<p align="center">
<img height="90" src="https://user-images.githubusercontent.com/8450091/123720914-cb9a5200-d84a-11eb-97d9-830776297b87.PNG"/>
</p>
`Box` is a text-based visual programming language inspired by Unreal Engine blueprint function graphs.
```console
$ cat factorial.box
┌─ƒ(Factorial)───┐ ┌─[Branch]─────┐ ┌─[Set]─┐
│ ►┼─────────────────────┼► True ►┼───────────────────────┼► ►┼─────────┐ ┌─[For Loop]───────────┐ ┌───────┐
│ n ○┼──┐ ┌──┼○ False ►┼──┐ ┌──────────┐ ┌───┼○ │ └─────────┼► Loop body ►┼───────────────────┼► │
└────────────────┘ │ ┌────────┐ │ │ │ │ │ result ○┼──┘ ┌─┼○ │ │ │ ┌──────────┐ ┌────┼○ *= │
┌────┐ └────┼○ >= ○┼─┘ └──────────────┘ │ └──────────┘ │ └───────┘ ┌────┐ │ │ │ result ○┼─┘ ┌─┼○ │
│ 1 ○┼───────┼○ │ │ ┌────┐ │ │ 1 ○┼────┼○ start │ └──────────┘ │ └───────┘
└────┘ └────────┘ │ │ 1 ○┼─────┘ └────┘ │ │ │
│ └────┘ │ index ○┼─────────────────┘
│ ┌────┐ │ │
│ │ n ○┼─┐ ┌───────┐ │ │
│ └────┘ └──┼○ + │ │ │
│ ┌────┐ ┌──┼○ ○┼─────┼○ end │
│ │ 1 ○┼─┘ └───────┘ │ │
│ └────┘ │ │
│ ┌────┐ │ │
│ ┌─[Return]─┐ │ 1 ○┼────┼○ step │
┌────┐ └───┼► │ └────┘ │ Completed ►┼────┐
│ 1 ○┼─────┼○ │ └──────────────────────┘ │ ┌─[Return]─┐
└────┘ └──────────┘ ┌─────────┐ └──┼► │
│ result ○┼──────┼○ │
└─────────┘ └──────────┘
$ box factorial.box -e 5
120
$ box factorial.box -e 5
87178291200
$ box factorial.box -o factorial.py
$ cat factorial.py
def Factorial(n):
if (n >= 1):
result = 1
for index_8b6ee4f2 in range(1, (n + 1), 1):
result *= index_8b6ee4f2
return result
else:
return 1
```
### Getting Started
Install the box interpreter with `pip`
```console
pip3 install boxlang
```
Now open your text editor and start drawing your program! Check out existing samples [here](https://github.com/p-ranav/box/tree/main/samples).
### Anatomy of a Box
A Box has 2 types of ports: control flow ports (`─►┼─`) and data flow ports (`─○┼─`). These ports can additionally be classified as input or output ports. All ports to the left side of a box are input ports and all ports on the right side of the box are output ports.
Below, you can see a `[For Loop]` box which is a special type of box that the interpreter can parse - It has 1 input control flow port, 3 input data flow ports (start, end, and step), 2 output control flow ports (the loop body and completed control flows), and 1 output data flow port (the index)
![image](https://user-images.githubusercontent.com/8450091/124202730-a69f1c80-daa0-11eb-8cd8-55a8447dc224.png)
### Function Graphs
`Box` programs are function graphs. Functions have a single entry point designated by a node with the name of the Function containing a single output control flow port.
Here's a simple hello world example. This example declares a `Greet()` function that prints the string "Hello, World!" to the console. It calls the built-in print function.
![image](https://user-images.githubusercontent.com/8450091/124202751-b28ade80-daa0-11eb-8be6-6d5157eed822.png)
Execute the above program with the box interpreter like so:
```console
$ box samples/hello_world.box -e
Hello,World!
```
### Features
* ✅ Function declarations
* ✅ Defining constants and variables
* ✅ Operators - Unary, binary, and assignment operators
* ✅ `[Set]` - set the value of variables
* ✅ Function calls - Call Python built-in functions
* ✅ `[Branch]` - if-else box
* ✅ `[For Loop]` - Python-style for loop with (start,end,step)
* ✅ `[While Loop]` - Python-style while loop
* ✅ `[For Each]` for iterables
* ✅ `[Break]` and `[Continue]` boxes
* ✅ `[Return]` box to return values from functions
### Gotchas
* The interpreter will likely fail if you have tabs in your file - replace all tabs with the appropriate number of spaces
* There are a number of UNICODE character you'll need for this to work - Just look through the samples and COPY-PASTE (no, seriously)
## Contributing
Contributions are welcome, have a look at the [CONTRIBUTING.md](CONTRIBUTING.md) document for more information.
## License
The project is available under the [MIT](https://opensource.org/licenses/MIT) license.