/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Equality comparison. */
public bool Equals(lalr_item_set other)
{
if (other == null || other.size() != size())
{
return(false);
}
/* once we know they are the same size, then improper subset does test */
try
{
return(is_subset_of(other));
}
catch (internal_error e)
{
/* can't throw error from here (because superclass doesn't) so crash */
e.crash();
return(false);
}
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Equality comparison. */
public bool Equals(lalr_item_set other)
{
if (other == null || other.size() != size()) return false;
/* once we know they are the same size, then improper subset does test */
try
{
return is_subset_of(other);
}
catch (internal_error e)
{
/* can't throw error from here (because superclass doesn't) so crash */
e.crash();
return false;
}
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Compute the closure of the Set using the LALR closure rules. Basically
* for every item of the form: <pre>
* [L ::= a *N alpha, l]
* </pre>
* (where N is a a non terminal and alpha is a string of symbols) make
* sure there are also items of the form: <pre>
* [N ::= *beta, first(alpha l)]
* </pre>
* corresponding to each production of N. Items with identical cores but
* differing lookahead sets are merged by creating a new item with the same
* core and the union of the lookahead sets (the LA in LALR stands for
* "lookahead merged" and this is where the merger is). This routine
* assumes that nullability and first sets have been computed for all
* productions before it is called.
*/
public void compute_closure()
{
lalr_item_set consider;
lalr_item itm, new_itm, add_itm;
non_terminal nt;
terminal_set new_lookaheads;
IEnumerator p;
production prod;
bool need_prop;
/* invalidate cached hashcode */
is_cached = false;
/* each current element needs to be considered */
consider = new lalr_item_set(this);
/* repeat this until there is nothing else to consider */
while (consider.size() > 0)
{
/* get one item to consider */
itm = consider.get_one();
/* do we have a dot before a non terminal */
nt = itm.dot_before_nt();
if (nt != null)
{
/* create the lookahead Set based on first after dot */
new_lookaheads = itm.calc_lookahead(itm.lookahead());
/* are we going to need to propagate our lookahead to new item */
need_prop = itm.lookahead_visible();
/* create items for each production of that non term */
p = nt.productions();
while (p.MoveNext())
{
prod = (production)p.Current;
/* create new item with dot at start and that lookahead */
new_itm = new lalr_item(prod,
new terminal_set(new_lookaheads));
/* add/merge item into the Set */
add_itm = add(new_itm);
/* if propagation is needed link to that item */
if (need_prop)
{
itm.add_propagate(add_itm);
}
/* was this was a new item*/
if (add_itm == new_itm)
{
/* that may need further closure, consider it also */
consider.add(new_itm);
}
}
}
}
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Compute the closure of the Set using the LALR closure rules. Basically
* for every item of the form: <pre>
* [L ::= a *N alpha, l]
* </pre>
* (where N is a a non terminal and alpha is a string of symbols) make
* sure there are also items of the form: <pre>
* [N ::= *beta, first(alpha l)]
* </pre>
* corresponding to each production of N. Items with identical cores but
* differing lookahead sets are merged by creating a new item with the same
* core and the union of the lookahead sets (the LA in LALR stands for
* "lookahead merged" and this is where the merger is). This routine
* assumes that nullability and first sets have been computed for all
* productions before it is called.
*/
public void compute_closure()
{
lalr_item_set consider;
lalr_item itm, new_itm, add_itm;
non_terminal nt;
terminal_set new_lookaheads;
IEnumerator p;
production prod;
bool need_prop;
/* invalidate cached hashcode */
is_cached=false;
/* each current element needs to be considered */
consider = new lalr_item_set(this);
/* repeat this until there is nothing else to consider */
while (consider.size() > 0)
{
/* get one item to consider */
itm = consider.get_one();
/* do we have a dot before a non terminal */
nt = itm.dot_before_nt();
if (nt != null)
{
/* create the lookahead Set based on first after dot */
new_lookaheads = itm.calc_lookahead(itm.lookahead());
/* are we going to need to propagate our lookahead to new item */
need_prop = itm.lookahead_visible();
/* create items for each production of that non term */
p = nt.productions();
while ( p.MoveNext() )
{
prod = (production)p.Current;
/* create new item with dot at start and that lookahead */
new_itm = new lalr_item(prod,
new terminal_set(new_lookaheads));
/* add/merge item into the Set */
add_itm = add(new_itm);
/* if propagation is needed link to that item */
if (need_prop)
itm.add_propagate(add_itm);
/* was this was a new item*/
if (add_itm == new_itm)
{
/* that may need further closure, consider it also */
consider.add(new_itm);
}
}
}
}
}