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https://github.com/p-ranav/pprint

Pretty Printer for Modern C++
https://github.com/p-ranav/pprint

cpp17 mit-license pretty-printer single-header-lib

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Pretty Printer for Modern C++

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README 

        


  pprint




## Highlights



* Single header file

* Requires C++17

* MIT License



## Quick Start



Simply include pprint.hpp and you're good to go.



```cpp

#include 

```



To start printing, create a ```PrettyPrinter```



```cpp

pprint::PrettyPrinter printer;

```



You can construct a ```PrettyPrinter``` with any stream that inherits from ```std::ostream``` , e.g, ```std::stringstream```



```cpp

std::stringstream stream;

pprint::PrettyPrinter printer(stream);

```



## Fundamental Types



```cpp

printer.print(5);

printer.print(3.14f);

printer.print(2.718);

printer.print(true);

printer.print('x');

printer.print("Hello, 世界");

printer.print(nullptr);

```



```bash

5

3.14f

2.718

true

x

Hello, 世界

nullptr

```



## Strings



Maybe you want your strings to be quoted? Simply set ```printer.quotes(true)```



```cpp

printer.quotes(true);

printer.print("A", "B", "C");

```



```bash

"A" "B" "C"

```



## Complex Numbers



```cpp

using namespace std::complex_literals;

std::complex foo = 1. + 2.5i;

std::complex bar = 9. + 4i;

printer.print(foo, "*", bar, "=", (foo * bar));   // parameter packing

```



```bash

(1 + 2.5i) * (9 + 4i) = (-1 + 26.5i)

```

## Enumeration Types



```cpp

enum Color { RED = 2, BLUE = 4, GREEN = 8 };

Color color = BLUE;

printer.print(color);

```



```bash

4

```



If you compile with

* Clang/LLVM >= 5

* Visual C++ >= 15.3 / Visual Studio >= 2017

* Xcode >= 10.2

* GCC >= 9



then pprint will print the name of the enum for you (thanks to [magic_enum](https://github.com/Neargye/magic_enum))



```cpp

enum Level { LOW, MEDIUM, HIGH };

Level current_level = MEDIUM;

std::cout << "Current level: ";

printer.print(current_level);

```



```bash

Current level: MEDIUM

```



## STL Sequence Containers



pprint supports a variety of STL sequence containers including ```std::vector```, ```std::list```, ```std::deque```, and ```std::array```. 



Here's an example pretty print of a simple 3x3 matrix:



```cpp

typedef std::array, 3> Mat3x3;

Mat3x3 matrix;

matrix[0] = {1, 2, 3};

matrix[1] = {4, 5, 6};

matrix[2] = {7, 8, 9};

printer.print("Matrix =", matrix);

```



```bash

Matrix = [

  [1, 2, 3], 

  [4, 5, 6], 

  [7, 8, 9]

]

```



### Compact Printing



pprint also supports compact printing of containers. Simply call ```printer.compact(true)``` to enable this:



```cpp

std::vector> foo {{{"a", 1}, {"b", 2}}, {{"c", 3}, {"d", 4}}};

printer.compact(true);

printer.print("Foo =", foo);

```



```bash

Foo = [{a : 1, b : 2}, {c : 3, d : 4}]

```



## STL Associative Containers



Support for associative containers includes pretty printing of ```std::map```, ```std::multimap```, ```std::unordered_map```, ```std::unordered_multimap```, ```std::set```, ```std::multiset```, ```std::unordered_set``` and , ```std::unordered_multiset``` 



```cpp

printer.print(std::map>{ 

    {"foo", {1, 2, 3, 3, 2, 1}}, {"bar", {7, 6, 5, 4}}});

```



```bash

{

  "bar" : {4, 5, 6, 7}, 

  "foo" : {1, 2, 3}

}

```



## STL Container Adaptors



pprint can print container adaptors including ```std::queue```, ```std::priority_queue``` and ```std::stack```. Here's an example print of a priority queue:



```cpp

std::priority_queue queue;

for(int n : {1,8,5,6,3,4,0,9,7,2}) queue.push(n);

printer.print(queue);

```



```bash

[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

```



## Fixed-size Heterogeneous Tuples



```cpp

auto get_student = [](int id) {

  if (id == 0) return std::make_tuple(3.8, 'A', "Lisa Simpson");

  if (id == 1) return std::make_tuple(2.9, 'C', "Milhouse Van Houten");

  if (id == 2) return std::make_tuple(1.7, 'D', "Ralph Wiggum");

  throw std::invalid_argument("id");

};

printer.print({ get_student(0), get_student(1), get_student(2) });

```



```bash

{(1.7, 'D', "Ralph Wiggum"), (2.9, 'C', "Milhouse Van Houten"), (3.8, 'A', "Lisa Simpson")}

```



## Type-safe Unions



```cpp

// Construct a vector of values

std::vector,		      

       std::map>, 

       std::pair>> var;

var.push_back(5);

var.push_back(nullptr);

var.push_back(3.14f);

var.push_back(std::string{"Hello World"});

var.push_back(std::vector{1, 2, 3, 4});

var.push_back(std::map>{{"a",{{"b",1}}}, {"c",{{"d",2}, {"e",3}}}});

var.push_back(true);

var.push_back(std::pair{1.1, 2.2});



// Print the vector

pprint::PrettyPrinter printer;

printer.indent(2);

printer.quotes(true);

printer.print(var);

```



```bash

[

  5, 

  nullptr,

  3.14f, 

  "Hello World", 

  [1, 2, 3, 4], 

  {"a" : {"b" : 1}, "c" : {"d" : 2, "e" : 3}}, 

  true, 

  (1.1, 2.2)

]

```



## Optional Values



```cpp

std::optional opt = 5;

std::optional opt2;



printer.print(opt);

printer.print(opt2);

```



```bash

5

nullopt

```



## Class Objects



pprint print class objects with or without an overloaded ```<<``` operator 



```cpp

class Foo {};

Foo foo;

printer.print(foo);

```



```



```



If an ```<<``` operator is available, pprint will use it to print your object:



```cpp

class Date {

  unsigned int month, day, year;

public:

  Date(unsigned int m, unsigned int d, unsigned int y) : month(m), day(d), year(y) {}

  friend std::ostream& operator<<(std::ostream& os, const Date& dt);

};



    

std::ostream& operator<<(std::ostream& os, const Date& dt) {

  os << dt.month << '/' << dt.day << '/' << dt.year;

  return os;

}

```



```cpp

Date date(04, 07, 2019);

printer.print("Today's date is", date);

```



```bash

Today's date is 4/7/2019

```



## User-defined types



Here's an example to print user-defined types. Let's say you want to print Mesh objects



```cpp

struct Vector3 {

  float x, y, z;

};



struct Mesh {

  std::vector vertices;

};

```



First, overload the ```<<``` operator for these structs:



```cpp

std::ostream& operator<<(std::ostream& os, const Vector3& v) {

  pprint::PrettyPrinter printer(os);

  printer.print_inline(std::make_tuple(v.x, v.y, v.z));

  return os;

}



std::ostream& operator<<(std::ostream& os, const Mesh& mesh) {

  pprint::PrettyPrinter printer(os);

  printer.print("Mesh {");

  printer.indent(2);

  printer.print_inline("vertices:", mesh.vertices);

  printer.print("}");

  return os;

}

```



then simply call ```printer.print(Mesh)```



```cpp

Mesh quads = {{

  {0, 0, 0}, {1, 0, 0}, {1, 1, 0}, {0, 0, 0}, {1, 1, 0}, {0, 1, 0},

  {0, 0, 1}, {1, 0, 1}, {1, 1, 1}, {0, 0, 1}, {1, 1, 1}, {0, 1, 1},

  }};



pprint::PrettyPrinter printer;

printer.print(quads);

```



```bash

Mesh {

  vertices: [

      (0, 0, 0), 

      (1, 0, 0), 

      (1, 1, 0), 

      (0, 0, 0), 

      (1, 1, 0), 

      (0, 1, 0), 

      (0, 0, 1), 

      (1, 0, 1), 

      (1, 1, 1), 

      (0, 0, 1), 

      (1, 1, 1), 

      (0, 1, 1)

  ]

}

```

## License

The project is available under the [MIT](https://opensource.org/licenses/MIT) license.