text_delegate.hpp

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// Copyright Take Vos 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 "../observer/observer.hpp"
#include "../utility/utility.hpp"
#include "../concurrency/concurrency.hpp"
#include "../dispatch/dispatch.hpp"
#include "../GUI/GUI.hpp"
#include "../macros.hpp"
#include "../unicode/unicode.hpp"
#include "../l10n/l10n.hpp"
#include "../macros.hpp"
#include <string>
#include <memory>
#include <functional>
 
hi_export_module(hikogui.widgets.text_delegate);
 
hi_export namespace hi { inline namespace v1 {
class text_widget;
 
struct text_delegate {
public:
    virtual ~text_delegate() = default;
 
    virtual void init(widget_intf const& sender) noexcept {}
    virtual void deinit(widget_intf const& sender) noexcept {}
 
    [[nodiscard]] virtual gstring get_text(widget_intf const& sender) noexcept = 0;
    [[nodiscard]] virtual void set_text(widget_intf const& sender, gstring const& text) noexcept = 0;
    [[nodiscard]] virtual bool can_set_text(widget_intf const& sender) noexcept = 0;
 
 
    [[nodiscard]] virtual gstring read(widget_intf const& sender) noexcept = 0;
 
    virtual void write(widget_intf const& sender, gstring const& text) noexcept = 0;
 
protected:
    notifier<void()> _notifier;
};
 
template<typename T>
class default_text_delegate;
 
template<>
class default_text_delegate<char const *> : public text_delegate {
public:
    using value_type = char const *;
 
    observer<value_type> value;
 
    template<forward_of<observer<value_type>> Value>
    explicit default_text_delegate(Value&& value) noexcept : value(std::forward<Value>(value))
    {
        _value_cbt = this->value.subscribe([&](auto...) {
            this->_notifier();
        });
    }
 
    [[nodiscard]] gstring read(widget_intf const& sender) noexcept override
    {
        return to_gstring(std::string{*value});
    }
 
    void write(widget_intf const& sender, gstring const& text) noexcept override
    {
        hi_no_default();
    }
 
private:
    callback<void(value_type)> _value_cbt;
};
 
template<>
class default_text_delegate<std::string> : public text_delegate {
public:
    using value_type = std::string;
 
    observer<value_type> value;
 
    template<forward_of<observer<value_type>> Value>
    explicit default_text_delegate(Value&& value) noexcept : value(std::forward<Value>(value))
    {
        _value_cbt = this->value.subscribe([&](auto...) {
            this->_notifier();
        });
    }
 
    [[nodiscard]] gstring read(widget_intf const& sender) noexcept override
    {
        return to_gstring(*value);
    }
 
    void write(widget_intf const& sender, gstring const& text) noexcept override
    {
        value = to_string(text);
    }
 
private:
    callback<void(value_type)> _value_cbt;
};
 
template<>
class default_text_delegate<gstring> : public text_delegate {
public:
    using value_type = gstring;
 
    observer<value_type> value;
 
    template<forward_of<observer<value_type>> Value>
    explicit default_text_delegate(Value&& value) noexcept : value(std::forward<Value>(value))
    {
        _value_cbt = this->value.subscribe([&](auto...) {
            this->_notifier();
        });
    }
 
    [[nodiscard]] gstring read(widget_intf const& sender) noexcept override
    {
        return *value;
    }
 
    void write(widget_intf const& sender, gstring const& text) noexcept override
    {
        value = text;
    }
 
private:
    callback<void(value_type)> _value_cbt;
};
 
template<>
class default_text_delegate<txt> : public text_delegate {
public:
    using value_type = txt;
 
    observer<value_type> value;
 
    template<forward_of<observer<value_type>> Value>
    explicit default_text_delegate(Value&& value) noexcept : value(std::forward<Value>(value))
    {
        _value_cbt = this->value.subscribe([&](auto...) {
            this->_notifier();
        });
    }
 
    [[nodiscard]] gstring read(widget_intf const& sender) noexcept override
    {
        return value->translate();
    }
 
    void write(widget_intf const& sender, gstring const& text) noexcept override
    {
        hi_no_default();
    }
 
private:
    callback<void(value_type)> _value_cbt;
};
 
template<typename Value>
std::shared_ptr<text_delegate> make_default_text_delegate(Value&& value) noexcept
    requires requires { default_text_delegate<observer_decay_t<Value>>{std::forward<Value>(value)}; }
{
    return std::make_shared<default_text_delegate<observer_decay_t<Value>>>(std::forward<Value>(value));
}
 
}} // namespace hi::v1