PythiaStdlib.h

// PythiaStdlib.h is a part of the PYTHIA event generator.
// Copyright (C) 2026 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.

// Header file for functionality pulled in from Stdlib,
// plus a few useful utilities (small powers; positive square root,
// convert strings to lowercase, Gamma function).

#ifndef Pythia8_PythiaStdlib_H
#define Pythia8_PythiaStdlib_H

// Stdlib header files for mathematics.
#include <cstddef>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <memory>
#include <functional>
#include <limits>
#include <utility>

// Stdlib header files for strings and containers.
#include <string>
#include <vector>
#include <array>
#include <valarray>
#include <map>
#include <unordered_map>
#include <deque>
#include <queue>
#include <set>
#include <list>
#include <functional>

// Stdlib header file for dynamic library loading.
#include <dlfcn.h>

// Stdlib header file for input and output.
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>

// Thread header files.
#include <mutex>
#include <atomic>
#include <thread>

// Handle floating point exceptions.
#include "Pythia8/PythiaFpe.h"

// Define pi if not yet done.
#ifndef M_PI
#define M_PI 3.1415926535897932385
#endif

// Define the default subrun.
#ifndef SUBRUNDEFAULT
#define SUBRUNDEFAULT -999
#endif

// By this declaration you do not need to use std:: qualifier everywhere.
// using namespace std;

// Alternatively you can specify exactly which std:: methods will be used.
// Now made default so std does not spill outside namespace Pythia8.
namespace Pythia8 {

// Generic utilities and mathematical functions.
using std::swap;
using std::max;
using std::min;
using std::abs;
using std::sort;
using std::function;
using std::isnan;
using std::isinf;
using std::isfinite;
using std::numeric_limits;

// Strings and containers.
using std::pair;
using std::make_pair;
using std::string;
using std::to_string;
using std::vector;
using std::array;
using std::valarray;
using std::map;
using std::multimap;
using std::unordered_map;
using std::deque;
using std::priority_queue;
using std::set;
using std::multiset;
using std::list;
using std::tuple;
using std::function;
using std::fill;
using std::end;
using std::begin;

// Input/output streams.
using std::cin;
using std::cout;
using std::cerr;
using std::streambuf;
using std::istream;
using std::ostream;
using std::fstream;
using std::ifstream;
using std::ofstream;
using std::stringstream;
using std::istringstream;
using std::ostringstream;
using std::ios;

// Input/output formatting.
using std::endl;
using std::fixed;
using std::scientific;
using std::left;
using std::right;
using std::setw;
using std::setprecision;

// Pointers
using std::shared_ptr;
using std::weak_ptr;
using std::unique_ptr;
using std::dynamic_pointer_cast;
using std::make_shared;

// Threading.
using std::queue;
using std::mutex;
using std::thread;
using std::atomic;
using std::lock_guard;

} // end namespace Pythia8

namespace Pythia8 {

// Define conversion hbar * c = 0.2 GeV * fm = 1 and related.
constexpr double HBARC     = 0.19732698;
constexpr double GEV2FMINV = 1. / HBARC;
constexpr double GEVINV2FM = HBARC;
constexpr double FM2GEVINV = 1./HBARC;
constexpr double FMINV2GEV = HBARC;

// Define conversion (hbar * c)^2 = 0.4 GeV^2 * mb = 1 and related.
constexpr double HBARCSQ     = 0.38937937;
constexpr double GEVSQ2MBINV = 1. / HBARCSQ;
constexpr double GEVSQINV2MB = HBARCSQ;
constexpr double MB2GEVSQINV = 1. / HBARCSQ;
constexpr double MBINV2GEVSQ = HBARCSQ;

// Define conversion between fm and mm, in both directions.
constexpr double FM2MM   = 1e-12;
constexpr double MM2FM   = 1e12;

// Define conversion between mb and pb or fb, in both directions.
constexpr double MB2PB   = 1e9;
constexpr double PB2MB   = 1e-9;
constexpr double MB2FB   = 1e12;
constexpr double FB2MB   = 1e-12;

// Define conversion between fm^2 and mb, in both directions.
constexpr double FMSQ2MB = 10.;
constexpr double MB2FMSQ = 0.1;

// Powers of small integers - for balance speed/code clarity.
constexpr double pow2(const double& x) {return x*x;}
constexpr double pow3(const double& x) {return x*x*x;}
constexpr double pow4(const double& x) {return x*x*x*x;}
constexpr double pow5(const double& x) {return x*x*x*x*x;}
constexpr double pow6(const double& x) {return x*x*x*x*x*x;}
constexpr double pow7(const double& x) {return x*x*x*x*x*x*x;}
constexpr double pow8(const double& x) {return x*x*x*x*x*x*x*x;}

// Avoid problem with negative square root argument (from roundoff).
inline double sqrtpos(const double& x) {return sqrt( max( 0., x));}

// Explicitly return NaN if negative square root argument, without FPE.
inline double sqrtnan(const double& x) {
  return x > 0 ? sqrt(x) : numeric_limits<double>::quiet_NaN(); }

// Restrinct value to lie in specified range.
inline double clamp(const double& x, const double& xmin, const double& xmax) {
  return (x < xmin) ? xmin : (x > xmax) ? xmax : x; }

// Convert a string to lowercase for case-insensitive comparisons.
// By default remove any initial and trailing blanks or escape characters.
string toLower(const string& name, bool trim = true);

// Variant of above, with in-place replacement.
inline void toLowerRep(string& name, bool trim = true) {
  name = toLower( name, trim);}

// Remove any initial and trailing blanks or escape characters.
string trimString(const string& name);

// Variant of above, with in-place replacement.
inline void trimStringRep(string& name) {
  name = trimString( name);}

// Convert a boolean to a string.
inline string toString(bool val) {return val ? "on" : "off";}

// Convert an integer to a string.
inline string toString(int val) {return to_string(val);}

// Convert a double to a string.
string toString(double val);

// Split a string by a delimiter.
vector<string> splitString(string val, string delim);

// Useful functions for string handling.
bool   boolString(string tag);
string attributeValue(string line, string attribute);
bool   boolAttributeValue(string line, string attribute);
int    intAttributeValue(string line, string attribute);
double doubleAttributeValue(string line, string attribute);
vector<bool>   boolVectorAttributeValue(string line, string attribute);
vector<int>    intVectorAttributeValue(string line, string attribute);
vector<double> doubleVectorAttributeValue(string line, string attribute);
vector<string> stringVectorAttributeValue(string line, string attribute);
void completeTag(istream& stream, string& line);

//==========================================================================

// Print a method name using the appropriate pre-processor macro.

//  The following method was modified from
//  boost/current_function.hpp - BOOST_CURRENT_FUNCTION
//
//  Copyright (c) 2002 Peter Dimov and Multi Media Ltd.
//
//  Distributed under the Boost Software License, Version 1.0.
//  Boost Software License - Version 1.0 - August 17th, 2003
//
//  Permission is hereby granted, free of charge, to any person or
//  organization obtaining a copy of the software and accompanying
//  documentation covered by this license (the "Software") to use,
//  reproduce, display, distribute, execute, and transmit the
//  Software, and to prepare derivative works of the Software, and to
//  permit third-parties to whom the Software is furnished to do so,
//  all subject to the following:
//
//  The copyright notices in the Software and this entire statement,
//  including the above license grant, this restriction and the
//  following disclaimer, must be included in all copies of the
//  Software, in whole or in part, and all derivative works of the
//  Software, unless such copies or derivative works are solely in the
//  form of machine-executable object code generated by a source
//  language processor.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
//  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
//  NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
//  ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR
//  OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//  OTHER DEALINGS IN THE SOFTWARE.
//
//  http://www.boost.org/libs/utility/current_function.html
//
//  Note that Boost Software License - Version 1.0 is fully compatible
//  with GPLV2
//  For more information see https://www.gnu.org/licenses/license-list.en.html

#ifndef __METHOD_NAME__

#ifndef PYTHIA_FUNCTION
#if ( defined(__GNUC__) || (defined(__MWERKS__) && (__MWERKS__ >= 0x3000)) \
|| (defined(__ICC) && (__ICC >= 600)) )
# define PYTHIA_FUNCTION __PRETTY_FUNCTION__
#elif defined(__DMC__) && (__DMC__ >= 0x810)
# define PYTHIA_FUNCTION __PRETTY_FUNCTION__
#elif defined(__FUNCSIG__)
# define PYTHIA_FUNCTION __FUNCSIG__
#elif ( (defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 600)) \
|| (defined(__IBMCPP__) && (__IBMCPP__ >= 500)) )
# define PYTHIA_FUNCTION __FUNCTION__
#elif defined(__BORLANDC__) && (__BORLANDC__ >= 0x550)
# define PYTHIA_FUNCTION __FUNC__
#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901)
# define PYTHIA_FUNCTION __func__
#else
# define PYTHIA_FUNCTION "unknown"
#endif
#endif // end PYTHIA_FUNCTION

inline std::string methodName(const std::string& prettyFunction, bool
  withNamespace=false) {

  // Find the beginning of the argument list.
  size_t end = prettyFunction.rfind(')');
  int bracketCount = 1;
  while (bracketCount > 0) {
    --end;
    if (prettyFunction[end] == ')') ++bracketCount;
    else if (prettyFunction[end] == '(') --bracketCount;
  }

  // Find the start of the function name.
  size_t begin = prettyFunction.rfind(' ', end) + 1;
  if (!withNamespace)
    begin = prettyFunction.find("::", begin) + 2;

  // Return the correct substring.
  return prettyFunction.substr(begin, end - begin);
}

#define __METHOD_NAME__ methodName(PYTHIA_FUNCTION)
#endif // __METHOD_NAME__

//==========================================================================

} // end namespace Pythia8

// Define the hash for a pair.
namespace std {
  template <class T1, class T2> struct hash<pair<T1, T2> > {
  public:
    size_t operator()(const pair<T1, T2>& p) const {
      return hash<T1>{}(p.first) ^ hash<T2>{}(p.second);
    }
  };

//==========================================================================

} // end namespace std

#endif // Pythia8_PythiaStdlib_H