This is a helper class for the MCDecayFinderModule. More...

#include <DecayTree.h>

Public Member Functions
	DecayTree ()
	Default constructor.

	~DecayTree ()
	Destructor.

std::vector< DecayTree< T > * >	getDaughters () const
	Return list of decay daughters.

T *	getObj () const
	Return the decaying object itself, e.g.

void	setObj (T *obj)
	Set the decaying object, e.g.

void	append (DecayTree< T > *t)
	Add a daughter, which is a DecayTree itself.

	DecayTree (const std::string &decaystring, bool removeRadiativeGammaFlag=false)
	Create a new Decay tree from a decaystring.

	DecayTree (const DecayTree &tree)
	Copy constructor Required because we need to rebuild the node cache.

DecayTree &	operator= (const DecayTree &tree)
	Assign operator Required because we need to rebuild the node cache.

std::vector< DecayNode >	build_tree (const std::string &decaystring, bool removeRadiativeGammaFlag)
	Recursively build a new tree.

bool	find_decay (const DecayTree &tree) const
	Check if the decay tree contains the given decay tree.

std::string	to_string () const
	Output string representation of DecayTree.

int	getMatchSymbolPosition () const
	Returns position of match symbol.

bool	isValid () const
	Returns if the decay tree is valid (constructed from a decay string which has a match)

const DecayNode &	getDecayNode (unsigned int n) const
	Returns n-th node as const.

DecayNode &	getDecayNode (unsigned int n)
	Returns n-th node.

size_t	getNumberOfDecayNodes () const
	Return number of nodes in this tree.

Private Member Functions
void	build_cache (DecayNode &node)
	Build nodes_cache in order of appearance in the decay string for fast access.

Private Attributes
T *	m_myObject
	The decaying object, e.g.

std::vector< DecayTree< T > * >	m_daughters
	Decay daughters of m_myObject.

bool	m_valid
	True if the tree is valid (invalid can happen if is constructed from a node with "No match")

size_t	m_i
	Current position in the building of the DecayTree.

unsigned int	m_token_count
	Count current tokens.

int	m_match_symbol_position
	Position of the token with the match symbol ^.

DecayNode	m_root_node
	root DecayNode

std::vector< DecayNode * >	m_nodes_cache
	Vector of decay nodes of the particles in the order of their appearance in the decay string for fast access.

Detailed Description

template<class T>
class Belle2::DecayTree< T >

This is a helper class for the MCDecayFinderModule.

Consists of a tree of DecayNodes Can be constructed from the output of the ParticleMCDecayString module.

It is designed to hold MCParticle objects when trying to match a given DecayString.

Definition at line 20 of file DecayTree.h.

Constructor & Destructor Documentation

◆ DecayTree() [1/2]

DecayTree	(	const std::string &	decaystring,
		bool	removeRadiativeGammaFlag = `false`
	)

explicit

Create a new Decay tree from a decaystring.

Definition at line 16 of file DecayTree.cc.

                                                                                : m_i(0), m_token_count(0),
  m_match_symbol_position(-1)
{
 
  m_valid = decaystring.find("No match") == std::string::npos;
  if (m_valid) {
    const auto& root_nodes = this->build_tree(decaystring, removeRadiativeGammaFlag);
    if (root_nodes.size() == 1) {
      m_root_node = root_nodes[0];
      // Build cache
      build_cache(m_root_node);
    } else
      m_valid = false;
  }
}

◆ DecayTree() [2/2]

DecayTree ( const DecayTree< T > & tree )

Copy constructor Required because we need to rebuild the node cache.

Definition at line 32 of file DecayTree.cc.

                                         :
  m_root_node(tree.m_root_node)
{
  m_valid = tree.m_valid;
  m_token_count = tree.m_token_count;
  m_match_symbol_position = tree.m_match_symbol_position;
  m_i = tree.m_i;
 
  if (m_valid) {
    build_cache(m_root_node);
  }
}

Member Function Documentation

◆ build_cache()

void build_cache ( DecayNode & node )

private

Build nodes_cache in order of appearance in the decay string for fast access.

Parameters

node	current node

Definition at line 60 of file DecayTree.cc.

{
  m_nodes_cache.push_back(&node);
  for (auto& daughter : node.daughters) {
    build_cache(daughter);
  }
}

◆ build_tree()

std::vector< DecayNode > build_tree	(	const std::string &	decaystring,
		bool	removeRadiativeGammaFlag
	)

Recursively build a new tree.

Parameters

decaystring	as outputted by the ParticleMCDecayString module (after splitting by \| )
removeRadiativeGammaFlag	remove radiative photons from decay string. Handle with care: In the decay B+ --> e+ nu_e gamma, the gamma would be removed although this might be your signal.

Definition at line 69 of file DecayTree.cc.

{
 
  const unsigned int N = decaystring.size();
  std::vector<DecayNode> nodes;
  nodes.reserve(5);
 
  for (; m_i < N; ++m_i) {
    // Skip ' ', '^' and "->"
    if (decaystring[m_i] == ' ' or decaystring[m_i] == '>' or (m_i + 1 < N and decaystring[m_i] == '-'
                                                               and decaystring[m_i + 1] == '>')) {
      continue;
    }
 
    // Match symbol
    if (decaystring[m_i] == '^') {
      m_match_symbol_position = m_token_count;
      continue;
    }
 
    // Handle start of subdecay of the form X ( ... )
    if (decaystring[m_i] == '(') {
      m_i++;
      nodes.back().daughters = this->build_tree(decaystring, removeRadiativeGammaFlag);
      continue;
    }
 
    // Handle end of subdecay
    if (decaystring[m_i] == ')') {
      return nodes;
    }
 
    // Search end of token
    unsigned int j = m_i + 1;
    for (; j < N; ++j) {
      if (decaystring[j] == ' ' or decaystring[j] == ')' or decaystring[j] == '(')
        break;
    }
 
    // Parse token and add it as new node
    try {
      const int pdg = std::stoi(decaystring.substr(m_i, j - m_i));
      if (removeRadiativeGammaFlag) {
        if (nodes.size() < 2 or pdg != Const::photon.getPDGCode()) {
          nodes.emplace_back(pdg);
          m_token_count++;
        }
      } else {
        nodes.emplace_back(pdg);
        m_token_count++;
      }
      m_i = j - 1;
    } catch (const std::invalid_argument&) {
      // We ignore if the token cannot be parsed
    }
  }
 
  return nodes;
}

◆ find_decay()

bool find_decay ( const DecayTree< T > & tree ) const

Check if the decay tree contains the given decay tree.

Parameters

tree	DecayTree describing the decay

Definition at line 129 of file DecayTree.cc.

{
  return m_root_node.find_decay(tree.m_root_node);
}

◆ getDecayNode() [1/2]

DecayNode & getDecayNode ( unsigned int n )

Returns n-th node.

Parameters

n nth node

Definition at line 134 of file DecayTree.cc.

{
  return *(m_nodes_cache[n]);
}

◆ getDecayNode() [2/2]

const DecayNode & getDecayNode ( unsigned int n ) const

Returns n-th node as const.

Parameters

n nth node

Definition at line 139 of file DecayTree.cc.

{
  return *(m_nodes_cache[n]);
}

◆ getMatchSymbolPosition()

int getMatchSymbolPosition ( ) const

inline

Returns position of match symbol.

Definition at line 68 of file DecayTree.h.

68{ return m_match_symbol_position; }

◆ getNumberOfDecayNodes()

size_t getNumberOfDecayNodes ( ) const

inline

Return number of nodes in this tree.

Definition at line 90 of file DecayTree.h.

90{ return m_nodes_cache.size(); }

◆ isValid()

bool isValid ( ) const

inline

Returns if the decay tree is valid (constructed from a decay string which has a match)

Definition at line 73 of file DecayTree.h.

73{ return m_valid; }

◆ operator=()

DecayTree & operator= ( const DecayTree< T > & tree )

Assign operator Required because we need to rebuild the node cache.

Definition at line 45 of file DecayTree.cc.

{
  m_valid = tree.m_valid;
  m_token_count = tree.m_token_count;
  m_match_symbol_position = tree.m_match_symbol_position;
  m_root_node = tree.m_root_node;
  m_i = tree.m_i;
 
  if (m_valid) {
    build_cache(m_root_node);
  }
 
  return *this;
}

◆ to_string()

std::string to_string ( ) const

Output string representation of DecayTree.

Definition at line 145 of file DecayTree.cc.

{
  return m_root_node.print_node();
}

Member Data Documentation

◆ m_daughters

std::vector< DecayTree<T>* > m_daughters

private

Decay daughters of m_myObject.

Definition at line 25 of file DecayTree.h.

◆ m_i

size_t m_i

private

Current position in the building of the DecayTree.

Definition at line 101 of file DecayTree.h.

◆ m_match_symbol_position

int m_match_symbol_position

private

Position of the token with the match symbol ^.

Definition at line 103 of file DecayTree.h.

◆ m_myObject

T* m_myObject

private

The decaying object, e.g.

MCParticle.

Definition at line 23 of file DecayTree.h.

◆ m_nodes_cache

std::vector<DecayNode*> m_nodes_cache

private

Vector of decay nodes of the particles in the order of their appearance in the decay string for fast access.

Definition at line 106 of file DecayTree.h.

◆ m_root_node

DecayNode m_root_node

private

root DecayNode

Definition at line 104 of file DecayTree.h.

◆ m_token_count

unsigned int m_token_count

private

Count current tokens.

Definition at line 102 of file DecayTree.h.

◆ m_valid

bool m_valid

private

True if the tree is valid (invalid can happen if is constructed from a node with "No match")

Definition at line 100 of file DecayTree.h.

The documentation for this class was generated from the following files:

analysis/modules/MCDecayFinder/include/DecayTree.h
analysis/utility/include/DecayTree.h
analysis/utility/src/DecayTree.cc

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ DecayTree() [1/2]

◆ DecayTree() [2/2]

Member Function Documentation

◆ build_cache()

◆ build_tree()

◆ find_decay()

◆ getDecayNode() [1/2]

◆ getDecayNode() [2/2]

◆ getMatchSymbolPosition()

◆ getNumberOfDecayNodes()

◆ isValid()

◆ operator=()

◆ to_string()

Member Data Documentation

◆ m_daughters

◆ m_i

◆ m_match_symbol_position

◆ m_myObject

◆ m_nodes_cache

◆ m_root_node

◆ m_token_count

◆ m_valid