Add vehicle graph core: .vhg loader, logic and cab blocks, -graph-run and -graph-catalog

vehicle/graph/graph_instance.h

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+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#pragma once
+
+#include "vehicle/graph/graph_block.h"
+#include "vehicle/graph/graph_template.h"
+
+#include <memory>
+#include <string_view>
+#include <vector>
+
+namespace vgraph
+{
+
+// simulation state of the graph of a single vehicle
+class graph_instance
+{
+public:
+	explicit graph_instance(std::shared_ptr<graph_template const> Template);
+
+	// advances the graph by the specified time. the order of evaluation is fixed, and there's no other source
+	// of time or randomness, so the same inputs always produce the same results
+	void update(double Deltatime);
+
+	graph_template const &definition() const
+	{
+		return *m_template;
+	}
+	double time() const
+	{
+		return m_time;
+	}
+
+	// block of the node with the specified index (see graph_template::nodes())
+	block &node_block(std::size_t Index)
+	{
+		return *m_blocks[Index];
+	}
+	block const &node_block(std::size_t Index) const
+	{
+		return *m_blocks[Index];
+	}
+	// block of the node with the specified id, or null
+	block *find_block(std::string_view Id);
+
+	double signal(int Slot) const
+	{
+		return m_signals[Slot];
+	}
+	// keeps the slot at the specified value regardless of what its block writes, until released
+	void force(int Slot, double Value);
+	void release(int Slot);
+	bool is_forced(int Slot) const
+	{
+		return m_forced[Slot] != 0;
+	}
+
+private:
+	frame make_frame(double Deltatime);
+
+	std::shared_ptr<graph_template const> m_template;
+	std::vector<std::unique_ptr<block>> m_blocks; // in the order of the template's nodes
+	std::vector<block *> m_order; // blocks in the order of evaluation
+	std::vector<block *> m_deferred; // blocks publishing their outputs after the step
+	std::vector<double> m_signals;
+	std::vector<std::uint8_t> m_forced;
+	std::vector<link_state> m_links;
+	double m_time{0.0};
+};
+
+} // namespace vgraph