json/test/snippets.cpp

//
// 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
//

#include <boost/json.hpp>

#ifndef BOOST_JSON_STANDALONE

#include <algorithm>
#include <cmath>
#include <complex>
#include <iostream>
#include <map>
#include <numeric>
#include <string>
#include <unordered_map>
#include <vector>

#include "test_suite.hpp"

#ifdef _MSC_VER
# pragma warning(push)
# pragma warning(disable: 4101)
#elif defined(__clang__)
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wunused"
# pragma clang diagnostic ignored "-Wmismatched-tags"
#elif defined(__GNUC__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wunused"
#endif

//[snippet_conv_3

template< std::size_t N >
struct static_string { };

namespace std
{

template< std::size_t N >
class hash< static_string< N > >
{
public:
    std::size_t
    operator()(const static_string< N >& str ) const noexcept
    {
        return std::hash< std::string >()( str );
    }
};

} // std

//]

BOOST_JSON_NS_BEGIN

//[snippet_conv_4

template< class T >
void
tag_invoke( const value_from_tag&, value& jv, std::complex< T > const& t)
{
    // Store a complex number as a 2-element array
    // with the real part followed by the imaginary part
    jv = { t.real(), t.imag() };
}

template< class T >
std::complex< T >
tag_invoke( const value_to_tag< std::complex< T > >&, value const& jv )
{
    return std::complex< T >(
        jv.as_array().at(0).to_number< T >(),
        jv.as_array().at(1).to_number< T >());
}

//]

namespace {

void
usingStrings()
{
    {
        //[snippet_strings_1

        string str1; // empty string, uses the default memory resource

        string str2( make_shared_resource<monotonic_resource>() ); // empty string, uses a counted monotonic resource

        //]
    }
    {
        //[snippet_strings_2

        std::string sstr1 = "helloworld";
        std::string sstr2 = "world";

        json::string jstr1 = "helloworld";
        json::string jstr2 = "world";

        assert( jstr2.insert(0, jstr1.subview(0, 5)) == "helloworld" );

        // this is equivalent to
        assert( sstr2.insert(0, sstr1, 0, 5) == "helloworld" );

        //]
    }
    {
        //[snippet_strings_3

        std::string sstr = "hello";

        json::string jstr = "hello";

        assert(sstr.append({'w', 'o', 'r', 'l', 'd'}) == "helloworld");

        // such syntax is inefficient, and the same can
        // be achieved with a character array.

        assert(jstr.append("world") == "helloworld");

        //]
    }

    {
        //[snippet_strings_4

        json::string str = "Boost.JSON";
        json::string_view sv = str;

        // all of these call compare(string_view)
        str.compare(sv);

        str.compare(sv.substr(0, 5));

        str.compare(str);

        str.compare("Boost");

        //]
    }
}

//----------------------------------------------------------

void
usingValues()
{
    {
        //[snippet_value_1

        value jv1;
        value jv2( nullptr );

        assert( jv1.is_null() );
        assert( jv2.is_null() );

        //]
    }
    {
        //[snippet_value_2

        value jv( object_kind );

        assert( jv.kind() == kind::object );
        assert( jv.is_object() );
        assert( ! jv.is_number() );

        //]
    }
    {
        auto f = []{
        //[snippet_value_3

        value jv( object_kind );

        if( auto p = jv.if_object() )
            return p->size();

        //]
        return std::size_t(0);
        };
        (void)f;
    }
    {
        //[snippet_value_4

        value jv;
        jv = value( array_kind );

        assert( jv.is_array() );

        jv.emplace_string();

        assert( jv.is_string() );

        //]
    }
    {
        //[snippet_value_5

        value jv;
        jv.emplace_string() = "Hello, world!";

        int64_t& num = jv.emplace_int64();
        num = 1;

        assert( jv.is_int64() );

        //]
    }
    {
        try
        {
            //[snippet_value_6

            value jv( true );
            jv.as_bool() = true;

            jv.as_string() = "Hello, world!"; // throws an exception

            //]
        }
        catch(...)
        {
        }
    }
    {
        //[snippet_value_7

        value jv( string_kind );
        if( string* str = jv.if_string() )
            *str = "Hello, world!";

        //]
    }
    {
        //[snippet_value_8

        value jv( string_kind );

        // The compiler's static analysis can see that
        // a null pointer is never dereferenced.
        *jv.if_string() = "Hello, world!";

        //]
    }
}

//----------------------------------------------------------

void
usingInitLists()
{
    {
        //[snippet_init_list_1

        value jv = {
            { "name", "John Doe" },
            { "active", true },
            { "associated-accounts", nullptr },
            { "total-balance", 330.00 },
            { "account-balances", { 84, 120, 126 } } };

        //]
    }

    {
        //[snippet_init_list_2

        value jv = { true, 2, "hello", nullptr };

        assert( jv.is_array() );

        assert( jv.as_array().size() == 4 );

        assert( serialize(jv) == "[true,2,\"hello\",null]" );

        //]
    }

    {
        //[snippet_init_list_3

        value jv = { true, 2, "hello", { "bye", nullptr, false } };

        assert( jv.is_array() );

        assert( jv.as_array().back().is_array() );

        assert( serialize(jv) == "[true,2,\"hello\",[\"bye\",null,false]]" );

        //]
    }

    {
        //[snippet_init_list_4

        // Should this be an array or an object?
        value jv = { { "hello", 42 }, { "world", 43 } };

        //]
    }

    {
        //[snippet_init_list_5

        value jv1 = { { "hello", 42 }, { "world", 43 } };

        assert( jv1.is_object() );

        assert( jv1.as_object().size() == 2 );

        assert( serialize(jv1) == R"({"hello":42,"world":43})" );

        // All of the following are arrays

        value jv2 = { { "make", "Tesla" }, { "model", 3 }, "black" };

        value jv3 = { { "library", "JSON" }, { "Boost", "C++", "Fast", "JSON" } };

        value jv4 = { { "color", "blue" }, { 1, "red" } };

        assert( jv2.is_array() && jv3.is_array() && jv4.is_array() );

        //]
    }

    {
        //[snippet_init_list_6

        value jv = { { "hello", 42 }, array{ "world", 43 } };

        assert( jv.is_array() );

        array& ja = jv.as_array();

        assert( ja[0].is_array() && ja[1].is_array());

        assert ( serialize(jv) == R"([["hello",42],["world",43]])" );

        //]

        (void)ja;
    }

    {
        //[snippet_init_list_7

        value jv = { { "mercury", 36 }, { "venus", 67 }, { "earth", 93 } };

        assert( jv.is_object() );

        assert( serialize(jv) == "{\"mercury\":36,\"venus\":67,\"earth\":93}" );

        array ja = { { "mercury", 36 }, { "venus", 67 }, { "earth", 93 } };

        assert( serialize(ja) == "[[\"mercury\",36],[\"venus\",67],[\"earth\",93]]" );

        //]

        (void)ja;
    }

    {
        //[snippet_init_list_8

        object jo = { { "mercury", { { "distance", 36 } } }, { "venus", { 67, "million miles" } }, { "earth", 93 } };

        assert( jo["mercury"].is_object() );

        assert( jo["venus"].is_array() );

        //]
    }

    {
        //[snippet_init_list_9

        object jo1 = { { "john", 100 }, { "dave", 500 }, { "joe", 300 } };

        value jv = { { "clients", std::move(jo1) } };

        object& jo2 = jv.as_object()["clients"].as_object();

        assert( ! jo2.empty() && jo1.empty() );

        assert( serialize(jv) == R"({"clients":{"john":100,"dave":500,"joe":300}})" );

        //]

        (void)jo2;
    }
}

//----------------------------------------------------------

void
usingArrays()
{
    {
        //[snippet_arrays_1

        array arr1; // empty array, uses the default memory resource

        array arr2( make_shared_resource<monotonic_resource>() ); // empty array, uses a counted monotonic resource

        //]
    }
    {
        //[snippet_arrays_2

        array arr( { "Hello", 42, true } );

        //]
    }
    try
    {
        //[snippet_arrays_3

        array arr;

        arr.emplace_back( "Hello" );
        arr.emplace_back( 42 );
        arr.emplace_back( true );

        //]

        //[snippet_arrays_4

        assert( arr[0].as_string() == "Hello" );

        // The following line throws std::out_of_range, since the index is out of range
        arr.at( 3 ) = nullptr;

        //]
    }
    catch (...)
    {
    }
}

//----------------------------------------------------------

void
usingObjects()
{
    {
        //[snippet_objects_1

        object obj1; // empty object, uses the default memory resource

        object obj2( make_shared_resource<monotonic_resource>() ); // empty object, uses a counted monotonic resource

        //]
    }
    {
        //[snippet_objects_2

        object obj( {{"key1", "value1" }, { "key2", 42 }, { "key3", false }} );

        //]
    }
    {
        //[snippet_objects_3

        object obj;

        obj.emplace( "key1", "value1" );
        obj.emplace( "key2", 42 );
        obj.emplace( "key3", false );

        //]
    }
    try
    {
        //[snippet_objects_4

        object obj;

        obj["key1"] = "value1";
        obj["key2"] = 42;
        obj["key3"] = false;

        // The following line throws std::out_of_range, since the key does not exist
        obj.at( "key4" );

        //]
    }
    catch (...)
    {
    }
}

//----------------------------------------------------------

//[snippet_conv_2

template< class T >
void identity_swap( T& a, T& b )
{
    // introduces the declaration of
    // std::swap into this scope
    using std::swap;
    if( &a == &b )
        return;
    // the overload set will contain std::swap,
    // any declarations of swap within the enclosing
    // namespace, and any declarations of swap within
    // the namespaces associated with T
    swap( a, b );
}

//]

//[snippet_conv_5

template< class T >
struct vec3
{
    T x, y, z;
};

template< class T >
void tag_invoke( const value_from_tag&, value& jv, const vec3<T>& vec )
{
    jv = {
        { "x", vec.x },
        { "y", vec.y },
        { "z", vec.z }
    };
}

//]

#ifdef BOOST_JSON_DOCS
//[snippet_conv_7

template< class T, typename std::enable_if<
    std::is_floating_point< T >::value>::type* = nullptr >
void tag_invoke( const value_from_tag&, value& jv, T t )
{
    jv = std::llround( t );
}

//]
#endif

//[snippet_conv_10

struct customer
{
    std::uint64_t id;
    std::string name;
    bool late;

    customer() = default;

    customer( std::uint64_t i, const std::string& n, bool l )
        : id( i ), name( n ), late( l ) { }

    explicit customer( value const& );
};

void tag_invoke( const value_from_tag&, value& jv, customer const& c )
{
    // Assign a JSON value
    jv = {
        { "id", c.id },
        { "name", c.name },
        { "late", c.late }
    };
}

//]

//[snippet_conv_14

customer tag_invoke( const value_to_tag<customer>&, const value& jv )
{
    // at() throws if `jv` is not an object, or if the key is not found.
    // as_uint64() will throw if the value is not an unsigned 64-bit integer.
    std::uint64_t id = jv.at( "id" ).as_uint64();

    // We already know that jv is an object from
    // the previous call to jv.as_object() succeeding,
    // now we use jv.get_object() which skips the
    // check. value_to will throw if jv.kind() != kind::string
    std::string name = value_to< std::string >( jv.get_object().at( "name" ) );

    // id and name are constructed from JSON in the member
    // initializer list above, but we can also use regular
    // assignments in the body of the function as shown below.
    // as_bool() will throw if kv.kind() != kind::bool
    bool late = jv.get_object().at( "late" ).as_bool();

    return customer(id, name, late);
}

//]

void
usingExchange()
{
    {
        //[snippet_conv_1

        std::vector< int > v1{ 1, 2, 3, 4 };

        // Convert the vector to a JSON array
        value jv = value_from( v1 );

        assert( jv.is_array() );

        array& ja = jv.as_array();

        assert( ja.size() == 4 );

        for ( std::size_t i = 0; i < v1.size(); ++i )
            assert( v1[i] == ja[i].as_int64() );

        // Convert back to vector< int >
        std::vector< int > v2 = value_to< std::vector< int > >( jv );

        assert( v1 == v2 );

        //]

        (void)ja;
    }
    {
        //[snippet_conv_6

        vec3< int > pos = { 4, 1, 4 };

        value jv = value_from( pos );

        assert( serialize( jv ) == "{\"x\":4,\"y\":1,\"z\":4}" );

        //]
    }
    {
        //[snippet_conv_8

       value jv = value_from( 1.5 ); // error

        //]
    }
    {
        //[snippet_conv_9

        std::map< std::string, vec3< int > > positions = {
            { "Alex", { 42, -60, 18 } },
            { "Blake", { 300, -60, -240} },
            { "Carol", { -60, 30, 30 } }
        };

        // conversions are applied recursively;
        // the key type and value type will be converted
        // using value_from as well
        value jv = value_from( positions );

        assert( jv.is_object() );

        object& jo = jv.as_object();

        assert( jo.size() == 3 );

        // The sum of the coordinates is 0
        assert( std::accumulate( jo.begin(), jo.end(), std::int64_t(0),
            []( std::int64_t total, const key_value_pair& jp )
            {
                assert ( jp.value().is_object() );

                const object& pos = jp.value().as_object();

                return total + pos.at( "x" ).as_int64() +
                    pos.at( "y" ).as_int64() +
                    pos.at( "z" ).as_int64();

            } ) == 0 );

        //]

        (void)jo;
    }
    {
        //[snippet_conv_11

        std::vector< customer > customers = {
            customer( 0, "Alison", false ),
            customer( 1, "Bill", false ),
            customer( 3, "Catherine", true ),
            customer( 4, "Doug", false )
         };

        storage_ptr sp = make_shared_resource< monotonic_resource >();

        value jv = value_from( customers, sp );

        assert( jv.storage() == sp );

        assert( jv.is_array() );

        //]
    }

    {
        //[snippet_conv_12

        // Satisfies both FromMapLike and FromContainerLike
        std::unordered_map< std::string, bool > available_tools = {
            { "Crowbar", true },
            { "Hammer", true },
            { "Drill", true },
            { "Saw", false },
        };

        value jv = value_from( available_tools );

        assert( jv.is_object() );

        //]
    }
    {
        //[snippet_conv_13

        std::complex< double > c1 = { 3.14159, 2.71828 };

        // Convert a complex number to JSON
        value jv = value_from( c1 );

        assert ( jv.is_array() );

        // Convert back to a complex number

        std::complex< double > c2 = value_to< std::complex< double > >( jv );

        //]

        (void)c2;
    }
    {
        //[snippet_conv_15

        customer c1( 5, "Ed", false );

        // Convert customer to value
        value jv = value_from( c1 );

        // Convert the result back to customer
        customer c2 = value_to< customer >( jv );

        // The resulting customer is unchanged
        assert( c1.name == c2.name );

        //]
    }
    {
        //[snippet_conv_16

        value available_tools = {
            { "Crowbar", true },
            { "Hammer", true },
            { "Drill", true },
            { "Saw", false }
        };

        assert( available_tools.is_object() );

        auto as_map = value_to< std::map< std::string, bool > >( available_tools );

        assert( available_tools.as_object().size() == as_map.size() );

        //]
    }
}

BOOST_STATIC_ASSERT(
    has_value_from<customer>::value);

BOOST_STATIC_ASSERT(
    has_value_from<std::complex<float>>::value);
BOOST_STATIC_ASSERT(
    has_value_from<std::complex<double>>::value);

BOOST_STATIC_ASSERT(
    has_value_to<std::complex<float>>::value);
BOOST_STATIC_ASSERT(
    has_value_to<std::complex<double>>::value);

} // (anon)

} // json
} // boost

//----------------------------------------------------------


namespace {

class my_non_deallocating_resource { };

} // (anon)

//[snippet_allocators_14
namespace boost {
namespace json {

template<>
struct is_deallocate_trivial< my_non_deallocating_resource >
{
    static constexpr bool value = true;
};

} // json
} // boost

//]

namespace boost {
namespace json {

class snippets_test
{
public:
    void
    run()
    {
        usingValues();
        usingInitLists();
        usingExchange();
        usingArrays();
        usingObjects();
        usingStrings();

        BOOST_TEST_PASS();
    }
};

TEST_SUITE(snippets_test, "boost.json.snippets");

BOOST_JSON_NS_END

#endif