parsing function calls as expressions using boost spirit x3

Question

I am currently developing a DSL using boost spirit X3. I am using this example, to implementing expressions and the operator hierachy, and avoiding left recursion in the expression parsers. I also would like to implement a .-operator for member accesses, the []-operator for index accesses for example for arrays, and since the DSL will be a functional language, I would like to implement function calls, the ()-operator, also as an operator, since every expression could return a function, the ()-operator should be applyable on any other expression. The sturcts, I want to parse in look like this:

enum class operator_t {
    _eq_,       // ==
    _ne_,       // !=
   ...
    _idx_,      // []
    _apply_,    // ()
    _access_    // .
};

typedef x3::variant<
        nil,
        std::string,
        NumberLiteral,
        x3::forward_ast<Unary>,
        x3::forward_ast<Expression>,
> Operand;

struct Unary {
    operator_t operator_;
    Operand operand_;
};

struct Operation {
    operator_t operator_;
    Operand operand_;
};

struct Expression {
    Operand first_;
    std::vector<Operation> rest_;
};

I was able to create parsers for the []-operator and the .-operator, using the following rules(have a look at the mcve in the EDIT):

typedef x3::rule<struct primary_expr_class, ast::Operand> primary_expr_type;
typedef x3::rule<struct index_access_expr_class, ast::Expression> index_access_expr_type;
typedef x3::rule<struct data_access_expr_class, ast::Expression> data_access_expr_type;

auto const index_access_expr_def =
        primary_expr >> *(helper::idxaccess_op > expression > "]");

auto const data_access_expr_def =
        index_access_expr >> *(helper::access_op > index_access_expr);

now I am trying to do the same for function calls, but I wasnt able to do this, also index_access_expr and data_access_expr doesnt have the precedence, how can I make these two rules haveing the precedence and how can I implement function calls as operator expressions, also with the same precedence?

EDIT: here is a mcve on how I did it with index_access_expr and data_access_expr. To this example I would like to add the ()-operator, and I would like to have the three operators the same precedence.

EDIT II: here is another mcve, on how I tired to implement the function calls as expressions, but like you can see in the example it doesnt work at all. My approach was to add std::vector<Expression> to the Operand variant and then tried to add the function call parser like this:

 auto const func_call_expr_def =
        data_access_expr >> *(func_call_op > (expression % ",") > ")");

This doest work at all, have a look at my tests in the main, also to operator hierachy problem still exists.

parsing function calls as expressions using boost spirit x3

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