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Posted 19 Sep 2012
Licenced CPOL

Yet Another Math Parser (YAMP)

, 30 Sep 2012
Constructing a fast math parser using Reflection to do numerics like Matlab.
YAMP
YAMPCompare
LLMathParser
MathFormula
MathParser
MathParserNet
Exceptions
MathParserTK
YAMPCompare.pidb
YAMPConsole
YAMPConsole.pidb
Exceptions
Expressions
Functions
ArgumentFunctions
LinearAlgebra
LogicFunctions
Spectroscopy
StandardFunctions
Trigonometric
Interfaces
Numerics
Decompositions
Integration
Interpolations
ODE
Optimization
Others
Solvers
Operators
AssigmentOperators
BinaryOperators
DotOperators
LogicOperators
UnaryOperators
Values
YAMP.csproj.user
YAMP.pidb
YAMP.csproj.user
YAMP.pidb
using System;
using System.Text;
using System.Collections;
using System.Collections.Generic;

namespace YAMP
{
    class IndexOperator : UnaryOperator
    {
		BracketExpression _bracket;
		object[][] _indices;
		Type[] _types;
		int _dimX;
		int _dimY;

		static readonly Type mt = typeof(MatrixValue);

		public override string Input
		{
			get 
			{
				return _bracket.Input;
			}
		}
		
        public IndexOperator() : base("[", 1000)
		{
		}

        public override Operator Create()
        {
            return new IndexOperator();
        }
		
		public override string Set (string input)
		{
			_bracket = new BracketExpression();
			return _bracket.Set(input, true);
		}
		
		public override Value Perform (Value left)
		{
			if(left is MatrixValue)
			{
                if (_indices.Length == 1)
                    return mt.GetProperty("Item", _types).GetValue(left, _indices[0]) as ScalarValue;

				var m = new MatrixValue(_dimY, _dimX);

				for(var k = 0; k < _indices.Length; k++)
					m[k + 1] = mt.GetProperty("Item", _types).GetValue(left, _indices[k]) as ScalarValue;

				return m;
			}
			
			throw new OperationNotSupportedException("[]", left);
		}
		
		public Value Perform (Value left, Value value)
		{
			if(left is MatrixValue)
			{
				var frm = new MatrixValue(1,1);

				if (value is ScalarValue)
					frm[1] = value as ScalarValue;
				else if (value is MatrixValue)
					frm = value as MatrixValue;
				else
					throw new AssignmentException("Cannot assign non-numeric values to numeric matrices");

				if(frm.DimensionX != _dimX)
					throw new DimensionException(frm.DimensionX, _dimX);

				if(frm.DimensionY != _dimY)
					throw new DimensionException(frm.DimensionY, _dimY);

				for(var k = 0; k < _indices.Length; k++)
					Assign(left, frm[k + 1], _indices[k]);

				return left;
			}
			
			throw new OperationNotSupportedException("[]", left);
		}

		void Assign(Value to, Value value, object[] index)
		{
			mt.GetProperty("Item", _types).SetValue(to, value, index);
		}

		int GetLength (Value value)
		{
			if(value is StringValue)
				return (value as StringValue).Length;
			else if(value is MatrixValue)
				return (value as MatrixValue).Length;

			throw new OperationNotSupportedException("[]", value);
		}
		
		int GetDimX (Value value)
		{
			if(value is StringValue)
				return (value as StringValue).Length;
			else if(value is MatrixValue)
				return (value as MatrixValue).DimensionX;
			
			throw new OperationNotSupportedException("[]", value);
		}
		
		int GetDimY (Value value)
		{
			if(value is StringValue)
				return 1;
			else if(value is MatrixValue)
				return (value as MatrixValue).DimensionY;
			
			throw new OperationNotSupportedException("[]", value);
		}
		
		void GetIndex(Hashtable symbols, Value left)
		{
			Value _value;

			if (_bracket.Tree.Operator != null)
				_value = _bracket.Tree.Operator.Evaluate(_bracket.Tree.Expressions, symbols);
			else
				_value = _bracket.Tree.Expressions[0].Interpret(symbols);
			
			if(_value is ScalarValue || _value is MatrixValue)
			{
				if(_value is MatrixValue)
				{
					var m = _value as MatrixValue;

					if(m.DimensionX == GetDimX (left) && m.DimensionY == GetDimY(left))
					{
						LogicalSubscripting(m);
						return;
					}
				}

				_types = new Type[] { typeof(int) };
				var values = GetIndices(_value, GetLength(left));
				BuildIndices(values);
			}
			else if(_value is ArgumentsValue)
			{
				var list = _value as ArgumentsValue;

				if(list.Length != 2)
					throw new ArgumentsException("[]", list.Length);
				
				_types = new Type[] { typeof(int), typeof(int) };
				var rows = GetIndices(list.Values[0], GetDimX(left));
				var cols = GetIndices(list.Values[1], GetDimY(left));
				BuildIndices(rows, cols);
			}
			else
				throw new OperationNotSupportedException("[]", _value);
		}

		int[] GetIndices(Value indices, int maxLength)
		{
			var z = new List<int>();

			if(indices is ScalarValue)
				z.Add((indices as ScalarValue).IntValue);
			else if(indices is RangeValue)
			{
				var r = indices as RangeValue;
				var step = (int)r.Step;

				if(!r.All)
					maxLength = (int)r.End;

				for(var j = (int)r.Start; j <= maxLength; j += step)
					z.Add(j);
			}
			else if(indices is MatrixValue)
			{
				var m = indices as MatrixValue;

				for(var j = 1; j <= m.Length; j++)
					z.Add(m[j].IntValue);
			}

			return z.ToArray();
		}

		void BuildIndices (int[] idx)
		{
			_dimX = 1;
			_dimY = idx.Length;
			_indices = new object[idx.Length][];

			for(var i = 0; i < idx.Length; i++)
				_indices[i] = new object[] { idx[i] };
		}
		
		void BuildIndices (int[] rows, int[] cols)
		{
			_dimY = rows.Length;
			_dimX = cols.Length;
			_indices = new object[_dimX * _dimY][];
			var k = 0;

			for(var i = 0; i < _dimX; i++)
				for(var j = 0; j < _dimY; j++)
					_indices[k++] = new object[] { rows[j], cols[i] };
		}

		void LogicalSubscripting(MatrixValue m)
		{
			_types = new Type[] { typeof(int), typeof(int) };
			var idx = new List<object[]>();

			for(var i = 1; i <= m.DimensionX; i++)
				for(var j = 1; j <= m.DimensionY; j++)
					if(m[j, i].Value != 0.0)
						idx.Add(new object[] { j, i });

			_dimX = 1;
			_dimY = idx.Count;
			_indices = idx.ToArray();
		}
		
		public override Value Handle (Expression expression, Hashtable symbols)
		{
			var left = expression.Interpret(symbols);
            GetIndex(symbols, left);			
			return Perform(left);
		}
		
		public Value Handle (Expression expression, Value value, Hashtable symbols)
		{
			if(expression is SymbolExpression)
			{
				var sym = expression as SymbolExpression;
				
				if(sym.IsSymbol && !Tokens.Instance.Variables.ContainsKey(sym.SymbolName))
					Tokens.Instance.AssignVariable(sym.SymbolName, new MatrixValue(1, 1));
			}

			var left = expression.Interpret(symbols);
			GetIndex(symbols, left);
			return Perform(left, value);
		}

		public override string ToString ()
		{
			return base.ToString() + Environment.NewLine + _bracket.ToString();
		}
    }
}

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Florian Rappl
Architect
Germany Germany
Florian lives in Munich, Germany. He started his programming career with Perl. After programming C/C++ for some years he discovered his favorite programming language C#. He did work at Siemens as a programmer until he decided to study Physics.

During his studies he worked as an IT consultant for various companies. After graduating with a PhD in theoretical particle Physics he is working as a senior technical consultant in the field of home automation and IoT.

Florian has been giving lectures in C#, HTML5 with CSS3 and JavaScript, software design, and other topics. He is regularly giving talks at user groups, conferences, and companies. He is actively contributing to open-source projects. Florian is the maintainer of AngleSharp, a completely managed browser engine.

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