305 lines
9.1 KiB
C++
305 lines
9.1 KiB
C++
/*
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*******************************************************************************
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*
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* Copyright (C) 2009-2012, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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*******************************************************************************
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* file name: localpointer.h
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* encoding: US-ASCII
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 2009nov13
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* created by: Markus W. Scherer
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*/
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#ifndef __LOCALPOINTER_H__
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#define __LOCALPOINTER_H__
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/**
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* \file
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* \brief C++ API: "Smart pointers" for use with and in ICU4C C++ code.
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*
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* These classes are inspired by
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* - std::auto_ptr
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* - boost::scoped_ptr & boost::scoped_array
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* - Taligent Safe Pointers (TOnlyPointerTo)
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*
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* but none of those provide for all of the goals for ICU smart pointers:
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* - Smart pointer owns the object and releases it when it goes out of scope.
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* - No transfer of ownership via copy/assignment to reduce misuse. Simpler & more robust.
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* - ICU-compatible: No exceptions.
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* - Need to be able to orphan/release the pointer and its ownership.
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* - Need variants for normal C++ object pointers, C++ arrays, and ICU C service objects.
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*
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* For details see http://site.icu-project.org/design/cpp/scoped_ptr
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*/
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#include "unicode/utypes.h"
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#if U_SHOW_CPLUSPLUS_API
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U_NAMESPACE_BEGIN
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/**
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* "Smart pointer" base class; do not use directly: use LocalPointer etc.
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*
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* Base class for smart pointer classes that do not throw exceptions.
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*
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* Do not use this base class directly, since it does not delete its pointer.
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* A subclass must implement methods that delete the pointer:
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* Destructor and adoptInstead().
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*
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* There is no operator T *() provided because the programmer must decide
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* whether to use getAlias() (without transfer of ownership) or orpan()
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* (with transfer of ownership and NULLing of the pointer).
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*
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* @see LocalPointer
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* @see LocalArray
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* @see U_DEFINE_LOCAL_OPEN_POINTER
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* @stable ICU 4.4
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*/
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template<typename T>
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class LocalPointerBase {
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public:
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/**
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* Constructor takes ownership.
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* @param p simple pointer to an object that is adopted
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* @stable ICU 4.4
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*/
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explicit LocalPointerBase(T *p=NULL) : ptr(p) {}
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/**
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* Destructor deletes the object it owns.
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* Subclass must override: Base class does nothing.
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* @stable ICU 4.4
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*/
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~LocalPointerBase() { /* delete ptr; */ }
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/**
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* NULL check.
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* @return TRUE if ==NULL
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* @stable ICU 4.4
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*/
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UBool isNull() const { return ptr==NULL; }
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/**
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* NULL check.
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* @return TRUE if !=NULL
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* @stable ICU 4.4
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*/
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UBool isValid() const { return ptr!=NULL; }
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/**
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* Comparison with a simple pointer, so that existing code
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* with ==NULL need not be changed.
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* @param other simple pointer for comparison
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* @return true if this pointer value equals other
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* @stable ICU 4.4
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*/
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bool operator==(const T *other) const { return ptr==other; }
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/**
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* Comparison with a simple pointer, so that existing code
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* with !=NULL need not be changed.
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* @param other simple pointer for comparison
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* @return true if this pointer value differs from other
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* @stable ICU 4.4
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*/
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bool operator!=(const T *other) const { return ptr!=other; }
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/**
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* Access without ownership change.
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* @return the pointer value
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* @stable ICU 4.4
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*/
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T *getAlias() const { return ptr; }
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/**
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* Access without ownership change.
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* @return the pointer value as a reference
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* @stable ICU 4.4
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*/
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T &operator*() const { return *ptr; }
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/**
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* Access without ownership change.
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* @return the pointer value
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* @stable ICU 4.4
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*/
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T *operator->() const { return ptr; }
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/**
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* Gives up ownership; the internal pointer becomes NULL.
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* @return the pointer value;
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* caller becomes responsible for deleting the object
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* @stable ICU 4.4
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*/
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T *orphan() {
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T *p=ptr;
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ptr=NULL;
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return p;
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}
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/**
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* Deletes the object it owns,
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* and adopts (takes ownership of) the one passed in.
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* Subclass must override: Base class does not delete the object.
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* @param p simple pointer to an object that is adopted
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* @stable ICU 4.4
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*/
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void adoptInstead(T *p) {
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// delete ptr;
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ptr=p;
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}
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protected:
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/**
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* Actual pointer.
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* @internal
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*/
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T *ptr;
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private:
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// No comparison operators with other LocalPointerBases.
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bool operator==(const LocalPointerBase &other);
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bool operator!=(const LocalPointerBase &other);
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// No ownership transfer: No copy constructor, no assignment operator.
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LocalPointerBase(const LocalPointerBase &other);
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void operator=(const LocalPointerBase &other);
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// No heap allocation. Use only on the stack.
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static void * U_EXPORT2 operator new(size_t size);
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static void * U_EXPORT2 operator new[](size_t size);
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#if U_HAVE_PLACEMENT_NEW
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static void * U_EXPORT2 operator new(size_t, void *ptr);
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#endif
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};
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/**
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* "Smart pointer" class, deletes objects via the standard C++ delete operator.
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* For most methods see the LocalPointerBase base class.
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*
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* Usage example:
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* \code
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* LocalPointer<UnicodeString> s(new UnicodeString((UChar32)0x50005));
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* int32_t length=s->length(); // 2
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* UChar lead=s->charAt(0); // 0xd900
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* if(some condition) { return; } // no need to explicitly delete the pointer
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* s.adoptInstead(new UnicodeString((UChar)0xfffc));
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* length=s->length(); // 1
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* // no need to explicitly delete the pointer
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* \endcode
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*
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* @see LocalPointerBase
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* @stable ICU 4.4
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*/
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template<typename T>
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class LocalPointer : public LocalPointerBase<T> {
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public:
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/**
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* Constructor takes ownership.
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* @param p simple pointer to an object that is adopted
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* @stable ICU 4.4
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*/
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explicit LocalPointer(T *p=NULL) : LocalPointerBase<T>(p) {}
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/**
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* Destructor deletes the object it owns.
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* @stable ICU 4.4
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*/
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~LocalPointer() {
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delete LocalPointerBase<T>::ptr;
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}
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/**
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* Deletes the object it owns,
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* and adopts (takes ownership of) the one passed in.
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* @param p simple pointer to an object that is adopted
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* @stable ICU 4.4
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*/
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void adoptInstead(T *p) {
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delete LocalPointerBase<T>::ptr;
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LocalPointerBase<T>::ptr=p;
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}
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};
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/**
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* "Smart pointer" class, deletes objects via the C++ array delete[] operator.
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* For most methods see the LocalPointerBase base class.
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* Adds operator[] for array item access.
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*
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* Usage example:
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* \code
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* LocalArray<UnicodeString> a(new UnicodeString[2]);
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* a[0].append((UChar)0x61);
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* if(some condition) { return; } // no need to explicitly delete the array
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* a.adoptInstead(new UnicodeString[4]);
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* a[3].append((UChar)0x62).append((UChar)0x63).reverse();
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* // no need to explicitly delete the array
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* \endcode
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*
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* @see LocalPointerBase
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* @stable ICU 4.4
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*/
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template<typename T>
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class LocalArray : public LocalPointerBase<T> {
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public:
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/**
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* Constructor takes ownership.
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* @param p simple pointer to an array of T objects that is adopted
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* @stable ICU 4.4
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*/
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explicit LocalArray(T *p=NULL) : LocalPointerBase<T>(p) {}
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/**
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* Destructor deletes the array it owns.
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* @stable ICU 4.4
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*/
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~LocalArray() {
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delete[] LocalPointerBase<T>::ptr;
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}
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/**
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* Deletes the array it owns,
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* and adopts (takes ownership of) the one passed in.
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* @param p simple pointer to an array of T objects that is adopted
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* @stable ICU 4.4
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*/
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void adoptInstead(T *p) {
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delete[] LocalPointerBase<T>::ptr;
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LocalPointerBase<T>::ptr=p;
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}
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/**
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* Array item access (writable).
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* No index bounds check.
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* @param i array index
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* @return reference to the array item
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* @stable ICU 4.4
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*/
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T &operator[](ptrdiff_t i) const { return LocalPointerBase<T>::ptr[i]; }
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};
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/**
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* \def U_DEFINE_LOCAL_OPEN_POINTER
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* "Smart pointer" definition macro, deletes objects via the closeFunction.
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* Defines a subclass of LocalPointerBase which works just
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* like LocalPointer<Type> except that this subclass will use the closeFunction
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* rather than the C++ delete operator.
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*
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* Requirement: The closeFunction must tolerate a NULL pointer.
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* (We could add a NULL check here but it is normally redundant.)
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*
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* Usage example:
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* \code
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* LocalUCaseMapPointer csm(ucasemap_open(localeID, options, &errorCode));
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* utf8OutLength=ucasemap_utf8ToLower(csm.getAlias(),
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* utf8Out, (int32_t)sizeof(utf8Out),
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* utf8In, utf8InLength, &errorCode);
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* if(U_FAILURE(errorCode)) { return; } // no need to explicitly delete the UCaseMap
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* \endcode
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*
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* @see LocalPointerBase
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* @see LocalPointer
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* @stable ICU 4.4
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*/
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#define U_DEFINE_LOCAL_OPEN_POINTER(LocalPointerClassName, Type, closeFunction) \
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class LocalPointerClassName : public LocalPointerBase<Type> { \
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public: \
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explicit LocalPointerClassName(Type *p=NULL) : LocalPointerBase<Type>(p) {} \
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~LocalPointerClassName() { closeFunction(ptr); } \
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void adoptInstead(Type *p) { \
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closeFunction(ptr); \
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ptr=p; \
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} \
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}
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U_NAMESPACE_END
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#endif /* U_SHOW_CPLUSPLUS_API */
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#endif /* __LOCALPOINTER_H__ */
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