Minor additions to propositional parsing

Author: ShobhitLamba

aima-csharp/aima-csharp.csproj

@@ -191,11 +191,6 @@
     <Compile Include="logic\fol\Unifier.cs" />
     <Compile Include="logic\fol\VariableCollector.cs" />
     <Compile Include="logic\propositional\agent\KBAgent.cs" />
-    <Compile Include="logic\propositional\kb\data\Clause.cs" />
-    <Compile Include="logic\propositional\kb\data\ConjunctionOfClauses.cs" />
-    <Compile Include="logic\propositional\kb\data\Literal.cs" />
-    <Compile Include="logic\propositional\kb\data\Model.cs" />
-    <Compile Include="logic\propositional\kb\KnowledgeBase.cs" />
     <Compile Include="obj\Debug\TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs" />
     <Compile Include="obj\Debug\TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs" />
     <Compile Include="obj\Debug\TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs" />

aima-csharp/logic/propositional/parsing/PLVisitor.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using aima.core.logic.propositional.parsing.ast;
+
+namespace aima.core.logic.propositional.parsing
+{
+    /**
+     * <b>Propositional Logic Visitor:</b> A <a
+     * href="http://en.wikipedia.org/wiki/Visitor_pattern">Visitor Pattern/</a> for
+     * traversing the abstract syntax tree structural representation of
+     * propositional logic used in this library. The key difference between the
+     * default Visitor pattern and the code here, is that in the former the visit()
+     * methods have a void visit(ConcreteNode) signature while the visitors used
+     * here have a Object visit(ConcreteNode, Object arg) signature. This simplifies
+     * testing and allows some recursive code that is hard with the former .
+     * 
+     * @author Ravi Mohan
+     * @author Ciaran O'Reilly
+     * 
+     * @param <A>
+     *            the argument type to be passed to the visitor methods.
+     * @param <R>
+     *            the return type to be returned from the visitor methods.
+     */
+    public interface PLVisitor<A, R>
+    {
+	/**
+	 * Visit a proposition symbol (e.g A).
+	 * 
+	 * @param sentence
+	 *            a Sentence that is a propositional symbol.
+	 * @param arg
+	 *            optional argument to be used by the visitor.
+	 * @return optional return value to be used by the visitor.
+	 */
+	R visitPropositionSymbol(PropositionSymbol sentence, A arg);
+
+	/**
+	 * Visit a unary complex sentence (e.g. ~A).
+	 * 
+	 * @param sentence
+	 *            a Sentence that is a unary complex sentence.
+	 * @param arg
+	 *            optional argument to be used by the visitor.
+	 * @return optional return value to be used by the visitor.
+	 */
+	R visitUnarySentence(ComplexSentence sentence, A arg);
+
+	/**
+	 * Visit a binary complex sentence (e.g. A & B).
+	 * 
+	 * @param sentence
+	 *            a Sentence that is a binary complex sentence.
+	 * @param arg
+	 *            optional argument to be used by the visitor.
+	 * @return optional return value to be used by the visitor.
+	 */
+	R visitBinarySentence(ComplexSentence sentence, A arg);
+    }
+}

aima-csharp/logic/propositional/parsing/ast/AtomicSentence.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace aima.core.logic.propositional.parsing.ast
+{
+    /**
+     * Artificial Intelligence A Modern Approach (3rd Edition): page 244.<br>
+     * <br>
+     * The <b>atomic sentences</b> consist of a single proposition symbol.
+     * 
+     * @author Ravi Mohan
+     * @author Ciaran O'Reilly
+     * 
+     */
+    public abstract class AtomicSentence : Sentence
+    {
+
+    }
+}