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/*************************************************************************************************
* Comparator functions
* Copyright (C) 2009-2012 FAL Labs
* This file is part of Kyoto Cabinet.
* This program is free software: you can redistribute it and/or modify it under the terms of
* the GNU General Public License as published by the Free Software Foundation, either version
* 3 of the License, or any later version.
* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
* You should have received a copy of the GNU General Public License along with this program.
* If not, see <http://www.gnu.org/licenses/>.
*************************************************************************************************/
#ifndef _KCCOMPARE_H // duplication check
#define _KCCOMPARE_H
#include <kccommon.h>
#include <kcutil.h>
namespace kyotocabinet { // common namespace
/**
* Interfrace of comparator of record keys.
*/
class Comparator {
public:
/**
* Destructor.
*/
virtual ~Comparator() {}
/**
* Compare two keys.
* @param akbuf the pointer to the region of one key.
* @param aksiz the size of the region of one key.
* @param bkbuf the pointer to the region of the other key.
* @param bksiz the size of the region of the other key.
* @return positive if the former is big, negative if the latter is big, 0 if both are
* equivalent.
*/
virtual int32_t compare(const char* akbuf, size_t aksiz, const char* bkbuf, size_t bksiz) = 0;
};
/**
* Comparator in the lexical order.
*/
class LexicalComparator : public Comparator {
public:
explicit LexicalComparator() {}
int32_t compare(const char* akbuf, size_t aksiz, const char* bkbuf, size_t bksiz) {
_assert_(akbuf && bkbuf);
size_t msiz = aksiz < bksiz ? aksiz : bksiz;
for (size_t i = 0; i < msiz; i++) {
if (((uint8_t*)akbuf)[i] != ((uint8_t*)bkbuf)[i])
return ((uint8_t*)akbuf)[i] - ((uint8_t*)bkbuf)[i];
}
return (int32_t)aksiz - (int32_t)bksiz;
}
};
/**
* Comparator in the lexical descending order.
*/
class LexicalDescendingComparator : public Comparator {
public:
explicit LexicalDescendingComparator() : comp_() {}
int32_t compare(const char* akbuf, size_t aksiz, const char* bkbuf, size_t bksiz) {
return -comp_.compare(akbuf, aksiz, bkbuf, bksiz);
}
private:
LexicalComparator comp_;
};
/**
* Comparator in the decimal order.
*/
class DecimalComparator : public Comparator {
public:
explicit DecimalComparator() {}
int32_t compare(const char* akbuf, size_t aksiz, const char* bkbuf, size_t bksiz) {
_assert_(akbuf && bkbuf);
const int32_t LDBLCOLMAX = 16;
const unsigned char* arp = (unsigned char*)akbuf;
int32_t alen = aksiz;
while (alen > 0 && (*arp <= ' ' || *arp == 0x7f)) {
arp++;
alen--;
}
int64_t anum = 0;
int32_t asign = 1;
if (alen > 0 && *arp == '-') {
arp++;
alen--;
asign = -1;
}
while (alen > 0) {
int32_t c = *arp;
if (c < '0' || c > '9') break;
anum = anum * 10 + c - '0';
arp++;
alen--;
}
anum *= asign;
const unsigned char* brp = (unsigned char*)bkbuf;
int32_t blen = bksiz;
while (blen > 0 && (*brp <= ' ' || *brp == 0x7f)) {
brp++;
blen--;
}
int64_t bnum = 0;
int32_t bsign = 1;
if (blen > 0 && *brp == '-') {
brp++;
blen--;
bsign = -1;
}
while (blen > 0) {
int32_t c = *brp;
if (c < '0' || c > '9') break;
bnum = bnum * 10 + c - '0';
brp++;
blen--;
}
bnum *= bsign;
if (anum < bnum) return -1;
if (anum > bnum) return 1;
if ((alen > 1 && *arp == '.') || (blen > 1 && *brp == '.')) {
long double aflt = 0;
if (alen > 1 && *arp == '.') {
arp++;
alen--;
if (alen > LDBLCOLMAX) alen = LDBLCOLMAX;
long double base = 10;
while (alen > 0) {
if (*arp < '0' || *arp > '9') break;
aflt += (*arp - '0') / base;
arp++;
alen--;
base *= 10;
}
aflt *= asign;
}
long double bflt = 0;
if (blen > 1 && *brp == '.') {
brp++;
blen--;
if (blen > LDBLCOLMAX) blen = LDBLCOLMAX;
long double base = 10;
while (blen > 0) {
if (*brp < '0' || *brp > '9') break;
bflt += (*brp - '0') / base;
brp++;
blen--;
base *= 10;
}
bflt *= bsign;
}
if (aflt < bflt) return -1;
if (aflt > bflt) return 1;
}
LexicalComparator lexcomp;
int32_t rv = lexcomp.compare(akbuf, aksiz, bkbuf, bksiz);
return rv;
}
};
/**
* Comparator in the decimal descending order.
*/
class DecimalDescendingComparator : public Comparator {
public:
explicit DecimalDescendingComparator() : comp_() {}
int32_t compare(const char* akbuf, size_t aksiz, const char* bkbuf, size_t bksiz) {
return -comp_.compare(akbuf, aksiz, bkbuf, bksiz);
}
private:
DecimalComparator comp_;
};
/**
* Prepared pointer of the comparator in the lexical order.
*/
extern LexicalComparator* const LEXICALCOMP;
/**
* Prepared pointer of the comparator in the lexical descending order.
*/
extern LexicalDescendingComparator* const LEXICALDESCCOMP;
/**
* Prepared pointer of the comparator in the decimal order.
*/
extern DecimalComparator* const DECIMALCOMP;
/**
* Prepared pointer of the comparator in the decimal descending order.
*/
extern DecimalDescendingComparator* const DECIMALDESCCOMP;
} // common namespace
#endif // duplication check
// END OF FILE
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