/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/ /// <summary>Pop the stack. /// </summary> public virtual void pop() { if ((vstack.Count == 0)) { throw new System.Exception("Internal parser error: pop from empty virtual stack"); } /* pop it */ vstack.Pop(); /* if we are now empty transfer an element (if there is one) */ if ((vstack.Count == 0)) { 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; }
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/ /// <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); }