/********************************************************************
Function name: st_create()
Purpose: Creates a new empty symbol table
Author: Warren Rainey
History/Versions: 1.0
Called functions: malloc(), st_setsize(), b_create(), free()
In parameters: int
Return Value: STD (Symbol Table Descriptor)
**********************************************************************/
STD st_create(int st_size){
STD symTable;
symTable.plsBD=0;
sym_table.st_size = 0;
if(st_size <= 0){
return symTable;
}
symTable.pstvr = (STVR*) malloc(sizeof (STVR)*st_size);
if(symTable.pstvr == NULL){
st_setsize();/*This is useless. Setting to 0 inorder to not return garbage*/
return symTable;
}
symTable.plsBD = b_create(INITIAL_CAPACITY,INCREMENT_FACTOR,'a');
symTable.st_offset = 0;
if(symTable.plsBD == NULL){
free(sym_table.pstvr);
st_setsize();
}else{
symTable.st_size = st_size;
}
return symTable;
}
/*******************************************************************************
* Purpose: Frees memory occupied by symbol table dynamic areas and sets
* global symbol table size to 0.
* Author: Skye Turriff
* History: Version 1, 21 November 2015
* Called functions: b_destroy(), free(), st_setsize()
* Parameters: STD sym_table struct
* Return value: None
*******************************************************************************/
void st_destroy(STD sym_table) {
if (sym_table.st_size != 0) {
b_destroy(sym_table.plsBD);
free(sym_table.pstvr);
st_setsize();
}
}
/********************************************************************
Function name: st_destroy()
Purpose: This function frees the memory occupied by the symbol table dynamic areas and sets st_size to 0.
Author: Warren Rainey
History/Versions: 1.0
Called functions: b_destroy(), free(), st_setsize()
In parameters: STD
Return Value: Void
**********************************************************************/
void st_destroy(STD sym_table){
if(sym_table.plsBD==NULL && sym_table.pstvr == NULL){
return;
}
if(sym_table.st_size != 0){
b_destroy(sym_table.plsBD);
free(sym_table.pstvr);
st_setsize();/*Set size of symboltable to 0*/
}
return;
}
/**********************************************************************************************************
Purpose: Free all the dynamically allocated memory associated with the symbol table.
Author: Thom Palmer
History/Versions: 10.18.13
Called functions: b_destroy(), free()
Parameters: STD sym_table
Return value: void
Algorithm: Check to ensure both dynamically allocated structures have valid pointers before
freeing the memory. We thought this was safer then checking the size.
**********************************************************************************************************/
void st_destroy(STD sym_table)
{
/* Even though b_destroy handles NULL this check avoids creating an unnecessary stack frame */
if(sym_table.plsBD)
{
b_destroy(sym_table.plsBD);
}
/* Ensure the pointer is valid before freeing the memory to avoid crashing */
if(sym_table.pstvr)
{
free((STVR*)sym_table.pstvr);
}
/* Set the size to 0 so the STD will be marked as invalid */
st_setsize();
}