skeleton_function_node.hpp

// Copyright Take Vos 2020.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "skeleton_node.hpp"
 
namespace tt {
 
struct skeleton_function_node final: skeleton_node {
    std::string name;
    std::vector<std::string> argument_names;
    statement_vector children;
 
    formula_post_process_context::function_type super_function;
 
    skeleton_function_node(parse_location location, formula_post_process_context &context, std::unique_ptr<formula_node> function_declaration_expression) noexcept :
        skeleton_node(std::move(location))
    {
        auto name_and_arguments = function_declaration_expression->get_name_and_argument_names();
        tt_assert(name_and_arguments.size() >= 1);
 
        name = name_and_arguments[0];
        name_and_arguments.erase(name_and_arguments.begin());
        argument_names = std::move(name_and_arguments);
 
        super_function = context.set_function(name,
            [this,&location](formula_evaluation_context &context, datum::vector const &arguments) {
            try {
                return this->evaluate_call(context, arguments);
 
            } catch (std::exception const &e) {
                throw operation_error("{}: Failed during handling of function call.\n{}", location, e.what());
            }
        }
        );
    }
 
    bool append(std::unique_ptr<skeleton_node> x) noexcept override {
        append_child(children, std::move(x));
        return true;
    }
 
    void post_process(formula_post_process_context &context) override {
        if (std::ssize(children) > 0) {
            children.back()->left_align();
        }
 
        context.push_super(super_function);
        for (ttlet &child: children) {
            child->post_process(context);
        }
        context.pop_super();
    }
 
    datum evaluate(formula_evaluation_context &context) override {
        return {};
    }
 
    datum evaluate_call(formula_evaluation_context &context, datum::vector const &arguments) {
        context.push();
        if (std::ssize(argument_names) != std::ssize(arguments)) {
            throw operation_error("{}: Invalid number of arguments to function {}() expecting {} got {}.", location, name, argument_names.size(), arguments.size());
        }
 
        for (ssize_t i = 0; i != std::ssize(argument_names); ++i) {
            context.set(argument_names[i], arguments[i]);
        }
 
        ttlet output_size = context.output_size();
        auto tmp = evaluate_children(context, children);
        context.pop();
 
        if (tmp.is_break()) {
            throw operation_error("{}: Found #break not inside a loop statement.", location);
 
        } else if (tmp.is_continue()) {
            throw operation_error("{}: Found #continue not inside a loop statement.", location);
 
        } else if (tmp.is_undefined()) {
            return {};
 
        } else {
            // When a function returns, it should not have written data to the output.
            context.set_output_size(output_size);
            return tmp;
        }
    }
 
    std::string string() const noexcept override {
        std::string s = "<function ";
        s += name;
        s += "(";
        s += join(argument_names, ",");
        s += ")";
        s += join(transform<std::vector<std::string>>(children, [](auto &x) { return to_string(*x); }));
        s += ">";
        return s;
    }
};
 
}