307 lines
6.4 KiB
C++
307 lines
6.4 KiB
C++
/*
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----
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This file is part of SECONDO.
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Copyright (C) 2008, University in Hagen,
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Faculty of Mathematics and Computer Science,
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Database Systems for New Applications.
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SECONDO is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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SECONDO is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with SECONDO; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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----
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//[secondo] [\textsc{Secondo}]
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*/
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/*
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1 Generic Type Constructors
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This file provides some template functions for an easy creation
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of [secondo] type constructors.
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This method only works for simple attribute types, i.e. non-composite
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attributes. But this case covers the most secondo type constructors.
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To use the generic approach, the C++ class representing the corrsponding
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[secondo] type must provide some funtions described in the following:
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1.1 Requirements
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1.1.1 ~Attribute~
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First of all, the class must be derived from the class __Attribute__ and
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implement all functions required by this class.
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1.1.2 ~ToListExpr~
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----
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ListExpr ToListExpr(const typeInfo ListExpr) const
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----
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This function converts the calling instance into a nested list.
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In the most cases, the argument ~typeInfo~ can be ignored.
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1.1.3 ~ReadFrom~
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----
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bool ReadFrom(const ListExpr instance, const ListExpr typeInfo)
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----
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This function sets the value of the calling instance to this one described
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by the ~instance~ argument. If the list is not a valid representation for
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this class, the result is __false__ otherwise the result is __true__.
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The second argument can be ignored in the most cases.
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1.1.4 ~BasicType~
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----
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static string BasicType()
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----
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This static function just returns the name for the [secondo] type.
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1.1.5 ~Property~
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----
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static ListExpr Property()
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----
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This static function returns the nested list describing the
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corresponding [secondo] type. For a simple implementation of this function,
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you can use the __GenProperty__ function in the follwing way:
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----
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gentc::GenProperty(signature, example_type_list, list_rep, example_list, remarks)
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----
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e.g.
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----
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gentc::GenProperty("-> DATA", "int", "<intvalue>", "-21", "");
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----
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1.1.6 ~CheckKind~
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----
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static bool CheckKind(ListExpr type, ListExpr& errorInfo)
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----
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This function checks whether the nested list ~type~ represents [secondo]'s type
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for this class.
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1.2 Creating the Secondo Type Constructor
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After these preparations, a [secondo] type constructor is just created by:
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----
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GenTC<ClassName> name;
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----
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*/
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#ifndef GENERIC_TC
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#define GENERIC_TC
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#include "Attribute.h"
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#include "NestedList.h"
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#include "../Tools/Flob/Flob.h"
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#include "Algebra.h"
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extern NestedList* nl;
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namespace gentc{
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/*
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1.1 ListConversions
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1.1.1 Out function
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*/
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template<class T>
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ListExpr Out(ListExpr typeInfo, Word value){
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return (static_cast<T*>(value.addr))->ToListExpr(typeInfo);
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}
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/*
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1.1.2 In Function
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*/
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template<class T>
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Word In(const ListExpr typeInfo, const ListExpr instance,
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const int errorPos, ListExpr& errorInfo, bool& correct ){
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T* t = new T(0);
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if(t->ReadFrom(instance,typeInfo)){
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correct = true;
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return SetWord(t);
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} else {
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correct = false;
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delete t;
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return SetWord(Address(0));
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}
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}
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/*
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1.2 ~Create~ Function
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The following function is used to create instances of the
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template argument.
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*/
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template<class T>
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Word Create(const ListExpr typeInfo){
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return SetWord(new T(1));
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}
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/*
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1.3 ~Delete~ Functions
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The ~delete~ functions can be used to destroy the
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instances of types of this algebra.
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*/
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template<class T>
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void Delete(const ListExpr typeInfo,Word &w){
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T* B = static_cast<T*>(w.addr);
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int nof = B->NumOfFLOBs();
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for(int i=0;i< nof; i++){
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(B->GetFLOB(i))->destroy();
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}
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delete B;
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B = NULL;
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w.addr=0;
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}
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/*
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1.4 ~Close~-Functions
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The close functions destroy the instances.
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*/
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template<class T>
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void Close(const ListExpr typeInfo, Word& w ){
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delete static_cast<T*>(w.addr);
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w.addr = 0;
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}
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/*
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1.5 ~Clone~-Functions
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The clone functions can be used for get a copy
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of an existing object.
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*/
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template<class T>
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Word Clone(const ListExpr typeInfo, const Word& w){
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return SetWord( (static_cast<T*>(w.addr))->Clone());
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}
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/*
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1.6 ~SizeOf~-Functions
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This functions must be provided for allocating the
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correct memory space for an object in query processing.
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*/
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template<class T>
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int SizeOf(){
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return sizeof(T);
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}
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/*
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1.7 ~Cast~-Functions
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Some functions proving dynamic casts.
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*/
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template<class T>
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void* Cast(void* addr){
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return new (addr) T;
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}
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inline ListExpr GenProperty(std::string signature,
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std::string example_type_list,
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std::string list_rep,
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std::string example_list,
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std::string remarks = ""){
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return ::nl->TwoElemList(
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::nl->FiveElemList(
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::nl->StringAtom("Signature"),
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::nl->StringAtom("Example Type List"),
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::nl->StringAtom("List Rep"),
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::nl->StringAtom("Example List"),
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::nl->StringAtom("Remarks")),
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::nl->FiveElemList(
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::nl->TextAtom(signature),
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::nl->TextAtom(example_type_list),
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::nl->TextAtom(list_rep),
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::nl->TextAtom(example_list),
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::nl->TextAtom(remarks))
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);
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}
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} // end of namespace gentc
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/*
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5. TypeConstructors
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In this section, the type constructors for using in the
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algebra are defined.
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*/
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template<class T>
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class GenTC : public TypeConstructor{
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public:
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GenTC()
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:TypeConstructor(T::BasicType(),
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T::Property,
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gentc::Out<T >,
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gentc::In<T >,
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0,0,
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gentc::Create<T>,
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gentc::Delete<T>,
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OpenAttribute<T>,
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SaveAttribute<T>,
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gentc::Close<T>,
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gentc::Clone<T>,
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gentc::Cast<T>,
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gentc::SizeOf<T>,
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T::CheckKind){}
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};
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#endif
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