apiel / dustscript

DustScript

DustScript is ultra minimalistic scripting language. Minimalistic as it is only few hundred lines of code, not even 1000 lines. Therefor the feature are limited to if statement, loop, variables and mathematical calculation.

The syntax is also simplified to make it easy to parse:

someAction: some parameters, 1 + 2, should be equal to 3
  anotherAction: indented with 2 spaces

# define a variable
$width=100

print: this should print a variable $width

if: $width < 100
  print: this should not be printed as $width is not inferior to 100

if: $width > 50
  print: this should be printed as $width is superior to 50

$i=0
while: $i < 5
  print: This is a loop at index position $i
  $i=$i + 1

print: (10 + sqr(2) - 1 + 4 / 2) should be equal to 15

# comments commented line start with a dash sign. Only a full line can be commented. It is not possible to comment the end of a command.

command: parameters the value before the colon is the command, the values after is/are the parameter(s). Parameter(s) is a simple string value that is not processed by dustscript, only variable and math calculation are applied to it. if and while are reserved command name.

$var=1 if a line start with dollar sign $ it will assign a variable. The variable are all global, so even if they are indented, they will stay global. A variable can be used in a command parameter or in a variable assignement.

For the if and while statement, indentation matter. Spaces are use for indention, tab will not work. A code block will be defined by his indentation (similar to python).

if statement take 3 parameters where the second parameter is the operator to compare parameter 1 and 3. The available operators are == (equal), != (not equal), > (superior), < (inferior), >= (superior or equal), <= (inferior or equal). There if no elseif or else statement.

while will loop till the condition is true. The condtion work in the same way as the if statement.

include: filename.dust will include another script and instanciate it.

Mathematical operation are supported. The following operators are supported: +, -, *, /, %, ^. It does also support basic math function, e.g. sqr(2) will result to 4. The following math function are supported: sin, cos, tan, asin, acos, atan, sinh, cosh, tanh, asinh, acosh, atanh, ln (for log), log (for log10), sqrt, sqr (for square value), round, floor, ceil, abs. All mathematical operation are return as double and all trailing zero will be removed. To evaluate a math expression within a string it must be surrounded by parentheses, e.g. print: this (1+2) should be equal to 3, in this example (1+2) will be evaluated as math expression.

To get styling for .dust extension in VScode, use Ctrl + Shift + P and type Change Language Mode. Then select Configure File Association for '.dust'... and select CoffeeScript or JavaScript (the color seem to work pretty well).

To use DustScript in your application, just include dustscript.h.

As example, see dustscript.cpp.

#include <stdio.h>
#include "dustscript.h"

void scriptCallback(char *command, char* params, const char *filename, uint16_t indentation)
{
    // callback function to bind custom function and params
}

int main()
{
    DustScript::load("demo.dust", scriptCallback);
    return 0;
}

Simply call DustScript::load with the script path as first parameter and the callback function as second parameter. The callback function is used to bind custom function. For example, to print out the first parameter with the command print do:

void scriptCallback(char *command, char* params, const char *filename, uint16_t indentation)
{
    if (strcmp(command, "print") == 0)
    {
        printf(">> LOG: %s\n", params);
    }
}

DustScript can run multiple instance to have a separate stack for the variables, instead to call the static method DustScript::load, create a new DustScript object new DustScript and call the method dustScript.run("demo.dust", scriptCallback):

#include <stdio.h>
#include "dustscript.h"

void scriptCallback(char *command, char* params, const char *filename, uint16_t indentation)
{
    // callback function to bind custom function and params
}

int main()
{
    DustScript dust1 = new DustScript;
    DustScript dust2 = new DustScript;
    dust1.run("demo.dust", scriptCallback);
    dust2.run("demo2.dust", scriptCallback);
    return 0;
}

That's it!

MathParser

The math parser is used by DustScript to parse mathematical operations. However it could be use alone to parse mathematical string operation. To use it, include mathParser.h and call MathParser::eval:

#include "mathParser.h"

int main()
{
    double val = MathParser::eval("10 + sqr(2) - 1 + 4 / 2");
    // do something with the result...
    return 0;
}