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LICENSE.MIT Normal file
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@ -0,0 +1,22 @@
The library is licensed under the MIT License
<http://opensource.org/licenses/MIT>:
Copyright (c) 2013-2014 Niels Lohmann
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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README.md
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@ -1,4 +1,4 @@
# Yet another JSON class for C++
# JSON for Modern C++
[![Build Status](https://travis-ci.org/nlohmann/json.png?branch=master)](https://travis-ci.org/nlohmann/json)
[![Coverage Status](https://img.shields.io/coveralls/nlohmann/json.svg)](https://coveralls.io/r/nlohmann/json)
@ -12,9 +12,11 @@ There are myriads of [JSON](http://json.org) libraries out there, and each may e
- **Intuitive syntax**. In languages such as Python, JSON feels like a first class data type. We used all the operator magic of C++ to achieve the same feeling in your code. Check out the [examples below](#examples) and you know, what I mean.
- **Serious testing**. Our library is heavily unit-tested and covers [100%](https://coveralls.io/r/nlohmann/json) of the code, including all exceptional behavior. Furthermore, we use [Valgrind](http://valgrind.org) to make sure no memory leaks exist.
Other aspects were not so important to us:
- **Memory efficiency**. Each JSON object has an overhead of one pointer (the maximal size of a union) and one enumeration element (1 byte). We use the following C++ data types: `std::string` for strings, `int` or `double` for numbers, `std::map` for objects, `std::vector` for arrays, and `bool` for Booleans. We know that there are more efficient ways to store the values, but we are happy enough right now. And by the way: [Valgrind](http://valgrind.org) says our code is free of leaks.
- **Memory efficiency**. Each JSON object has an overhead of one pointer (the maximal size of a union) and one enumeration element (1 byte). We use the following C++ data types: `std::string` for strings, `int` or `double` for numbers, `std::map` for objects, `std::vector` for arrays, and `bool` for Booleans. We know that there are more efficient ways to store the values, but we are happy enough right now.
- **Speed**. We currently implement the parser as naive [recursive descent parser](http://en.wikipedia.org/wiki/Recursive_descent_parser) with hand coded string handling. It is fast enough, but a [LALR-parser](http://en.wikipedia.org/wiki/LALR_parser) with a decent regular expression processor should be even faster (but would consist of more files which makes the integration harder).
@ -28,17 +30,17 @@ All you need to do is add
#include "JSON.h"
```
to the files you want to use JSON objects. Furthermore, you need to compile the file `JSON.cc` and link it to your binaries.
to the files you want to use JSON objects. Furthermore, you need to compile the file `JSON.cc` and link it to your binaries. Do not forget to set the necessary switches to enable C++11 (e.g., `-std=c++11` for GCC and Clang).
## Examples
Here are some examples to give you an idea how to use the class:
```cpp
// create an empty structure
// create an empty structure (null)
JSON j;
// add a number that is stored as double
// add a number that is stored as double (note the implicit conversion of j to an object)
j["pi"] = 3.141;
// add a Boolean that is stored as bool
@ -47,21 +49,39 @@ j["happy"] = true;
// add a string that is stored as std::string
j["name"] = "Niels";
// add a null object
// add another null object by passing nullptr
j["nothing"] = nullptr;
// add an object inside the object
j["further"]["entry"] = 42;
// add an array that is stored as std::vector
// add an array that is stored as std::vector (using an initializer list)
j["list"] = { 1, 0, 2 };
// add another object
// add another object (using an initializer list of pairs)
j["object"] = { {"currency", "USD"}, {"value", "42.99"} };
```
### Input / Output
You can create an object by appending `_json` to a string literal:
```cpp
// create object from string literal
JSON j = "{ \"pi\": 3.141, \"happy\": true }"_json;
```
You can also get a string representation:
```cpp
// explicit conversion to string
std::string s = j.toString();
```
The value of s could be `{"pi": 3.141, "happy": true}`, but the order of the entries in the object is not fixed.
You can also use streams:
```cpp
// create object from stream
JSON j;
@ -73,13 +93,10 @@ std::cout << j;
These operators work for any subclasses of `std::istream` or `std::ostream`.
```cpp
// create object from string literal
JSON j = "{ \"pi\": 3.141, \"happy\": true }"_json;
```
### STL-like access
We designed the JSON class to behave just like an STL container:
```cpp
// create an array
JSON j;
@ -104,7 +121,8 @@ j[1] = 42;
// other stuff
j.size(); // 3
j.empty(); // false
j.type(); // JSON::valeu_type::array
j.type(); // JSON::value_type::array
j.clear(); // the array is empty again
// create an object
JSON o;
@ -125,7 +143,7 @@ for (JSON::iterator it = o.begin(); it != o.end(); ++it) {
### Implicit conversions
The type of the JSON object is determined automatically by the expression to store. Likewise, the stored value is implicitly converted
The type of the JSON object is determined automatically by the expression to store. Likewise, the stored value is implicitly converted.
```cpp
/// strings
@ -142,5 +160,28 @@ bool b2 = jb;
int i = 42;
JSON jn = i;
double f = jn;
// etc.
```
You can also explicitly ask for the value:
```cpp
std::string vs = js.get<std::string>();
bool vb = jb.get<bool>();
int vi = jn.get<int>();
// etc.
```
## License
The library is licensed under the [MIT License](http://opensource.org/licenses/MIT):
Copyright (c) 2013-2014 Niels Lohmann
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.