chore: import upstream snapshot with attribution

modules/gapi/src/api/gcall.cpp

@@ -0,0 +1,95 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+//
+// Copyright (C) 2018 Intel Corporation
+
+
+#include "precomp.hpp"
+#include <cassert>
+#include <opencv2/gapi/gcall.hpp>
+#include "api/gcall_priv.hpp"
+
+// GCall private implementation ////////////////////////////////////////////////
+cv::GCall::Priv::Priv(const cv::GKernel &k)
+    : m_k(k)
+{
+}
+
+// GCall public implementation /////////////////////////////////////////////////
+
+cv::GCall::GCall(const cv::GKernel &k)
+    : m_priv(new Priv(k))
+{
+    // Here we have a reference to GNode,
+    // and GNode has a reference to us. Cycle! Now see destructor.
+    m_priv->m_node = GNode::Call(*this);
+}
+
+cv::GCall::~GCall()
+{
+    // FIXME: current behavior of the destructor can cause troubles in a threaded environment. GCall
+    // is not supposed to be accessed for modification within multiple threads. There should be a
+    // way to ensure somehow that no problem occurs in future. For now, this is a reminder that
+    // GCall is not supposed to be copied inside a code block that is executed in parallel.
+
+    // When a GCall object is destroyed (and GCall::Priv is likely still alive,
+    // as there might be other references), reset m_node to break cycle.
+    m_priv->m_node = GNode();
+}
+
+void cv::GCall::setArgs(std::vector<GArg> &&args)
+{
+    // FIXME: Check if argument number is matching kernel prototype
+    m_priv->m_args = std::move(args);
+}
+
+cv::GMat cv::GCall::yield(int output)
+{
+    return cv::GMat(m_priv->m_node, output);
+}
+
+cv::GMatP cv::GCall::yieldP(int output)
+{
+    return cv::GMatP(m_priv->m_node, output);
+}
+
+cv::GScalar cv::GCall::yieldScalar(int output)
+{
+    return cv::GScalar(m_priv->m_node, output);
+}
+
+cv::detail::GArrayU cv::GCall::yieldArray(int output)
+{
+    return cv::detail::GArrayU(m_priv->m_node, output);
+}
+
+cv::detail::GOpaqueU cv::GCall::yieldOpaque(int output)
+{
+    return cv::detail::GOpaqueU(m_priv->m_node, output);
+}
+
+cv::GFrame cv::GCall::yieldFrame(int output)
+{
+    return cv::GFrame(m_priv->m_node, output);
+}
+
+cv::GCall::Priv& cv::GCall::priv()
+{
+    return *m_priv;
+}
+
+const cv::GCall::Priv& cv::GCall::priv() const
+{
+    return *m_priv;
+}
+
+cv::GKernel& cv::GCall::kernel()
+{
+    return m_priv->m_k;
+}
+
+cv::util::any& cv::GCall::params()
+{
+    return m_priv->m_params;
+}