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4680 | right-hear | 1 | #ifndef __refcount_h__ |
2 | #define __refcount_h__ |
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3 | |||
4 | #include "lispassert.h" |
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5 | #include "yacasbase.h" |
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6 | |||
7 | //------------------------------------------------------------------------------ |
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8 | // RefPtr - Smart pointer for (intrusive) reference counting. |
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9 | // Simply, an object's reference count is the number of RefPtrs refering to it. |
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10 | // The RefPtr will delete the referenced object when the count reaches zero. |
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11 | |||
12 | /*TODO: this might be improved a little by having RefPtr wrap the object being |
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13 | pointed to so the user of RefPtr does not need to add ReferenceCount explicitly. |
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14 | One can use RefPtr on any arbitrary object from that moment on. |
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15 | */ |
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16 | |||
17 | typedef ReferenceType ReferenceCount; |
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18 | |||
19 | template |
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20 | class RefPtr : public YacasBase // derived, so we can 'NEW LispPtr[nnn]' |
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21 | { |
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22 | public: |
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23 | // Default constructor (not explicit, so it auto-initializes) |
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24 | inline RefPtr() : iPtr(NULL) {} |
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25 | // Construct from pointer to T |
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26 | explicit RefPtr(T *ptr) : iPtr(ptr) { if (ptr) { ptr->iReferenceCount++; } } |
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27 | // Copy constructor |
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28 | RefPtr(const RefPtr &refPtr) : iPtr(refPtr.ptr()) { if (iPtr) { iPtr->iReferenceCount++; } } |
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29 | // Destructor |
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30 | ~RefPtr() |
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31 | { |
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32 | if (iPtr) |
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33 | { |
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34 | iPtr->iReferenceCount--; |
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35 | if (iPtr->iReferenceCount == 0) |
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36 | { |
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37 | delete iPtr; |
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38 | } |
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39 | } |
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40 | } |
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41 | // Assignment from pointer |
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42 | RefPtr &operator=(T *ptr) |
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43 | { |
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44 | if (ptr) |
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45 | { |
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46 | ptr->iReferenceCount++; |
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47 | } |
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48 | if (iPtr) |
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49 | { |
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50 | iPtr->iReferenceCount--; |
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51 | if (iPtr->iReferenceCount == 0) |
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52 | { |
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53 | delete iPtr; |
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54 | } |
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55 | } |
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56 | iPtr = ptr; |
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57 | return *this; |
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58 | } |
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59 | // Assignment from another |
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60 | RefPtr &operator=(const RefPtr &refPtr) { return this->operator=(refPtr.ptr()); } |
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61 | |||
62 | operator T*() const { return iPtr; } // implicit conversion to pointer to T |
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63 | T &operator*() const { return *iPtr; } // so (*refPtr) is a reference to T |
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64 | T *operator->() const { return iPtr; } // so (refPtr->member) accesses T's member |
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65 | T *ptr() const { return iPtr; } // so (refPtr.ptr()) returns the pointer to T (boost calls this method 'get') |
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66 | bool operator!() const { return !iPtr; } // is null pointer |
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67 | |||
68 | private: |
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69 | T *iPtr; |
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70 | }; |
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71 | |||
72 | |||
73 | #endif |
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74 |