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TTreeReaderArray.h
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1// @(#)root/tree:$Id$
2// Author: Axel Naumann, 2010-08-02
3
4/*************************************************************************
5 * Copyright (C) 1995-2013, Rene Brun and Fons Rademakers. *
6 * All rights reserved. *
7 * *
8 * For the licensing terms see $ROOTSYS/LICENSE. *
9 * For the list of contributors see $ROOTSYS/README/CREDITS. *
10 *************************************************************************/
11
12#ifndef ROOT_TTreeReaderArray
13#define ROOT_TTreeReaderArray
14
15
16
17
18#include "TTreeReaderValue.h"
19#include "TTreeReaderUtils.h"
20#include <type_traits>
21
22namespace ROOT {
23namespace Internal {
24
25/** \class TTreeReaderArrayBase
26Base class of TTreeReaderArray.
27*/
28
30 public:
31 TTreeReaderArrayBase(TTreeReader* reader, const char* branchname,
32 TDictionary* dict):
33 TTreeReaderValueBase(reader, branchname, dict) {}
34
35 std::size_t GetSize() const { return fImpl->GetSize(GetProxy()); }
36 Bool_t IsEmpty() const { return !GetSize(); }
37
38 virtual EReadStatus GetReadStatus() const { return fImpl ? fImpl->fReadStatus : kReadError; }
39
40 protected:
41 void *UntypedAt(std::size_t idx) const { return fImpl->At(GetProxy(), idx); }
42 virtual void CreateProxy();
43 bool GetBranchAndLeaf(TBranch* &branch, TLeaf* &myLeaf,
44 TDictionary* &branchActualType);
45 void SetImpl(TBranch* branch, TLeaf* myLeaf);
46 const char* GetBranchContentDataType(TBranch* branch,
47 TString& contentTypeName,
48 TDictionary* &dict);
49
50 std::unique_ptr<TVirtualCollectionReader> fImpl; // Common interface to collections
51
52 // FIXME: re-introduce once we have ClassDefInline!
53 //ClassDef(TTreeReaderArrayBase, 0);//Accessor to member of an object stored in a collection
54 };
55
56} // namespace Internal
57} // namespace ROOT
58
59// clang-format off
60/**
61 * \class TTreeReaderArray
62 * \ingroup treeplayer
63 * \brief An interface for reading collections stored in ROOT columnar datasets
64 *
65 * The TTreeReaderArray is a type-safe tool to be used in association with a TTreeReader
66 * to access the collections stored in TTree, TNtuple and TChain datasets.
67 * In order to access values which are not collections, the TTreeReaderValue class can
68 * be used.
69 *
70 * See the documentation of TTreeReader for more details and examples.
71*/
72// clang-format on
73
74template <typename T>
75class R__CLING_PTRCHECK(off) TTreeReaderArray final : public ROOT::Internal::TTreeReaderArrayBase {
76// R__CLING_PTRCHECK is disabled because pointer / types are checked by CreateProxy().
77
78public:
79 /// Random access iterator to the elements of a TTreeReaderArray.
80 // The template parameter is there to allow distinguishing between the `const` and `non-const` cases.
81 template <typename ReaderArrayType>
82 class Iterator_t {
83 public:
84 // iterators must define the following types
85 using iterator_category = std::random_access_iterator_tag;
86 using value_type = T;
87 using difference_type = std::ptrdiff_t;
88 using pointer = std::conditional_t<std::is_const<ReaderArrayType>::value, const T *, T *>;
89 using reference = std::conditional_t<std::is_const<ReaderArrayType>::value, const T &, T &>;
90
91 private:
92 TTreeReaderArray *fArray; ///< The array iterated over; nullptr if invalid/past-the-end.
93 std::size_t fIndex; ///< Current index in the array.
94 std::size_t fSize; ///< Size of the TTreeReaderArray
95 public:
96 /// Default ctor: constructs a past-the-end iterator
97 Iterator_t() : fArray(nullptr), fIndex(0u), fSize(0u) {}
98
99 /// Construct iterator
100 Iterator_t(std::size_t index, TTreeReaderArray *array)
101 : fArray(array), fIndex(index), fSize(fArray ? fArray->GetSize() : 0u)
102 {
103 if (fIndex >= fSize)
104 fArray = nullptr; // invalidate iterator
105 }
106
107 /// Construct iterator from a const TTreeReaderArray
108 Iterator_t(std::size_t index, const TTreeReaderArray *array)
109 : Iterator_t(index, const_cast<TTreeReaderArray *>(array)) {}
110
111 Iterator_t(Iterator_t &&) = default;
112 Iterator_t(const Iterator_t &) = default;
114 Iterator_t &operator=(const Iterator_t &) = default;
115
117 {
118 R__ASSERT(fArray && "invalid iterator!");
119 return fArray->At(fIndex);
120 }
121
122 pointer operator->() const { return IsValid() ? &fArray->At(fIndex) : nullptr; }
123
124 bool operator==(const Iterator_t &other) const
125 {
126 // Follow C++14 requiring two past-the-end iterators to be equal.
127 if (!IsValid() && !other.IsValid())
128 return true;
129 return fArray == other.fArray && fIndex == other.fIndex;
130 }
131
132 bool operator!=(const Iterator_t &other) const { return !(*this == other); }
133
134 /// Pre-increment operator
136 {
137 if (IsValid())
138 ++fIndex;
139 if (fIndex >= fSize)
140 fArray = nullptr; // invalidate iterator
141 return *this;
142 }
143
144 /// Post-increment operator
146 {
147 auto ret = *this;
148 this->operator++();
149 return ret;
150 }
151
152 /// Pre-decrement operator
154 {
155 if (fIndex == 0u)
156 fArray = nullptr; // invalidate iterator
157 else
158 --fIndex;
159 return *this;
160 }
161
162 /// Post-decrement operator
164 {
165 auto ret = *this;
166 this->operator--();
167 return ret;
168 }
169
170 Iterator_t operator+(std::ptrdiff_t n) const { return Iterator_t(fIndex + n, fArray); }
171 friend auto operator+(std::ptrdiff_t n, const Iterator_t &it) -> decltype(it + n) { return it + n; }
172
173 Iterator_t operator-(std::ptrdiff_t n) const
174 {
175 const auto index = std::ptrdiff_t(fIndex);
176 const auto newIndex = index >= n ? index - n : std::numeric_limits<decltype(fIndex)>::max();
177 return Iterator_t(newIndex, fArray);
178 }
179
180 std::ptrdiff_t operator-(const Iterator_t &other) const { return fIndex - other.fIndex; }
181
182 Iterator_t &operator+=(std::ptrdiff_t n) { return (*this = *this + n); }
183
184 Iterator_t &operator-=(std::ptrdiff_t n) { return (*this = *this - n); }
185
186 bool operator<(const Iterator_t &other) const { return fIndex < other.fIndex; }
187 bool operator>(const Iterator_t &other) const { return fIndex > other.fIndex; }
188 bool operator<=(const Iterator_t &other) const { return !(*this > other); }
189 bool operator>=(const Iterator_t &other) const { return !(*this < other); }
190
191 reference operator[](std::size_t index) const { return *(*this + index); }
192
193 operator pointer() { return &fArray->At(fIndex); }
194
195 bool IsValid() const { return fArray != nullptr; }
196 };
197
200
201 /// Create an array reader of branch "branchname" for TTreeReader "tr".
202 TTreeReaderArray(TTreeReader &tr, const char *branchname)
203 : TTreeReaderArrayBase(&tr, branchname, TDictionary::GetDictionary(typeid(T))) {}
204
205 T &At(std::size_t idx) { return *static_cast<T *>(UntypedAt(idx)); }
206 const T &At(std::size_t idx) const { return *static_cast<T *>(UntypedAt(idx)); }
207 T &operator[](std::size_t idx) { return At(idx); }
208 const T &operator[](std::size_t idx) const { return At(idx); }
209
210 iterator begin() { return iterator(0u, this); }
211 iterator end() { return iterator(GetSize(), this); }
212 const_iterator begin() const { return cbegin(); }
213 const_iterator end() const { return cend(); }
214 const_iterator cbegin() const { return const_iterator(0u, this); }
215 const_iterator cend() const { return const_iterator(GetSize(), this); }
216
217protected:
218#define R__TTreeReaderArray_TypeString(T) #T
219 virtual const char *GetDerivedTypeName() const { return R__TTreeReaderArray_TypeString(T); }
220#undef R__TTreeReaderArray_TypeString
221 // FIXME: re-introduce once we have ClassDefTInline!
222 // ClassDefT(TTreeReaderArray, 0);//Accessor to member of an object stored in a collection
223};
224
225#endif // ROOT_TTreeReaderArray
size_t fSize
#define R__ASSERT(e)
Definition: TError.h:118
#define R__TTreeReaderArray_TypeString(T)
Base class of TTreeReaderArray.
std::unique_ptr< TVirtualCollectionReader > fImpl
bool GetBranchAndLeaf(TBranch *&branch, TLeaf *&myLeaf, TDictionary *&branchActualType)
Determine the branch / leaf and its type; reset fProxy / fSetupStatus on error.
TTreeReaderArrayBase(TTreeReader *reader, const char *branchname, TDictionary *dict)
void * UntypedAt(std::size_t idx) const
virtual void CreateProxy()
Create the proxy object for our branch.
virtual EReadStatus GetReadStatus() const
void SetImpl(TBranch *branch, TLeaf *myLeaf)
Create the TVirtualCollectionReader object for our branch.
const char * GetBranchContentDataType(TBranch *branch, TString &contentTypeName, TDictionary *&dict)
Access a branch's collection content (not the collection itself) through a proxy.
Base class of TTreeReaderValue.
Detail::TBranchProxy * GetProxy() const
A TTree is a list of TBranches.
Definition: TBranch.h:89
This class defines an abstract interface that must be implemented by all classes that contain diction...
Definition: TDictionary.h:167
A TLeaf describes individual elements of a TBranch See TBranch structure in TTree.
Definition: TLeaf.h:57
Basic string class.
Definition: TString.h:136
Random access iterator to the elements of a TTreeReaderArray.
Iterator_t()
Default ctor: constructs a past-the-end iterator.
std::size_t fIndex
Current index in the array.
bool operator>(const Iterator_t &other) const
reference operator[](std::size_t index) const
Iterator_t & operator--()
Pre-decrement operator.
bool operator!=(const Iterator_t &other) const
Iterator_t operator++(int)
Post-increment operator.
bool operator>=(const Iterator_t &other) const
Iterator_t(const Iterator_t &)=default
Iterator_t & operator++()
Pre-increment operator.
Iterator_t operator--(int)
Post-decrement operator.
std::size_t fSize
Size of the TTreeReaderArray.
Iterator_t & operator-=(std::ptrdiff_t n)
Iterator_t & operator=(Iterator_t &&)=default
std::conditional_t< std::is_const< ReaderArrayType >::value, const T *, T * > pointer
bool operator<(const Iterator_t &other) const
std::ptrdiff_t operator-(const Iterator_t &other) const
TTreeReaderArray * fArray
The array iterated over; nullptr if invalid/past-the-end.
Iterator_t & operator=(const Iterator_t &)=default
std::conditional_t< std::is_const< ReaderArrayType >::value, const T &, T & > reference
Iterator_t & operator+=(std::ptrdiff_t n)
Iterator_t(Iterator_t &&)=default
bool operator<=(const Iterator_t &other) const
Iterator_t operator-(std::ptrdiff_t n) const
bool operator==(const Iterator_t &other) const
friend auto operator+(std::ptrdiff_t n, const Iterator_t &it) -> decltype(it+n)
Iterator_t operator+(std::ptrdiff_t n) const
std::random_access_iterator_tag iterator_category
Iterator_t(std::size_t index, TTreeReaderArray *array)
Construct iterator.
Iterator_t(std::size_t index, const TTreeReaderArray *array)
Construct iterator from a const TTreeReaderArray.
An interface for reading collections stored in ROOT columnar datasets.
T & At(std::size_t idx)
TTreeReaderArray(TTreeReader &tr, const char *branchname)
Create an array reader of branch "branchname" for TTreeReader "tr".
const_iterator cend() const
virtual const char * GetDerivedTypeName() const
const_iterator cbegin() const
const T & At(std::size_t idx) const
const_iterator begin() const
const T & operator[](std::size_t idx) const
T & operator[](std::size_t idx)
const_iterator end() const
A simple, robust and fast interface to read values from ROOT columnar datasets such as TTree,...
Definition: TTreeReader.h:44
const Int_t n
Definition: legend1.C:16
double T(double x)
Definition: ChebyshevPol.h:34
This file contains a specialised ROOT message handler to test for diagnostic in unit tests.