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/************************************************************************
************************************************************************
FAUST compiler
Copyright (C) 2003-2004 GRAME, Centre National de Creation Musicale
---------------------------------------------------------------------
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 2 of the License, or
(at your option) 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
************************************************************************
************************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "symbol.hh"
#include "compatibility.hh"
#include <iostream>
#include <cstring>
#include <assert.h>
using namespace std;
/**
* Hash table used to store the symbols
*/
Symbol* Symbol::gSymbolTable[kHashTableSize];
/**
* Search the hash table for the symbol of name \p str or returns a new one.
* \param str the name of the symbol
* \return a symbol of name str
*/
Symbol* Symbol::get(const string& str)
{
char buf[1024];
int i;
int n = str.length();
if (n>1023) n = 1023;
for (i = 0; i < n; i++) { buf[i] = str[i]; }
buf[i] = 0;
return Symbol::get(buf);
}
/**
* Search the hash table for the symbol of name \p str or returns a new one.
* \param str the name of the symbol
* \return a symbol of name str
*/
Symbol* Symbol::get(const char* str)
{
unsigned int hsh = calcHashKey(str);
int bckt = hsh % kHashTableSize;
Symbol* item = gSymbolTable[bckt];
while ( item && !item->equiv(hsh,str) ) item = item->fNext;
Symbol* r = item ? item : gSymbolTable[bckt] = new Symbol(str, hsh, gSymbolTable[bckt]);
return r;
}
/**
* Static method that searches the symbol table for a string.
* \param str string to search
* \return true if the string is NOT in the table (it is a new string)
*/
bool Symbol::isnew(const char* str)
{
unsigned int hsh = calcHashKey(str);
int bckt = hsh % kHashTableSize;
Symbol* item = gSymbolTable[bckt];
while ( item && !item->equiv(hsh,str) ) item = item->fNext;
return item == 0;
}
/**
* Creates a new symbol with a name obtained by concatenating the \p str prefix with a number in order to make it unique
* \param str the prefix of the name
* \return a symbol of name \p prefix++n
*/
Symbol* Symbol::prefix (const char* str)
{
char name[256];
static map<const char*, unsigned int> gPrefixCounters;
for (int n = 0; n<10000; n++) {
snprintf(name, 256, "%s%d", str, gPrefixCounters[str]++);
if (isnew(name)) return get(name);
}
assert(false);
return get("UNIQUEOVERFLOW");
}
/**
* Check if the name of the symbol is equal to string \p str
* This method is used by isnew() and make() when searching the hashtable
* for an existing symbol.
*
* \param hash the hash key of the string (used to speedup the comparison)
* \param str the string to compare
* \return \p true if the name of the symbol and \p str are the same
*/
bool Symbol::equiv (unsigned int hash, const char *str) const
{
return (fHash == hash) && (strcmp(fName,str) == 0);
}
/**
* Compute the 32-bits hash key of string \p str
* \param str the string
* \return a 32-bits hash key
*/
unsigned int Symbol::calcHashKey (const char* str)
{
unsigned int h = 0;
while (*str) h = (h << 1) ^ (h >> 20) ^ (*str++);
return h;
}
/**
* Constructs a symbol ready to be placed in the hash table.
* It makes a private copy of its name.
* \param str the name of the symbol
* \param hsh the hash key of the symbol
* \param nxt a pointer to the next symbol in the hash table entry
*/
Symbol::Symbol(const char* str, unsigned int hsh, Symbol* nxt)
{
int len = strlen(str);
fName = new char [len+1];
memcpy(fName, str, len+1);
fHash = hsh;
fNext = nxt;
fData = 0;
}
Symbol::~Symbol ()
{
delete [] fName;
}
ostream& Symbol::print (ostream& fout) const ///< print a symbol on a stream
{
return fout << fName;
}
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