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Intentional Logic in C#

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4.84/5 (42 votes)
7 Oct 200310 min read 104.8K   910   45  
Allow your programs to reason with incomplete data.
 
using System;
using IntentionalLogic;
using NUnit.Framework;

namespace IntentionalLogicTest
{
	[TestFixture]
	public class IntentionalBoolTest
	{
		[Test]
		public void ObjectOperations()
		{
			IntentionalBool p;

			p = IntentionalBool.True;
			Assert.IsTrue(p.Equals(IntentionalBool.True));
			Assert.IsTrue(p == IntentionalBool.True);
			Assert.IsTrue(p != IntentionalBool.False);
			Assert.IsTrue(p != IntentionalBool.Unknown);
			Assert.IsTrue(p != IntentionalBool.NotUnknown);
			Assert.IsTrue(p.ToString() == "True");
			Assert.IsTrue(p.IsKnown);

			p = IntentionalBool.False;
			Assert.IsTrue(p.Equals(IntentionalBool.False));
			Assert.IsTrue(p != IntentionalBool.True);
			Assert.IsTrue(p == IntentionalBool.False);
			Assert.IsTrue(p != IntentionalBool.Unknown);
			Assert.IsTrue(p != IntentionalBool.NotUnknown);
			Assert.IsTrue(p.ToString() == "False");
			Assert.IsTrue(p.IsKnown);

			p = IntentionalBool.Unknown;
			Assert.IsTrue(p.Equals(IntentionalBool.Unknown));
			Assert.IsTrue(p != IntentionalBool.True);
			Assert.IsTrue(p != IntentionalBool.False);
			Assert.IsTrue(p == IntentionalBool.Unknown);
			Assert.IsTrue(p != IntentionalBool.NotUnknown);
			Assert.IsTrue(p.ToString() == "Unknown");
			Assert.IsFalse(p.IsKnown);
		
			p = IntentionalBool.NotUnknown;
			Assert.IsTrue(p.Equals(IntentionalBool.NotUnknown));
			Assert.IsTrue(p != IntentionalBool.True);
			Assert.IsTrue(p != IntentionalBool.False);
			Assert.IsTrue(p != IntentionalBool.Unknown);
			Assert.IsTrue(p == IntentionalBool.NotUnknown);
			Assert.IsTrue(p.ToString() == "NotUnknown");
			Assert.IsFalse(p.IsKnown);
		}

		[Test]
		public void Parse()
		{
			Assert.IsTrue(IntentionalBool.Parse("True") == IntentionalBool.True);
			Assert.IsTrue(IntentionalBool.Parse("False") == IntentionalBool.False);
			Assert.IsTrue(IntentionalBool.Parse("Unknown") == IntentionalBool.Unknown);
			Assert.IsTrue(IntentionalBool.Parse("NotUnknown") == IntentionalBool.NotUnknown);
		}

		[Test, ExpectedException(typeof(ArgumentNullException))]
		public void ParseArgumentNull()
		{
			IntentionalBool.Parse(null);
		}

		[Test, ExpectedException(typeof(ArgumentException))]
		public void ParseBadArgument()
		{
			IntentionalBool.Parse("BadValue");
		}

		[Test]
		public void AndOperator()
		{
			Assert.IsTrue((IntentionalBool.True & IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True & IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.True & IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.True & IntentionalBool.False) == IntentionalBool.False);

			Assert.IsTrue((IntentionalBool.Unknown & IntentionalBool.True) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.Unknown & IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.Unknown & IntentionalBool.NotUnknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.Unknown & IntentionalBool.False) == IntentionalBool.False);

			Assert.IsTrue((IntentionalBool.NotUnknown & IntentionalBool.True) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.NotUnknown & IntentionalBool.Unknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.NotUnknown & IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.NotUnknown & IntentionalBool.False) == IntentionalBool.False);

			Assert.IsTrue((IntentionalBool.False & IntentionalBool.True) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.False & IntentionalBool.Unknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.False & IntentionalBool.NotUnknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.False & IntentionalBool.False) == IntentionalBool.False);
		}

		[Test]
		public void OrOperator()
		{
			Assert.IsTrue((IntentionalBool.True | IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True | IntentionalBool.Unknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True | IntentionalBool.NotUnknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True | IntentionalBool.False) == IntentionalBool.True);

			Assert.IsTrue((IntentionalBool.Unknown | IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.Unknown | IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.Unknown | IntentionalBool.NotUnknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.Unknown | IntentionalBool.False) == IntentionalBool.Unknown);

			Assert.IsTrue((IntentionalBool.NotUnknown | IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.NotUnknown | IntentionalBool.Unknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.NotUnknown | IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.NotUnknown | IntentionalBool.False) == IntentionalBool.NotUnknown);

			Assert.IsTrue((IntentionalBool.False | IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.False | IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.False | IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.False | IntentionalBool.False) == IntentionalBool.False);
		}

		[Test]
		public void XorOperator()
		{
			Assert.IsTrue((IntentionalBool.True ^ IntentionalBool.True) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.True ^ IntentionalBool.Unknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.True ^ IntentionalBool.NotUnknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.True ^ IntentionalBool.False) == IntentionalBool.True);

			Assert.IsTrue((IntentionalBool.Unknown ^ IntentionalBool.True) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.Unknown ^ IntentionalBool.Unknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.Unknown ^ IntentionalBool.NotUnknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.Unknown ^ IntentionalBool.False) == IntentionalBool.Unknown);

			Assert.IsTrue((IntentionalBool.NotUnknown ^ IntentionalBool.True) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.NotUnknown ^ IntentionalBool.Unknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.NotUnknown ^ IntentionalBool.NotUnknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.NotUnknown ^ IntentionalBool.False) == IntentionalBool.NotUnknown);

			Assert.IsTrue((IntentionalBool.False ^ IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.False ^ IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.False ^ IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.False ^ IntentionalBool.False) == IntentionalBool.False);
		}

		[Test]
		public void NotOperator()
		{
			Assert.IsTrue(!IntentionalBool.True == IntentionalBool.False);
			Assert.IsTrue(!IntentionalBool.Unknown == IntentionalBool.NotUnknown);
			Assert.IsTrue(!IntentionalBool.NotUnknown == IntentionalBool.Unknown);
			Assert.IsTrue(!IntentionalBool.False == IntentionalBool.True);
		}

		[Test]
		public void ShortAndOperator()
		{
			Assert.IsTrue((IntentionalBool.True && IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True && IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.True && IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.True && IntentionalBool.False) == IntentionalBool.False);

			Assert.IsTrue((IntentionalBool.Unknown && IntentionalBool.True) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.Unknown && IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.Unknown && IntentionalBool.NotUnknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.Unknown && IntentionalBool.False) == IntentionalBool.False);

			Assert.IsTrue((IntentionalBool.NotUnknown && IntentionalBool.True) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.NotUnknown && IntentionalBool.Unknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.NotUnknown && IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.NotUnknown && IntentionalBool.False) == IntentionalBool.False);

			Assert.IsTrue((IntentionalBool.False && IntentionalBool.True) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.False && IntentionalBool.Unknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.False && IntentionalBool.NotUnknown) == IntentionalBool.False);
			Assert.IsTrue((IntentionalBool.False && IntentionalBool.False) == IntentionalBool.False);
		}

		[Test]
		public void ShortOrOperator()
		{
			Assert.IsTrue((IntentionalBool.True || IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True || IntentionalBool.Unknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True || IntentionalBool.NotUnknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.True || IntentionalBool.False) == IntentionalBool.True);

			Assert.IsTrue((IntentionalBool.Unknown || IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.Unknown || IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.Unknown || IntentionalBool.NotUnknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.Unknown || IntentionalBool.False) == IntentionalBool.Unknown);

			Assert.IsTrue((IntentionalBool.NotUnknown || IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.NotUnknown || IntentionalBool.Unknown) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.NotUnknown || IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.NotUnknown || IntentionalBool.False) == IntentionalBool.NotUnknown);

			Assert.IsTrue((IntentionalBool.False || IntentionalBool.True) == IntentionalBool.True);
			Assert.IsTrue((IntentionalBool.False || IntentionalBool.Unknown) == IntentionalBool.Unknown);
			Assert.IsTrue((IntentionalBool.False || IntentionalBool.NotUnknown) == IntentionalBool.NotUnknown);
			Assert.IsTrue((IntentionalBool.False || IntentionalBool.False) == IntentionalBool.False);
		}

		[Test]
		public void IfStatement()
		{
			bool success = false;
			if (IntentionalBool.True)
			{
				success = true;
			}
			Assert.IsTrue(success);

			if (IntentionalBool.False)
			{
				Assert.Fail();
			}

			if (IntentionalBool.Unknown)
			{
				Assert.Fail();
			}

			if (IntentionalBool.NotUnknown)
			{
				Assert.Fail();
			}
		}

		[Test]
		public void BoolCastOperator()
		{
			Assert.IsTrue(IntentionalBool.True ==  true); // implicit cast of true to IntentionalBool.True
			Assert.IsTrue(IntentionalBool.False == false); // implicit cast of false to IntentionalBool.False

			Assert.IsTrue((bool) IntentionalBool.True);
			Assert.IsFalse((bool) IntentionalBool.Unknown);
			Assert.IsFalse((bool) IntentionalBool.NotUnknown);
			Assert.IsFalse((bool) IntentionalBool.False);
		}

		[Test]
		public void Examples()
		{
			Examples(IntentionalBool.True, IntentionalBool.True);
			Examples(IntentionalBool.True, IntentionalBool.Unknown);
			Examples(IntentionalBool.True, IntentionalBool.NotUnknown);
			Examples(IntentionalBool.True, IntentionalBool.False);

			Examples(IntentionalBool.Unknown, IntentionalBool.True);
			Examples(IntentionalBool.Unknown, IntentionalBool.Unknown);
			Examples(IntentionalBool.Unknown, IntentionalBool.NotUnknown);
			Examples(IntentionalBool.Unknown, IntentionalBool.False);

			Examples(IntentionalBool.NotUnknown, IntentionalBool.True);
			Examples(IntentionalBool.NotUnknown, IntentionalBool.Unknown);
			Examples(IntentionalBool.NotUnknown, IntentionalBool.NotUnknown);
			Examples(IntentionalBool.NotUnknown, IntentionalBool.False);

			Examples(IntentionalBool.False, IntentionalBool.True);
			Examples(IntentionalBool.False, IntentionalBool.Unknown);
			Examples(IntentionalBool.False, IntentionalBool.NotUnknown);
			Examples(IntentionalBool.False, IntentionalBool.False);
		}

		private void Examples(IntentionalBool p, IntentionalBool q)
		{
			Assert.IsTrue( (bool) (p == !!p) );
			Assert.IsTrue( (bool) (p != !p) );

			Assert.IsTrue( (bool) (p | !p) );
			Assert.IsTrue( (bool) !(p & !p) );

			// &, | and ^ commute
			Assert.IsTrue( (p & q) == (q & p) );
			Assert.IsTrue( (p | q) == (q | p) );
			Assert.IsTrue( (p ^ q) == (q ^ p) );

			// short circuit operators have the same semantics as their corresponding basic operators
			Assert.IsTrue( (p && q) == (p & q) );
			Assert.IsTrue( (p || q) == (p | q) );

			// (p & q) => (p | q)
			Assert.IsTrue( (bool) ( !(p & q) | (p | q) ) );
		}

	}
}

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Written By
Kris Vandermotten
Web Developer
Belgium Belgium
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

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Posted 5 Oct 2003

Article Copyright 2003 by Kris Vandermotten
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