text_field_delegate.hpp

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// Copyright Take Vos 2021-2022.
// 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 "../l10n/l10n.hpp"
#include "../observer/module.hpp"
#include "../macros.hpp"
#include <string>
#include <string_view>
#include <optional>
#include <concepts>
 
namespace hi { inline namespace v1 {
class text_field_widget;
 
class text_field_delegate {
public:
    using notifier_type = notifier<>;
    using callback_token = notifier_type::callback_token;
    using callback_proto = notifier_type::callback_proto;
 
    virtual ~text_field_delegate() = default;
    virtual void init(text_field_widget const& sender) noexcept {}
    virtual void deinit(text_field_widget const& sender) noexcept {}
 
    virtual label validate(text_field_widget& sender, gstring const &text) noexcept
    {
        return {};
    }
 
    virtual gstring text(text_field_widget& sender) noexcept
    {
        return {};
    }
 
    virtual void set_text(text_field_widget& sender, gstring const &text) noexcept {}
 
    callback_token
    subscribe(forward_of<callback_proto> auto&& callback, callback_flags flags = callback_flags::synchronous) noexcept
    {
        return _notifier.subscribe(hi_forward(callback), flags);
    }
 
protected:
    notifier_type _notifier;
};
 
template<typename T>
class default_text_field_delegate;
 
template<std::integral T>
class default_text_field_delegate<T> : public text_field_delegate {
public:
    using value_type = T;
 
    observer<value_type> value;
 
    default_text_field_delegate(forward_of<observer<value_type>> auto&& value) noexcept : value(hi_forward(value))
    {
        _value_cbt = this->value.subscribe([&](auto...) {
            this->_notifier();
        });
    }
 
    std::optional<label> validate(text_field_widget& sender, gstring const &text) noexcept override
    {
        try {
            [[maybe_unused]] auto dummy = from_string<value_type>(to_string(text), 10);
        } catch (parse_error const&) {
            return {txt("Invalid integer")};
        }
 
        return {};
    }
 
    gstring text(text_field_widget& sender) noexcept override
    {
        return to_gstring(to_string(*value));
    }
 
    void set_text(text_field_widget& sender, gstring text) noexcept override
    {
        try {
            value = from_string<value_type>(to_string(text), 10);
        } catch (std::exception const&) {
            // Ignore the error, don't modify the value.
            return;
        }
    }
 
private:
    typename decltype(value)::callback_token _value_cbt;
};
 
template<std::floating_point T>
class default_text_field_delegate<T> : public text_field_delegate {
public:
    using value_type = T;
 
    observer<value_type> value;
 
    default_text_field_delegate(forward_of<observer<value_type>> auto&& value) noexcept : value(hi_forward(value))
    {
        _value_cbt = this->value.subscribe([&](auto...) {
            this->_notifier();
        });
    }
 
    label validate(text_field_widget& sender, gstring const &text) noexcept override
    {
        try {
            [[maybe_unused]] auto dummy = from_string<value_type>(to_string(text));
        } catch (parse_error const&) {
            return {elusive_icon::WarningSign, txt("Invalid floating point number")};
        }
 
        return {};
    }
 
    gstring text(text_field_widget& sender) noexcept override
    {
        return to_gstring(to_string(*value));
    }
 
    void set_text(text_field_widget& sender, gstring const &text) noexcept override
    {
        try {
            value = from_string<value_type>(to_string(text));
        } catch (std::exception const&) {
            // Ignore the error, don't modify the value.
            return;
        }
    }
 
private:
    typename decltype(value)::callback_token _value_cbt;
};
 
[[nodiscard]] std::shared_ptr<text_field_delegate> make_default_text_field_delegate(auto&& value) noexcept requires requires
{
    default_text_field_delegate<observer_decay_t<decltype(value)>>{hi_forward(value)};
}
{
    using value_type = observer_decay_t<decltype(value)>;
    return std::make_shared<default_text_field_delegate<value_type>>(hi_forward(value));
}
 
}} // namespace hi::v1