rpn/src/rpn-program.hpp

//
bool find_variable(string& variable, object*& obj, unsigned int& size)
{
    bool found = false;
    program* parent = _parent_prog;

    // find variable in local heap, parens heaps, global heap
    if (_local_heap.get(variable, obj, size))
        found = true;
    else
    {
        while(parent != NULL)
        {
            if (parent->_local_heap.get(variable, obj, size))
            {
                found = true;
                break;
            }
            parent = parent->_parent_prog;
        }
        if (!found)
        {
            if (_heap->get(variable, obj, size))
                found = true;
        }
    }
    
    return found;
}

void eval(void)
{
    bool run_prog = false;
    string prog_text;

    MIN_ARGUMENTS(1);
    if (IS_ARG_TYPE(0, cmd_symbol))
    {
        // recall a variable
        object* obj;
        unsigned int size;
        string variable(((symbol*)_stack->back())->_value);
        
        // if variable holds a program, run this program
        if (find_variable(variable, obj, size))
        {
            if (obj->_type == cmd_program)
            {
                prog_text = ((oprogram*)obj)->_value;
                (void)_stack->pop_back();
                run_prog = true;
            }
            else
            {
                // else recall this variable (i.e. stack its content)
                (void)_stack->pop_back();
                stack::copy_and_push_back(obj, *_stack, size);
            }
        }
        else
            ERR_CONTEXT(ret_unknown_variable);
    }
    else if (IS_ARG_TYPE(0, cmd_program))
    {
        // eval a program
        prog_text = ((oprogram*)_stack->pop_back())->_value;
        run_prog = true;
    }
    else
        ERR_CONTEXT(ret_bad_operand_type);

    // run prog if any
    if (run_prog)
    {
        program prog(this);

        // make program from entry
        if (program::parse(prog_text.c_str(), prog) == ret_ok)
        {
            // run it
            prog.run(*_stack, *_heap, &_local_heap);
        }
    }
}

// carefull, this not a command but a branch
int inprog(branch& myobj)
{
    string context("->");// for showing errors
    int count_symbols = 0;
    bool prog_found = false;

    if (myobj.arg1 == -1)
    {
        ERR_CONTEXT(ret_unknown_err);
        return -1;
    }

    // syntax must be
    // -> <auto evaluated symbol #1> ... <auto evaluated symbol #n> <oprogram>

    // find next oprogram object
    for (unsigned int i = myobj.arg1 + 1; i < size(); i++)
    {
        // count symbol
        if (seq_type(i) == cmd_symbol)
            count_symbols++;
        // stop if prog
        else if (seq_type(i) == cmd_program)
        {
            prog_found = true;
            break;
        }
        // found something other than symbol
        else
        {
            ERR_CONTEXT(ret_bad_operand_type);
            show_error(_err, context);
            return -1;
        }
    }

    // found 0 symbols
    if (count_symbols == 0)
    {
        ERR_CONTEXT(ret_syntax);
        show_error(_err, context);
        return -1;
    }

    // <oprogram> is missing
    if (! prog_found)
    {
        ERR_CONTEXT(ret_syntax);
        show_error(_err, context);
        return -1;
    }

    // check symbols number vs stack size
    if (stack_size() < count_symbols)
    {
        ERR_CONTEXT(ret_missing_operand);
        show_error(_err, context);
        return -1;
    }

    // load variables
    heap local_heap;
    for (unsigned int i = myobj.arg1 + count_symbols; i > myobj.arg1; i--)
    {
        local_heap.add(string(((symbol*)seq_obj(i))->_value), _stack->get_obj(0), _stack->get_len(0));
        (void)_stack->pop_back();
    }

    // run the program
    string entry(((oprogram*)seq_obj(myobj.arg1 + count_symbols + 1))->_value);
    program prog;

    // make the program from entry
    if (program::parse(entry.c_str(), prog) == ret_ok)
    {
        // run it
        prog.run(*_stack, *_heap, &local_heap);
    }

    // point on next command
    return myobj.arg1 + count_symbols + 2;
}