Work in progress: To continue on this ticket additional work has to be done enable dynamic collection and organisation of built-in types to be callable (#7)

MathEngine/MathEngine/Evaluator/Evaluator.cs

@@ -1,74 +0,0 @@
-using MathEngine.Parser.Parser;
-using MathEngine.Parser.Tokeniser;
-
-namespace MathEngine.Parser.Evaluator
-{
-    /// <summary>
-    /// Class that evaluate TreeNodes
-    /// </summary>
-    internal class Evaluator
-    {
-        /*public static TreeNode? Evaluate(TreeNode rootNode)
-        {
-            if (rootNode == null)
-            {
-                return null;
-            }
-            else // To evaluate we go anti-clockwise around the tree
-            {
-                TreeNode? Root, LeftBranch, RightBranch;
-                if (rootNode.NodeValue.Token_Type == Token.Type.Numeric)
-                    return rootNode;
-                else
-                { //For now these can't be null, this will need to be updated in the future
-                    LeftBranch = Evaluate_Tree_Branch(rootNode.GetChildNode(0));
-                    RightBranch = Evaluate_Tree_Branch(rootNode.GetChildNode(1));
-                    Root = Evaluate_Operator(rootNode.NodeValue, LeftBranch, RightBranch);
-                    return Root;
-                }
-            }
-        }
-
-
-        /// <summary>
-        /// Evaluates branches of a given tree
-        /// </summary>
-        /// <param name="Branch">The TreeNode branch to evaluate</param>
-        /// <returns>Returns the Evaluation of the Branch</returns>
-        private static TreeNode Evaluate_Tree_Branch(TreeNode Branch)
-        {
-            TreeNode Root, LeftBranch, RightBranch;
-            if (Branch.NodeValue.Token_Type == Token.Type.Numeric)
-                return Branch;
-            else
-            {
-                LeftBranch = Evaluate_Tree_Branch(Branch.GetChildNode(0));
-                RightBranch = Evaluate_Tree_Branch(Branch.GetChildNode(1));
-                // We finally combine the computed branches with the operator that links them and return the result
-                Root = Evaluate_Operator(Branch.NodeValue, LeftBranch, RightBranch);
-                return Root;
-            }
-        }
-
-        /// <summary>
-        /// Evlautes a binary node where the root node is an operator and given two branches the left and the right
-        /// </summary>
-        /// <param name="Operator_Token"></param>
-        /// <param name="Left_Branch"></param>
-        /// <param name="Right_Branch"></param>
-        /// <returns>Returns the evaluated value of the operator as a TreeNode</returns>
-        private static TreeNode Evaluate_Operator(Token Operator_Token, TreeNode Left_Branch, TreeNode Right_Branch)
-        {
-            decimal lhs = decimal.Parse(Left_Branch.NodeValue.TokenValue);
-            decimal rhs = decimal.Parse(Right_Branch.NodeValue.TokenValue);
-            return Operator_Token.Token_Type switch
-            {
-                Token.Type.Addition => new TreeNode(new Token((lhs + rhs).ToString(), Token.Type.Numeric, Token.NumericType.Decimal, 0)),
-                Token.Type.Subtraction => new TreeNode(new Token((lhs - rhs).ToString(), Token.Type.Numeric, Token.NumericType.Decimal, 0)),
-                Token.Type.Multiplication => new TreeNode(new Token(((decimal)(lhs * rhs)).ToString(), Token.Type.Numeric, Token.NumericType.Decimal, 0)),
-                Token.Type.Division => new TreeNode(new Token(((decimal)(lhs / rhs)).ToString(), Token.Type.Numeric, Token.NumericType.Decimal, 0)),
-                _ => throw new Exception("Potentially invalid token?"),
-            };
-        }*/
-    }
-}

MathEngine/MathEngine/Parser/Nodes/FunctionNode.cs

@@ -0,0 +1,30 @@
+using MathEngine.Parser.Parser.Nodes;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace MathEngine.Parser.Parser
+{
+    /// <summary>
+    /// Represents a Tree node that stores a function
+    /// </summary>
+    internal class FunctionNode<T>: BaseNode where T : INumber<T>
+    {
+        Action func;
+        List<NumericNode<T>> args;
+
+        public FunctionNode(Action Function, List<NumericNode<T>> arguments)
+        {
+            this.func = Function;
+            args = arguments;
+        }
+
+        public override BaseNode Evaluate()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

MathEngine/MathEngine/Parser/Nodes/NodeFactory.cs

@@ -7,6 +7,8 @@ namespace MathEngine.Parser.Parser
     /// </summary>
     internal class NodeFactory
     {
+
+
         /// <summary>
         /// Creates a binary TreeNode, that is a node with a root value and two children
         /// </summary>
@@ -33,6 +35,33 @@ namespace MathEngine.Parser.Parser
             }
         }
 
+        /// <summary>
+        /// Creates a Function Node, that is a node that operates a number of arguments
+        /// </summary>
+        /// <param name="FunctionToken">The function to create the node for</param>
+        /// <param name="ArgumentStack">Reference to Stack of BaseNode objects to take the arguments from</param>
+        /// <returns></returns>
+        public static BaseNode CreateFunctionNode(Token FunctionToken, Stack<BaseNode> ArgumentStack)
+        {
+            throw new NotImplementedException("Not implemented at this time");
+            /* Check that the function exists, if it does we then check that the number of arguments
+             * for the function is are avaliable on the ArgumentStack. If so we can construct the Node.
+             * Otherwise, either the function does not exist or there is an argument mismatch */
+            /*try
+            {
+                functionAction = GetFunction(FunctionToken, out int functionArity);
+                if (functionArity >= ArgumentStack.Count)
+                {
+                    throw new ArgumentException("Number of required arguments is greater than avaliable arugments");
+                }
+            }
+            catch (Exception)
+            {
+
+                throw;
+            }*/
+        }
+
         /// <summary>
         /// Returns a Node that holds a numerical value
         /// </summary>

MathEngine/MathEngine/Parser/Parser/Parser.cs

@@ -126,6 +126,24 @@ namespace MathEngine.Parser.Parser
                         }
                         OperatorStack.Push(CurrentToken);
                         break;
+                    case Token.Type.Function:
+                        OperatorStack.Push(CurrentToken);   
+                        break;
+                    case Token.Type.LeftParenthesis:
+                        OperatorStack.Push(CurrentToken);
+                        break;
+                    case Token.Type.RightParenthesis:
+                        while (OperatorStack.Peek() != Token.LeftParenthesis && OperatorStack.Count != 0)
+                        {
+                            OutputStack.Push(OperatorStack.Pop());
+                        }
+                        OperatorStack.Pop(); // Discard the left parenthesis
+
+                        if (OperatorStack.Peek().Token_Type == Token.Type.Function)
+                        {
+                            OutputStack.Push(OperatorStack.Pop());
+                        }
+                        break;
                 }
             }
 

MathEngine/MathEngine/Parser/Parser/TreeGenerator.cs

@@ -44,6 +44,10 @@ namespace MathEngine.Parser.Parser
                         //Node = NodeFactory.CreateUnaryNode(CurrentToken, OutputStack.Pop());
                         //OutputStack.Push(Node);
                         break;
+                    case Token.Type.Function:
+                        Node = NodeFactory.CreateFunctionNode(CurrentToken, OutputStack);
+                        OutputStack.Push(Node);
+                        break;
                 }
             }
             return OutputStack.Pop();

MathEngine/MathEngine/Parser/Tokeniser/Token.cs

@@ -5,6 +5,7 @@
     /// </summary>
     internal readonly struct Token
     {
+
         /// <summary>
         /// Represents the token for +
         /// </summary>
@@ -26,10 +27,20 @@
         public static readonly Token Divide = new("/", Type.Division, NumericType.NaN, 0);
 
         /// <summary>
+        /// Represents the token for (
+        /// </summary>
+        public static readonly Token LeftParenthesis = new Token("(", Token.Type.LeftParenthesis, Token.NumericType.NaN, 0);
+
+        /// <summary>
+        /// Represents the token for )
+        /// </summary>
+        public readonly static Token RightParenthesis = new Token(")", Token.Type.RightParenthesis, Token.NumericType.NaN, 0);
+
         /// Represents the token for ^
         /// </summary>
         public static readonly Token Exponentiation = new("^", Type.Exponentiation, NumericType.NaN, 0);
 
+
         /// <summary>
         /// Enum representing the token type
         /// </summary>
@@ -138,6 +149,22 @@
             this.Arity = FunctionArity;
         }
 
+
+        /// <summary>
+        /// Initializes a new instance of the Tokeniser.Token structure with a given TokenValue, TokenType, TokenNumericType and Arity
+        /// </summary>
+        /// <param name="TokenValue">Char representing the value of the token</param>
+        /// <param name="TokenType">The type that the token instance represents</param>
+        /// <param name="TokenNumericType">The numeric type of the token</param>
+        /// <param name="FunctionArity">The token Arity</param>
+        public Token(char TokenValue, Type TokenType, NumericType TokenNumericType, uint FunctionArity = 0)
+        {
+            this.Value = TokenValue.ToString();
+            this.TokenType = TokenType;
+            this.Numeric_Type = TokenNumericType;
+            this.Arity = FunctionArity;
+        }
+
 #if DEBUG
         /// <summary>
         /// Debug String; Used to give a string representation of a token

MathEngine/MathEngine/Parser/Tokeniser/Tokeniser.cs

@@ -6,6 +6,7 @@
     internal static class Tokeniser
     {
         private static readonly List<char> Operators = new(new char[] { '+', '-', '*', '/', '^' });
+        private static readonly List<char> Parenthesis = new(new char[] { '(', ')'});
 
         /// <summary>
         /// Gets the next non-whitespace char or returns the null terminator is at EOS (End of stream)
@@ -36,6 +37,16 @@
             };
         }
 
+        static private Token GetParenthesisToken(char curChar)
+        {
+            return curChar switch
+            {
+                '(' => Token.LeftParenthesis,
+                ')' => Token.RightParenthesis,
+                _ => throw new Exception(String.Format("Character {0} is not Parenthesis", curChar)),
+            };
+        }
+
         /// <summary>
         /// Tokenises a given Mathematical expression given as a string to a list of tokens 
         /// </summary>
@@ -65,9 +76,14 @@
                         Tokenstack.Add(Tokeniser.GetOperatorToken(curChar));
                         continue; //Next loop interation
                     }
+                    if (Parenthesis.Contains(curChar))
+                    {
+                        Tokenstack.Add(Tokeniser.GetParenthesisToken(curChar));
+                        continue;
+                    }   
                     //Number, two cases two consider,  case 1) number is something like 142.2; case 2 .5 which is clearly 0.5. 
                     //Case 1
-                    if (Char.IsDigit(curChar)) 
+                    if (Char.IsDigit(curChar))
                     {
                         bool hasDecimalPlace = false;
                         Int32 tempIndex = currentIndex;
@@ -86,14 +102,27 @@
                                     tempChar = GetNextChar(Expression, ref tempIndex);
                                 }
                                 string errString = Expression[currentIndex..tempIndex];
-                                throw new Exception(String.Format("Syntax error: {0} has multiple decimal point when at most one is allowed",errString));
+                                throw new Exception(String.Format("Syntax error: {0} has multiple decimal point when at most one is allowed", errString));
                             }
                         } while (Char.IsDigit(tempChar) || tempChar == '.');
                         //Iterate until we hit the next special character or EOS
 
                         //Token is a number so add this to the stack
                         Tokenstack.Add(new Token(Expression[currentIndex..tempIndex], Token.Type.Numeric, Token.NumericType.Decimal, 0));
-                        currentIndex = tempIndex-1; //Sets the index variable to just before the non numeric char
+                        currentIndex = tempIndex - 1; //Sets the index variable to just before the non numeric char
+                    }
+                    else if (Char.IsAsciiLetter(curChar)) // Keep reading until a parenthesis
+                    {
+                        Int32 tempIndex = currentIndex;
+                        char tempChar;
+                        do
+                        {
+                            tempChar = GetNextChar(Expression, ref tempIndex);
+
+                        } while (Char.IsAscii(tempChar) && tempChar != '(');
+                        //Token is a potential function so add this to the stack
+                        Tokenstack.Add(new Token(Expression[currentIndex..tempIndex], Token.Type.Function, Token.NumericType.NaN, 0));
+                        currentIndex = tempIndex - 1; //Sets the index variable to just before the end of the function
                     }
                 }