/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Build the (internal) parser from the previously parsed specification.
* This includes:<ul>
* <li> Computing nullability of non-terminals.
* <li> Computing first sets of non-terminals and productions.
* <li> Building the viable prefix recognizer machine.
* <li> Filling in the (internal) parse tables.
* <li> Checking for unreduced productions.
* </ul>
*/
protected static void build_parser()
{
/* compute nullability of all non terminals */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Computing non-terminal nullability...");
non_terminal.compute_nullability();
nullability_end = DateTime.Now.Ticks;
/* compute first sets of all non terminals */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Computing first sets...");
non_terminal.compute_first_sets();
first_end = DateTime.Now.Ticks;
/* build the LR viable prefix recognition machine */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Building state machine...");
start_state = lalr_state.build_machine(emit.start_production);
machine_end = DateTime.Now.Ticks;
/* build the LR parser action and reduce-goto tables */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Filling in tables...");
action_table = new parse_action_table();
reduce_table = new parse_reduce_table();
IEnumerator st = lalr_state.all();
while ( st.MoveNext() )
{
lalr_state lst = (lalr_state)st.Current;
lst.build_table_entries(
action_table, reduce_table);
}
table_end = DateTime.Now.Ticks;
/* check and warn for non-reduced productions */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Checking for non-reduced productions...");
action_table.check_reductions();
reduce_check_end = DateTime.Now.Ticks;
/* if we have more conflicts than we expected issue a message and die */
if (emit.num_conflicts > expect_conflicts)
{
System.Console.Error.WriteLine("*** More conflicts encountered than expected " +
"-- parser generation aborted");
lexer.error_count++; // indicate the problem.
// we'll die on return, after clean up.
}
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Emit the parser subclass with embedded tables.
* @param out stream to produce output on.
* @param action_table internal representation of the action table.
* @param reduce_table internal representation of the reduce-goto table.
* @param start_st start state of the parse machine.
* @param start_prod start production of the grammar.
* @param compact_reduces do we use most frequent reduce as default?
* @param suppress_scanner should scanner be suppressed for compatibility?
*/
public static void parser(
TextWriter cout,
parse_action_table action_table,
parse_reduce_table reduce_table,
int start_st,
production start_prod,
bool compact_reduces,
bool suppress_scanner)
{
long start_time = DateTime.Now.Ticks;
/* top of file */
cout.WriteLine();
cout.WriteLine("//----------------------------------------------------");
cout.WriteLine("// The following code was generated by " +
version.title_str);
cout.WriteLine("// " + DateTime.Now);
cout.WriteLine("//----------------------------------------------------");
cout.WriteLine();
emit_package(cout);
/* user supplied imports */
IEnumerator myEnum= import_list.GetEnumerator();
while (myEnum.MoveNext())
cout.WriteLine("using " + myEnum.Current.ToString() + ";");
/* class header */
cout.WriteLine();
cout.WriteLine("/** "+version.title_str+" generated parser.");
cout.WriteLine(" * @version " + DateTime.Now);
cout.WriteLine(" */");
cout.WriteLine("public class " + parser_class_name +
" : TUVienna.CS_CUP.Runtime.lr_parser {");
/* constructors [CSA/davidm, 24-jul-99] */
cout.WriteLine();
cout.WriteLine(" /** Default constructor. */");
cout.WriteLine(" public " + parser_class_name + "():base() {;}");
if (!suppress_scanner) {
cout.WriteLine();
cout.WriteLine(" /** Constructor which sets the default scanner. */");
cout.WriteLine(" public " + parser_class_name +
"(TUVienna.CS_CUP.Runtime.Scanner s): base(s) {;}");
}
/* emit the various tables */
emit_production_table(cout);
do_action_table(cout, action_table, compact_reduces);
do_reduce_table(cout, reduce_table);
/* instance of the action encapsulation class */
cout.WriteLine(" /** Instance of action encapsulation class. */");
cout.WriteLine(" protected " + pre("actions") + " action_obj;");
cout.WriteLine();
/* action object initializer */
cout.WriteLine(" /** Action encapsulation object initializer. */");
cout.WriteLine(" protected override void init_actions()");
cout.WriteLine(" {");
cout.WriteLine(" action_obj = new " + pre("actions") + "(this);");
cout.WriteLine(" }");
cout.WriteLine();
/* access to action code */
cout.WriteLine(" /** Invoke a user supplied parse action. */");
cout.WriteLine(" public override TUVienna.CS_CUP.Runtime.Symbol do_action(");
cout.WriteLine(" int act_num,");
cout.WriteLine(" TUVienna.CS_CUP.Runtime.lr_parser parser,");
cout.WriteLine(" System.Collections.Stack xstack1,");
cout.WriteLine(" int top)");
cout.WriteLine(" {");
cout.WriteLine(" mStack CUP_parser_stack= new mStack(xstack1);");
cout.WriteLine(" /* call code in generated class */");
cout.WriteLine(" return action_obj." + pre("do_action(") +
"act_num, parser, stack, top);");
cout.WriteLine(" }");
cout.WriteLine("");
/* method to tell the parser about the start state */
cout.WriteLine(" /** Indicates start state. */");
cout.WriteLine(" public override int start_state() {return " + start_st + ";}");
/* method to indicate start production */
cout.WriteLine(" /** Indicates start production. */");
cout.WriteLine(" public override int start_production() {return " +
start_production.index() + ";}");
cout.WriteLine();
/* methods to indicate EOF and error symbol indexes */
cout.WriteLine(" /** <code>EOF</code> Symbol index. */");
cout.WriteLine(" public override int EOF_sym() {return " + terminal.EOF.index() +
";}");
cout.WriteLine();
cout.WriteLine(" /** <code>error</code> Symbol index. */");
cout.WriteLine(" public override int error_sym() {return " + terminal.error.index() +
";}");
cout.WriteLine();
/* user supplied code for user_init() */
if (init_code != null)
{
cout.WriteLine();
cout.WriteLine(" /** User initialization code. */");
cout.WriteLine(" public override void user_init() ");
cout.WriteLine(" {");
cout.WriteLine(init_code);
cout.WriteLine(" }");
}
/* user supplied code for scan */
if (scan_code != null)
{
cout.WriteLine();
cout.WriteLine(" /** Scan to get the next Symbol. */");
cout.WriteLine(" public override TUVienna.CS_CUP.Runtime.Symbol scan()");
cout.WriteLine(" {");
cout.WriteLine(scan_code);
cout.WriteLine(" }");
}
/* user supplied code */
if (parser_code != null)
{
cout.WriteLine();
cout.WriteLine(parser_code);
}
/* end of class */
cout.WriteLine("}");
/* put out the action code class */
emit_action_code(cout, start_prod);
if (package_name!=null)
cout.WriteLine("}");
parser_time = DateTime.Now.Ticks - start_time;
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Emit the action table.
* @param out stream to produce output on.
* @param act_tab the internal representation of the action table.
* @param compact_reduces do we use the most frequent reduce as default?
*/
protected static void do_action_table(
TextWriter cout,
parse_action_table act_tab,
bool compact_reduces)
{
parse_action_row row;
parse_action act;
int red;
long start_time = DateTime.Now.Ticks;
/* collect values for the action table */
short[][] action_table = new short[act_tab.num_states()][];
/* do each state (row) of the action table */
for (int i = 0; i < act_tab.num_states(); i++)
{
/* get the row */
row = act_tab.under_state[i];
/* determine the default for the row */
if (compact_reduces)
row.compute_default();
else
row.default_reduce = -1;
/* make temporary table for the row. */
short[] temp_table = new short[2*parse_action_row.size()];
int nentries = 0;
/* do each column */
for (int j = 0; j < parse_action_row.size(); j++)
{
/* extract the action from the table */
act = row.under_term[j];
/* skip error entries these are all defaulted out */
if (act.kind() != parse_action.ERROR)
{
/* first put in the symbol index, then the actual entry */
/* shifts get positive entries of state number + 1 */
if (act.kind() == parse_action.SHIFT)
{
/* make entry */
temp_table[nentries++] = (short) j;
temp_table[nentries++] = (short)
(((shift_action)act).shift_to().index() + 1);
}
/* reduce actions get negated entries of production# + 1 */
else if (act.kind() == parse_action.REDUCE)
{
/* if its the default entry let it get defaulted out */
red = ((reduce_action)act).reduce_with().index();
if (red != row.default_reduce) {
/* make entry */
temp_table[nentries++] = (short) j;
temp_table[nentries++] = (short) (-(red+1));
}
} else if (act.kind() == parse_action.NONASSOC)
{
/* do nothing, since we just want a syntax error */
}
/* shouldn't be anything else */
else
throw new internal_error("Unrecognized action code " +
act.kind() + " found in parse table");
}
}
/* now we know how big to make the row */
action_table[i] = new short[nentries + 2];
//System.arraycopy(temp_table, 0, action_table[i], 0, nentries);
Array.Copy(temp_table,action_table[i],nentries);
/* finish off the row with a default entry */
action_table[i][nentries++] = -1;
if (row.default_reduce != -1)
action_table[i][nentries++] = (short) (-(row.default_reduce+1));
else
action_table[i][nentries++] = 0;
}
/* finish off the init of the table */
cout.WriteLine();
cout.WriteLine(" /** Parse-action table. */");
cout.WriteLine(" protected static readonly short[][] _action_table = ");
cout.Write (" unpackFromStrings(");
do_table_as_string(cout, action_table);
cout.WriteLine(");");
/* do the public accessor method */
cout.WriteLine();
cout.WriteLine(" /** Access to parse-action table. */");
cout.WriteLine(" public override short[][] action_table() {return _action_table;}");
action_table_time = DateTime.Now.Ticks - start_time;
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Emit the parser subclass with embedded tables.
* @param out stream to produce output on.
* @param action_table internal representation of the action table.
* @param reduce_table internal representation of the reduce-goto table.
* @param start_st start state of the parse machine.
* @param start_prod start production of the grammar.
* @param compact_reduces do we use most frequent reduce as default?
* @param suppress_scanner should scanner be suppressed for compatibility?
*/
public static void parser(
TextWriter cout,
parse_action_table action_table,
parse_reduce_table reduce_table,
int start_st,
production start_prod,
bool compact_reduces,
bool suppress_scanner)
{
long start_time = DateTime.Now.Ticks;
/* top of file */
cout.WriteLine();
cout.WriteLine("//----------------------------------------------------");
cout.WriteLine("// The following code was generated by " +
version.title_str);
cout.WriteLine("// " + DateTime.Now);
cout.WriteLine("//----------------------------------------------------");
cout.WriteLine();
emit_package(cout);
/* user supplied imports */
IEnumerator myEnum = import_list.GetEnumerator();
while (myEnum.MoveNext())
{
cout.WriteLine("using " + myEnum.Current.ToString() + ";");
}
/* class header */
cout.WriteLine();
cout.WriteLine("/** " + version.title_str + " generated parser.");
cout.WriteLine(" * @version " + DateTime.Now);
cout.WriteLine(" */");
cout.WriteLine("public class " + parser_class_name +
" : TUVienna.CS_CUP.Runtime.lr_parser {");
/* constructors [CSA/davidm, 24-jul-99] */
cout.WriteLine();
cout.WriteLine(" /** Default constructor. */");
cout.WriteLine(" public " + parser_class_name + "():base() {;}");
if (!suppress_scanner)
{
cout.WriteLine();
cout.WriteLine(" /** Constructor which sets the default scanner. */");
cout.WriteLine(" public " + parser_class_name +
"(TUVienna.CS_CUP.Runtime.Scanner s): base(s) {;}");
}
/* emit the various tables */
emit_production_table(cout);
do_action_table(cout, action_table, compact_reduces);
do_reduce_table(cout, reduce_table);
/* instance of the action encapsulation class */
cout.WriteLine(" /** Instance of action encapsulation class. */");
cout.WriteLine(" protected " + pre("actions") + " action_obj;");
cout.WriteLine();
/* action object initializer */
cout.WriteLine(" /** Action encapsulation object initializer. */");
cout.WriteLine(" protected override void init_actions()");
cout.WriteLine(" {");
cout.WriteLine(" action_obj = new " + pre("actions") + "(this);");
cout.WriteLine(" }");
cout.WriteLine();
/* access to action code */
cout.WriteLine(" /** Invoke a user supplied parse action. */");
cout.WriteLine(" public override TUVienna.CS_CUP.Runtime.Symbol do_action(");
cout.WriteLine(" int act_num,");
cout.WriteLine(" TUVienna.CS_CUP.Runtime.lr_parser parser,");
cout.WriteLine(" System.Collections.Stack xstack1,");
cout.WriteLine(" int top)");
cout.WriteLine(" {");
cout.WriteLine(" mStack CUP_parser_stack= new mStack(xstack1);");
cout.WriteLine(" /* call code in generated class */");
cout.WriteLine(" return action_obj." + pre("do_action(") +
"act_num, parser, stack, top);");
cout.WriteLine(" }");
cout.WriteLine("");
/* method to tell the parser about the start state */
cout.WriteLine(" /** Indicates start state. */");
cout.WriteLine(" public override int start_state() {return " + start_st + ";}");
/* method to indicate start production */
cout.WriteLine(" /** Indicates start production. */");
cout.WriteLine(" public override int start_production() {return " +
start_production.index() + ";}");
cout.WriteLine();
/* methods to indicate EOF and error symbol indexes */
cout.WriteLine(" /** <code>EOF</code> Symbol index. */");
cout.WriteLine(" public override int EOF_sym() {return " + terminal.EOF.index() +
";}");
cout.WriteLine();
cout.WriteLine(" /** <code>error</code> Symbol index. */");
cout.WriteLine(" public override int error_sym() {return " + terminal.error.index() +
";}");
cout.WriteLine();
/* user supplied code for user_init() */
if (init_code != null)
{
cout.WriteLine();
cout.WriteLine(" /** User initialization code. */");
cout.WriteLine(" public override void user_init() ");
cout.WriteLine(" {");
cout.WriteLine(init_code);
cout.WriteLine(" }");
}
/* user supplied code for scan */
if (scan_code != null)
{
cout.WriteLine();
cout.WriteLine(" /** Scan to get the next Symbol. */");
cout.WriteLine(" public override TUVienna.CS_CUP.Runtime.Symbol scan()");
cout.WriteLine(" {");
cout.WriteLine(scan_code);
cout.WriteLine(" }");
}
/* user supplied code */
if (parser_code != null)
{
cout.WriteLine();
cout.WriteLine(parser_code);
}
/* end of class */
cout.WriteLine("}");
/* put out the action code class */
emit_action_code(cout, start_prod);
if (package_name != null)
{
cout.WriteLine("}");
}
parser_time = DateTime.Now.Ticks - start_time;
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Emit the action table.
* @param out stream to produce output on.
* @param act_tab the internal representation of the action table.
* @param compact_reduces do we use the most frequent reduce as default?
*/
protected static void do_action_table(
TextWriter cout,
parse_action_table act_tab,
bool compact_reduces)
{
parse_action_row row;
parse_action act;
int red;
long start_time = DateTime.Now.Ticks;
/* collect values for the action table */
short[][] action_table = new short[act_tab.num_states()][];
/* do each state (row) of the action table */
for (int i = 0; i < act_tab.num_states(); i++)
{
/* get the row */
row = act_tab.under_state[i];
/* determine the default for the row */
if (compact_reduces)
{
row.compute_default();
}
else
{
row.default_reduce = -1;
}
/* make temporary table for the row. */
short[] temp_table = new short[2 * parse_action_row.size()];
int nentries = 0;
/* do each column */
for (int j = 0; j < parse_action_row.size(); j++)
{
/* extract the action from the table */
act = row.under_term[j];
/* skip error entries these are all defaulted out */
if (act.kind() != parse_action.ERROR)
{
/* first put in the symbol index, then the actual entry */
/* shifts get positive entries of state number + 1 */
if (act.kind() == parse_action.SHIFT)
{
/* make entry */
temp_table[nentries++] = (short)j;
temp_table[nentries++] = (short)
(((shift_action)act).shift_to().index() + 1);
}
/* reduce actions get negated entries of production# + 1 */
else if (act.kind() == parse_action.REDUCE)
{
/* if its the default entry let it get defaulted out */
red = ((reduce_action)act).reduce_with().index();
if (red != row.default_reduce)
{
/* make entry */
temp_table[nentries++] = (short)j;
temp_table[nentries++] = (short)(-(red + 1));
}
}
else if (act.kind() == parse_action.NONASSOC)
{
/* do nothing, since we just want a syntax error */
}
/* shouldn't be anything else */
else
{
throw new internal_error("Unrecognized action code " +
act.kind() + " found in parse table");
}
}
}
/* now we know how big to make the row */
action_table[i] = new short[nentries + 2];
//System.arraycopy(temp_table, 0, action_table[i], 0, nentries);
Array.Copy(temp_table, action_table[i], nentries);
/* finish off the row with a default entry */
action_table[i][nentries++] = -1;
if (row.default_reduce != -1)
{
action_table[i][nentries++] = (short)(-(row.default_reduce + 1));
}
else
{
action_table[i][nentries++] = 0;
}
}
/* finish off the init of the table */
cout.WriteLine();
cout.WriteLine(" /** Parse-action table. */");
cout.WriteLine(" protected static readonly short[][] _action_table = ");
cout.Write(" unpackFromStrings(");
do_table_as_string(cout, action_table);
cout.WriteLine(");");
/* do the public accessor method */
cout.WriteLine();
cout.WriteLine(" /** Access to parse-action table. */");
cout.WriteLine(" public override short[][] action_table() {return _action_table;}");
action_table_time = DateTime.Now.Ticks - start_time;
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Fill in the parse table entries for this state. There are two
* parse tables that encode the viable prefix recognition machine, an
* action table and a reduce-goto table. The rows in each table
* correspond to states of the machine. The columns of the action table
* are indexed by terminal symbols and correspond to either transitions
* out of the state (shift entries) or reductions from the state to some
* previous state saved on the stack (reduce entries). All entries in the
* action table that are not shifts or reduces, represent errors. The
* reduce-goto table is indexed by non terminals and represents transitions
* out of a state on that non-terminal.<p>
* Conflicts occur if more than one action needs to go in one entry of the
* action table (this cannot happen with the reduce-goto table). Conflicts
* are resolved by always shifting for shift/reduce conflicts and choosing
* the lowest numbered production (hence the one that appeared first in
* the specification) in reduce/reduce conflicts. All conflicts are
* reported and if more conflicts are detected than were declared by the
* user, code generation is aborted.
*
* @param act_table the action table to put entries in.
* @param reduce_table the reduce-goto table to put entries in.
*/
public void build_table_entries(
parse_action_table act_table,
parse_reduce_table reduce_table)
{
parse_action_row our_act_row;
parse_reduce_row our_red_row;
lalr_item itm;
parse_action act, other_act;
symbol sym;
terminal_set conflict_set = new terminal_set();
/* pull out our rows from the tables */
our_act_row = act_table.under_state[index()];
our_red_row = reduce_table.under_state[index()];
/* consider each item in our state */
IEnumerator i = items().all();
while (i.MoveNext())
{
itm = (lalr_item)i.Current;
/* if its completed (dot at end) then reduce under the lookahead */
if (itm.dot_at_end())
{
act = new reduce_action(itm.the_production());
/* consider each lookahead symbol */
for (int t = 0; t < terminal.number(); t++)
{
/* skip over the ones not in the lookahead */
if (!itm.lookahead().contains(t))
{
continue;
}
/* if we don't already have an action put this one in */
if (our_act_row.under_term[t].kind() ==
parse_action.ERROR)
{
our_act_row.under_term[t] = act;
}
else
{
/* we now have at least one conflict */
terminal term = terminal.find(t);
other_act = our_act_row.under_term[t];
/* if the other act was not a shift */
if ((other_act.kind() != parse_action.SHIFT) &&
(other_act.kind() != parse_action.NONASSOC))
{
/* if we have lower index hence priority, replace it*/
if (itm.the_production().index() <
((reduce_action)other_act).reduce_with().index())
{
/* replace the action */
our_act_row.under_term[t] = act;
}
}
else
{
/* Check precedences,see if problem is correctable */
if (fix_with_precedence(itm.the_production(),
t, our_act_row, act))
{
term = null;
}
}
if (term != null)
{
conflict_set.add(term);
}
}
}
}
}
/* consider each outgoing transition */
for (lalr_transition trans = transitions(); trans != null; trans = trans.next())
{
/* if its on an terminal add a shift entry */
sym = trans.on_symbol();
if (!sym.is_non_term())
{
act = new shift_action(trans.to_state());
/* if we don't already have an action put this one in */
if (our_act_row.under_term[sym.index()].kind() ==
parse_action.ERROR)
{
our_act_row.under_term[sym.index()] = act;
}
else
{
/* we now have at least one conflict */
production p = ((reduce_action)our_act_row.under_term[sym.index()]).reduce_with();
/* shift always wins */
if (!fix_with_precedence(p, sym.index(), our_act_row, act))
{
our_act_row.under_term[sym.index()] = act;
conflict_set.add(terminal.find(sym.index()));
}
}
}
else
{
/* for non terminals add an entry to the reduce-goto table */
our_red_row.under_non_term[sym.index()] = trans.to_state();
}
}
/* if we end up with conflict(s), report them */
if (!conflict_set.empty())
{
report_conflicts(conflict_set);
}
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Build the (internal) parser from the previously parsed specification.
* This includes:<ul>
* <li> Computing nullability of non-terminals.
* <li> Computing first sets of non-terminals and productions.
* <li> Building the viable prefix recognizer machine.
* <li> Filling in the (internal) parse tables.
* <li> Checking for unreduced productions.
* </ul>
*/
protected static void build_parser()
{
/* compute nullability of all non terminals */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Computing non-terminal nullability...");
non_terminal.compute_nullability();
nullability_end = DateTime.Now.Ticks;
/* compute first sets of all non terminals */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Computing first sets...");
non_terminal.compute_first_sets();
first_end = DateTime.Now.Ticks;
/* build the LR viable prefix recognition machine */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Building state machine...");
start_state = lalr_state.build_machine(emit.start_production);
machine_end = DateTime.Now.Ticks;
/* build the LR parser action and reduce-goto tables */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Filling in tables...");
action_table = new parse_action_table();
reduce_table = new parse_reduce_table();
IEnumerator st = lalr_state.all();
while ( st.MoveNext() )
{
lalr_state lst = (lalr_state)st.Current;
lst.build_table_entries(
action_table, reduce_table);
}
table_end = DateTime.Now.Ticks;
/* check and warn for non-reduced productions */
if (opt_do_debug || print_progress)
System.Console.Error.WriteLine(" Checking for non-reduced productions...");
action_table.check_reductions();
reduce_check_end = DateTime.Now.Ticks;
/* if we have more conflicts than we expected issue a message and die */
if (emit.num_conflicts > expect_conflicts)
{
System.Console.Error.WriteLine("*** More conflicts encountered than expected " +
"-- parser generation aborted");
lexer.error_count++; // indicate the problem.
// we'll die on return, after clean up.
}
}
/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
/** Fill in the parse table entries for this state. There are two
* parse tables that encode the viable prefix recognition machine, an
* action table and a reduce-goto table. The rows in each table
* correspond to states of the machine. The columns of the action table
* are indexed by terminal symbols and correspond to either transitions
* out of the state (shift entries) or reductions from the state to some
* previous state saved on the stack (reduce entries). All entries in the
* action table that are not shifts or reduces, represent errors. The
* reduce-goto table is indexed by non terminals and represents transitions
* out of a state on that non-terminal.<p>
* Conflicts occur if more than one action needs to go in one entry of the
* action table (this cannot happen with the reduce-goto table). Conflicts
* are resolved by always shifting for shift/reduce conflicts and choosing
* the lowest numbered production (hence the one that appeared first in
* the specification) in reduce/reduce conflicts. All conflicts are
* reported and if more conflicts are detected than were declared by the
* user, code generation is aborted.
*
* @param act_table the action table to put entries in.
* @param reduce_table the reduce-goto table to put entries in.
*/
public void build_table_entries(
parse_action_table act_table,
parse_reduce_table reduce_table)
{
parse_action_row our_act_row;
parse_reduce_row our_red_row;
lalr_item itm;
parse_action act, other_act;
symbol sym;
terminal_set conflict_set = new terminal_set();
/* pull out our rows from the tables */
our_act_row = act_table.under_state[index()];
our_red_row = reduce_table.under_state[index()];
/* consider each item in our state */
IEnumerator i = items().all();
while ( i.MoveNext() )
{
itm = (lalr_item)i.Current;
/* if its completed (dot at end) then reduce under the lookahead */
if (itm.dot_at_end())
{
act = new reduce_action(itm.the_production());
/* consider each lookahead symbol */
for (int t = 0; t < terminal.number(); t++)
{
/* skip over the ones not in the lookahead */
if (!itm.lookahead().contains(t)) continue;
/* if we don't already have an action put this one in */
if (our_act_row.under_term[t].kind() ==
parse_action.ERROR)
{
our_act_row.under_term[t] = act;
}
else
{
/* we now have at least one conflict */
terminal term = terminal.find(t);
other_act = our_act_row.under_term[t];
/* if the other act was not a shift */
if ((other_act.kind() != parse_action.SHIFT) &&
(other_act.kind() != parse_action.NONASSOC))
{
/* if we have lower index hence priority, replace it*/
if (itm.the_production().index() <
((reduce_action)other_act).reduce_with().index())
{
/* replace the action */
our_act_row.under_term[t] = act;
}
} else {
/* Check precedences,see if problem is correctable */
if(fix_with_precedence(itm.the_production(),
t, our_act_row, act)) {
term = null;
}
}
if(term!=null) {
conflict_set.add(term);
}
}
}
}
}
/* consider each outgoing transition */
for (lalr_transition trans=transitions(); trans!=null; trans=trans.next())
{
/* if its on an terminal add a shift entry */
sym = trans.on_symbol();
if (!sym.is_non_term())
{
act = new shift_action(trans.to_state());
/* if we don't already have an action put this one in */
if ( our_act_row.under_term[sym.index()].kind() ==
parse_action.ERROR)
{
our_act_row.under_term[sym.index()] = act;
}
else
{
/* we now have at least one conflict */
production p = ((reduce_action)our_act_row.under_term[sym.index()]).reduce_with();
/* shift always wins */
if (!fix_with_precedence(p, sym.index(), our_act_row, act)) {
our_act_row.under_term[sym.index()] = act;
conflict_set.add(terminal.find(sym.index()));
}
}
}
else
{
/* for non terminals add an entry to the reduce-goto table */
our_red_row.under_non_term[sym.index()] = trans.to_state();
}
}
/* if we end up with conflict(s), report them */
if (!conflict_set.empty())
report_conflicts(conflict_set);
}
