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//
// 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( error_code& ) { return true; }
bool on_document_end( error_code& ) { return true; }
bool on_object_begin( error_code& ) { return true; }
bool on_object_end( std::size_t, error_code& ) { return true; }
bool on_array_begin( error_code& ) { return true; }
bool on_array_end( std::size_t, error_code& ) { return true; }
bool on_key_part( string_view, std::size_t, error_code& ) { return true; }
bool on_key( string_view, std::size_t, error_code& ) { return true; }
bool on_string_part( string_view, std::size_t, error_code& ) { return true; }
bool on_string( string_view, std::size_t, error_code& ) { return true; }
bool on_number_part( string_view, error_code& ) { return true; }
bool on_int64( std::int64_t, string_view, error_code& ) { return true; }
bool on_uint64( std::uint64_t, string_view, error_code& ) { return true; }
bool on_double( double, string_view, error_code& ) { return true; }
bool on_bool( bool, error_code& ) { return true; }
bool on_null( error_code& ) { return true; }
bool on_comment_part(string_view, error_code&) { return true; }
bool on_comment(string_view, 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,
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;
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;
}
//]
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