skia2/include/core/SkTSearch.h

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SkTSearch_DEFINED
#define SkTSearch_DEFINED

#include "SkTypes.h"

template <typename T>
int SkTSearch(const T* base, int count, const T& target, size_t elemSize)
{
    SkASSERT(count >= 0);
    if (count <= 0)
        return ~0;

    SkASSERT(base != NULL); // base may be NULL if count is zero

    int lo = 0;
    int hi = count - 1;

    while (lo < hi)
    {
        int mid = (hi + lo) >> 1;
        const T* elem = (const T*)((const char*)base + mid * elemSize);

        if (*elem < target)
            lo = mid + 1;
        else
            hi = mid;
    }

    const T* elem = (const T*)((const char*)base + hi * elemSize);
    if (*elem != target)
    {
        if (*elem < target)
            hi += 1;
        hi = ~hi;
    }
    return hi;
}

template <typename T>
int SkTSearch(const T* base, int count, const T& target, size_t elemSize,
              int (*compare)(const T&, const T&))
{
    SkASSERT(count >= 0);
    if (count <= 0) {
        return ~0;
    }

    SkASSERT(base != NULL); // base may be NULL if count is zero

    int lo = 0;
    int hi = count - 1;

    while (lo < hi) {
        int mid = (hi + lo) >> 1;
        const T* elem = (const T*)((const char*)base + mid * elemSize);

        if ((*compare)(*elem, target) < 0)
            lo = mid + 1;
        else
            hi = mid;
    }

    const T* elem = (const T*)((const char*)base + hi * elemSize);
    int pred = (*compare)(*elem, target);
    if (pred != 0) {
        if (pred < 0)
            hi += 1;
        hi = ~hi;
    }
    return hi;
}

template <typename T>
int SkTSearch(const T** base, int count, const T* target, size_t elemSize,
    int (*compare)(const T*, const T*))
{
    SkASSERT(count >= 0);
    if (count <= 0)
        return ~0;

    SkASSERT(base != NULL); // base may be NULL if count is zero

    int lo = 0;
    int hi = count - 1;

    while (lo < hi)
    {
        int mid = (hi + lo) >> 1;
        const T* elem = *(const T**)((const char*)base + mid * elemSize);

        if ((*compare)(elem, target) < 0)
            lo = mid + 1;
        else
            hi = mid;
    }

    const T* elem = *(const T**)((const char*)base + hi * elemSize);
    int pred = (*compare)(elem, target);
    if (pred != 0)
    {
        if (pred < 0)
            hi += 1;
        hi = ~hi;
    }
    return hi;
}

int SkStrSearch(const char*const* base, int count, const char target[],
                size_t target_len, size_t elemSize);
int SkStrSearch(const char*const* base, int count, const char target[],
                size_t elemSize);

/** Like SkStrSearch, but treats target as if it were all lower-case. Assumes that
    base points to a table of lower-case strings.
*/
int SkStrLCSearch(const char*const* base, int count, const char target[],
                  size_t target_len, size_t elemSize);
int SkStrLCSearch(const char*const* base, int count, const char target[],
                  size_t elemSize);

/** Helper class to convert a string to lower-case, but only modifying the ascii
    characters. This makes the routine very fast and never changes the string
    length, but it is not suitable for linguistic purposes. Normally this is
    used for buiding and searching string tables.
*/
class SkAutoAsciiToLC {
public:
    SkAutoAsciiToLC(const char str[], size_t len = (size_t)-1);
    ~SkAutoAsciiToLC();
    
    const char* lc() const { return fLC; }
    size_t      length() const { return fLength; }

private:
    char*   fLC;    // points to either the heap or fStorage
    size_t  fLength;
    enum {
        STORAGE = 64
    };
    char    fStorage[STORAGE+1];
};

extern "C" {
    typedef int (*SkQSortCompareProc)(const void*, const void*);
    void SkQSort(void* base, size_t count, size_t elemSize, SkQSortCompareProc);
}

SkDEBUGCODE(void SkQSort_UnitTest();)

#endif