/usr/include/colib/hash.h is in libiulib-dev 0.4+is+0.3-3ubuntu1.
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// Copyright 2006 Deutsches Forschungszentrum fuer Kuenstliche Intelligenz
// or its licensors, as applicable.
// Copyright 1995-2005 Thomas M. Breuel.
//
// You may not use this file except under the terms of the accompanying license.
//
// 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.
//
// Project: iulib -- image understanding library
// File: hash.h
// Purpose: simple hash table imlpementation
// Responsible: tmb
// Reviewer:
// Primary Repository:
// Web Sites: www.iupr.org, www.dfki.de
/// \file hash.h
/// \brief Simple hash table implementations.
#ifndef h_hash_
#define h_hash_
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "colib/narray.h"
#include "smartptr.h"
namespace colib {
namespace {
const int hash_empty = 999999;
inline int hash_next(int size) {
int i = 1;
while(i<=size) i<<=1;
return i+1;
}
inline int hash_value(int key,int n) {
ASSERT(n>0);
return int(unsigned(98.209328340918084289029384908 * key
+ 0.2349082034802840982092834098)%n);
}
inline int hash_value(int key1,int key2,int n) {
ASSERT(n>0);
return int(unsigned(1793.02934802983402808942308402389908 * key1 +
34.34983902935890238058909480840238 * key2
+ 0.8949173412390482890423908048) % n);
}
inline int hash_value(const char *p,int n) {
double total = 0.0;
while(*p) {
total = total * 1.29008352390840238 + (*p++) * 0.209384902384;
}
return int(unsigned(total)%n);
}
}
/// \brief A simple int-to-something hash class.
///
/// This is not particularly high performance, but it should be good enough for most uses.
template <class T>
class inthash {
private:
struct kvp {
int key;
T value;
kvp() { key = hash_empty; }
};
narray<kvp> data;
int fill;
void maybe_grow() {
if(fill>data.length()/2)
grow(data.length()+1);
}
public:
/// Allocate a hash table with a given initial size.
inthash(int initial=3) {
data.resize(max(3,initial));
fill = 0;
}
/// Make the hash table empty again and deallocate all the data it holds.
void dealloc() {
data.dealloc();
data.resize(3);
fill = 0;
}
/// Grow the hash table by the given amount.
void grow_by(int n) {
ASSERT(n>=0);
inthash nhash(data.length()+n);
for(int i=0;i<data.length();i++) {
kvp &entry = data[i];
if(entry.key==hash_empty) continue;
nhash(entry.key) = entry.value;
}
move(data,nhash.data);
fill = nhash.fill;
}
/// Return a reference to the location associated with the given key.
T &operator()(int key) {
if(key==hash_empty) throw "key value reserved for hash table implementation";
int n = data.length();
int base = hash_value(key,n);
for(int i=0;i<n;i++) {
int index = (base+i)%n;
kvp &entry = data[index];
if(entry.key==key)
return entry.value;
if(entry.key==hash_empty) {
if(fill<data.length()/2) {
fill++;
entry.key = key;
return entry.value;
}
grow_by(hash_next(data.length())-data.length());
return operator()(key);
}
}
throw "internal error: no empty hash bucket found";
}
T &at(int key) {
return this->operator()(key);
}
/// Return a list of keys.
void keys(narray<int> &result) {
result.clear();
for(int i=0;i<data.length();i++) {
kvp &entry = data[i];
if(entry.key!=hash_empty) {
result.push(entry.key);
}
}
}
};
/// \brief A simple pair-of-int-to-something hash class.
///
/// This is not particularly high performance, but it should be good enough for most uses.
template <class T>
class int2hash {
private:
struct kvp {
int key1,key2;
T value;
kvp() { key1 = hash_empty; }
};
narray<kvp> data;
int fill;
void maybe_grow() {
if(fill>data.length()/2)
grow(data.length()+1);
}
public:
/// Allocate a hash table with a given initial size.
int2hash(int initial=3) {
data.dealloc();
data.resize(max(3,initial));
fill = 0;
}
/// Make the hash table empty again and deallocate all the data it holds.
void dealloc() {
data.dealloc();
data.resize(3);
fill = 0;
}
/// Grow the hash table by the given amount.
void grow_by(int n) {
ASSERT(n>=0);
int2hash<T> nhash(data.length()+n);
for(int i=0;i<data.length();i++) {
kvp &entry = data[i];
if(entry.key1==hash_empty) continue;
nhash(entry.key1,entry.key2) = entry.value;
}
move(data,nhash.data);
fill = nhash.fill;
}
/// Return a reference to the location associated with the given key.
T &operator()(int key1,int key2) {
if(key1==hash_empty) throw "key value reserved for hash table implementation";
int n = data.length();
int base = hash_value(key1,key2,n);
for(int i=0;i<n;i++) {
int index = (base+i)%n;
kvp &entry = data[index];
if(entry.key1==key1 && entry.key2==key2)
return entry.value;
if(entry.key1==hash_empty) {
if(fill<data.length()/2) {
fill++;
entry.key1 = key1;
entry.key2 = key2;
return entry.value;
}
grow_by(hash_next(data.length())-data.length());
return operator()(key1,key2);
}
}
throw "internal error: no empty hash bucket found";
}
};
/// A string-to-something hash class.
/// \brief A simple string-to-something hash class.
///
/// This is not particularly high performance, but it should be good enough for most uses.
template <class T>
class strhash {
private:
struct kvp {
autofree<char> key;
T value;
};
narray<kvp> data;
int fill;
void maybe_grow() {
if(fill>data.length()/2)
grow(data.length()+1);
}
public:
/// Allocate a hash table with a given initial size.
strhash(int initial=3) {
data.dealloc();
data.resize(max(3,initial));
fill = 0;
}
/// Make the hash table empty again and deallocate all the data it holds.
void dealloc() {
data.dealloc();
data.resize(3);
fill = 0;
}
/// Grow the hash table by the given amount.
void grow_by(int n) {
ASSERT(n>=0);
strhash nhash(data.length()+n);
for(int i=0;i<data.length();i++) {
kvp &entry = data[i];
if(entry.key.ptr()==0) continue;
nhash(entry.key.ptr()) = entry.value;
}
move(data,nhash.data);
fill = nhash.fill;
}
/// Return a reference to the location associated with the given key.
T &operator()(const char *key) {
if(key==0) throw "key value reserved for hash table implementation";
int n = data.length();
int base = hash_value(key,n);
for(int i=0;i<n;i++) {
int index = (base+i)%n;
kvp &entry = data[index];
if(entry.key.ptr() && !strcmp(entry.key.ptr(),key))
return entry.value;
if(!entry.key) {
if(fill<data.length()/2) {
fill++;
entry.key = strdup(key);
return entry.value;
}
grow_by(hash_next(data.length())-data.length());
return operator()(key);
}
}
throw "internal error: no empty hash bucket found";
}
};
}
#endif
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