ceph/src/boost/libs/json/example/validate.cpp

   1 //
   2 // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Official repository: https://github.com/boostorg/json
   8 //
   9
  10 //[example_validate
  11
  12 /*
  13     This example verifies that a file contains valid JSON.
  14 */
  15
  16 #include <boost/json.hpp>
  17
  18 // This file must be manually included when
  19 // using basic_parser to implement a parser.
  20 #include <boost/json/basic_parser_impl.hpp>
  21
  22 #include <iomanip>
  23 #include <iostream>
  24
  25 #include "file.hpp"
  26
  27 using namespace boost::json;
  28
  29 // The null parser discards all the data
  30 class null_parser
  31 {
  32     struct handler
  33     {
  34         constexpr static std::size_t max_object_size = std::size_t(-1);
  35         constexpr static std::size_t max_array_size = std::size_t(-1);
  36         constexpr static std::size_t max_key_size = std::size_t(-1);
  37         constexpr static std::size_t max_string_size = std::size_t(-1);
  38
  39         bool on_document_begin( error_code& ) { return true; }
  40         bool on_document_end( error_code& ) { return true; }
  41         bool on_object_begin( error_code& ) { return true; }
  42         bool on_object_end( std::size_t, error_code& ) { return true; }
  43         bool on_array_begin( error_code& ) { return true; }
  44         bool on_array_end( std::size_t, error_code& ) { return true; }
  45         bool on_key_part( string_view, std::size_t, error_code& ) { return true; }
  46         bool on_key( string_view, std::size_t, error_code& ) { return true; }
  47         bool on_string_part( string_view, std::size_t, error_code& ) { return true; }
  48         bool on_string( string_view, std::size_t, error_code& ) { return true; }
  49         bool on_number_part( string_view, error_code& ) { return true; }
  50         bool on_int64( std::int64_t, string_view, error_code& ) { return true; }
  51         bool on_uint64( std::uint64_t, string_view, error_code& ) { return true; }
  52         bool on_double( double, string_view, error_code& ) { return true; }
  53         bool on_bool( bool, error_code& ) { return true; }
  54         bool on_null( error_code& ) { return true; }
  55         bool on_comment_part(string_view, error_code&) { return true; }
  56         bool on_comment(string_view, error_code&) { return true; }
  57     };
  58
  59     basic_parser<handler> p_;
  60
  61 public:
  62     null_parser()
  63         : p_(parse_options())
  64     {
  65     }
  66
  67     ~null_parser()
  68     {
  69     }
  70
  71     std::size_t
  72     write(
  73         char const* data,
  74         std::size_t size,
  75         error_code& ec)
  76     {
  77         auto const n = p_.write_some( false, data, size, ec );
  78         if(! ec && n < size)
  79             ec = error::extra_data;
  80         return n;
  81     }
  82 };
  83
  84 bool
  85 validate( string_view s )
  86 {
  87     // Parse with the null parser and return false on error
  88     null_parser p;
  89     error_code ec;
  90     p.write( s.data(), s.size(), ec );
  91     if( ec )
  92         return false;
  93
  94     // The string is valid JSON.
  95     return true;
  96 }
  97
  98 int
  99 main(int argc, char** argv)
 100 {
 101     if(argc != 2)
 102     {
 103         std::cerr <<
 104             "Usage: validate <filename>"
 105             << std::endl;
 106         return EXIT_FAILURE;
 107     }
 108
 109     try
 110     {
 111         // Read the file into a string
 112         auto const s = read_file( argv[1] );
 113
 114         // See if the string is valid JSON
 115         auto const valid = validate( s );
 116
 117         // Print the result
 118         if( valid )
 119             std::cout << argv[1] << " contains a valid JSON\n";
 120         else
 121             std::cout << argv[1] << " does not contain a valid JSON\n";
 122     }
 123     catch(std::exception const& e)
 124     {
 125         std::cerr <<
 126             "Caught exception: "
 127             << e.what() << std::endl;
 128         return EXIT_FAILURE;
 129     }
 130
 131     return EXIT_SUCCESS;
 132 }
 133
 134 //]