Many applications require the parsing of mathematical expressions. The main objective of this library is to provide a fast and easy way of doing this. muParser is an extensible high performance math expression parser library written in C++. It works by transforming a mathematical expression into bytecode and precalculating constant parts of the expression. For more information about this library, visit their official website.
You can find here the Muparser library site.
The following example is a math interactive interpreter.
main_muparser.cpp
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//
// __________
// _____ __ __\______ \_____ _______ ______ ____ _______
// / \ | | \| ___/\__ \ \_ __ \/ ___/_/ __ \\_ __ \
// | Y Y \| | /| | / __ \_| | \/\___ \ \ ___/ | | \/
// |__|_| /|____/ |____| (____ /|__| /____ > \___ >|__|
// \/ \/ \/ \/
// (C) 2013 Ingo Berg
//
// example1.cpp - using the parser as a static library
//
//---------------------------------------------------------------------------
#include "ingoberg/muparser/include/muParserTest.h"
#if defined(_WIN32) && defined(_DEBUG)
#define _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
#define CREATE_LEAKAGE_REPORT
#endif
#if defined( USINGDLL ) && defined( _WIN32 )
#error This sample can be used only with STATIC builds of muParser (on win32)
#endif
/** \brief This macro will enable mathematical constants like M_PI. */
#define _USE_MATH_DEFINES
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
#include <locale>
#include <limits>
#include <ios>
#include <iomanip>
#include <numeric>
#include "ingoberg/muparser/include/muParser.h"
using namespace std;
using namespace mu;
#if defined(CREATE_LEAKAGE_REPORT)
// Dumping memory leaks in the destructor of the static guard
// guarantees i won't get false positives from the ParserErrorMsg
// class wich is a singleton with a static instance.
struct DumpLeaks
{
~DumpLeaks()
{
_CrtDumpMemoryLeaks();
}
} static LeakDumper;
#endif
// Forward declarations
void CalcBulk();
// Operator callback functions
value_type Mega(value_type a_fVal) { return a_fVal * 1e6; }
value_type Milli(value_type a_fVal) { return a_fVal / (value_type)1e3; }
value_type Rnd(value_type v) { return v*std::rand()/(value_type)(RAND_MAX+1.0); }
value_type Not(value_type v) { return v==0; }
value_type Add(value_type v1, value_type v2) { return v1+v2; }
value_type Mul(value_type v1, value_type v2) { return v1*v2; }
//---------------------------------------------------------------------------
value_type ThrowAnException(value_type)
{
throw std::runtime_error("This function does throw an exception.");
}
//---------------------------------------------------------------------------
value_type BulkFun1(int nBulkIdx, int nThreadIdx, value_type v1)
{
// Note: I'm just doing something with all three parameters to shut
// compiler warnings up!
return nBulkIdx + nThreadIdx + v1;
}
//---------------------------------------------------------------------------
value_type Ping()
{
mu::console() << "ping\n";
return 0;
}
//---------------------------------------------------------------------------
value_type StrFun0(const char_type *szMsg)
{
if (szMsg)
mu::console() << szMsg << std::endl;
return 999;
}
//---------------------------------------------------------------------------
value_type StrFun2(const char_type *v1, value_type v2,value_type v3)
{
mu::console() << v1 << std::endl;
return v2+v3;
}
//---------------------------------------------------------------------------
value_type Debug(mu::value_type v1, mu::value_type v2)
{
ParserBase::EnableDebugDump(v1!=0, v2!=0);
mu::console() << _T("Bytecode dumping ") << ((v1!=0) ? _T("active") : _T("inactive")) << _T("\n");
return 1;
}
//---------------------------------------------------------------------------
// Factory function for creating new parser variables
// This could as well be a function performing database queries.
value_type* AddVariable(const char_type *a_szName, void *a_pUserData)
{
// I don't want dynamic allocation here, so i used this static buffer
// If you want dynamic allocation you must allocate all variables dynamically
// in order to delete them later on. Or you find other ways to keep track of
// variables that have been created implicitely.
static value_type afValBuf[100];
static int iVal = -1;
++iVal;
mu::console() << _T("Generating new variable \"")
<< a_szName << std::dec << _T("\" (slots left: ")
<< 99-iVal << _T(")")
<< _T(" User data pointer is:")
<< std::hex << a_pUserData <<endl;
afValBuf[iVal] = 0;
if (iVal>=99)
throw mu::ParserError( _T("Variable buffer overflow.") );
else
return &afValBuf[iVal];
}
int IsHexValue(const char_type *a_szExpr, int *a_iPos, value_type *a_fVal)
{
if (a_szExpr[1]==0 || (a_szExpr[0]!='0' || a_szExpr[1]!='x') )
return 0;
unsigned iVal(0);
// New code based on streams for UNICODE compliance:
stringstream_type::pos_type nPos(0);
stringstream_type ss(a_szExpr + 2);
ss >> std::hex >> iVal;
nPos = ss.tellg();
if (nPos==(stringstream_type::pos_type)0)
return 1;
*a_iPos += (int)(2 + nPos);
*a_fVal = (value_type)iVal;
return 1;
}
//---------------------------------------------------------------------------
void Splash()
{
mu::console() << _T(" __________ \n");
mu::console() << _T(" _____ __ __\\______ \\_____ _______ ______ ____ _______\n");
mu::console() << _T(" / \\ | | \\| ___/\\__ \\ \\_ __ \\/ ___/_/ __ \\\\_ __ \\ \n");
mu::console() << _T(" | Y Y \\| | /| | / __ \\_| | \\/\\___ \\ \\ ___/ | | \\/ \n");
mu::console() << _T(" |__|_| /|____/ |____| (____ /|__| /____ > \\___ >|__| \n");
mu::console() << _T(" \\/ \\/ \\/ \\/ \n");
mu::console() << _T(" Version ") << Parser().GetVersion(pviFULL) << _T("\n");
mu::console() << _T(" (C) 2013 Ingo Berg\n");
}
//---------------------------------------------------------------------------
value_type SelfTest()
{
mu::console() << _T( "-----------------------------------------------------------\n");
mu::console() << _T( "Running test suite:\n\n");
// Skip the self test if the value type is set to an integer type.
if (mu::TypeInfo<mu::value_type>::IsInteger())
{
mu::console() << _T( " Test skipped: integer data type are not compatible with the unit test!\n\n");
}
else
{
mu::Test::ParserTester pt;
pt.Run();
}
return 0;
}
//---------------------------------------------------------------------------
value_type Help()
{
mu::console() << _T( "-----------------------------------------------------------\n");
mu::console() << _T( "Commands:\n\n");
mu::console() << _T( " list var - list parser variables\n");
mu::console() << _T( " list exprvar - list expression variables\n");
mu::console() << _T( " list const - list all numeric parser constants\n");
mu::console() << _T( " opt on - enable optimizer (default)\n");
mu::console() << _T( " opt off - disable optimizer\n");
mu::console() << _T( " locale de - switch to german locale\n");
mu::console() << _T( " locale en - switch to english locale\n");
mu::console() << _T( " locale reset - reset locale\n");
mu::console() << _T( " test bulk - test bulk mode\n");
mu::console() << _T( " quit - exits the parser\n");
mu::console() << _T( "\nConstants:\n\n");
mu::console() << _T( " \"_e\" 2.718281828459045235360287\n");
mu::console() << _T( " \"_pi\" 3.141592653589793238462643\n");
mu::console() << _T( "-----------------------------------------------------------\n");
return 0;
}
//---------------------------------------------------------------------------
/*
void CheckLocale()
{
// Local names:
// "C" - the classic C locale
// "de_DE" - not for Windows?
// "en_US" - not for Windows?
// "German_germany" - For MSVC8
try
{
std::locale loc("German_germany");
console() << _T("Locale settings:\n");
console() << _T(" Decimal point: '") << std::use_facet<numpunct<char_type> >(loc).decimal_point() << _T("'\n");
console() << _T(" Thousands sep: '") << std::use_facet<numpunct<char_type> >(loc).thousands_sep() << _T("'\n");
console() << _T(" Grouping: '") << std::use_facet<numpunct<char_type> >(loc).grouping() << _T("'\n");
console() << _T(" True is named: '") << std::use_facet<numpunct<char_type> >(loc).truename() << _T("'\n");
console() << _T(" False is named: '") << std::use_facet<numpunct<char_type> >(loc).falsename() << _T("'\n");
console() << _T("-----------------------------------------------------------\n");
}
catch(...)
{
console() << _T("Locale settings:\n");
console() << _T(" invalid locale name\n");
console() << _T("-----------------------------------------------------------\n");
}
}
//---------------------------------------------------------------------------
void CheckDiff()
{
mu::Parser parser;
value_type x = 1,
v1,
v2,
v3,
eps(pow(std::numeric_limits<value_type>::epsilon(), 0.2));
parser.DefineVar(_T("x"), &x);
parser.SetExpr(_T("_e^-x*sin(x)"));
v1 = parser.Diff(&x, 1),
v2 = parser.Diff(&x, 1, eps);
v3 = cos((value_type)1.0)/exp((value_type)1) - sin((value_type)1.0)/exp((value_type)1); //-0.110793765307;
mu::console() << parser.GetExpr() << _T("\n");
mu::console() << _T("v1 = ") << v1 << _T("; v1-v3 = ") << v1-v3 << _T("\n");
mu::console() << _T("v2 = ") << v2 << _T("; v2-v3 = ") << v2-v3 << _T("\n");
}
*/
//---------------------------------------------------------------------------
void ListVar(const mu::ParserBase &parser)
{
// Query the used variables (must be done after calc)
mu::varmap_type variables = parser.GetVar();
if (!variables.size())
return;
cout << "\nParser variables:\n";
cout << "-----------------\n";
cout << "Number: " << (int)variables.size() << "\n";
varmap_type::const_iterator item = variables.begin();
for (; item!=variables.end(); ++item)
mu::console() << _T("Name: ") << item->first << _T(" Address: [0x") << item->second << _T("]\n");
}
//---------------------------------------------------------------------------
void ListConst(const mu::ParserBase &parser)
{
mu::console() << _T("\nParser constants:\n");
mu::console() << _T("-----------------\n");
mu::valmap_type cmap = parser.GetConst();
if (!cmap.size())
{
mu::console() << _T("Expression does not contain constants\n");
}
else
{
valmap_type::const_iterator item = cmap.begin();
for (; item!=cmap.end(); ++item)
mu::console() << _T(" ") << item->first << _T(" = ") << item->second << _T("\n");
}
}
//---------------------------------------------------------------------------
void ListExprVar(const mu::ParserBase &parser)
{
string_type sExpr = parser.GetExpr();
if (sExpr.length()==0)
{
cout << _T("Expression string is empty\n");
return;
}
// Query the used variables (must be done after calc)
mu::console() << _T("\nExpression variables:\n");
mu::console() << _T("---------------------\n");
mu::console() << _T("Expression: ") << parser.GetExpr() << _T("\n");
varmap_type variables = parser.GetUsedVar();
if (!variables.size())
{
mu::console() << _T("Expression does not contain variables\n");
}
else
{
mu::console() << _T("Number: ") << (int)variables.size() << _T("\n");
mu::varmap_type::const_iterator item = variables.begin();
for (; item!=variables.end(); ++item)
mu::console() << _T("Name: ") << item->first << _T(" Address: [0x") << item->second << _T("]\n");
}
}
//---------------------------------------------------------------------------
/** \brief Check for external keywords.
*/
int CheckKeywords(const mu::char_type *a_szLine, mu::Parser &a_Parser)
{
string_type sLine(a_szLine);
if ( sLine == _T("quit") )
{
return -1;
}
else if ( sLine == _T("list var") )
{
ListVar(a_Parser);
return 1;
}
else if ( sLine == _T("opt on") )
{
a_Parser.EnableOptimizer(true);
mu::console() << _T("Optimizer enabled\n");
return 1;
}
else if ( sLine == _T("opt off") )
{
a_Parser.EnableOptimizer(false);
mu::console() << _T("Optimizer disabled\n");
return 1;
}
else if ( sLine == _T("list const") )
{
ListConst(a_Parser);
return 1;
}
else if ( sLine == _T("list exprvar") )
{
ListExprVar(a_Parser);
return 1;
}
else if ( sLine == _T("list const") )
{
ListConst(a_Parser);
return 1;
}
else if ( sLine == _T("locale de") )
{
mu::console() << _T("Setting german locale: ArgSep=';' DecSep=',' ThousandsSep='.'\n");
a_Parser.SetArgSep(';');
a_Parser.SetDecSep(',');
a_Parser.SetThousandsSep('.');
return 1;
}
else if ( sLine == _T("locale en") )
{
mu::console() << _T("Setting english locale: ArgSep=',' DecSep='.' ThousandsSep=''\n");
a_Parser.SetArgSep(',');
a_Parser.SetDecSep('.');
a_Parser.SetThousandsSep();
return 1;
}
else if ( sLine == _T("locale reset") )
{
mu::console() << _T("Resetting locale\n");
a_Parser.ResetLocale();
return 1;
}
else if ( sLine == _T("test bulk") )
{
mu::console() << _T("Testing bulk mode\n");
CalcBulk();
return 1;
}
return 0;
}
//---------------------------------------------------------------------------
void CalcBulk()
{
const int nBulkSize = 200;
value_type *x = new value_type[nBulkSize];
value_type *y = new value_type[nBulkSize];
value_type *result = new value_type[nBulkSize];
try
{
for (int i=0; i<nBulkSize; ++i)
{
x[i] = i;
y[i] = (value_type)i/10;
}
mu::Parser parser;
parser.DefineVar(_T("x"), x);
parser.DefineVar(_T("y"), y);
parser.DefineFun(_T("fun1"), BulkFun1);
parser.SetExpr(_T("fun1(0)+x+y"));
parser.Eval(result, nBulkSize);
for (int i=0; i<nBulkSize; ++i)
{
mu::console() << _T("Eqn. ") << i << _T(": x=") << x[i] << _T("; y=") << y[i] << _T("; result=") << result[i] << _T("\n");
}
}
catch(...)
{
delete [] x;
delete [] y;
delete [] result;
throw;
}
delete [] x;
delete [] y;
delete [] result;
}
//---------------------------------------------------------------------------
void Calc()
{
mu::Parser parser;
// Change locale settings if necessary
// function argument separator: sum(2;3;4) vs. sum(2,3,4)
// decimal separator: 3,14 vs. 3.14
// thousands separator: 1000000 vs 1.000.000
//#define USE_GERMAN_LOCALE
#ifdef USE_GERMAN_LOCALE
parser.SetArgSep(';');
parser.SetDecSep(',');
parser.SetThousandsSep('.');
#else
// this is the default, so i it's commented:
//parser.SetArgSep(',');
//parser.SetDecSep('.');
//parser.SetThousandsSep('');
#endif
// Add some variables
value_type vVarVal[] = { 1, 2 }; // Values of the parser variables
parser.DefineVar(_T("a"), &vVarVal[0]); // Assign Variable names and bind them to the C++ variables
parser.DefineVar(_T("b"), &vVarVal[1]);
parser.DefineStrConst(_T("strBuf"), _T("hello world") );
parser.AddValIdent(IsHexValue);
// Add user defined unary operators
parser.DefinePostfixOprt(_T("M"), Mega);
parser.DefinePostfixOprt(_T("m"), Milli);
parser.DefineInfixOprt(_T("!"), Not);
parser.DefineFun(_T("strfun0"), StrFun0);
parser.DefineFun(_T("strfun2"), StrFun2);
parser.DefineFun(_T("ping"), Ping);
parser.DefineFun(_T("rnd"), Rnd); // Add an unoptimizeable function
parser.DefineFun(_T("throw"), ThrowAnException);
parser.DefineOprt(_T("add"), Add, 0);
parser.DefineOprt(_T("mul"), Mul, 1);
// These are service and debug functions
parser.DefineFun(_T("debug"), Debug);
parser.DefineFun(_T("selftest"), SelfTest);
parser.DefineFun(_T("help"), Help);
#ifdef _DEBUG
// parser.EnableDebugDump(1, 0);
#endif
// Define the variable factory
parser.SetVarFactory(AddVariable, &parser);
for(;;)
{
try
{
string_type sLine;
std::getline(mu::console_in(), sLine);
switch (CheckKeywords(sLine.c_str(), parser))
{
case 0: break;
case 1: continue;
case -1: return;
}
if (!sLine.length())
continue;
parser.SetExpr(sLine);
mu::console() << std::setprecision(12);
// There are multiple ways to retrieve the result...
// 1.) If you know there is only a single return value or in case you only need the last
// result of an expression consisting of comma separated subexpressions you can
// simply use:
mu::console() << _T("ans=") << parser.Eval() << _T("\n");
// 2.) As an alternative you can also retrieve multiple return values using this API:
int nNum = parser.GetNumResults();
if (nNum>1)
{
mu::console() << _T("Multiple return values detected! Complete list:\n");
// this is the hard way if you need to retrieve multiple subexpression
// results
value_type *v = parser.Eval(nNum);
mu::console() << std::setprecision(12);
for (int i=0; i<nNum; ++i)
{
mu::console() << v[i] << _T("\n");
}
}
}
catch(mu::Parser::exception_type &e)
{
mu::console() << _T("\nError:\n");
mu::console() << _T("------\n");
mu::console() << _T("Message: ") << e.GetMsg() << _T("\n");
mu::console() << _T("Expression: \"") << e.GetExpr() << _T("\"\n");
mu::console() << _T("Token: \"") << e.GetToken() << _T("\"\n");
mu::console() << _T("Position: ") << (int)e.GetPos() << _T("\n");
mu::console() << _T("Errc: ") << std::dec << e.GetCode() << _T("\n");
}
} // while running
}
//---------------------------------------------------------------------------
int main(int, char**)
{
Splash();
SelfTest();
Help();
// CheckLocale();
// CheckDiff();
mu::console() << _T("Enter an expression or a command:\n");
try
{
Calc();
}
catch(Parser::exception_type &e)
{
// Only erros raised during the initialization will end up here
// formula related errors are treated in Calc()
console() << _T("Initialization error: ") << e.GetMsg() << endl;
console() << _T("aborting...") << endl;
string_type sBuf;
console_in() >> sBuf;
}
catch(std::exception & /*exc*/)
{
// there is no unicode compliant way to query exc.what()
// so i'll leave it for this example.
console() << _T("aborting...\n");
}
return 0;
}
|
Create a block and open the example block:
$ bii init my_project
$ cd my_project
$ bii open examples/muparser
The main.cpp
file is now in your block. Now you just have to build it and run the executable:
$ bii build
$ cd bin
$ # run executable
You will see next console output after executing the command:
__________
_____ __ __\______ \_____ _______ ______ ____ _______
/ \ | | \| ___/\__ \ \_ __ \/ ___/_/ __ \\_ __ \
| Y Y \| | /| | / __ \_| | \/\___ \ \ ___/ | | \/
|__|_| /|____/ |____| (____ /|__| /____ > \___ >|__|
\/ \/ \/ \/
Version 2.2.3 (20121222; SF; 64BIT; RELEASE; ASCII)
(C) 2013 Ingo Berg
-----------------------------------------------------------
Running test suite:
testing name restriction enforcement...passed
testing syntax engine...passed
testing postfix operators...
fail: 1000{m} (Unexpected token "1000" found at position 0.)
fail: 1000 {m} (Unexpected token "1000" found at position 0.)
fail: f1of1(1000){m} (Unexpected token "1000" found at position 6.)
fail: -f1of1(1000){m} (Unexpected token "1000" found at position 7.)
fail: -f1of1(-1000){m} (Unexpected token "1000" found at position 8.)
fail: f4of4(0,0,0,1000){m} (Unexpected token "1000" found at position 12.)
fail: 2+(a*1000){m} (Unexpected token "1000" found at position 5.)
fail: 2*3000meg+2 (Unexpected token "3000meg" found at position 2.)
failed with 8 errors
testing infix operators...passed
testing variable/constant detection...passed
testing multiarg functions...passed
testing expression samples...passed
testing if-then-else operator...passed
testing member functions...passed
testing binary operators...passed
testing error codes...passed
testing string arguments...passed
Test failed with 8 errors (527 expressions)
-----------------------------------------------------------
Commands:
list var - list parser variables
list exprvar - list expression variables
list const - list all numeric parser constants
opt on - enable optimizer (default)
opt off - disable optimizer
locale de - switch to german locale
locale en - switch to english locale
locale reset - reset locale
test bulk - test bulk mode
quit - exits the parser
Constants:
"_e" 2.718281828459045235360287
"_pi" 3.141592653589793238462643
-----------------------------------------------------------
Enter an expression or a command:
You can now start typing mathematical expressions in the console.
Any doubts? Do not hesitate to contact us visit our forum and feel free to ask any questions.