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// Copyright 2009-present MongoDB, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <bsoncxx/builder/core.hpp>
#include <bsoncxx/types.hpp>
#include <examples/macros.hh>
using namespace bsoncxx;
int EXAMPLES_CDECL main() {
// bsoncxx::builder::core is a low-level primitive that can be useful for building other
// BSON abstractions. Most users should just use builder::stream or builder::basic.
// the boolean argument to core should be true if the top-level BSON datum is an array.
// if false, it will be created as a document.
auto builder = builder::core{false};
// When building a document, we have two ways of passing keys.
// 1. We can pass a key using key_owned(). This is less efficient but
// frees us from worrying about the lifetime of the key.
// Example: if we have a stack allocated std::string, key_owned will take ownership
// of it, so the following code is legal.
{
std::string temp{"foo"};
builder.key_owned(temp);
builder.append(types::b_bool{false});
}
// 2. We can pass a key using key_view(). This is more efficient (less copying)
// but we need to manage the lifetime of the key until a matching value is appended, at which
// point it will be copied into an internally managed buffer.
{
// THIS IS ILLEGAL: DO NOT DO THIS
auto illegal_do_not_do_this = builder::core{false};
std::string temp{"bar"};
illegal_do_not_do_this.key_view(temp);
// the builder has dangling ref to temp at the end of this scope!!
}
{
// This is legal, because we append a corresponding value before the key goes out of scope.
std::string temp{"baz"};
builder.key_view(temp);
builder.append(types::b_bool{false});
}
// Appending values is pretty simple.
// Just call append() and pass a value wrapped in the corresponding BSON type.
auto array = builder::core{true}; // we are building an array
array.append(types::b_string{"hello"}); // append a UTF-8 string
array.append(types::b_double{1.234}); // append a double
array.append(types::b_int32{1234}); // append an int32
// ... etc.
}
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