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00001 //# PoolStack.h: A parameterized stack of re-usable objects 00002 //# Copyright (C) 2001,2002,2004 00003 //# Associated Universities, Inc. Washington DC, USA. 00004 //# 00005 //# This library is free software; you can redistribute it and/or modify it 00006 //# under the terms of the GNU Library General Public License as published by 00007 //# the Free Software Foundation; either version 2 of the License, or (at your 00008 //# option) any later version. 00009 //# 00010 //# This library is distributed in the hope that it will be useful, but WITHOUT 00011 //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00012 //# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public 00013 //# License for more details. 00014 //# 00015 //# You should have received a copy of the GNU Library General Public License 00016 //# along with this library; if not, write to the Free Software Foundation, 00017 //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA. 00018 //# 00019 //# Correspondence concerning AIPS++ should be addressed as follows: 00020 //# Internet email: aips2-request@nrao.edu. 00021 //# Postal address: AIPS++ Project Office 00022 //# National Radio Astronomy Observatory 00023 //# 520 Edgemont Road 00024 //# Charlottesville, VA 22903-2475 USA 00025 //# 00026 //# $Id: PoolStack.h 20551 2009-03-25 00:11:33Z Malte.Marquarding $ 00027 00028 #ifndef CASA_POOLSTACK_H 00029 #define CASA_POOLSTACK_H 00030 00031 //# Includes 00032 #include <casa/aips.h> 00033 #include <casa/Containers/Block.h> 00034 00035 namespace casa { //# NAMESPACE CASA - BEGIN 00036 00037 //# Forward declarations 00038 00039 // <summary> 00040 // A parameterized stack of re-usable objects 00041 // </summary> 00042 // 00043 // <use visibility=export> 00044 // 00045 // <reviewed reviewer="Ger van Diepen" date="2001/07/03" tests="tPoolStack.cc" demos=""> 00046 // </reviewed> 00047 // 00048 // <prerequisite> 00049 // <li> 00050 // </prerequisite> 00051 // 00052 // <synopsis> 00053 // A PoolStack contains a set of pre-allocated Objects of the type 00054 // <src>T</src>, with a parameter <src>Key</src> (e.g. an object could be 00055 // a <src>Vector</src> of <src>T Double</src> with an <src>uInt Key</src>). 00056 // The stack is a very simple stack, without the 00057 // linking/unlinking of a normal Stack implementation. 00058 // This lightweight implementation was especially designed for use 00059 // with the <linkto class=ObjectPool>ObjectPool</linkto> 00060 // class, but can be used independently. 00061 // 00062 // Objects can be obtained with the <src>get()</src> method, and 00063 // returned for re-use with <src>release()</src>. 00064 // 00065 // Objects are not initialised when popped. The user should never delete the 00066 // object returned by get; but return it to the pool. 00067 // </synopsis> 00068 // 00069 // <example> 00070 // <srcblock> 00071 // // Create a pool of length 5 vectors 00072 // PoolStack<Vector<Double>, uInt> pool5(5); 00073 // // Get an element 00074 // Vector<Double> *elem(pool5.get()); 00075 // // Use it 00076 // (*elem)(2) = 27; 00077 // // Release it 00078 // pool5.release(elem); 00079 // </srcblock> 00080 // </example> 00081 // 00082 // <motivation> 00083 // To improve the speed for the auto differentiating class. 00084 // </motivation> 00085 // 00086 // <templating arg=T> 00087 // <li> the class T must have a constructor with a Key argument 00088 // </templating> 00089 // 00090 // <templating arg=Key> 00091 // <li> the class Key must be usable as a constructor argument for T 00092 // </templating> 00093 // 00094 // <todo asof="2001/06/07"> 00095 // <li> Nothing I know of 00096 // </todo> 00097 00098 template <class T, class Key> class PoolStack { 00099 public: 00100 //# Constants 00101 // Number of default stack entries. 00102 static const uInt NDEF=8; 00103 //# Constructors 00104 // Create the stack with the default Key 00105 PoolStack(); 00106 // Create the stack for the specified key 00107 explicit PoolStack(const Key &key); 00108 // Delete the stack 00109 ~PoolStack(); 00110 00111 //# Member functions 00112 // Get a pointer to an object in the stack. The stack will be extended if 00113 // no objects left. Extension is done with the NDEF number of elements. 00114 // Different extension can be done manually with the addElements() method. 00115 T *get() { if (!top_p) addElements(NDEF); T *tmp = stack_p[--top_p]; 00116 stack_p[top_p] = 0; return tmp; }; 00117 00118 // Return an object to the stack for re-use 00119 void release(T *obj) {if (obj) stack_p[top_p++] = obj; }; 00120 00121 // Add n elements 00122 void addElements(const uInt n); 00123 00124 // Decimate the stack by getting rid of all unused elements in it 00125 void clear(); 00126 00127 // Test if stack empty 00128 Bool empty() { return top_p == 0; }; 00129 00130 // Return the key belonging to the stack 00131 const Key &key() const { return key_p; } 00132 // return the stack extend (for debugging use and checking mainly) 00133 uInt nelements() const { return stack_p.nelements(); }; 00134 00135 private: 00136 //# Data 00137 // Current pointer to top-of-stack 00138 uInt top_p; 00139 // The stack 00140 PtrBlock<T*> stack_p; 00141 // The key belonging to this stack 00142 Key key_p; 00143 00144 //# Constructors 00145 // Copy and assignment constructors and assignment (not implemented) 00146 // <group> 00147 PoolStack(const PoolStack<T, Key> &other); 00148 PoolStack<T, Key> &operator=(const PoolStack<T, Key> &other); 00149 // </group> 00150 00151 //# Member functions 00152 }; 00153 00154 00155 } //# NAMESPACE CASA - END 00156 00157 #ifndef CASACORE_NO_AUTO_TEMPLATES 00158 #include <casa/Containers/PoolStack.tcc> 00159 #endif //# CASACORE_NO_AUTO_TEMPLATES 00160 #endif