array_contract.cairo

%lang starknet

from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.starknet.common.syscalls import get_contract_address
from starkware.cairo.common.registers import get_fp_and_pc

struct BasicStruct {
    first_member: felt,
    second_member: felt,
}

@view
func view_product{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}(
    array_len: felt, array: BasicStruct*
) -> (res: felt) {
    alloc_locals;
    let fp_and_pc = get_fp_and_pc();
    tempvar __fp__ = fp_and_pc.fp_val;
    tempvar ptr = array;
    local dummy = 9;
    // This could be useful for debugging...
    tempvar val = [array];
    %{
        from rich.pretty import pprint
        from rich.console import Console
        from starkware.starknet.public.abi import starknet_keccak
        from starkware.cairo.lang.vm.crypto import pedersen_hash
        console = Console(markup=False, highlight=False)
        console.print("\nHey big boy look at me".upper(), style="bold underline #FFA500")
        console.print(f"Printing {ids.val.first_member=}", style="bold #FFA500") 
        console.print("Now that you reached this why do you try exotic stuff ...?", style="bold #FFA500")
        console.print("We're gonna mess with the memory now so brace yourself ", style="bold #FFA500")
        console.print("Print the last filled memory cell with memory[ap-1]", style="bold green") # should print 1
        console.print("This is the 2nd member of the struct element guess what would output memory[ap-2] ??", style="bold green") # should print 1
        console.print("Pretty cool huh? Now we're going to access a pointer's value", style="bold #FFA500")
        console.print("Lets access a local that relies on fp's value", style="bold #FFA500")
        console.print("try memory[memory[fp+1]]", style="bold green") # should print array_len
        console.print("if you don't understand why it works like this you might want to read this https://www.cairo-lang.org/docs/how_cairo_works/consts.html#local-variables", style="bold green")
        breakpoint()
    %}
    let (res) = array_product(array_len, array);
    let (add) = get_contract_address();
    return (res + add,);
}

func array_product{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}(
    array_len: felt, array: BasicStruct*
) -> (res: felt) {
    if (array_len == 0) {
        return (0,);
    }
    let temp = [array].first_member * [array].second_member;
    let (temp2) = array_product(array_len - 1, array);
    let res = temp * temp2;
    return (res,);
}