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2 garren 1 //--------------------------------------------------------------------------
2 #ifndef HEPMC_FLOW_H
3 #define HEPMC_FLOW_H
4  
5 //////////////////////////////////////////////////////////////////////////
6 // Matt.Dobbs@Cern.CH, January 2000, refer to:
7 // M. Dobbs and J.B. Hansen, "The HepMC C++ Monte Carlo Event Record for
8 // High Energy Physics", Computer Physics Communications (to be published).
9 //
10 // particle's flow object
11 // keeps track of an arbitrary number of flow patterns within a graph
12 // (i.e. color flow, charge flow, lepton number flow, ...)
13 // Flow patterns are coded with an integer, in the same manner as in Herwig.
14 // Note: 0 is NOT allowed as code index nor as flow code since it
15 //       is used to indicate null.
16 //////////////////////////////////////////////////////////////////////////
17  
18 // This class can be used to keep track of flow patterns within
19 //  a graph. An example is color flow. If we have two quarks going through
20 //  an s-channel gluon to form two more quarks:
21 //
22 //  \q1       /q3   then we can keep track of the color flow with the
23 //   \_______/      HepMC::Flow class as follows:
24 //   /   g   \.
25 //  /q2       \q4
26 //
27 //  lets say the color flows from q2-->g-->q3  and q1-->g-->q4
28 //  the individual colors are unimportant, but the flow pattern is.
29 //  We can capture this flow by assigning the first pattern (q2-->g-->q3)
30 //  a unique (arbitrary) flow code 678 and the second pattern (q1-->g-->q4)
31 //  flow code 269  ( you can ask HepMC::Flow to choose
32 //  a unique code for you using Flow::set_unique_icode() ).
33 //  The first two code indices are reserved for color codes, so we store
34 //  these codes with the particles as follows:
35 //    q2->flow().set_icode(1,678);
36 //    g->flow().set_icode(1,678);
37 //    q3->flow().set_icode(1,678);
38 //    q1->flow().set_icode(1,269);
39 //    g->flow().set_icode(2,269);
40 //    q4->flow().set_icode(1,269);
41 //  later on if we wish to know the color partner of q1 we can ask for a list
42 //  of all particles connected via this code to q1 which do have less than
43 //  2 color partners using:
44 //    set<GenParticle*> result=q1->dangling_connected_partners(q1->icode(1),1,2);
45 //  this will return a list containing q1 and q4.
46 //    set<GenParticle*> result=q1->connected_partners(q1->icode(1),1,2);
47 //  would return a list containing q1, g, and q4.
48 //
49  
50 #include <iostream>
51 #include <map>
52 #include <set>
53  
54 namespace HepMC {
55  
56     class GenParticle;
57  
58     class Flow {
59  
60         friend std::ostream& operator<<( std::ostream& ostr, const Flow& f );
61  
62     public:
63         Flow( GenParticle* particle_owner = 0 );
64         Flow( const Flow& );
65         virtual         ~Flow();
66         Flow&           operator=( const Flow& );
67         bool            operator==( const Flow& a ) const; //compares only flow
68         bool            operator!=( const Flow& a ) const; //patterns not owner
69  
70         void            print( std::ostream& ostr = std::cout ) const;
71  
72         // returns all connected particles which have "code" in any  of the
73         //  num_indices beginning with index code_index.
74         std::set<GenParticle*> connected_partners( int code, int code_index =1,
75                                                    int num_indices = 2 ) const;
76         // same as connected_partners, but returns only those particles which
77         //  are connected to <=1 other particles (i.e. the flow line "dangles"
78         //  at these particles)
79         std::set<GenParticle*> dangling_connected_partners( int code,
80                                int code_index = 1, int num_indices = 2 ) const;
81  
82         ////////////////////
83         // access methods //
84         ////////////////////
85         const GenParticle* particle_owner() const;
86         int             icode( int code_index = 1 ) const;
87         Flow            set_icode( int code_index, int code );
88         Flow            set_unique_icode( int code_index = 1 );
89  
90         //////////////////////
91         // container access //
92         //////////////////////
93  
94         bool            empty() const;
95         int             size() const;
96         void            clear();
97         bool            erase( int code_index );
98  
99         typedef std::map<int,int>::iterator       iterator;
100         typedef std::map<int,int>::const_iterator const_iterator;
101         iterator            begin();
102         iterator            end();
103         const_iterator      begin() const;
104         const_iterator      end() const;
105  
106     protected: // intended for internal use only
107         void            connected_partners( std::set<GenParticle*>* output,
108                                             int code,
109                                             int code_index,
110                                             int num_indices ) const;
111         void            dangling_connected_partners( std::set<GenParticle*>*
112                                                      output,
113                                                      std::set<GenParticle*>*
114                                                      visited_particles,
115                                                      int code, int code_index,
116                                                      int num_indices ) const;
117     private:
118         GenParticle*         m_particle_owner;
119         std::map<int,int> m_icode; // stores flow patterns as(code_index,icode)
120     };  
121  
122     ///////////////////////////
123     // INLINE Access Methods //
124     ///////////////////////////
125  
126     inline const GenParticle* Flow::particle_owner() const {
127         return m_particle_owner;
128     }
129     inline int Flow::icode( int code_index ) const {
130         std::map<int,int>::const_iterator a = m_icode.find(code_index);
131         return a==m_icode.end() ? 0 : (*a).second;
132     }
133     inline Flow Flow::set_icode( int code_index, int code ) {
134         m_icode[code_index] = code;
135         return *this;
136     }
137     inline Flow Flow::set_unique_icode( int flow_num ) {
138         // use this method if you want to assign a unique flow code, but
139         // do not want the burden of choosing it yourself
31 garren 140         m_icode[flow_num] = size_t(this);
2 garren 141         return *this;
142     }
143     inline bool Flow::empty() const { return (bool)m_icode.empty(); }
144     inline int Flow::size() const { return (int)m_icode.size(); }
145     inline void Flow::clear() { m_icode.clear(); }
146     inline bool Flow::erase( int code_index ) {
147         return (bool)m_icode.erase( code_index );
148     }
149     inline Flow::iterator Flow::begin() { return m_icode.begin(); }
150     inline Flow::iterator Flow::end() { return m_icode.end(); }
151     inline Flow::const_iterator Flow::begin() const { return m_icode.begin(); }
152     inline Flow::const_iterator Flow::end() const { return m_icode.end(); }
153  
154     ///////////////////////////
155     // INLINE Operators      //
156     ///////////////////////////
157  
158     inline bool Flow::operator==( const Flow& a ) const {
159         // equivalent flows have the same flow codes for all flow_numbers
160         // (i.e. their m_icode maps are identical), but they need not have the
161         // same m_particle owner
162         return (m_icode == a.m_icode);
163     }
164     inline bool Flow::operator!=( const Flow& a ) const {
165         return !( *this == a );
166     }
167     inline Flow& Flow::operator=( const Flow& inflow ) {
168         // copies only the m_icode ... not the particle_owner
169         // this is intuitive behaviour so you can do
170         // oneparticle->flow() = otherparticle->flow()
171         //
172         m_icode = inflow.m_icode;
173         return *this;
174     }
175  
176 } // HepMC
177  
178 #endif  // HEPMC_FLOW_H
179 //--------------------------------------------------------------------------
180