Calc++

UNFINISHED JUST FOR EXAMPLE

Simple turing complete interpreted programming language

Code is simply for demonstration, not finished. First version worked by interpreting text, new one will work from compiled bytecode (VM). Not finished yet, haven't worked on it for a while so might not work. I've added a somewhat restrictive license to make sure people are able to see the code but won't use it for any applications, just educational - I guess.

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

© 2020 Nicolas Ortiz

Written in C++

Current features:

• while loops while x < 5 { if x % 2 == 0 { print x; }; x = x + 1; };
• if statements: if x % 4 == 3 { print x; }; considers any value != 0 to be true and 0 to be false
• def statements: def name { ret 5; }; call name;
• ret from function ret x;
• print something print x;
• out exit with the program returning value out -1;
• call a function inside expression (argument is identifier of function)
• + - * / % <= >= < > operators with precedence
• '()' parenthesis: can have any expression inside it (duh)
• not function: makes any value != 0 -> 0 and value == 0 -> 1
• sqrt function: cause why not
• time constant: returns time since program start in nanoseconds
• if def while all use bodies enclosed in {}
• functions don't require parenthesis, but they're allowed as they are part of atom: ( expr )
• numeric literals: integers (currently long long type)
• type safety: only two types for now (num, func. ptr which can only be used to call functions)
• stack based architecture (only one stack for all variables and symbol table with reference to stack locations) also used for data from recursive descent
• compiler/interpreter runs from command line first argument is filename of program to run
• fast? (loops can run at less than 150 microseconds (1e-6) per iteration)

Todo:

• integrate parallelism (openmp? cuda -> for gpus?)
• input
• make stuff currently using {} to allow for single line statements as well
• encapsulate unsafe stuff better maybe actually use safer methods (check performance)
• memory management: allocation and freeing
• arbitrary precision integers (maybe with fixed point, no decimals to avoid non-precision of floating points)
• other data types (strings as arrays of integers)
• arrays (on stack, with first num being size, we already have type safety)
• function ptrs as data types
• pointers and references (with rust type safety)
• implement on virtual machine by compiling code into byte code maybe adapter (onto AST first) so we can write an actual x86-64 compiler later and optimizer (some things will be difficult however as we cannot see data but already used stack structure still applies I guess)
• YES, create ASTs, that's better probably!
• more abstraction (compiler class as parent, implementations describe actual grammar, generic expr stuff and unsafe stuff on parent)

Example code (also as files in release directory, capp is set to be opened by Calc++.exe in order to act as executables python-style):

Even nums.capp

i = 0;

while(i <= 30)
{
	if i % 2 == 0 {
		print i;
	};

	i = i + 1;
};

Powers of two.capp

i = 0;
x = 2;

while(i <= 30)
{
	print x;
	x = x * 2;
	i = i + 1;
};

Functions.capp

def add 
{
	x = 5 + 5 * 2;
	x = 0;
	
	if x == 0 { ret 55;}; 
	
	ret x + 1;
};

out (call add);