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engines/stark/tools/block.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef STARK_TOOLS_BLOCK_H
+#define STARK_TOOLS_BLOCK_H
+
+#include "common/array.h"
+
+namespace Stark {
+namespace Tools {
+
+class CFGCommand;
+struct ControlStructure;
+
+/**
+ * An aggregate of script commands
+ *
+ * Commands in the same group are always executed in sequence.
+ *
+ * This class is a node in the disassembly node graph.
+ */
+class Block {
+public:
+	Block();
+
+	/** Add a command at the end of the block, and set it as the command's block */
+	void appendCommand(CFGCommand *command);
+
+	/** Get the commands from the block that are not part of a condition */
+	Common::Array<CFGCommand *> getLinearCommands() const;
+
+	/** Get the command from the block that plays as a condition in a control structure */
+	CFGCommand *getConditionCommand() const;
+
+	/** Does the block contain commands? */
+	bool isEmpty() const;
+
+	/** Can the block branch? */
+	bool isCondition() const;
+
+	/**
+	 * Blocks are linked together in the block graph with these relationships:
+	 * - follower: The natural follower of the block. Used when the block is not a branch, nor an end point.
+	 * - true branch: The next block when the block's condition evaluates to true.
+	 * - false branch: The next block when the block's condition evaluates to false.
+	 * - predecessors: A list of blocks whose execution can lead to this block.
+	 */
+	void setBranches(Block *trueBranch, Block *falseBranch);
+	void setFollower(Block *follower);
+	void addPredecessor(Block *predecessor);
+	Block *getTrueBranch() const;
+	Block *getFalseBranch() const;
+	Block *getFollower() const;
+
+	/**
+	 * Print a list of this block's commands to the debug output
+	 */
+	void print() const;
+
+	/**
+	 * The high level control structure this block has the main role in
+	 */
+	bool hasControlStructure() const;
+	ControlStructure *getControlStructure() const;
+	void setControlStructure(ControlStructure *controlStructure);
+
+	/** Flag to indicate this block is the first in an unconditional infinite loop */
+	bool isInfiniteLoopStart() const;
+	void setInfiniteLoopStart(bool infiniteLoopStart);
+
+	/** Can this block appear multiple times in the decompiled output? */
+	bool allowDuplication() const;
+
+	// Graph query methods
+	bool hasPredecessor(Block *predecessor) const;
+	bool hasSuccessor(Block *successor) const;
+	Block *findMergePoint(Block *other);
+	bool checkAllBranchesConverge(Block *junction) const;
+
+private:
+	bool hasPredecessorIntern(Common::Array<const Block *> &visited, Block *predecessor) const;
+	bool hasSuccessorIntern(Common::Array<const Block *> &visited, Block *successor) const;
+	bool hasChildSuccessorIntern(Common::Array<const Block *> &visited, Block *child, Block *successor) const;
+	Block *findMergePointIntern(Common::Array<const Block *> &visited, Block *other);
+	Block *findChildMergePoint(Common::Array<const Block *> &visited, Block *child, Block *other) const;
+	bool checkAllBranchesConvergeIntern(Common::Array<const Block *> &visited, Block *junction) const;
+	bool checkChildConvergeIntern(Common::Array<const Block *> &visited, Block *child, Block *junction) const;
+
+	uint16 getFirstCommandIndex() const;
+
+	Common::Array<CFGCommand *> _commands;
+
+	Block *_follower;
+	Block *_trueBranch;
+	Block *_falseBranch;
+	Common::Array<Block *> _predecessors;
+
+	ControlStructure *_controlStructure;
+	bool _infiniteLoopStart;
+};
+
+struct ControlStructure {
+	enum ControlStructureType {
+		kTypeIf,
+		kTypeWhile
+	};
+
+	ControlStructureType type;
+	Block *condition;
+	bool invertedCondition;
+	Block *loopHead;
+	Block *thenHead;
+	Block *elseHead;
+	Block *next;
+
+	ControlStructure(ControlStructureType t);
+};
+
+} // End of namespace Tools
+} // End of namespace Stark
+
+#endif // STARK_TOOLS_BLOCK_H