view_adapter_base.hpp

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#pragma once
 
// ============================================================================
//  view_adapter_base.hpp
// ----------------------------------------------------------------------------
//  `ViewAdapterBase` — an opt-in base class for writing an `IViewAdapter`
//  without implementing all 25 pure virtuals.
//
//  Why
//  ---
//  `IViewAdapter` is a wide interface by design: text, bool, int, int64,
//  uint64, float, double each with `set_` / `get_` / `on_*_changed`, plus
//  `set_visible`, `set_enabled`, `on_click`, `platform_name`. That is the
//  right shape for the four shipped first-party adapters, which support most
//  of it — but it makes the floor for a *new* adapter 25 methods regardless
//  of ambition. An adapter that only drives labels and buttons still has to
//  write out every numeric channel by hand, and hand-roll its own
//  "unsupported" path for each one to satisfy contract L-39.
//
//  This base implements every operation as the compliant unsupported path
//  (warn once through the framework's diagnostics boundary, then return a
//  safe default), so an author overrides only what the platform genuinely
//  supports:
//
//      class MyAdapter final : public ViewAdapterBase {
//      public:
//          std::string_view platform_name() const noexcept override {
//              return "mytoolkit";      // still required — no sane default
//          }
//
//          void set_text(IView& v, std::string_view t) override { ... }
//          std::string get_text(IView& v) override { ... }
//          Subscription on_click(IView& v, std::function<void()> cb) override { ... }
//          // everything else: inherited, warns if a binding reaches it
//      };
//
//  `IViewAdapter` itself is unchanged — it is shipped and ABI-stable, and
//  the four first-party adapters continue to derive from it directly. This
//  base is purely additive.
//
//  Verifying an adapter
//  --------------------
//  The shared conformance battery is installed with the public headers, so a
//  third-party adapter can check itself against the same suite the built-in
//  ones run:
//
//      #include "aria/binding/testing/adapter_conformance.hpp"
//
//  See docs/cookbook/08-writing-a-view-adapter.md.
// ============================================================================
 
#include "aria/abi/export.hpp"
#include "aria/binding/view_adapter.hpp"
 
#include <cstdint>
#include <functional>
#include <string>
#include <string_view>
 
namespace aria::binding {

class ARIA_BINDING_API ViewAdapterBase : public IViewAdapter {
public:
    ~ViewAdapterBase() override;
 
    // ── Text ───────────────────────────────────────────────────────────
    void set_text(IView& v, std::string_view text) override;
    [[nodiscard]] std::string get_text(IView& v) override;
    Subscription on_text_changed(IView& v,
        std::function<void(std::string_view)> cb) override;
 
    // ── Bool ───────────────────────────────────────────────────────────
    void set_bool(IView& v, bool value) override;
    [[nodiscard]] bool get_bool(IView& v) override;
    Subscription on_bool_changed(IView& v,
        std::function<void(bool)> cb) override;
 
    // ── Int ────────────────────────────────────────────────────────────
    void set_int(IView& v, int value) override;
    [[nodiscard]] int get_int(IView& v) override;
    Subscription on_int_changed(IView& v,
        std::function<void(int)> cb) override;
 
    // ── Int64 ──────────────────────────────────────────────────────────
    void set_int64(IView& v, std::int64_t value) override;
    [[nodiscard]] std::int64_t get_int64(IView& v) override;
    Subscription on_int64_changed(IView& v,
        std::function<void(std::int64_t)> cb) override;
 
    // ── UInt64 ─────────────────────────────────────────────────────────
    void set_uint64(IView& v, std::uint64_t value) override;
    [[nodiscard]] std::uint64_t get_uint64(IView& v) override;
    Subscription on_uint64_changed(IView& v,
        std::function<void(std::uint64_t)> cb) override;
 
    // ── Float ──────────────────────────────────────────────────────────
    void set_float(IView& v, float value) override;
    [[nodiscard]] float get_float(IView& v) override;
    Subscription on_float_changed(IView& v,
        std::function<void(float)> cb) override;
 
    // ── Double ─────────────────────────────────────────────────────────
    void set_double(IView& v, double value) override;
    [[nodiscard]] double get_double(IView& v) override;
    Subscription on_double_changed(IView& v,
        std::function<void(double)> cb) override;
 
    // ── Visible / Enabled ──────────────────────────────────────────────
    void set_visible(IView& v, bool visible) override;
    void set_enabled(IView& v, bool enabled) override;
 
    // ── Click ──────────────────────────────────────────────────────────
    Subscription on_click(IView& v, std::function<void()> cb) override;
 
protected:
    virtual void report_unsupported(std::string_view op, const IView& v) const;
};
 
}  // namespace aria::binding