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Posted 19 Sep 2012
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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
{
	/// <summary>
	/// The YAMP interaction class.
	/// </summary>
	public class Parser
	{
		#region Members
		
		Context _expression;
		BracketExpression _interpreter;
		ParseTree _tree;
		
		#endregion
		
		#region ctor
		
		private Parser (Context expression)
		{
			_expression = expression;
			_tree = new ParseTree(expression.Input);
			_interpreter = new BracketExpression(_tree);
		}

		/// <summary>
		/// Creates the parse tree for the given expression.
		/// </summary>
		/// <param name='input'>
		/// The expression to evaluate.
		/// </param>
		public static Parser Parse(string input)
		{
			return new Parser(new Context(input));
		}

		/// <summary>
		/// Load the required functions, operators and expressions (CAN only be performed once).
		/// </summary>
		public static void Load()
		{
			Tokens.Instance.Touch();
		}

		/// <summary>
		/// Gets the currently set variables.
		/// </summary>
		/// <value>
		/// The variables.
		/// </value>
		public static IDictionary<string, Value> Variables
		{
			get { return Tokens.Instance.Variables; }
		}
		
		#endregion
		
		#region Properties

		/// <summary>
		/// Gets the context of the current parser instance (expression, value, ...).
		/// </summary>
		/// <value>
		/// The current context of this parser instance.
		/// </value>
		public Context Context
		{
			get { return _expression; }
		}

		/// <summary>
		/// Gets the expression tree.
		/// </summary>
		/// <value>
		/// The generated expression tree.
		/// </value>
		public ParseTree Tree
		{
			get { return _tree; }
		}
		
		#endregion
		
		#region Execution

		/// <summary>
		/// Execute the evaluation of this parser instance without any external symbols.
		/// </summary>
		public Value Execute()
		{
			return Execute(new Hashtable());
		}

		/// <summary>
		/// Execute the evaluation of this parser instance with external symbols.
		/// </summary>
		/// <param name='values'>
		/// The values in an Hashtable containing string (name), Value (value) pairs.
		/// </param>
		public Value Execute (Hashtable values)
		{
			_expression.Output = _interpreter.Interpret(values);
			Tokens.Instance.AssignVariable("$", _expression.Output);
			
			if(_expression.IsMuted)
				return null;
			
			return _expression.Output;
		}

		/// <summary>
		/// Execute the evaluation of this parser instance with external symbols.
		/// </summary>
		/// <param name='values'>
		/// The values in an anonymous object - containing name - value pairs.
		/// </param>
		public Value Execute(object values)
		{
			var symbols = new Hashtable();
			
			if(values != null)
			{
				var props = values.GetType().GetProperties();
				
				foreach(var prop in props)
					symbols.Add(prop.Name, prop.GetValue(values, null));
			}

			return Execute(symbols);
		}
		
		#endregion
		
		#region Customization

		/// <summary>
		/// Adds a custom constant to the parser.
		/// </summary>
		/// <param name='name'>
		/// The name of the symbol corresponding to the constant.
		/// </param>
		/// <param name='constant'>
		/// The value of the constant.
		/// </param>
		public static void AddCustomConstant(string name, double constant)
		{
			Tokens.Instance.AddConstant(name, constant, true);
		}

		/// <summary>
		/// Adds a custom constant to the parser.
		/// </summary>
		/// <param name='name'>
		/// The name of the symbol corresponding to the constant.
		/// </param>
		/// <param name='constant'>
		/// The value of the constant.
		/// </param>
		public static void AddCustomConstant(string name, Value constant)
		{
			Tokens.Instance.AddConstant(name, constant, true);
		}

		/// <summary>
		/// Removes a custom constant.
		/// </summary>
		/// <param name='name'>
		/// The name of the symbol corresponding to the constant that should be removed.
		/// </param>
		public static void RemoveCustomConstant(string name)
		{
			Tokens.Instance.RemoveConstant(name);
		}

		/// <summary>
		/// Adds a custom function to be used by the parser.
		/// </summary>
		/// <param name='name'>
		/// The name of the symbol corresponding to the function that should be added.
		/// </param>
		/// <param name='f'>
		/// The function that fulfills the signature Value f(Value v).
		/// </param>
		public static void AddCustomFunction(string name, FunctionDelegate f)
		{
			Tokens.Instance.AddFunction(name, f, true);
		}

		/// <summary>
		/// Removes a custom function.
		/// </summary>
		/// <param name='name'>
		/// The name of the symbol corresponding to the function that should be removed.
		/// </param>
		public static void RemoveCustomFunction(string name)
		{
			Tokens.Instance.RemoveFunction(name);
		}
		
		#endregion
		
		#region General 
		
		public override string ToString ()
		{
			var sb = new StringBuilder();
			sb.Append("YAMP [ input = ").Append(_expression.Original).AppendLine(" ]");
			sb.AppendLine("--------------");
			sb.Append(_interpreter.Tree.ToString());
			return sb.ToString();
		}
		
		#endregion
	}
}

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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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