sem 15

2 files changed, 272 insertions, 0 deletions

diff --git a/Sem. 15/ExpessionCalculator/ExpressionCalculator.cpp b/Sem. 15/ExpessionCalculator/ExpressionCalculator.cpp
new file mode 100644
index 0000000..86c68c8
--- /dev/null
+++ b/Sem. 15/ExpessionCalculator/ExpressionCalculator.cpp
@@ -0,0 +1,77 @@
+#include "ExpressionCalculator.h"
+
+void ExpressionCalculator::copyFrom(const ExpressionCalculator& other)
+{
+	expr = other.expr->clone();
+}
+
+void ExpressionCalculator::free()
+{
+	delete expr;
+}
+
+bool isOperator(char ch)
+{
+	return ch == AND || ch == OR || ch == IFF || ch == IMPL || ch == XOR || ch == NEG;
+}
+
+ExpressionCalculator::BooleanExpr* parse(const MyString& str)
+{
+
+	if (str.getSize() == 1)
+	{
+		return new ExpressionCalculator::Variable(str[0]);
+	}
+
+	MyString strWithoutBrackets = str.subString(1, str.getSize() - 2); //We remove the brackets.
+
+	
+	int countBrackets = 0;
+	for (size_t i = 0; i < strWithoutBrackets.getSize(); i++) //we start searching for the operation.
+	{														 // then we split to two expressions
+		if (strWithoutBrackets[i] == '(')
+			countBrackets++;
+		else if (strWithoutBrackets[i] == ')')
+			countBrackets--;
+		else if (isOperator(strWithoutBrackets[i]) && countBrackets == 0)
+		{
+			if (strWithoutBrackets[i] == NEG)
+				return new ExpressionCalculator::UnaryOperation('!', parse(strWithoutBrackets.subString(i + 1, strWithoutBrackets.getSize() - 1)));
+			else
+				return new ExpressionCalculator::BinaryOperation(parse(strWithoutBrackets.subString(0, i - 1)), strWithoutBrackets[i], parse(strWithoutBrackets.subString(i+1, strWithoutBrackets.getSize() - 1)));
+		}
+
+	}
+}
+
+ExpressionCalculator::ExpressionCalculator(const MyString& str)
+{
+	expr = parse(str);
+
+}
+ExpressionCalculator::ExpressionCalculator(const ExpressionCalculator& other)
+{
+	copyFrom(other);
+}
+ExpressionCalculator& ExpressionCalculator::operator=(const ExpressionCalculator& other)
+{
+	if (this != &other)
+	{
+		free();
+		copyFrom(other);
+	}
+	return *this;
+}
+ExpressionCalculator::~ExpressionCalculator()
+{
+	free();
+}
+
+bool ExpressionCalculator::isTautology() const
+{
+	return checkAll(expr, true);
+}
+bool ExpressionCalculator::isContradiction() const
+{
+	return checkAll(expr, false);
+}
\ No newline at end of file
diff --git a/Sem. 15/ExpessionCalculator/ExpressionCalculator.h b/Sem. 15/ExpessionCalculator/ExpressionCalculator.h
new file mode 100644
index 0000000..eb21a99
--- /dev/null
+++ b/Sem. 15/ExpessionCalculator/ExpressionCalculator.h
@@ -0,0 +1,195 @@
+#include <iostream>
+#include <exception>
+#include "../MyString/MyString.h"
+
+const char AND = '^';
+const char OR = 'v';
+const char IMPL = '>'; //=>
+const char IFF = '='; // <=>
+const char XOR = '+';
+const char NEG = '!';
+
+class ExpressionCalculator
+{
+
+	class BooleanExpr
+	{
+	public:
+		bool vars[26] = { false };
+		size_t countVars = 0;
+
+
+		struct BooleanInterpretation
+		{
+			bool values[26] = { false };
+			BooleanInterpretation()
+			{	}
+			void setValue(char ch, bool value)
+			{
+				if (ch < 'A' || ch > 'Z')
+					throw "error";
+
+				values[ch - 'A'] = value;
+			}
+			bool getValue(char ch) const
+			{
+				if (ch < 'A' || ch > 'Z')
+					throw "error";
+				return 	values[ch - 'A'];
+			}
+		};
+
+		virtual bool eval(const BooleanInterpretation& interpret) const = 0;
+
+		virtual BooleanExpr* clone() const = 0;
+		virtual ~BooleanExpr() = default;
+
+	};
+	class Variable : public BooleanExpr
+	{
+		char ch;
+	public:
+		Variable(char ch) : ch(ch)
+		{
+			vars[ch - 'A'] = true;
+			countVars = 1;
+		} ///only CAPITALS
+
+		bool eval(const BooleanInterpretation& interpret) const override
+		{
+			return interpret.getValue(ch);
+		}
+		BooleanExpr* clone() const override
+		{
+			return new Variable(*this);
+		}
+
+	};
+
+	class BinaryOperation : public BooleanExpr
+	{
+		BooleanExpr* left;
+		char op;
+		BooleanExpr* right;
+	public:
+		BinaryOperation(BooleanExpr* left, char op, BooleanExpr* right) : left(left), op(op), right(right)
+		{
+			for (int i = 0; i < 26; i++)
+			{
+				vars[i] = left->vars[i] || right->vars[i];
+				if (vars[i])
+					countVars++;
+
+			}
+		}
+
+		bool eval(const BooleanInterpretation& interpret) const override
+		{
+
+			switch (op)
+			{
+			case 'v': return  left->eval(interpret) || right->eval(interpret);
+			case '^': return left->eval(interpret) && right->eval(interpret);
+			default: return false;
+				break;
+			}
+		}
+
+		BooleanExpr* clone() const override
+		{
+			return new BinaryOperation(left->clone(), op, right->clone());
+		}
+
+
+
+		~BinaryOperation()
+		{
+			delete left;
+			delete right;
+		}
+	};
+
+	class UnaryOperation : public BooleanExpr
+	{
+		char ch; //!
+		BooleanExpr* expr;
+
+	public:
+		UnaryOperation(char ch, BooleanExpr* expr) : ch(ch), expr(expr)
+		{
+			for (int i = 0; i < 26; i++)
+			{
+				vars[i] = expr->vars[i];
+				if (vars[i])
+					countVars++;
+			}
+		}
+
+		BooleanExpr* clone() const override
+		{
+			return new UnaryOperation(ch, expr->clone());
+		}
+
+		bool eval(const BooleanInterpretation& interpret) const
+		{
+			if (ch == '!')
+			{
+				return !expr->eval(interpret);
+			}
+			else
+			{
+				// 
+				return false;
+			}
+		}
+		~UnaryOperation()
+		{
+			delete expr;
+		}
+	};
+
+	BooleanExpr::BooleanInterpretation convert(size_t number, bool vars[26]) const
+	{
+		BooleanExpr::BooleanInterpretation inter;
+
+		for (int i = 25; i >= 0; i--)
+		{
+			if (vars[i])
+			{
+				if (number % 2 == 1)
+					inter.setValue('A' + i, 1);
+				number /= 2;
+			}
+		}
+		return inter;
+	}
+
+	bool checkAll(BooleanExpr* expr, bool value) const
+	{
+		size_t varsCount = expr->countVars;
+		size_t intersCount = 1 << varsCount; ///!!!!! 2^varsCount
+
+		for (int i = 0; i < intersCount; i++)
+		{
+			if (expr->eval(convert(i, expr->vars)) != value)
+				return false;
+		}
+		return true;
+	}
+
+	BooleanExpr* expr;
+	void copyFrom(const ExpressionCalculator& other);
+	void free();
+	
+public:
+	ExpressionCalculator(const MyString& str);
+	ExpressionCalculator(const ExpressionCalculator& other);
+	ExpressionCalculator& operator=(const ExpressionCalculator& other);
+	~ExpressionCalculator();
+
+	bool isTautology() const;
+	bool isContradiction() const;
+
+	friend ExpressionCalculator::BooleanExpr* parse(const MyString& str);
+
+};
\ No newline at end of file