scriny 0.4.0

A tiny scripting language for Dart. Also supports evaluating simple math expressions.

Scriny is a tiny scripting language for Dart (it's actually the concatenation of "script" and "tiny").

Features

• Evaluates simple mathematical expressions.
• Supports variables of type string, number, boolean, list, map, and null.
• Includes control structures (if, else, for, while, etc.).
• Allows custom top-level functions and variables.
• Easy to use and integrate.

Scriny is already used in two of my projects :

• Mathonaut, for parsing and evaluating mathematical expressions.
• Révise tes maths !, for a similar purpose.

Getting Started

Add Scriny to your project by following the instructions here.

Usage

Code

All the code examples below can be parsed using ScrinyParser.parseProgram and executed using run().

Mathematical expressions

This evaluates to 9 :

(2 + 1) * 3

This evaluates to 8 :

2^3

This evaluates to true :

2 == (1 + 1)

Note

To negate a boolean, use the classic !. You can also use != instead of ==.

This evaluates to Dart’s math.e :

exp(1)

Note

You can find all available built-in functions here. We'll see how to add custom functions later.

Variables

This returns 8 :

a = 10;
b = -2;
return a + b;

This throws an error :

a = 10;
b = -2;
delete a;
return a + b;

This returns "Hello world !" :

list = ["Hello"];
map = {"w": "world"};
return list[0] + " " + map["w"] + " !";

Control statements

This evaluates to 1 :

if (true) {
  return 1;
} else {
  return 2;
}

This prints 0 to 9 and returns null :

for (i in range(10)) {
  print(i);
}

Note

If you don't return a value in your script, then null is returned. This is not the case for simple expressions (eg. 1 + 1 returns 2 once evaluated).

This returns 1998 :

n = 0;
while (true) {
  n = n + 1;
  if (n == 1998) {
    break;
  }
}
return n;

This returns [2, 4] :

list = [];
list = list + [1, 2, 3];
delete list[0];
list[1] = 4;
return list;

Custom top-level variables and functions

Adding custom top-level constants, variables and functions to Scriny is straightforward. All you have to do is to provide a custom EvaluationContext to ScrinyParser.parseProgram.

Check out the example on pub.dev, and see the EvaluationContext class documentation for more information.

Interpreter

Scriny comes with a built-in interpreter ! If you have a Scriny script file, you can run it with :

dart run scriny --file=<path>

If your script consists of a single line, you can run it with :

dart run scriny --code="<your_code>"

License

This project is licensed under the MIT License.

Contributions

There are many ways you can contribute to this project :

• Fork it on GitHub.
• Submit an issue for a feature request or bug report.
• Donate to support the developer.