73ef4ff3
 Hu Chunming
提交三方库
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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_pretty
/*
This example parses a JSON file and pretty-prints
it to standard output.
*/
#include <boost/json.hpp>
#include <iomanip>
#include <iostream>
#include "file.hpp"
namespace json = boost::json;
json::value
parse_file( char const* filename )
{
file f( filename, "r" );
json::stream_parser p;
json::error_code ec;
do
{
char buf[4096];
auto const nread = f.read( buf, sizeof(buf) );
p.write( buf, nread, ec );
}
while( ! f.eof() );
if( ec )
return nullptr;
p.finish( ec );
if( ec )
return nullptr;
return p.release();
}
void
pretty_print( std::ostream& os, json::value const& jv, std::string* indent = nullptr )
{
std::string indent_;
if(! indent)
indent = &indent_;
switch(jv.kind())
{
case json::kind::object:
{
os << "{\n";
indent->append(4, ' ');
auto const& obj = jv.get_object();
if(! obj.empty())
{
auto it = obj.begin();
for(;;)
{
os << *indent << json::serialize(it->key()) << " : ";
pretty_print(os, it->value(), indent);
if(++it == obj.end())
break;
os << ",\n";
}
}
os << "\n";
indent->resize(indent->size() - 4);
os << *indent << "}";
break;
}
case json::kind::array:
{
os << "[\n";
indent->append(4, ' ');
auto const& arr = jv.get_array();
if(! arr.empty())
{
auto it = arr.begin();
for(;;)
{
os << *indent;
pretty_print( os, *it, indent);
if(++it == arr.end())
break;
os << ",\n";
}
}
os << "\n";
indent->resize(indent->size() - 4);
os << *indent << "]";
break;
}
case json::kind::string:
{
os << json::serialize(jv.get_string());
break;
}
case json::kind::uint64:
os << jv.get_uint64();
break;
case json::kind::int64:
os << jv.get_int64();
break;
case json::kind::double_:
os << jv.get_double();
break;
case json::kind::bool_:
if(jv.get_bool())
os << "true";
else
os << "false";
break;
case json::kind::null:
os << "null";
break;
}
if(indent->empty())
os << "\n";
}
int
main(int argc, char** argv)
{
if(argc != 2)
{
std::cerr <<
"Usage: pretty <filename>"
<< std::endl;
return EXIT_FAILURE;
}
try
{
// Parse the file as JSON
auto const jv = parse_file( argv[1] );
// Now pretty-print the value
pretty_print(std::cout, jv);
}
catch(std::exception const& e)
{
std::cerr <<
"Caught exception: "
<< e.what() << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
//]
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