/**
* @return the position of the first occurrence of item in the Stack or -1
* if item cannot be found. The search begins at the top of the Stack
* (position 0) and proceeds downward (position 1, 2, etc.).
*
* Since ultimately the stack stores pointers, == is used to test for
* equality.
*/
LIBSBML_EXTERN
int
Stack_find (Stack_t *s, void *item)
{
int pos = Stack_size(s);
while ((pos-- > 0) && (s->stack[pos] != item)) ;
if (pos >= 0)
{
pos = s->sp - pos;
}
return pos;
}
/**
* Pushes item onto the top of the Stack.
*/
LIBSBML_EXTERN
void
Stack_push (Stack_t *s, void *item)
{
if (s == NULL) return;
if (Stack_size(s) == s->capacity)
{
s->capacity *= 2;
s->stack = (void **)
safe_realloc(s->stack, s->capacity * sizeof(void *));
}
s->stack[ ++(s->sp) ] = item;
}
/**
* @return (but does not remove) the nth item from the top of the Stack,
* starting at zero, i.e. Stack_peekAt(0) is equivalent to Stack_peek().
* If n is out of range (n < 0 or n >= Stack_size()) returns NULL.
*/
LIBSBML_EXTERN
void *
Stack_peekAt (Stack_t *s, int n)
{
int size = Stack_size(s);
if (s == NULL) return NULL;
if (n < 0 || n >= size)
{
REPORT_STACK_RANGE_ERROR("Stack_peekAt", n, size);
return NULL;
}
return s->stack[ s->sp - n ];
}
/**
* @if conly
* @memberof ASTNode_t
* @endif
*/
LIBSBML_EXTERN
ASTNode_t *
SBML_parseFormula (const char *formula)
{
long rule, state, action;
ASTNode_t *node = NULL;
FormulaTokenizer_t *tokenizer = NULL;
Stack_t *stack = NULL;
Token_t *token = NULL;
if (formula == NULL) return NULL;
tokenizer = FormulaTokenizer_createFromFormula(formula);
token = FormulaTokenizer_nextToken(tokenizer);
stack = Stack_create(20);
Stack_push(stack, (void *) START_STATE);
while (1)
{
state = (long) Stack_peek(stack);
action = FormulaParser_getAction(state, token);
if (action == ACCEPT_STATE)
{
node = Stack_peekAt(stack, 1);
break;
}
else if (action == ERROR_STATE)
{
/**
* Free ASTNodes on the Stack, skip the states.
*/
while (Stack_size(stack) > 1)
{
Stack_pop(stack);
ASTNode_free( Stack_pop(stack) );
}
node = NULL;
break;
}
/**
* Shift
*/
else if (action > 0)
{
Stack_push( stack, ASTNode_createFromToken(token) );
Stack_push( stack, (void *) action );
Token_free(token);
token = FormulaTokenizer_nextToken(tokenizer);
}
/**
* Reduce
*/
else if (action < 0)
{
rule = -action;
node = FormulaParser_reduceStackByRule(stack, rule);
state = (long) Stack_peek(stack);
Stack_push( stack, node );
Stack_push( stack, (void *) FormulaParser_getGoto(state, rule) );
}
}
FormulaTokenizer_free(tokenizer);
Stack_free(stack);
Token_free(token);
return node;
}
