/*
    Copyright (c) 2008-2022 Jan W. Krieger (<jan@jkrieger.de>)

    

    This software is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License (LGPL) as published by
    the Free Software Foundation, either version 2.1 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License (LGPL) for more details.

    You should have received a copy of the GNU Lesser General Public License (LGPL)
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/



/*! \defgroup jkmp Parser/Evaluator for Mathematical Expressions
    \ingroup jkqtptools_math

 In this group there are classes that form a parser and evaluator for mathematical expressions.
 In the context of the sequencer program this is a tool class that can be used by the classes
 in the project. E.g. used by JKQTPXParsedFunctionLineGraph, JKQTPYParsedFunctionLineGraph 

 \defgroup jkmpultil JKQTPMathParser: Utilities
 \ingroup jkmp

 \defgroup jkmpNodes JKQTPMathParser: Memory Representation of Expressions
 \ingroup jkmp

 \defgroup jkmpErrorhandling JKQTPMathParser Error Handling
 \ingroup jkmp
*/

#include <iostream>
#include <string>
#include <cstdio>
#include <vector>
#include <map>
#include <sstream>
#include <exception>
#include <ctype.h>
#include <list>
#include <utility>
#include "jkqtcommon_imexport.h"

#ifndef JKQTPMATHPARSER_H
#define JKQTPMATHPARSER_H




/*! \brief A simple function parser to parse (build memory tree representation) and
           evaluate simple mathematical expressions
    \ingroup jkmp
    
    
 This class implements a simple function parser which can parse
 mathematical expressions like <code> z=a*3+2.34^2*sin(pi*sqrt(x))</code> .
 More than one expression can be separated by semicolon ';'. The result of
 a parse operation will be a memory structure (tree) representing the given
 expression.
 The parser can cope with constants and (user defined) variables and supports
 the data types number (double precision floating point), boolean (true/false)
 and string. It already contains a lot of fundamental mathematical functions
 (i.e. nearly all the functions from C StdLib).

 \section jkmp_constantsAndVars constants and variables:
 This class provides management utilities for constants and variables. Variables
 can also be defined as external variables, when a pointer to corresponding
 memory is provided by the calling program. The parser supports a variable
 assign operation \code a=<expression>\endcode  which allows to define new
 variables during evaluation. There are some mathematical standard constants
 registered by calling JKQTPMathParser::addStandardVariables():
   - \c pi = \f$ \pi \f$
   - \c e = \f$ \exp(1) \f$
   - \c sqrt2 = \f$ \sqrt{2} \f$
   - \c version = the parser version
   - \c log2e = \f$ \log_2(e) \f$
   - \c log10e = \f$ \log_{10}(e) \f$
   - \c ln2 = \f$ \ln(2)=\log_{e}(2) \f$
   - \c ln10 = \f$ \ln(10)=\log_{e}(10) \f$
   - \c h = \f$ 6.6260689633\cdot 10^{-34}\;\mathrm{J\cdot s} \f$ (planck constant)
   - \c hbar = \f$ \hbar=\frac{h}{2\pi}= 1.05457162853\cdot 10^{-34}\;\mathrm{J\cdot s} \f$ (planck constant)
   - \c epsilon0 = \f$ \epsilon_0= 8.854187817\cdot 10^{-12}\;\mathrm{\frac{F}{m}} \f$ (electric constant)
   - \c mu0 = \f$ \mu_0=2\pi\cdot 10^{-7}= 12.566370614\cdot 10^{-7}\;\mathrm{\frac{N}{A^2}} \f$ (magnetic constant)
   - \c c = \f$ 299792458\;\mathrm{\frac{m}{s}} \f$ (speed of light in vacuum)
   - \c ce = \f$ 1.60217648740\cdot 10^{-19}\;\mathrm{C}\f$ (elementary charge)
   - \c muB = \f$ \mu_B= 927.40091523\cdot 10^{-26}\;\mathrm{\frac{J}{T}} \f$ (Bohr magneton)
   - \c muB_eV = \f$ \mu_B=5.788381755579\cdot 10^{-5}\;\mathrm{\frac{eV}{T}}  \f$ (Bohr magneton)
   - \c muN = \f$ \mu_N=5.0507832413\cdot 10^{-27}\;\mathrm{\frac{J}{T}}  \f$ (nuclear magneton)
   - \c muN_eV = \f$ \mu_N=3.152451232645\cdot 10^{-8}\;\mathrm{\frac{eV}{T}}  \f$ (nuclear magneton)
   - \c me = \f$ m_e= 9.1093821545\cdot 10^{-31}\;\mathrm{kg} \f$ (mass of electron)
   - \c mp = \f$ m_p= 1.67262163783\cdot 10^{-27}\;\mathrm{kg} \f$ (mass of proton)
   - \c mn = \f$ m_n= 1.67492721184\cdot 10^{-27}\;\mathrm{kg} \f$ (mass of neutron)
   - \c NA = \f$ N_A= 6.0221417930\cdot 10^{23} \f$ (Avogadro constant = particles in 1 mol)
   - \c kB = \f$ k_B=1.380650424\cdot 10^{-23}\;\mathrm{\frac{J}{K}}  \f$ (Boltzman constant)
   - \c kB_eV = \f$ k_B=8.61734315\cdot 10^{-5}\;\mathrm{\frac{eV}{K}}  \f$ (Boltzman constant)
.
 You can add user-defined contants by calling JKQTPMathParser::addVariableDouble()
 JKQTPMathParser::addVariableBoolean() or JKQTPMathParser::addVariableString()


 \section jkmp_functions functions:
 this class provides a wide range of (mathematical) functions:
   - sinc, gauss, slit, theta, tanc, sigmoid
   - asin, acos, atan, atan2,
   - sin, cos, tan,
   - sinh, cosh, tanh
   - log, log2, log10,
   - exp, sqr, sqrt
   - abs, sign
   - if
   - erf, erfc, lgamma, tgamma, j0, j1, jn, y0, y1, yn
   - rand, srand
   - ceil, floor, trunc, round,
   - fmod, min, max
   - floattostr, booltostr/bool2str, inttostr, num2str
   - tosystempathseparator
   - setdefault
   - strdate
   - cmdparam, argv
 .

 these functions are registered by calling JKQTPMathParser::addStandardFunctions().
 you can add new functions by calling JKQTPMathParser::addFunction();

 \section jkmp_resultsofparsing result of parsing and evaluation:
 The result of calling JKQTPMathParser::parse()
 will be a tree-like structure in memory. The parse() function will return
 a pointer to the root node of this structure. All nodes inherit from
 jkmpNode class. To evaluate such a structure simply call jkmpNode::evaluate()
 of the root node. This will then return a jkmpResult structure which contains
 the result. This scheme allows for once parsing and multiply evaluating an expression.
 So if you want to define a function by an expression you can provide an
 external variable x as the argument and then evaluate the function for
 each x.

 \section jkmp_ebnf EBNF definition of the parsed expressions

<pre> logical_expression ->  logical_term
                      | logical_expression <b>or</b> logical_term
                      | logical_expression <b>||</b> logical_term</pre>
<pre> logical_term    ->  comp_expression
                      | logical_term <b>and</b> comp_expression
                      | logical_term <b>&amp;&amp;</b> comp_expression</pre>
<pre> comp_expression  ->  math_expression
                      | expression <b>==</b> math_expression
                      | expression <b>!=</b> math_expression
                      | expression <b>&gt;=</b> math_expression
                      | expression <b>&lt;=</b> math_expression
                      | expression <b>&gt;</b> math_expression
                      | expression <b>&lt;</b> math_expression</pre>
<pre>  math_expression ->  term
                      | math_expression <b>+</b> math_term
                      | math_expression <b>-</b> math_term</pre>
<pre>  math_term       ->  primary
                      | term <b>*</b> primary
                      | term <b>/</b> primary
                      | term ( <b>%</b> | <b>mod</b> ) primary</pre>
<pre>  primary         ->  <b>true</b> | <b>false</b>
                      | string_constant
                      | NUMBER
                      | NAME
                      | NAME <b>=</b> logical_expression
                      | <b>+</b> primary | <b>-</b> primary | <b>!</b> primary | <b>not</b> primary
                      | <b>(</b> logical_expression <b>)</b>
                      | NAME<b>(</b> parameter_list <b>)</b>
                      | primary <b>^</b> primary</pre>
<pre>  string_constant -> <b>&quot;</b> STRING <b>&quot;</b> | <b>&apos;</b> STRING <b>&apos;</b></pre>
<pre>  parameter_list  ->  \f$ \lambda \f$ | logical_expression | logical_expression <b>,</b> parameter_list</pre>




 \section jkmp_example Simple Example of Usage
 \code
     try {
        JKQTPMathParser mp; // instanciate
        jkmpNode* n;
        jkmpResult r;
        // parse some numeric expression
        n=mp.parse("pi^2+4*sin(65*pi/exp(3.45))");
        r=n->evaluate();
        cout<<r.num<<endl;
        //delete n;

        // parse some boolean expression
        n=mp.parse("true==false");
        r=n->evaluate();
        if (r.type==jkmpBool) {
            if (r.boolean) cout<<"true";
            else cout<<"false";
        }
        if (r.type==jkmpDouble) cout<<r.num<<endl;
        if (r.type==jkmpString) cout<<r.str<<endl;
        delete n;

        // parse some string expression
        n=mp.parse("var1='false'; var1+'true'");
        r=n->evaluate();
        if (r.type==jkmpString) cout<<r.str<<endl;
        delete n;
     } catch(std::exception& E) {
        cout<<"ERROR!!!\n  "<<E.what()<<endl<<endl;
     }
 \endcode



 \section jkmp_errorhandling Error Handling

 In the above example we use error handling by use of exception (default behauviour).


 It is also possible to change the error handling from using exceptions to calling a specific
 error handling function. This can be usefull in programs that don't support exceptions.
 To do so, use this cod:
 \code
     void error(const std::string& message) {
       cout<<"error: "+message;
       system("PAUSE");
       abort();
     }

     int main() {
       JKQTPMathParser mp;
       mp.setException_function(error);  // make error ahndler known
       ...
     }
 \endcode
 */
class JKQTCOMMON_LIB_EXPORT JKQTPMathParser
{
    protected:
        void* data;

        /** \brief the possible tokens that can be recognized by the tokenizer in JKQTPMathParser::getToken() 
        *   \ingroup jkmpultil
        */
        enum jkmpTokenType {
            END,                /*!< \brief end token */
            PRINT,              /*!< \brief a semicolon ';' */
            PARAMETER_DIV,      /*!< \brief a comma ',' between two function parameters */
            STRING_DELIM,       /*!< \brief a string delimiter ' or " */
            NAME,               /*!< \brief a name (consisting of characters) of a variable or function */
            NUMBER,             /*!< \brief a number in scientific notation */
            PLUS,               /*!< \brief a plus operator '+' */
            MINUS,              /*!< \brief a minus operator '-' */
            MUL,                /*!< \brief a multiplication operator '*' */
            DIV,                /*!< \brief a division operator '/' */
            MODULO,             /*!< \brief a modulo operator '%' */
            ASSIGN,             /*!< \brief a variable assignment = */
            LBRACKET,           /*!< \brief left brackets '(' */
            RBRACKET,           /*!< \brief right brackets ')' */
            POWER,              /*!< \brief a power operator '^' */
            FACTORIAL_LOGIC_NOT, /*!< \brief a factorial operator or a logical NOT '!' */
            LOGIC_NOT,          /*!< \brief a logical NOT '!' / 'not' */
            LOGIC_AND,          /*!< \brief a logical AND operator '&&' / 'and' */
            LOGIC_OR,           /*!< \brief a logical OR operator '||' / 'or' */
            LOGIC_XOR,          /*!< \brief a logical XOR operator 'xor' */
            LOGIC_NOR,          /*!< \brief a logical NOR operator 'nor' */
            LOGIC_NAND,         /*!< \brief a logical NAND operator 'nand' */
            LOGIC_TRUE,         /*!< \brief 'true' */
            LOGIC_FALSE,        /*!< \brief  'false' */
            COMP_EQUALT,        /*!< \brief equals operation '==' */
            COMP_UNEQUAL,       /*!< \brief unequal operation '!=' */
            COMP_GREATER,       /*!< \brief greater than operation '>' */
            COMP_SMALLER,       /*!< \brief smaller than operation '<' */
            COMP_GEQUAL,        /*!< \brief greater than or equal operation '>=' */
            COMP_SEQUAL,        /*!< \brief smaller than or equal operation '<=' */
        };



        /** \brief internal names for logic operations
        *   \ingroup jkmpultil */
        enum {
          jkmpLOPand='a',
          jkmpLOPor='o',
          jkmpLOPxor='x',
          jkmpLOPnor='n',
          jkmpLOPnand='A',
          jkmpLOPnot='n'
        };


        /** \brief jkmpCOMPdefs internal names for compare operations 
        *   \ingroup jkmpultil*/
        enum {
            jkmpCOMPequal='=',
            jkmpCOMPnequal='!',
            jkmpCOMPlesser='<',
            jkmpCOMPgreater='>',
            jkmpCOMPlesserequal='a',
            jkmpCOMPgreaterequal='b'
        };


    public:

        /** \brief possible result types
         *   \ingroup jkmpultil
         */
        enum jkmpResultType {jkmpDouble,  /*!< \brief a floating-point number with double precision. This is also used to deal with integers */
                             jkmpString,  /*!< \brief a string of characters */
                             jkmpBool};   /*!< \brief a boolean value true|false */



        /** \brief result of any expression  
        *   \ingroup jkmpultil*/
        struct JKQTCOMMON_LIB_EXPORT jkmpResult {
          jkmpResult();

          bool isValid;
          jkmpResultType type;   /*!< \brief type of the result */
          std::string str;       /*!< \brief contains result if \c type==jkmpString */
          double num;            /*!< \brief contains result if \c type==jkmpDouble */
          bool boolean;          /*!< \brief contains result if \c type==jkmpBool */

          /** \brief convert the value this struct representens into a std::string */
          std::string toString();

          /** \brief convert the value this struct representens into a std::string and adds the name of the datatype in \c [...] */
          std::string toTypeString();
        };


        /** \brief This struct is for managing variables. Unlike jkmpResult this struct
          * only contains pointers to the data
        *   \ingroup jkmpultil
          */
        struct JKQTCOMMON_LIB_EXPORT jkmpVariable {
          jkmpVariable();
          jkmpResultType type;     /*!< \brief type of the variable */
          bool internal;           /*!< \brief this is an internal variable */
          std::string *str;        /*!< \brief this points to the variable data if \c type==jkmpString */
          double *num;             /*!< \brief this points to the variable data if \c type==jkmpDouble */
          bool *boolean;           /*!< \brief this points to the variable data if \c type==jkmpBool */
        };

        /** \brief This struct is for managing temporary variables. It is generally like jkmpVariable.
        *   \ingroup jkmpultil
          */
        struct JKQTCOMMON_LIB_EXPORT jkmpTempVariable {
          std::string name;       /*!< \brief name of the variable */
          jkmpResultType type;    /*!< \brief type of the variable */
          bool internal;          /*!< \brief this is an internal variable */
          std::string *str;       /*!< \brief this points to the variable data if \c type==jkmpString */
          double *num;            /*!< \brief this points to the variable data if \c type==jkmpDouble */
          bool *boolean;          /*!< \brief this points to the variable data if \c type==jkmpBool */
        };



        /** \brief This is a function prototype for adding new mathematical functions
         *         to the parser
         *
         * If you want to add more math functions (like sin, cos , abs ...) to the
         * parser, you will have to implement it with this prototype and then register
         * it with JKQTPMathParser::addFunction(). The first parameter points to an array
         * containing the input parameters while the second one specifies the number
         * of supplied parameters. The result has to be of type jkmpResult.
         *
         * All error handling has to be done inside the function definition. Here is a
         * simple example:
         * \code
         *    jkmpResult Abs(jkmpResult* params, unsigned char n){
         *        jkmpResult r;
         *        r.type=jkmpDouble;
         *        if (n!=1) jkmpError("abs accepts 1 argument");
         *        if (params[0].type!=jkmpDouble) jkmpError("abs needs double argument");
         *        r.num=fabs(params[0].num);
         *        return r;
         *    }
         * \endcode
         */
        typedef jkmpResult (*jkmpEvaluateFunc)(jkmpResult*, unsigned char, JKQTPMathParser*);


        /** \brief description of a user registered function */
        struct JKQTCOMMON_LIB_EXPORT jkmpFunctionDescriptor {
          jkmpEvaluateFunc function;    /*!< \brief a pointer to the function implementation */
          std::string name;             /*!< \brief name of the function */
        };





        
        /**
         * \brief This class is the abstract base class for nodes.
         * All allowed node types must inherit from jkmpNode
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpNode {
          protected:
            JKQTPMathParser* parser;  /*!< \brief points to the parser object that is used to evaluate this node */
            jkmpNode* parent;      /*!< \brief points to the parent node */
          public:
            /** \brief virtual class destructor */
            virtual ~jkmpNode();

            /** \brief evaluate this node */
            virtual jkmpResult evaluate()=0;

            /** \brief return a pointer to the JKQTPMathParser  */
            JKQTPMathParser *getParser();

            /** \brief set the JKQTPMathParser  */
            void setParser(JKQTPMathParser* mp);

            /** \brief returns a pointer to the parent node */
            jkmpNode *getParent();

            /** \brief sets the parent node  */
            void setParent(jkmpNode* par);
        };


        /**
         * \brief This class represents a binary arithmetic operation:
         *  add (+), subtract (-), multiply (*), divide (/), a to the power of b (a^b)
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpBinaryArithmeticNode: public jkmpNode {
          private:
            jkmpNode* left, *right;
            char operation;
          public:
            /** \brief constructor for a jkmpBinaryArithmeticNode
             *  \param op the operation to be performed: add (+), subtract (-), multiply (*), divide (/), a to the power of b (a^b)
             *  \param l left child node/operand
             *  \param r right child node/operand
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpBinaryArithmeticNode(char op, jkmpNode* l, jkmpNode* r, JKQTPMathParser* p, jkmpNode* par);

            /** \brief standard destructor, also destroy the children (recursively)  */
            virtual ~jkmpBinaryArithmeticNode() override;

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a binary boolean operation: and, or, xor, nor, nand
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpBinaryBoolNode: public jkmpNode {
          private:
            jkmpNode* left, *right;
            char operation;
          public:
            /** \brief constructor for a jkmpBinaryBoolNode
             *  \param op the operation to be performed: (a)nd, (o)r, (x)or, (n)or, nand (A)
             *  \param l left child node/operand
             *  \param r right child node/operand
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpBinaryBoolNode(char op, jkmpNode* l, jkmpNode* r, JKQTPMathParser* p, jkmpNode* par);

            /** \brief standard destructor, also destroy the children (recursively)  */
            virtual ~jkmpBinaryBoolNode() override;

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a binary compare operation: !=, ==, >=, <=, >, <
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpCompareNode: public jkmpNode {
          private:
            jkmpNode* left, *right;
            char operation;
          public:
            /** \brief constructor for a jkmpCompareNode
             *  \param op the operation to be performed: != (!), == (=), >= (b), <= (a), (>), (<)
             *  \param l left child node/operand
             *  \param r right child node/operand
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpCompareNode(char op, jkmpNode* l, jkmpNode* r, JKQTPMathParser* p, jkmpNode* par);

            /** \brief standard destructor, also destroy the children (recursively)  */
            virtual ~jkmpCompareNode () override;

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a unary operations: ! (bool negation), - (arithmetic negation)
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpUnaryNode: public jkmpNode {
          private:
            jkmpNode* child;
            char operation;
          public:
            /** \brief constructor for a jkmpUnaryNode
             *  \param op the operation to be performed: (!), (-)
             *  \param c child node/operand
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpUnaryNode(char op, jkmpNode* c, JKQTPMathParser* p, jkmpNode* par);

            /** \brief standard destructor, also destroy the children (recursively)  */
            virtual ~jkmpUnaryNode() override;

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a variable assignment (a = expression)
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpVariableAssignNode: public jkmpNode {
          private:
            jkmpNode* child;
            std::string variable;
            //char operation;
          public:
            /** \brief standard destructor, also destroy the children (recursively)  */
            virtual ~jkmpVariableAssignNode() override;

            /** \brief constructor for a jkmpVariableAssignNode
             *  \param var name of the variable to assign to
             *  \param c child node/right-hand-side expression
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpVariableAssignNode(const std::string& var, jkmpNode* c, JKQTPMathParser* p, jkmpNode* par);

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a number, a string contant or a boolean contant (true/false)
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpConstantNode: public jkmpNode {
          private:
            jkmpResult data;
          public:
            /** \brief constructor for a jkmpConstantNode
             *  \param d the value of the constant
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpConstantNode(jkmpResult d, JKQTPMathParser* p, jkmpNode* par);

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a variable.
         * \ingroup jkmpNodes 
         */
        class JKQTCOMMON_LIB_EXPORT jkmpVariableNode: public jkmpNode {
          private:
            std::string var;
          public:
            /** \brief constructor for a jkmpVariableNode
             *  \param name name of the variable
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpVariableNode(const std::string& name, JKQTPMathParser* p, jkmpNode* par);

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents an arbitrary function.
         * \ingroup jkmpNodes 
         *
         * When initialized this class will get the function description that is
         * linked to the supplied function name from JKQTPMathParser object. This
         * information is saved locally and won't be changed when evaluating!
         *
         * Functions may have 8 parameters at the most.
         */
        class JKQTCOMMON_LIB_EXPORT jkmpFunctionNode: public jkmpNode {
          private:
            std::string fun;
            jkmpNode** child;
            unsigned char n;
            jkmpEvaluateFunc function;
          public:
            /** \brief constructor for a jkmpFunctionNode
             *  \param name name of the function
             *  \param c a pointer to an array of jkmpNode objects that represent the parameter expressions
             *  \param num number of children in c
             *  \param p a pointer to a JKQTPMathParser object
             *  \param par a pointer to the parent node
             */
            jkmpFunctionNode(const std::string& name, jkmpNode** c, unsigned char num, JKQTPMathParser* p, jkmpNode* par);

            /** \brief standard destructor, also destroy the children (recursively) */
            virtual ~jkmpFunctionNode() override;

            /** \brief evaluate this node */
            virtual jkmpResult evaluate() override;
        };

        /**
         * \brief This class represents a list of jkmpNode.
         * \ingroup jkmpNodes 
         *
         * when evaluating the result will be the result of the last node in the list.
         */
        class JKQTCOMMON_LIB_EXPORT jkmpNodeList: public jkmpNode {
          private:
            std::vector<jkmpNode*> list;
          public:
            /** \brief constructor for a jkmpNodeList
             *  \param p a pointer to a JKQTPMathParser object
             */
            jkmpNodeList(JKQTPMathParser* p);

            /** \brief standard destructor, also destroy the children (recursively) */
            virtual ~jkmpNodeList() override;

            /** \brief add a jkmpNode n to the list */
            void add(jkmpNode* n);

            /** \brief evaluate the node */
            virtual jkmpResult evaluate() override;

            /** \brief get the number of nodes in the list */
            int getCount();
        };

        /*@}*/


    public:





        /** \brief error handling: exceptions of the type of this class will be thrown if an error occurs
         *  \ingroup jkmpErrorhandling 
         *
         * \attention If you do not want to use the exception handling which throws
         * jkmpException exceptions, but want to write your own error handling, you should write your own
         * error handler and assign it (function pointer) to the global variable jkmathparser_exception_function.
         * If this is not nullptr this function will be called instead of throwing an exception.
         */
        class JKQTCOMMON_LIB_EXPORT jkmpException : public std::exception {
          private:
               /** \brief the error message */
               std::string errormessage;
            public:
                /** \brief class constructors */
                jkmpException();

                /** \brief constructor with supplied error message */
                jkmpException(const std::string& msg);

                /** \brief class destructors */
                virtual ~jkmpException() override;

                /** \brief  returns the assigned errormessage */
                std::string getMessage() const;

                /** \brief returns the error description as C string */
                virtual const char* what() const noexcept override;
        };

        /** \brief type for a custom error handler. This an alternative error handling
         *  \ingroup jkmpErrorhandling  */
        typedef void (*jkmpexceptionf)(std::string);


        /** \brief function that throws an exception or calls an error handler 
         *  \ingroup jkmpErrorhandling */
        void jkmpError(const std::string& st);

    private:
        /** \brief if this is nullptr then an exception may be thrown otherwise this should point to an error handler that will be called.
         *  \ingroup jkmpErrorhandling  */
        jkmpexceptionf jkmathparser_exception_function;

    public:
        /** \brief activate error handling by use of an exception function
         *  \ingroup jkmpErrorhandling  */
        void setException_function(jkmpexceptionf exception_function);

        /** \brief deactivate error handling by use of an exception function
         *  \ingroup jkmpErrorhandling  */
        void resetException_function();


    protected:
        /** \brief return the given token as human-readable string */
        std::string tokentostring(jkmpTokenType token);

        /** \brief return the current token as human-readable string */
        std::string currenttokentostring();

        /** \brief Tokenizer: extract the next token from the input */
        jkmpTokenType getToken();

        /** \brief return a delimited text, i.e. extract the texte between the delimiters <code>"</code> in: of <code>"Hallo!"</code>, i.e. returns <code> Hallo!</code>
         *         This is used to parse string constants.
         *
         * This functions actually reads pascal style delimited string constants. So if you want to use the delimiter as part of the string you will have to
         * write it as doubled character. So <code>'Jan''s Test'</code> stands for <code>Jan's Test</code>.
         */
        std::string readDelim(char delimiter);

        /** \brief recognizes an compExpression while parsing. If \a get ist \c true, this function first retrieves a new token by calling getToken() */
        jkmpNode* compExpression(bool get);

        /** \brief recognizes a logicalExpression while parsing. If \a get ist \c true, this function first retrieves a new token by calling getToken() */
        jkmpNode* logicalExpression(bool get);

        /** \brief recognizes a logicalTerm while parsing. If \a get ist \c true, this function first retrieves a new token by calling getToken() */
        jkmpNode* logicalTerm(bool get);

        /** \brief recognizes a mathExpression while parsing. If \a get ist \c true, this function first retrieves a new token by calling getToken() */
        jkmpNode* mathExpression(bool get);

        /** \brief recognizes a term while parsing. If \a get ist \c true, this function first retrieves a new token by calling getToken() */
        jkmpNode* mathTerm(bool get);

        /** \brief recognizes a primary while parsing. If \a get ist \c true, this function first retrieves a new token by calling getToken() */
        jkmpNode* primary(bool get);

        /** \brief this stream is used to read in the program. An object is created and assigned
         * (and destroyed) by the parse()-function */
        std::istringstream* program;

        /** \brief vector containing all temporary variables */
        std::vector<jkmpTempVariable> tempvariables;

        /** \brief map to manage all currently defined variables */
        std::map<std::string, jkmpVariable> variables;

        /** \brief map to manage all currently rtegistered functions */
        std::map<std::string, jkmpFunctionDescriptor> functions;

        /** \brief the current token while parsing a string */
        jkmpTokenType CurrentToken;

        /** \brief the string value of the current token (when applicable) during the parsing step */
        std::string StringValue;

        /** \brief the string value of the current token (when applicable) during the parsing step */
        double NumberValue;

        /** \brief set the defining struct of the given variable */
        void setVariable(const std::string& name, jkmpResult value);
        /** \brief set the defining struct of the given variable */
        void setVariableDouble(const std::string& name, double value);


        /** \brief  adds a temporary variable */
        void addTempVariable(const std::string& name, jkmpResult value);

    protected:
        int argc;
        char **argv;

    public:
        /** \brief class constructor */
        JKQTPMathParser();

        /** \brief class destructor */
        virtual ~JKQTPMathParser();

        /** \copydoc data */ 
        virtual void setData(void* __value);
        /** \copydoc data */ 
        virtual void* getData() const;

        /** \brief  register a new function
         * \param name name of the new function
         * \param function a pointer to the implementation
         */
        void addFunction(const std::string& name, jkmpEvaluateFunc function);

        /** \brief  register a new external variable of type double
         * \param name name of the new variable
         * \param v pointer to the variable memory
         */
        void addVariableDouble(const std::string& name, double* v);

        /** \brief  register a new external variable of type string
         * \param name name of the new variable
         * \param v pointer to the variable memory
         */
        void addVariableString(const std::string& name, std::string* v);

        /** \brief  register a new external variable of type boolean
         * \param name name of the new variable
         * \param v pointer to the variable memory
         */
        void addVariableBoolean(const std::string& name, bool* v);


        /** \brief  register a new internal variable of type double
         * \param name name of the new variable
         * \param v initial value of this variable
         */
        void addVariableDouble(const std::string& name, double v);

        /** \brief  register a new internal variable of type string
         * \param name name of the new variable
         * \param v initial value of this variable
         */
        void addVariableString(const std::string& name, const std::string& v);

        /** \brief  register a new internal variable of type boolean
         * \param name name of the new variable
         * \param v initial value of this variable
         */
        void addVariableBoolean(const std::string& name, bool v);

        /** \brief  register a new internal variable of type boolean
         * \param name name of the new variable
         * \param result initial value of this variable
         */
        void addVariable(const std::string& name, jkmpResult result);



        /** \brief  returns the value of the given variable */
        jkmpResult getVariable(const std::string& name);
        /** \brief  returns the value of the given variable */
        jkmpResult getVariableOrInvalid(const std::string& name);

        /** \brief  returns the defining structure of the given variable */
        jkmpVariable getVariableDef(const std::string& name);


        /** \brief  evaluates a registered function
         * \param name name of the (registered function) to be evaluated
         * \param params array of the input parameters
         * \param n number of input parameters (<=8)
         */
        jkmpResult evaluateFunction(const std::string& name, jkmpResult* params, unsigned char n);

        /** \brief  returns the defining structure of the given function */
        jkmpEvaluateFunc getFunctionDef(const std::string& name);

        /** \brief  tests whether a temporary variable exists */
        bool tempvariableExists(const std::string& name);

        /** \brief  tests whether a variable exists */
        bool variableExists(const std::string& name);

        /** \brief  tests whether a function exists */
        bool functionExists(const std::string& name);

        /** \brief  deletes all defined variables. the memory of internal variables
         * will be released. the external memory will not be released.
         */
        void clearVariables();

        /** \brief  delete the specified variabale and releases its internal memory.*/
        void deleteVariable(const std::string& name);

        /** \brief  clears the list of internal functions*/
        void clearFunctions();

        /** \brief  registers standard variables*/
        void addStandardVariables();

        /** \brief  registers standard functions*/
        void addStandardFunctions();

        /** \brief  parses the given expression*/
        jkmpNode* parse(const std::string& prog);

        /** \brief evaluate the given expression */
        jkmpResult evaluate(const std::string& prog);

        /** \brief  prints a list of all registered variables */
        void printVariables();

        /** \brief returns all registered variables */
        std::vector<std::pair<std::string, jkmpVariable> > getVariables();

        /** \brief store programs command-line arguments, so they are available in the parser */
        void setArgCV(int argc, char **argv);

        /** \brief return one of programs command-line arguments, or \a defaultResult if it is not present */
        std::string getArgCVParam(const std::string& name, const std::string& defaultResult);
};

#endif // JKQTPMATHPARSER_H