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/*
* Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
* All rights reserved.
* This component and the accompanying materials are made available
* under the terms of the License "Eclipse Public License v1.0"
* which accompanies this distribution, and is available
* at the URL "http://www.eclipse.org/legal/epl-v10.html".
*
* Initial Contributors:
* Nokia Corporation - initial contribution.
*
* Contributors:
*
* Description:
* Hash class for imgcheck tool. All the executable names of ROM/ROFS
* are stored into this hash table. After gathering the dependencies
* for those executables, dependencies existence is checked very
* efficiently using this table.
*
*/
/**
@file
@internalComponent
@released
*/
#include "common.h"
#include "hash.h"
/**
Constructor, intializes the table size
@internalComponent
@released
@param aSize - Hash table size (Number of dissimilar data can stored)
*/
HashTable::HashTable(int aSize)
:iSize(aSize) {
}
/**
Destructor
@internalComponent
@released
*/
HashTable::~HashTable() {
}
/**
Function responsible to return the Hash value for the received string.
@internalComponent
@released
@param aString - const string& on which Hash value calcualtion
*/
int HashTable::Hash(const string& aString) {
unsigned int hashVal = 0;
int length = aString.length() ;
/* we start our hash out at 0 */
/* for each character, we multiply the old hash by 31 and add the current
* character. Remember that shifting a number left is equivalent to
* multiplying it by 2 raised to the number of places shifted. So we
* are in effect multiplying hashval by 32 and then subtracting hashval.
* Why do we do this? Because shifting and subtraction are much more
* efficient operations than multiplication.
*/
for(int strIter = 0; strIter < length ; strIter++) {
hashVal = aString[strIter] + (hashVal << 5) - hashVal;
}
/* we then return the hash value mod the hashtable size so that it will
* fit into the necessary range
*/
return hashVal % iSize;
}
/**
Function returns ture or false based on the string availability in Hash
@internalComponent
@released
@param aString - const char* which needs to be searched
*/
bool HashTable::IsAvailable(const string& aString) {
unsigned int hashVal = Hash(aString);
if (iTable.count(hashVal) > 0) {
pair<Table::iterator,Table::iterator> range = iTable.equal_range(hashVal);
for(Table::iterator it = range.first; it != range.second ; it++) {
if(aString == it->second ) {
return true;
}
}
}
return false;
}
/**
Function responsible to insert a single string into Hash table
@internalComponent
@released
@param aString - const char* which needs to be inserted
*/
void HashTable::Insert(const string& aString) {
unsigned int hashVal = Hash(aString);
if(!IsAvailable(aString)) {
iTable.insert(pair<unsigned int,string>(hashVal,aString));
}
}
/**
Function responsible to insert list of StringList into Hash table
@internalComponent
@released
@param aString - string which needs to be inserted
*/
void HashTable::InsertStringList(const StringList& aList) {
for(StringList::const_iterator it = aList.begin(); it != aList.end(); it++ ) {
Insert(*it);
}
}
/**
Function to delete an entry from Hash
@internalComponent
@released
@param aString - const char* which needs to be deleted
*/
void HashTable::Delete(const string& aString) {
unsigned int hashVal = Hash(aString);
if (iTable.count(hashVal) > 0) {
pair<Table::iterator,Table::iterator> range = iTable.equal_range(hashVal);
for(Table::iterator it = range.first; it != range.second ; it++) {
if(aString == it->second ) {
iTable.erase(it);
return ;
}
}
}
}