/*-----------------------------------------------------------*/
/*--- Constructor(s) ----------------------------------------*/
/*-----------------------------------------------------------*/
/// <summary>Full constructor.
/// </summary>
/// <param name="prod">the production for the item.
/// </param>
/// <param name="pos"> the position of the "dot" within the production.
/// </param>
/// <param name="look">the set of lookahead symbols.
///
/// </param>
public lalr_item(production prod, int pos, terminal_set look)
: base(prod, pos)
{
_lookahead = look;
_propagate_items = new CUP.runtime.SymbolStack();
needs_propagation = true;
}
/*-----------------------------------------------------------*/
/*--- Constructor(s) ----------------------------------------*/
/*-----------------------------------------------------------*/
/// <summary>Constructor to build a virtual stack out of a real stack.
/// </summary>
public virtual_parse_stack(CUP.runtime.SymbolStack shadowing_stack)
{
/* sanity check */
if (shadowing_stack == null)
throw new System.Exception("Internal parser error: attempt to create null virtual stack");
/* set up our internals */
real_stack = shadowing_stack;
vstack = new CUP.runtime.SymbolStack();
real_next = 0;
/* get one element onto the virtual portion of the stack */
get_from_real();
}
/*-----------------------------------------------------------*/
/*--- Constructor(s) ----------------------------------------*/
/*-----------------------------------------------------------*/
/// <summary>Constructor to build a virtual stack out of a real stack.
/// </summary>
public virtual_parse_stack(CUP.runtime.SymbolStack shadowing_stack)
{
/* sanity check */
if (shadowing_stack == null)
{
throw new System.Exception("Internal parser error: attempt to create null virtual stack");
}
/* set up our internals */
real_stack = shadowing_stack;
vstack = new CUP.runtime.SymbolStack();
real_next = 0;
/* get one element onto the virtual portion of the stack */
get_from_real();
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/// <summary>Build an LALR viable prefix recognition machine given a start
/// production. This method operates by first building a start state
/// from the start production (based on a single item with the dot at
/// the beginning and EOF as expected lookahead). Then for each state
/// it attempts to extend the machine by creating transitions out of
/// the state to new or existing states. When considering extension
/// from a state we make a transition on each symbol that appears before
/// the dot in some item. For example, if we have the items: <pre>
/// [A ::= a b * X c, {d,e}]
/// [B ::= a b * X d, {a,b}]
/// </pre>
/// in some state, then we would be making a transition under X to a new
/// state. This new state would be formed by a "kernel" of items
/// corresponding to moving the dot past the X. In this case: <pre>
/// [A ::= a b X * c, {d,e}]
/// [B ::= a b X * Y, {a,b}]
/// </pre>
/// The full state would then be formed by "closing" this kernel set of
/// items so that it included items that represented productions of things
/// the parser was now looking for. In this case we would items
/// corresponding to productions of Y, since various forms of Y are expected
/// next when in this state (see lalr_item_set.compute_closure() for details
/// on closure). <p>
/// *
/// The process of building the viable prefix recognizer terminates when no
/// new states can be added. However, in order to build a smaller number of
/// states (i.e., corresponding to LALR rather than canonical LR) the state
/// building process does not maintain full loookaheads in all items.
/// Consequently, after the machine is built, we go back and propagate
/// lookaheads through the constructed machine using a call to
/// propagate_all_lookaheads(). This makes use of propagation links
/// constructed during the closure and transition process.
/// *
/// </summary>
/// <param name="start_prod">the start production of the grammar
/// </param>
/// <seealso cref=" CUP.lalr_item_set#compute_closure
/// "/>
/// <seealso cref=" CUP.lalr_state#propagate_all_lookaheads
///
/// "/>
public static lalr_state build_machine(production start_prod)
{
lalr_state start_state;
lalr_item_set start_items;
lalr_item_set new_items;
lalr_item_set linked_items;
lalr_item_set kernel;
CUP.runtime.SymbolStack work_stack = new CUP.runtime.SymbolStack();
lalr_state st, new_st;
symbol_set outgoing;
lalr_item itm, new_itm, existing, fix_itm;
symbol sym, sym2;
System.Collections.IEnumerator i, s, fix;
/* sanity check */
if (start_prod == null)
throw new internal_error("Attempt to build viable prefix recognizer using a null production");
/* build item with dot at front of start production and EOF lookahead */
start_items = new lalr_item_set();
itm = new lalr_item(start_prod);
itm.lookahead().add(terminal.EOF);
start_items.add(itm);
/* create copy the item set to form the kernel */
kernel = new lalr_item_set(start_items);
/* create the closure from that item set */
start_items.compute_closure();
/* build a state out of that item set and put it in our work set */
start_state = new lalr_state(start_items);
System.Object temp_object;
temp_object = start_state;
System.Object generatedAux = temp_object;
work_stack.Push(temp_object);
/* enter the state using the kernel as the key */
SupportClass.PutElement(_all_kernels, kernel, start_state);
/* continue looking at new states until we have no more work to do */
while (!(work_stack.Count == 0))
{
/* remove a state from the work set */
st = (lalr_state) work_stack.Pop();
/* gather up all the symbols that appear before dots */
outgoing = new symbol_set();
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (i = st.items().all(); i.MoveNext(); )
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
itm = (lalr_item) i.Current;
/* add the symbol before the dot (if any) to our collection */
sym = itm.symbol_after_dot();
if (sym != null)
outgoing.add(sym);
}
/* now create a transition out for each individual symbol */
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (s = outgoing.all(); s.MoveNext(); )
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
sym = (symbol) s.Current;
/* will be keeping the set of items with propagate links */
linked_items = new lalr_item_set();
/* gather up shifted versions of all the items that have this
symbol before the dot */
new_items = new lalr_item_set();
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (i = st.items().all(); i.MoveNext(); )
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
itm = (lalr_item) i.Current;
/* if this is the symbol we are working on now, add to set */
sym2 = itm.symbol_after_dot();
if (sym.Equals(sym2))
{
/* add to the kernel of the new state */
new_items.add(itm.shift());
/* remember that itm has propagate link to it */
linked_items.add(itm);
}
}
/* use new items as state kernel */
kernel = new lalr_item_set(new_items);
/* have we seen this one already? */
new_st = (lalr_state) _all_kernels[kernel];
/* if we haven't, build a new state out of the item set */
if (new_st == null)
{
/* compute closure of the kernel for the full item set */
new_items.compute_closure();
/* build the new state */
new_st = new lalr_state(new_items);
/* add the new state to our work set */
System.Object temp_object2;
temp_object2 = new_st;
System.Object generatedAux2 = temp_object2;
work_stack.Push(temp_object2);
/* put it in our kernel table */
SupportClass.PutElement(_all_kernels, kernel, new_st);
}
else
{
/* walk through the items that have links to the new state */
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (fix = linked_items.all(); fix.MoveNext(); )
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
fix_itm = (lalr_item) fix.Current;
/* look at each propagate link out of that item */
for (int l = 0; l < fix_itm.propagate_items().Count; l++)
{
/* pull out item linked to in the new state */
new_itm = (lalr_item) (fix_itm.propagate_items().Peek(fix_itm.propagate_items().Count - (l + 1)));
/* find corresponding item in the existing state */
existing = new_st.items().find(new_itm);
/* fix up the item so it points to the existing set */
if (existing != null)
fix_itm.propagate_items()[l] = existing;
}
}
}
/* add a transition from current state to that state */
st.add_transition(sym, new_st);
}
}
/* all done building states */
/* propagate complete lookahead sets throughout the states */
propagate_all_lookaheads();
return start_state;
}
/*-----------------------------------------------------------*/
/*--- Constructor(s) ----------------------------------------*/
/*-----------------------------------------------------------*/
/// <summary>Full constructor.
/// </summary>
/// <param name="prod">the production for the item.
/// </param>
/// <param name="pos"> the position of the "dot" within the production.
/// </param>
/// <param name="look">the set of lookahead symbols.
///
/// </param>
public lalr_item(production prod, int pos, terminal_set look) : base(prod, pos)
{
_lookahead = look;
_propagate_items = new CUP.runtime.SymbolStack();
needs_propagation = true;
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/// <summary>Build an LALR viable prefix recognition machine given a start
/// production. This method operates by first building a start state
/// from the start production (based on a single item with the dot at
/// the beginning and EOF as expected lookahead). Then for each state
/// it attempts to extend the machine by creating transitions out of
/// the state to new or existing states. When considering extension
/// from a state we make a transition on each symbol that appears before
/// the dot in some item. For example, if we have the items: <pre>
/// [A ::= a b * X c, {d,e}]
/// [B ::= a b * X d, {a,b}]
/// </pre>
/// in some state, then we would be making a transition under X to a new
/// state. This new state would be formed by a "kernel" of items
/// corresponding to moving the dot past the X. In this case: <pre>
/// [A ::= a b X * c, {d,e}]
/// [B ::= a b X * Y, {a,b}]
/// </pre>
/// The full state would then be formed by "closing" this kernel set of
/// items so that it included items that represented productions of things
/// the parser was now looking for. In this case we would items
/// corresponding to productions of Y, since various forms of Y are expected
/// next when in this state (see lalr_item_set.compute_closure() for details
/// on closure). <p>
/// *
/// The process of building the viable prefix recognizer terminates when no
/// new states can be added. However, in order to build a smaller number of
/// states (i.e., corresponding to LALR rather than canonical LR) the state
/// building process does not maintain full loookaheads in all items.
/// Consequently, after the machine is built, we go back and propagate
/// lookaheads through the constructed machine using a call to
/// propagate_all_lookaheads(). This makes use of propagation links
/// constructed during the closure and transition process.
/// *
/// </summary>
/// <param name="start_prod">the start production of the grammar
/// </param>
/// <seealso cref=" CUP.lalr_item_set#compute_closure
/// "/>
/// <seealso cref=" CUP.lalr_state#propagate_all_lookaheads
///
/// "/>
public static lalr_state build_machine(production start_prod)
{
lalr_state start_state;
lalr_item_set start_items;
lalr_item_set new_items;
lalr_item_set linked_items;
lalr_item_set kernel;
CUP.runtime.SymbolStack work_stack = new CUP.runtime.SymbolStack();
lalr_state st, new_st;
symbol_set outgoing;
lalr_item itm, new_itm, existing, fix_itm;
symbol sym, sym2;
System.Collections.IEnumerator i, s, fix;
/* sanity check */
if (start_prod == null)
{
throw new internal_error("Attempt to build viable prefix recognizer using a null production");
}
/* build item with dot at front of start production and EOF lookahead */
start_items = new lalr_item_set();
itm = new lalr_item(start_prod);
itm.lookahead().add(terminal.EOF);
start_items.add(itm);
/* create copy the item set to form the kernel */
kernel = new lalr_item_set(start_items);
/* create the closure from that item set */
start_items.compute_closure();
/* build a state out of that item set and put it in our work set */
start_state = new lalr_state(start_items);
System.Object temp_object;
temp_object = start_state;
System.Object generatedAux = temp_object;
work_stack.Push(temp_object);
/* enter the state using the kernel as the key */
SupportClass.PutElement(_all_kernels, kernel, start_state);
/* continue looking at new states until we have no more work to do */
while (!(work_stack.Count == 0))
{
/* remove a state from the work set */
st = (lalr_state)work_stack.Pop();
/* gather up all the symbols that appear before dots */
outgoing = new symbol_set();
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (i = st.items().all(); i.MoveNext();)
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
itm = (lalr_item)i.Current;
/* add the symbol before the dot (if any) to our collection */
sym = itm.symbol_after_dot();
if (sym != null)
{
outgoing.add(sym);
}
}
/* now create a transition out for each individual symbol */
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (s = outgoing.all(); s.MoveNext();)
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
sym = (symbol)s.Current;
/* will be keeping the set of items with propagate links */
linked_items = new lalr_item_set();
/* gather up shifted versions of all the items that have this
* symbol before the dot */
new_items = new lalr_item_set();
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (i = st.items().all(); i.MoveNext();)
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
itm = (lalr_item)i.Current;
/* if this is the symbol we are working on now, add to set */
sym2 = itm.symbol_after_dot();
if (sym.Equals(sym2))
{
/* add to the kernel of the new state */
new_items.add(itm.shift());
/* remember that itm has propagate link to it */
linked_items.add(itm);
}
}
/* use new items as state kernel */
kernel = new lalr_item_set(new_items);
/* have we seen this one already? */
new_st = (lalr_state)_all_kernels[kernel];
/* if we haven't, build a new state out of the item set */
if (new_st == null)
{
/* compute closure of the kernel for the full item set */
new_items.compute_closure();
/* build the new state */
new_st = new lalr_state(new_items);
/* add the new state to our work set */
System.Object temp_object2;
temp_object2 = new_st;
System.Object generatedAux2 = temp_object2;
work_stack.Push(temp_object2);
/* put it in our kernel table */
SupportClass.PutElement(_all_kernels, kernel, new_st);
}
else
{
/* walk through the items that have links to the new state */
//UPGRADE_TODO: method 'java.util.Enumeration.hasMoreElements' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationhasMoreElements"'
for (fix = linked_items.all(); fix.MoveNext();)
{
//UPGRADE_TODO: method 'java.util.Enumeration.nextElement' was converted to ' ' which has a different behavior. 'ms-help://MS.VSCC/commoner/redir/redirect.htm?keyword="jlca1073_javautilEnumerationnextElement"'
fix_itm = (lalr_item)fix.Current;
/* look at each propagate link out of that item */
for (int l = 0; l < fix_itm.propagate_items().Count; l++)
{
/* pull out item linked to in the new state */
new_itm = (lalr_item)(fix_itm.propagate_items().Peek(fix_itm.propagate_items().Count - (l + 1)));
/* find corresponding item in the existing state */
existing = new_st.items().find(new_itm);
/* fix up the item so it points to the existing set */
if (existing != null)
{
fix_itm.propagate_items()[l] = existing;
}
}
}
}
/* add a transition from current state to that state */
st.add_transition(sym, new_st);
}
}
/* all done building states */
/* propagate complete lookahead sets throughout the states */
propagate_all_lookaheads();
return(start_state);
}
private void InitBlock()
{
stack = new CUP.runtime.SymbolStack();
}
