::system::error_code& ) { return true; }

bool on_null( boost::system::error_code& ) { return true; }

bool on_comment_part(string_view, boost::system::error_code&) { return true; }

bool on_comment(string_view, boost::system::error_code&) { return true; }

};

basic_parser<handler> p_;

public:

null_parser()

: p_(parse_options())

{

}

~null_parser()

{

}

std::size_t

write(

char const* data,

std::size_t size,

boost::system::error_code& ec)

{

auto const n = p_.write_some( false, data, size, ec );

if(! ec && n < size)

ec = error::extra_data;

return n;

}

};

bool

validate( string_view s )

{

// Parse with the null parser and return false on error

null_parser p;

boost::system::error_code ec;

p.write( s.data(), s.size(), ec );

if( ec )

return false;

// The string is valid JSON.

return true;

}

int

main(int argc, char** argv)

{

if(argc != 2)

{

std::cerr <<

"Usage: validate <filename>"

<< std::endl;

return EXIT_FAILURE;

}

try

{

// Read the file into a string

auto const s = read_file( argv[1] );

// See if the string is valid JSON

auto const valid = validate( s );

// Print the result

if( valid )

std::cout << argv[1] << " contains a valid JSON\n";

else

std::cout << argv[1] << " does not contain a valid JSON\n";

}

catch(std::exception const& e)

{

std::cerr <<

"Caught exception: "

<< e.what() << std::endl;

return EXIT_FAILURE;

}

return EXIT_SUCCESS;

}

//]