COMO: como object meta oriented

even.como

func isodd(num) {
	i = 0;
	odd = 0;
	while((i == num) == 0) {
		if(odd == 0) {
			odd = 1;
		} else {
			odd = 0;
		}
		i = i + 1;
	}
	return odd;
}

func print_even(num)
{
	while(num) {
		if(isodd(num)) {
			print(num + " is odd");
		} else {
			print(num + " is even");
		}
		num = num - 1;
	}
}

print_even(4);

range

func print_range(a, b) {
	while(a <= b) {
		print(a);
		a = a + 1;
	}
}

Build Requirements

I only compile this on UNIX like systems. You need the standard build tools such as autoconf, libtool, and flex and bison. Also there is a runtime requirement : libobject which you can get at https://github.com/libobject/libobject

License

Please see the file LICENSE located in the root directory of the project.

Virtual Machine

The compiler generates instructions of the custom instruction set (como_opcode.h) The virtual machine is stack based and only a few instructions take operands. Most instructions pop there arguments from the stack. Here is the relevant source code and instruction output generated from the compiler. This was run with the following command: ./como --print-asm test/for_loop

for(i = 5; i >= 0; i--)
{
  if(i % 2 == 0) {
    print(i);
  }
}

0       LABEL
1       LOAD_CONST 5
2       STORE_NAME i
3       LOAD_NAME i
4       LOAD_CONST 0
5       IS_GREATER_THAN_OR_EQUAL
6       JZ 25
7       LABEL
8       LOAD_NAME i
9       LOAD_CONST 2
10      IREM
11      LOAD_CONST 0
12      IS_EQUAL
13      JZ 17
14      LOAD_NAME i
15      IPRINT
16      JMP 18
17      LABEL
18      LABEL
19      POSTFIX_DEC
20      LOAD_NAME i
21      LOAD_CONST 0
22      IS_GREATER_THAN_OR_EQUAL
23      JZ 25
24      JMP 7
25      LABEL
26      HALT

Problems

• There is no continue, or break statements in loops at this time. The first idea that comes to mind to implement this is to have the executor keep track if the VM is in a loop and store the correct JMP address. This is on the roadmap for 2017