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      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef SkTDStack_DEFINED
     18 #define SkTDStack_DEFINED
     19 
     20 #include "SkTypes.h"
     21 
     22 template <typename T> class SkTDStack : SkNoncopyable {
     23 public:
     24     SkTDStack() : fCount(0), fTotalCount(0)
     25     {
     26         fInitialRec.fNext = NULL;
     27         fRec = &fInitialRec;
     28 
     29     //  fCount = kSlotCount;
     30     }
     31     ~SkTDStack()
     32     {
     33         Rec* rec = fRec;
     34         while (rec != &fInitialRec)
     35         {
     36             Rec* next = rec->fNext;
     37             sk_free(rec);
     38             rec = next;
     39         }
     40     }
     41 
     42     int count() const { return fTotalCount; }
     43     int depth() const { return fTotalCount; }
     44     bool empty() const { return fTotalCount == 0; }
     45 
     46     T* push()
     47     {
     48         SkASSERT(fCount <= kSlotCount);
     49         if (fCount == kSlotCount)
     50         {
     51             Rec* rec = (Rec*)sk_malloc_throw(sizeof(Rec));
     52             rec->fNext = fRec;
     53             fRec = rec;
     54             fCount = 0;
     55         }
     56         ++fTotalCount;
     57         return &fRec->fSlots[fCount++];
     58     }
     59     void push(const T& elem) { *this->push() = elem; }
     60     const T& index(int idx) const
     61     {
     62         SkASSERT(fRec && fCount > idx);
     63         return fRec->fSlots[fCount - idx - 1];
     64     }
     65     T& index(int idx)
     66     {
     67         SkASSERT(fRec && fCount > idx);
     68         return fRec->fSlots[fCount - idx - 1];
     69     }
     70     const T& top() const
     71     {
     72         SkASSERT(fRec && fCount > 0);
     73         return fRec->fSlots[fCount - 1];
     74     }
     75     T& top()
     76     {
     77         SkASSERT(fRec && fCount > 0);
     78         return fRec->fSlots[fCount - 1];
     79     }
     80     void pop(T* elem)
     81     {
     82         if (elem)
     83             *elem = fRec->fSlots[fCount - 1];
     84         this->pop();
     85     }
     86     void pop()
     87     {
     88         SkASSERT(fCount > 0 && fRec);
     89         --fTotalCount;
     90         if (--fCount == 0)
     91         {
     92             if (fRec != &fInitialRec)
     93             {
     94                 Rec* rec = fRec->fNext;
     95                 sk_free(fRec);
     96                 fCount = kSlotCount;
     97                 fRec = rec;
     98             }
     99             else
    100                 SkASSERT(fTotalCount == 0);
    101         }
    102     }
    103 
    104 private:
    105     enum {
    106         kSlotCount  = 8
    107     };
    108 
    109     struct Rec;
    110     friend struct Rec;
    111 
    112     struct Rec {
    113         Rec* fNext;
    114         T    fSlots[kSlotCount];
    115     };
    116     Rec     fInitialRec;
    117     Rec*    fRec;
    118     int     fCount, fTotalCount;
    119 };
    120 
    121 #endif
    122 
    123