PUserFcnBase.cpp File Reference

#include <vector>
#include <fstream>
#include "PUserFcnBase.h"

Include dependency graph for PUserFcnBase.cpp:

Go to the source code of this file.

Functions
	ClassImp (PUserFcnBase) Int_t parseXmlFile(TSAXParser *saxParser
	Parses an XML file using buffer-based parsing for better compatibility.
xmlFile	open (startup_path_name, std::ios::in|std::ios::ate)
	if (xmlFile.is_open())
	if (!xmlBuffer)

Variables
const char *	startup_path_name
std::fstream	xmlFile
UInt_t	xmlSize = 0
Char_t *	xmlBuffer = nullptr
	else
return	status
std::vector< void * >	gGlobalUserFcn
	Global storage for user function objects requiring persistent state.

Function Documentation

ClassImp()

ClassImp

(

PUserFcnBase

)

Parses an XML file using buffer-based parsing for better compatibility.

This function provides a replacement for TSAXParser::ParseFile() that works reliably across different environments. Some systems have issues with direct file parsing, but buffer-based parsing (ParseBuffer) works consistently.

Usage in User Functions

User functions that need to read XML configuration files should use this function instead of TSAXParser::ParseFile():

class TMyConfigurableFcn : public PUserFcnBase {
  private:
    MyConfigHandler fHandler;  // Derived from TSAXParser callbacks
 
  public:
    Bool_t LoadConfig(const char* configFile) {
        TSAXParser parser;
        parser.ConnectToHandler("MyConfigHandler", &fHandler);
 
        Int_t status = parseXmlFile(&parser, configFile);
        if (status != 0) {
            std::cerr << "Failed to parse config: " << configFile << std::endl;
            return false;
        }
        return true;
    }
};

Algorithm

1. Opens the file in binary mode, seeking to end
2. Determines file size from stream position
3. Allocates buffer and reads entire file
4. Passes buffer to TSAXParser::ParseBuffer()
5. Cleans up buffer memory

Parameters

saxParser	Pointer to a configured TSAXParser object. The parser should have its handler connected before calling this function.
startup_path_name	Full filesystem path to the XML file to parse.

Returns

Status code:

• 0: Success - file parsed without errors
• 1: File error - could not open or read the file
• >1: XML parse error from TSAXParser::ParseBuffer()

See also

PStartupHandler for an example of XML parsing in musrfit

TSAXParser for ROOT's SAX parser documentation

if() [1/2]

if

(

!

xmlBuffer

)

Definition at line 105 of file PUserFcnBase.cpp.

References if(), status, and xmlBuffer.

if() [2/2]

if

(

xmlFile.

is_open()

)

Definition at line 98 of file PUserFcnBase.cpp.

References xmlFile.

open()

xmlFile open	(	startup_path_name	,
		std::ios::in|std::ios::ate	)

References startup_path_name, and xmlFile.

Variable Documentation

else

else

Initial value:

{
    status = saxParser->ParseBuffer(xmlBuffer, xmlSize)

Definition at line 107 of file PUserFcnBase.cpp.

gGlobalUserFcn

std::vector<void *> gGlobalUserFcn

Global storage for user function objects requiring persistent state.

This vector provides a global container for user functions that need to maintain state across multiple evaluations or share data between runs. It is primarily used by user functions implementing the "global part" interface (NeedGlobalPart(), SetGlobalPart(), GlobalPartIsValid()).

Usage Pattern

User functions with expensive initialization (lookup tables, precomputed grids, loaded data files) store their global objects here:

// In user function's SetGlobalPart implementation:
void TMyFcn::SetGlobalPart(std::vector<void*> &globalPart, UInt_t idx) {
    if (idx < globalPart.size() && globalPart[idx] != nullptr) {
        fGlobal = static_cast<MyGlobalData*>(globalPart[idx]);
    } else {
        fGlobal = new MyGlobalData();
        fGlobal->Initialize();  // Expensive one-time computation
        if (idx < globalPart.size())
            globalPart[idx] = fGlobal;
        else
            globalPart.push_back(fGlobal);
    }
}

Note

The vector stores void pointers, so user functions must cast appropriately and manage memory for their specific data types.

Warning

User functions are responsible for proper cleanup of their global objects to avoid memory leaks.

See also

PUserFcnBase::SetGlobalPart() for the interface to populate this vector

PTheory for how global parts are initialized during theory setup

Definition at line 155 of file PUserFcnBase.cpp.

Referenced by PTheory::PTheory(), and PTheory::~PTheory().

startup_path_name

const char* startup_path_name

Initial value:

{
  Int_t status

Definition at line 90 of file PUserFcnBase.cpp.

status

return status

Definition at line 113 of file PUserFcnBase.cpp.

xmlBuffer

xmlBuffer = nullptr

Definition at line 95 of file PUserFcnBase.cpp.

xmlFile

std::fstream xmlFile

Definition at line 93 of file PUserFcnBase.cpp.

xmlSize

UInt_t xmlSize = 0

Definition at line 94 of file PUserFcnBase.cpp.