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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 SkTSearch_DEFINED
     18 #define SkTSearch_DEFINED
     19 
     20 #include "SkTypes.h"
     21 
     22 template <typename T>
     23 int SkTSearch(const T* base, int count, const T& target, size_t elemSize)
     24 {
     25     SkASSERT(count >= 0);
     26     if (count <= 0)
     27         return ~0;
     28 
     29     SkASSERT(base != NULL); // base may be NULL if count is zero
     30 
     31     int lo = 0;
     32     int hi = count - 1;
     33 
     34     while (lo < hi)
     35     {
     36         int mid = (hi + lo) >> 1;
     37         const T* elem = (const T*)((const char*)base + mid * elemSize);
     38 
     39         if (*elem < target)
     40             lo = mid + 1;
     41         else
     42             hi = mid;
     43     }
     44 
     45     const T* elem = (const T*)((const char*)base + hi * elemSize);
     46     if (*elem != target)
     47     {
     48         if (*elem < target)
     49             hi += 1;
     50         hi = ~hi;
     51     }
     52     return hi;
     53 }
     54 
     55 template <typename T>
     56 int SkTSearch(const T* base, int count, const T& target, size_t elemSize,
     57               int (*compare)(const T&, const T&))
     58 {
     59     SkASSERT(count >= 0);
     60     if (count <= 0) {
     61         return ~0;
     62     }
     63 
     64     SkASSERT(base != NULL); // base may be NULL if count is zero
     65 
     66     int lo = 0;
     67     int hi = count - 1;
     68 
     69     while (lo < hi) {
     70         int mid = (hi + lo) >> 1;
     71         const T* elem = (const T*)((const char*)base + mid * elemSize);
     72 
     73         if ((*compare)(*elem, target) < 0)
     74             lo = mid + 1;
     75         else
     76             hi = mid;
     77     }
     78 
     79     const T* elem = (const T*)((const char*)base + hi * elemSize);
     80     int pred = (*compare)(*elem, target);
     81     if (pred != 0) {
     82         if (pred < 0)
     83             hi += 1;
     84         hi = ~hi;
     85     }
     86     return hi;
     87 }
     88 
     89 template <typename T>
     90 int SkTSearch(const T** base, int count, const T* target, size_t elemSize,
     91     int (*compare)(const T*, const T*))
     92 {
     93     SkASSERT(count >= 0);
     94     if (count <= 0)
     95         return ~0;
     96 
     97     SkASSERT(base != NULL); // base may be NULL if count is zero
     98 
     99     int lo = 0;
    100     int hi = count - 1;
    101 
    102     while (lo < hi)
    103     {
    104         int mid = (hi + lo) >> 1;
    105         const T* elem = *(const T**)((const char*)base + mid * elemSize);
    106 
    107         if ((*compare)(elem, target) < 0)
    108             lo = mid + 1;
    109         else
    110             hi = mid;
    111     }
    112 
    113     const T* elem = *(const T**)((const char*)base + hi * elemSize);
    114     int pred = (*compare)(elem, target);
    115     if (pred != 0)
    116     {
    117         if (pred < 0)
    118             hi += 1;
    119         hi = ~hi;
    120     }
    121     return hi;
    122 }
    123 
    124 int SkStrSearch(const char*const* base, int count, const char target[],
    125                 size_t target_len, size_t elemSize);
    126 int SkStrSearch(const char*const* base, int count, const char target[],
    127                 size_t elemSize);
    128 
    129 /** Like SkStrSearch, but treats target as if it were all lower-case. Assumes that
    130     base points to a table of lower-case strings.
    131 */
    132 int SkStrLCSearch(const char*const* base, int count, const char target[],
    133                   size_t target_len, size_t elemSize);
    134 int SkStrLCSearch(const char*const* base, int count, const char target[],
    135                   size_t elemSize);
    136 
    137 /** Helper class to convert a string to lower-case, but only modifying the ascii
    138     characters. This makes the routine very fast and never changes the string
    139     length, but it is not suitable for linguistic purposes. Normally this is
    140     used for buiding and searching string tables.
    141 */
    142 class SkAutoAsciiToLC {
    143 public:
    144     SkAutoAsciiToLC(const char str[], size_t len = (size_t)-1);
    145     ~SkAutoAsciiToLC();
    146 
    147     const char* lc() const { return fLC; }
    148     size_t      length() const { return fLength; }
    149 
    150 private:
    151     char*   fLC;    // points to either the heap or fStorage
    152     size_t  fLength;
    153     enum {
    154         STORAGE = 64
    155     };
    156     char    fStorage[STORAGE+1];
    157 };
    158 
    159 extern "C" {
    160     typedef int (*SkQSortCompareProc)(const void*, const void*);
    161     void SkQSort(void* base, size_t count, size_t elemSize, SkQSortCompareProc);
    162 }
    163 
    164 #endif
    165 
    166