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engines/mutationofjb/commands/ifcommand.cpp

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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/>.
+ *
+ */
+
+#include "mutationofjb/commands/ifcommand.h"
+#include "mutationofjb/gamedata.h"
+#include "mutationofjb/script.h"
+#include "common/str.h"
+
+/** @file
+ * "IF" <tag> <sceneId> <objectId> <value> ["!"]
+ *
+ * IF command compares the value of the WX pseudo-register of the object in the specified scene.
+ * If the values match, execution continues to the next line.
+ * Otherwise execution continues after first "#ELSE" or "=ELSE" with the same <tag>.
+ * The logic can be reversed with exclamation mark at the end.
+ *
+ * <tag> is always 1 character long, <sceneId> and <objectId> 2 characters long.
+ *
+ * Please note that this does not work like you are used to from saner languages.
+ * IF does not have any blocks. It only searches for first #ELSE, so you can have stuff like:
+ *   IF something
+ *   IF something else
+ *   #ELSE
+ *   ...
+ * This is effectively logical AND.
+ */
+
+namespace MutationOfJB {
+
+bool IfCommandParser::parse(const Common::String &line, ScriptParseContext &, Command *&command) {
+	// IFtss oo val!
+	// <t>   1B Tag.
+	// <ss>  2B Scene.
+	// <oo>  2B Object ID.
+	// <val> VL Value.
+	// !     1B Negation (optional).
+
+	if (line.size() < 10) {
+		return false;
+	}
+
+	if (!line.hasPrefix("IF")) {
+		return false;
+	}
+
+	const char *const cstr = line.c_str();
+	const char tag = cstr[2] == ' ' ? 0 : cstr[2];
+	const uint8 sceneId = atoi(cstr + 3);
+	const uint8 objectId = atoi(cstr + 6);
+	const uint8 value = atoi(cstr + 9);
+	const bool negative = (line.lastChar() == '!');
+
+	_tags.push(tag);
+
+	command = new IfCommand(sceneId, objectId, value, negative);
+
+	return true;
+}
+
+
+IfCommand::IfCommand(uint8 sceneId, uint8 objectId, uint16 value, bool negative) :
+	_sceneId(sceneId),
+	_objectId(objectId),
+	_value(value),
+	_negative(negative) {}
+
+Command::ExecuteResult IfCommand::execute(ScriptExecutionContext &scriptExecCtx) {
+	Scene *const scene = scriptExecCtx.getGameData().getScene(_sceneId);
+	if (!scene) {
+		return Finished;
+	}
+
+	Object *const object = scene->getObject(_objectId, true);
+	if (!object) {
+		return Finished;
+	}
+
+	_cachedResult = (object->_WX == _value);
+	if (_negative) {
+		_cachedResult = !_cachedResult;
+	}
+
+	return Finished;
+}
+
+Common::String IfCommand::debugString() const {
+	return Common::String::format("IF scene%d.object%d.WX %s %d", _sceneId, _objectId, _negative ? "!=" : "==", _value);
+}
+
+}