[tmp/jakarta-migration.git] /

package org.collectionspace.services.structureddate.antlr;

import java.util.Stack;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.BailErrorStrategy;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.FailedPredicateException;
import org.antlr.v4.runtime.InputMismatchException;
import org.antlr.v4.runtime.NoViableAltException;
import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.misc.ParseCancellationException;
import org.antlr.v4.runtime.tree.TerminalNode;
import org.collectionspace.services.structureddate.Date;
import org.collectionspace.services.structureddate.DateUtils;
import org.collectionspace.services.structureddate.DeferredCenturyEndDate;
import org.collectionspace.services.structureddate.DeferredCenturyStartDate;
import org.collectionspace.services.structureddate.DeferredDate;
import org.collectionspace.services.structureddate.DeferredDecadeEndDate;
import org.collectionspace.services.structureddate.DeferredDecadeStartDate;
import org.collectionspace.services.structureddate.DeferredHalfCenturyEndDate;
import org.collectionspace.services.structureddate.DeferredHalfCenturyStartDate;
import org.collectionspace.services.structureddate.DeferredMillenniumEndDate;
import org.collectionspace.services.structureddate.DeferredMillenniumStartDate;
import org.collectionspace.services.structureddate.DeferredPartialCenturyEndDate;
import org.collectionspace.services.structureddate.DeferredPartialCenturyStartDate;
import org.collectionspace.services.structureddate.DeferredPartialDecadeEndDate;
import org.collectionspace.services.structureddate.DeferredPartialDecadeStartDate;
import org.collectionspace.services.structureddate.DeferredQuarterCenturyEndDate;
import org.collectionspace.services.structureddate.DeferredQuarterCenturyStartDate;
import org.collectionspace.services.structureddate.Era;
import org.collectionspace.services.structureddate.Part;
import org.collectionspace.services.structureddate.StructuredDateInternal;
import org.collectionspace.services.structureddate.StructuredDateEvaluator;
import org.collectionspace.services.structureddate.StructuredDateFormatException;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.AllOrPartOfContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.BeforeOrAfterDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.CenturyContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.CertainDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.DateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.DayFirstDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.DayOrYearFirstDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.DecadeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.DisplayDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.EraContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.HalfCenturyContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.HalfYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.HyphenatedRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.InvMonthYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.InvSeasonYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.InvStrDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.InvStrDateEraLastDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.MillenniumContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.MonthContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.MonthInYearRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.MonthYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NthCenturyRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NthContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NthHalfContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NthQuarterContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NthQuarterInYearRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NthQuarterYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumCenturyContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumDayInMonthRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumDayOfMonthContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumDecadeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumMonthContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.NumYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.PartOfContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.PartialCenturyContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.PartialDecadeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.PartialYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.QuarterCenturyContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.QuarterInYearRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.QuarterYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.SeasonYearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.StrCenturyContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.StrDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.StrDayInMonthRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.StrMonthContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.StrSeasonContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.StrSeasonInYearRangeContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.UncertainDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.UnknownDateContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.YearContext;
import org.collectionspace.services.structureddate.antlr.StructuredDateParser.YearSpanningWinterContext;

/**
 * A StructuredDateEvaluator that uses an ANTLR parser to parse the display date,
 * and an ANTLR listener to generate a structured date from the resulting parse
 * tree.
 */
public class ANTLRStructuredDateEvaluator extends StructuredDateBaseListener implements StructuredDateEvaluator {
        /**
         * The result of the evaluation.
         */
        protected StructuredDateInternal result;

        /**
         * The operation stack. The parse listener methods that are implemented here
         * pop input parameters off the stack, and push results back on to the stack.
         */
        protected Stack<Object> stack;

        public ANTLRStructuredDateEvaluator() {

        }

        @Override
        public StructuredDateInternal evaluate(String displayDate) throws StructuredDateFormatException {
                stack = new Stack<Object>();

                result = new StructuredDateInternal();
                result.setDisplayDate(displayDate);

                // Instantiate a parser from the lowercased display date, so that parsing will be
                // case insensitive.
                ANTLRInputStream inputStream = new ANTLRInputStream(displayDate.toLowerCase());
                StructuredDateLexer lexer = new StructuredDateLexer(inputStream);
                CommonTokenStream tokenStream = new CommonTokenStream(lexer);
                StructuredDateParser parser = new StructuredDateParser(tokenStream);

                // Don't try to recover from parse errors, just bail.
                parser.setErrorHandler(new BailErrorStrategy());

                // Don't print error messages to the console.
                parser.removeErrorListeners();

                // Generate our own custom error messages.
                parser.addParseListener(this);

                try {
                        // Attempt to fulfill the oneDisplayDate rule of the grammar.
                        parser.oneDisplayDate();
                }
                catch(ParseCancellationException e) {
                        // ParseCancellationException is thrown by the BailErrorStrategy when there is a
                        // parse error, with the underlying RecognitionException as the cause.
                        RecognitionException re = (RecognitionException) e.getCause();

                        throw new StructuredDateFormatException(getErrorMessage(re), re);
                }

                // The parsing was successful. Return the result.
                return result;
        }

        @Override
        public void exitDisplayDate(DisplayDateContext ctx) {
                if (ctx.exception != null) return;

                Date latestDate = (Date) stack.pop();
                Date earliestDate = (Date) stack.pop();

                // If the earliest date and the latest date are the same, it's just a "single" date.
                // There's no need to have the latest, so set it to null.

                if (earliestDate.equals(latestDate)) {
                        latestDate = null;
                }

                result.setEarliestSingleDate(earliestDate);
                result.setLatestDate(latestDate);
        }

        @Override
        public void exitBeforeOrAfterDate(BeforeOrAfterDateContext ctx) {
                if (ctx.exception != null) return;

                Date latestDate = (Date) stack.pop();
                Date earliestDate = (Date) stack.pop();

                // Set null eras to the default.

                if (earliestDate.getEra() == null) {
                        earliestDate.setEra(Date.DEFAULT_ERA);
                }

                if (latestDate.getEra() == null) {
                        latestDate.setEra(Date.DEFAULT_ERA);
                }

                // Finalize any deferred calculations.

                if (latestDate instanceof DeferredDate) {
                        ((DeferredDate) latestDate).resolveDate();
                }

                if (earliestDate instanceof DeferredDate) {
                        ((DeferredDate) earliestDate).resolveDate();
                }

                // Calculate the earliest date or end date.

                if (ctx.BEFORE() != null) {
                        latestDate = earliestDate;
                        earliestDate = DateUtils.getEarliestBeforeDate(earliestDate, latestDate);
                }
                else if (ctx.AFTER() != null) {
                        earliestDate = latestDate;
                        latestDate = DateUtils.getLatestAfterDate(earliestDate, latestDate);
                }

                stack.push(earliestDate);
                stack.push(latestDate);
        }

        @Override
        public void exitUncertainDate(UncertainDateContext ctx) {
                if (ctx.exception != null) return;

                Date latestDate = (Date) stack.pop();
                Date earliestDate = (Date) stack.pop();

                int earliestInterval = DateUtils.getCircaIntervalYears(earliestDate.getYear(), earliestDate.getEra());
                int latestInterval = DateUtils.getCircaIntervalYears(latestDate.getYear(), latestDate.getEra());

                // Express the circa interval as a qualifier.

                // stack.push(earliestDate.withQualifier(QualifierType.MINUS, earliestInterval, QualifierUnit.YEARS));
                // stack.push(latestDate.withQualifier(QualifierType.PLUS, latestInterval, QualifierUnit.YEARS));

                // OR:

                // Express the circa interval as an offset calculated into the year.

                DateUtils.subtractYears(earliestDate, earliestInterval);
                DateUtils.addYears(latestDate, latestInterval);

                stack.push(earliestDate);
                stack.push(latestDate);
        }

        @Override
        public void exitCertainDate(CertainDateContext ctx) {
                if (ctx.exception != null) return;

                Date latestDate = (Date) stack.pop();
                Date earliestDate = (Date) stack.pop();

                // Set null eras to the default.

                if (earliestDate.getEra() == null) {
                        earliestDate.setEra(Date.DEFAULT_ERA);
                }

                if (latestDate.getEra() == null) {
                        latestDate.setEra(Date.DEFAULT_ERA);
                }

                // Finalize any deferred calculations.

                if (latestDate instanceof DeferredDate) {
                        ((DeferredDate) latestDate).resolveDate();
                }

                if (earliestDate instanceof DeferredDate) {
                        ((DeferredDate) earliestDate).resolveDate();
                }

                stack.push(earliestDate);
                stack.push(latestDate);
        }

        @Override
        public void exitHyphenatedRange(HyphenatedRangeContext ctx) {
                if (ctx.exception != null) return;

                Date latestEndDate = (Date) stack.pop();
                stack.pop(); // latestStartDate
                stack.pop(); // earliestEndDate
                Date earliestStartDate = (Date) stack.pop();

                // If no era was explicitly specified for the first date,
                // make it inherit the era of the second date.

                if (earliestStartDate.getEra() == null && latestEndDate.getEra() != null) {
                        earliestStartDate.setEra(latestEndDate.getEra());
                }

                // Finalize any deferred calculations.

                if (earliestStartDate instanceof DeferredDate) {
                        ((DeferredDate) earliestStartDate).resolveDate();
                }

                if (latestEndDate instanceof DeferredDate) {
                        ((DeferredDate) latestEndDate).resolveDate();
                }

                stack.push(earliestStartDate);
                stack.push(latestEndDate);
        }

        @Override
        public void exitNthCenturyRange(NthCenturyRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer endN = (Integer) stack.pop();
                Part endPart = (Part) stack.pop();
                Integer startN = (Integer) stack.pop();
                Part startPart = (Part) stack.pop();

                if (era == null) {
                        era = Date.DEFAULT_ERA;
                }

                int startYear = DateUtils.nthCenturyToYear(startN);
                int endYear = DateUtils.nthCenturyToYear(endN);

                stack.push(startPart == null ? DateUtils.getCenturyStartDate(startYear, era) : DateUtils.getPartialCenturyStartDate(startYear, startPart, era));
                stack.push(startPart == null ? DateUtils.getCenturyEndDate(startYear, era) : DateUtils.getPartialCenturyEndDate(startYear, startPart, era));
                stack.push(endPart == null ? DateUtils.getCenturyStartDate(endYear, era) : DateUtils.getPartialCenturyStartDate(endYear, endPart, era));
                stack.push(endPart == null ? DateUtils.getCenturyEndDate(endYear, era) : DateUtils.getPartialCenturyEndDate(endYear, endPart, era));
        }

        @Override
        public void exitMonthInYearRange(MonthInYearRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer numMonthEnd = (Integer) stack.pop();
                Integer numMonthStart = (Integer) stack.pop();

                stack.push(new Date(year, numMonthStart, 1, era));
                stack.push(new Date(year, numMonthStart, DateUtils.getDaysInMonth(numMonthStart, year, era), era));
                stack.push(new Date(year, numMonthEnd, 1, era));
                stack.push(new Date(year, numMonthEnd, DateUtils.getDaysInMonth(numMonthEnd, year, era), era));
        }

        @Override
        public void exitQuarterInYearRange(QuarterInYearRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer lastQuarter = (Integer) stack.pop();
                Integer firstQuarter = (Integer) stack.pop();

                stack.push(DateUtils.getQuarterYearStartDate(firstQuarter, year).withEra(era));
                stack.push(DateUtils.getQuarterYearEndDate(firstQuarter, year, era).withEra(era));
                stack.push(DateUtils.getQuarterYearStartDate(lastQuarter, year).withEra(era));
                stack.push(DateUtils.getQuarterYearEndDate(lastQuarter, year, era).withEra(era));
        }

        @Override
        public void exitStrDayInMonthRange(StrDayInMonthRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer dayOfMonthEnd = (Integer) stack.pop();
                Integer dayOfMonthStart = (Integer) stack.pop();
                Integer numMonth = (Integer) stack.pop();

                stack.push(new Date(year, numMonth, dayOfMonthStart, era));
                stack.push(new Date(year, numMonth, dayOfMonthStart, era));
                stack.push(new Date(year, numMonth, dayOfMonthEnd, era));
                stack.push(new Date(year, numMonth, dayOfMonthEnd, era));
        }

        @Override
        public void exitNumDayInMonthRange(NumDayInMonthRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer num1 = (Integer) stack.pop();
                Integer num2 = (Integer) stack.pop();
                Integer num3 = (Integer) stack.pop();
                Integer num4 = (Integer) stack.pop();

                /* We can distinguish whether it is M/D-D/Y (Case 1) or M/Y-M/Y (Case 2) by checking if
                        The num1, num4, num2 and num1, num4, num3 are valid dates, since this would equate to
                        a set of two ranges. For examples: 04/13-19/1995 would be 04/13/1995-04/19/1995. If both these
                        dates are valid, we know that it shouldn't be interpreted as 04/01/13 - 19/31/1995 since these arent valid dates!
                */

                Integer lateYear = num1;
                Integer earlyMonth = num4;
                Integer dayOfMonthEnd = num2;
                Integer dayOfMonthStart = num3;

                if (DateUtils.isValidDate(num1, num4, num2, era) && DateUtils.isValidDate(num1, num4, num3, era)) {
                        // No need to alter the arguments, so just push to the stack
                        stack.push(new Date(lateYear, earlyMonth, dayOfMonthStart, era));
                        stack.push(new Date(lateYear, earlyMonth, dayOfMonthStart, era));
                        stack.push(new Date(lateYear, earlyMonth, dayOfMonthEnd, era));
                        stack.push(new Date(lateYear, earlyMonth, dayOfMonthEnd, era));

                } else {
                        // Separated these by case, since it makes the code more legible
                        Integer latestMonth = num2;
                        Integer earliestYear = num3;

                        stack.push(new Date(earliestYear, earlyMonth, 1, era)); // Earliest Early Date
                        stack.push(new Date(earliestYear, earlyMonth, DateUtils.getDaysInMonth(earlyMonth, earliestYear, era), era)); // Latest Early Date
                        stack.push(new Date(lateYear, latestMonth, 1, era)); // Earliest Latest Date
                        stack.push(new Date(lateYear, latestMonth, DateUtils.getDaysInMonth(latestMonth, lateYear, era), era)); // Latest Late Date
                        
                }
        }

        @Override
        public void exitDate(DateContext ctx) {
                if (ctx.exception != null) return;

                // Expect the canonical year-month-day-era ordering
                // to be on the stack.

                Era era = (stack.size() == 3) ? null : (Era) stack.pop();
                Integer dayOfMonth = (Integer) stack.pop();
                Integer numMonth = (Integer) stack.pop();
                Integer year = (Integer) stack.pop();

                // For the latest date we could either return null, or a copy of the earliest date,
                // since the UI doesn't care. Use a copy of the earliest date, since it makes
                // things easier here if we don't have to test for null up the tree.

                stack.push(new Date(year, numMonth, dayOfMonth, era));
                stack.push(new Date(year, numMonth, dayOfMonth, era));
        }

        @Override
        public void exitNumDate(NumDateContext ctx) {
                if (ctx.exception != null) return;

                // This could either be year-month-day, or
                // month-day-year. Try to determine which,
                // and reorder the stack into the canonical
                // year-month-day-era ordering.

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer num3 = (Integer) stack.pop();
                Integer num2 = (Integer) stack.pop();
                Integer num1 = (Integer) stack.pop();

                // Default to a month-day-year interpretation.

                int numMonth = num1;
                int dayOfMonth = num2;
                int year = num3;

                if (DateUtils.isValidDate(num3, num1, num2, era)) {
                        // Interpreting as month-day-year produces a valid date. Go with it.
                }
                else if (DateUtils.isValidDate(num1, num2, num3, era)) {
                        // Interpreting as month-day-year doesn't produce a valid date, but
                        // year-month-day does. Go with year-month-day.

                        year = num1;
                        numMonth = num2;
                        dayOfMonth = num3;
                }

                stack.push(year);
                stack.push(numMonth);
                stack.push(dayOfMonth);
                stack.push(era);
        }

        @Override
        public void exitStrDate(StrDateContext ctx) {
                if (ctx.exception != null) return;

                // Reorder the stack into a canonical ordering,
                // year-month-day-era.

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer dayOfMonth = (Integer) stack.pop();
                Integer numMonth = (Integer) stack.pop();

                stack.push(year);
                stack.push(numMonth);
                stack.push(dayOfMonth);
                stack.push(era);
        }

        @Override
        public void exitInvStrDate(InvStrDateContext ctx) {
                if (ctx.exception != null) return;

                // Reorder the stack into a canonical ordering,
                // year-month-day-era.

                Integer dayOfMonth = (Integer) stack.pop();
                Integer numMonth = (Integer) stack.pop();
                Integer year = (Integer) stack.pop();
                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(year);
                stack.push(numMonth);
                stack.push(dayOfMonth);
                stack.push(era);
        }

        @Override
        public void exitDayFirstDate(DayFirstDateContext ctx) {
                if (ctx.exception != null) return ;
                
                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer month = (Integer) stack.pop();
                Integer dayOfMonth = (Integer) stack.pop();

                stack.push(year);
                stack.push(month);
                stack.push(dayOfMonth);
                stack.push(era);
        }

        @Override
        public void exitDayOrYearFirstDate(DayOrYearFirstDateContext ctx) {
                if (ctx.exception != null) return;

                Era era = null;
                Integer num2 = (Integer) stack.pop();
                Integer numMonth = (Integer) stack.pop();
                Integer num1 = (Integer) stack.pop();

                Integer year = num1;
                Integer dayOfMonth = num2;

                if (DateUtils.isValidDate(num1, numMonth, num2, era)) {
                        // The first number is a year. Already correct
                } else if (DateUtils.isValidDate(num2, numMonth, num1, era)) {
                        // The second number is a year.
                        year = num2;
                        dayOfMonth = num1;
                }

                stack.push(year);
                stack.push(numMonth);
                stack.push(dayOfMonth);
                stack.push(era);

                if (dayOfMonth > 31 || dayOfMonth <= 0) {
                        throw new StructuredDateFormatException("unexpected day of month '" + Integer.toString(dayOfMonth) + "'");
                }
                if (year == 0) {
                        throw new StructuredDateFormatException("unexpected year '" + Integer.toString(year) + "'");
                }
        }

        @Override
        public void exitInvStrDateEraLastDate(InvStrDateEraLastDateContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer dayOfMonth = (Integer) stack.pop();
                Integer month = (Integer) stack.pop();
                Integer year = (Integer) stack.pop();

                stack.push(year);
                stack.push(month);
                stack.push(dayOfMonth);
                stack.push(era);
        }

        @Override
        public void exitMonth(MonthContext ctx) {
                if (ctx.exception != null) return;

                Era era = (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer numMonth = (Integer) stack.pop();

                stack.push(new Date(year, numMonth, 1, era));
                stack.push(new Date(year, numMonth, DateUtils.getDaysInMonth(numMonth, year, era), era));
        }

        @Override
        public void exitMonthYear(MonthYearContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(era);
        }

        @Override
        public void exitInvMonthYear(InvMonthYearContext ctx) {
                if (ctx.exception != null) return;

                // Invert the arguments.

                Integer numMonth = (Integer) stack.pop();
                Integer year = (Integer) stack.pop();
                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(numMonth);
                stack.push(year);
                stack.push(era);
        }

        @Override
        public void exitYearSpanningWinter(YearSpanningWinterContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer endYear = (Integer) stack.pop();
                Integer startYear = (Integer) stack.pop();

                stack.push(new Date(startYear, 12, 1).withEra(era));
                stack.push(DateUtils.getQuarterYearEndDate(1, endYear, era).withEra(era));
        }

        @Override
        public void exitPartialYear(PartialYearContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Part part = (Part) stack.pop();

                stack.push(DateUtils.getPartialYearStartDate(part, year).withEra(era));
                stack.push(DateUtils.getPartialYearEndDate(part, year, era).withEra(era));
        }

        @Override
        public void exitQuarterYear(QuarterYearContext ctx) {
                if (ctx.exception != null) return;

                Era era = (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer quarter = (Integer) stack.pop();

                stack.push(DateUtils.getQuarterYearStartDate(quarter, year).withEra(era));
                stack.push(DateUtils.getQuarterYearEndDate(quarter, year, era).withEra(era));
        }

        @Override
        public void exitHalfYear(HalfYearContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer half = (Integer) stack.pop();

                stack.push(DateUtils.getHalfYearStartDate(half, year).withEra(era));
                stack.push(DateUtils.getHalfYearEndDate(half, year, era).withEra(era));
        }

        @Override
        public void exitInvSeasonYear(InvSeasonYearContext ctx) {
                if (ctx.exception != null) return;

                // Invert the arguments.

                Integer quarter = (Integer) stack.pop();
                Integer year = (Integer) stack.pop();
                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(quarter);
                stack.push(year);
                stack.push(era);
        }

        @Override 
        public void exitSeasonYear(SeasonYearContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                stack.push(era);

        }

        @Override
        public void exitYear(YearContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();

                stack.push(new Date(year, 1, 1, era));
                stack.push(new Date(year, 12, 31, era));
        }

        @Override
        public void exitPartialDecade(PartialDecadeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Part part = (Part) stack.pop();

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getPartialDecadeStartDate(year, part, era));
                        stack.push(DateUtils.getPartialDecadeEndDate(year, part, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this partial decade may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredPartialDecadeStartDate(year, part));
                        stack.push(new DeferredPartialDecadeEndDate(year, part));
                }
        }

        @Override
        public void exitDecade(DecadeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();

                // Calculate the start and end year of the decade, which depends on the era.

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getDecadeStartDate(year, era));
                        stack.push(DateUtils.getDecadeEndDate(year, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this decade may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredDecadeStartDate(year));
                        stack.push(new DeferredDecadeEndDate(year));
                }
        }

        @Override
        public void exitPartialCentury(PartialCenturyContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Part part = (Part) stack.pop();

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getPartialCenturyStartDate(year, part, era));
                        stack.push(DateUtils.getPartialCenturyEndDate(year, part, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this partial century may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredPartialCenturyStartDate(year, part));
                        stack.push(new DeferredPartialCenturyEndDate(year, part));
                }
        }

        @Override
        public void exitQuarterCentury(QuarterCenturyContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer quarter = (Integer) stack.pop();

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getQuarterCenturyStartDate(year, quarter, era));
                        stack.push(DateUtils.getQuarterCenturyEndDate(year, quarter, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this century may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredQuarterCenturyStartDate(year, quarter));
                        stack.push(new DeferredQuarterCenturyEndDate(year, quarter));
                }
        }

        @Override
        public void exitHalfCentury(HalfCenturyContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();
                Integer half = (Integer) stack.pop();

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getHalfCenturyStartDate(year, half, era));
                        stack.push(DateUtils.getHalfCenturyEndDate(year, half, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this half century may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredHalfCenturyStartDate(year, half));
                        stack.push(new DeferredHalfCenturyEndDate(year, half));
                }
        }

        @Override
        public void exitCentury(CenturyContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer year = (Integer) stack.pop();

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getCenturyStartDate(year, era));
                        stack.push(DateUtils.getCenturyEndDate(year, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this quarter century may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredCenturyStartDate(year));
                        stack.push(new DeferredCenturyEndDate(year));
                }
        }

        @Override
        public void exitMillennium(MillenniumContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();
                Integer n = (Integer) stack.pop();

                if (era != null) {
                        // If the era was explicitly specified, the start and end years
                        // may be calculated now.

                        stack.push(DateUtils.getMillenniumStartDate(n, era));
                        stack.push(DateUtils.getMillenniumEndDate(n, era));
                }
                else {
                        // If the era was not explicitly specified, the start and end years
                        // can't be calculated yet. The calculation must be deferred until
                        // later. For example, this millennium may be the start of a hyphenated
                        // range, where the era will be inherited from the era of the end of
                        // the range; this era won't be known until farther up the parse tree,
                        // when both sides of the range will have been parsed.

                        stack.push(new DeferredMillenniumStartDate(n));
                        stack.push(new DeferredMillenniumEndDate(n));
                }
        }

        @Override
        public void exitStrCentury(StrCenturyContext ctx) {
                if (ctx.exception != null) return;

                Integer n = (Integer) stack.pop();

                // Convert the nth number to a year number,
                // and push on the stack.

                Integer year = DateUtils.nthCenturyToYear(n);

                stack.push(year);
        }

        @Override
        public void exitNumCentury(NumCenturyContext ctx) {
                if (ctx.exception != null) return;

                // Convert the string to a number,
                // and push on the stack.

                Integer year = new Integer(stripEndLetters(ctx.HUNDREDS().getText()));

                if (year == 0) {
                        throw new StructuredDateFormatException("unexpected century '" + ctx.HUNDREDS().getText() + "'");
                }

                stack.push(year);
        }

        @Override
        public void exitNumDecade(NumDecadeContext ctx) {
                if (ctx.exception != null) return;

                // Convert the string to a number,
                // and push on the stack.

                Integer year = new Integer(stripEndLetters(ctx.TENS().getText()));

                if (year == 0) {
                        throw new StructuredDateFormatException("unexpected decade '" + ctx.TENS().getText() + "'");
                }

                stack.push(year);
        }

        @Override
        public void exitNumYear(NumYearContext ctx) {
                if (ctx.exception != null) return;

                // Convert the string to a number,
                // and push on the stack.

                Integer year = new Integer(ctx.NUMBER().getText());

                if (year == 0) {
                        throw new StructuredDateFormatException("unexpected year '" + ctx.NUMBER().getText() + "'");
                }

                stack.push(year);
        }

        @Override
        public void exitNumMonth(NumMonthContext ctx) {
                if (ctx.exception != null) return;

                // Convert the string a number,
                // and push on the stack.

                Integer month = new Integer(ctx.NUMBER().getText());

                if (month < 1 || month > 12) {
                        throw new StructuredDateFormatException("unexpected month '" + ctx.NUMBER().getText() + "'");
                }

                stack.push(month);
        }

        @Override
        public void exitNthHalf(NthHalfContext ctx) {
                if (ctx.exception != null) return;

                // Convert LAST to a number (the last half
                // is the 2nd). If this rule matched the
                // alternative with nth instead of LAST,
                // the nth handler will already have pushed
                // a number on the stack.

                if (ctx.LAST() != null) {
                        stack.push(new Integer(2));
                }

                // Check for a valid half.

                Integer n = (Integer) stack.peek();

                if (n < 1 || n > 2) {
                        throw new StructuredDateFormatException("unexpected half '" + n + "'");
                }
        }
        

        @Override
        public void exitNthQuarterInYearRange(NthQuarterInYearRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(era);
        }

        @Override
        public void exitStrSeasonInYearRange(StrSeasonInYearRangeContext ctx) {
                if (ctx.exception != null) return;

                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(era);

        }

        @Override
        public void exitNthQuarterYear(NthQuarterYearContext ctx) {
                
                Era era = (ctx.era() == null) ? null : (Era) stack.pop();

                stack.push(era);
        }

        @Override
        public void exitNthQuarter(NthQuarterContext ctx) {
                if (ctx.exception != null) return;

                // Convert LAST to a number (the last quarter
                // is the 4th). If this rule matched the
                // alternative with nth instead of LAST,
                // the nth handler will already have pushed
                // a number on the stack.

                if (ctx.LAST() != null) {
                        stack.push(new Integer(4));
                }

                // Check for a valid quarter.

                Integer n = (Integer) stack.peek();

                if (n < 1 || n > 4) {
                        throw new StructuredDateFormatException("unexpected quarter '" + n + "'");
                }
        }

        @Override
        public void exitNth(NthContext ctx) {
                if (ctx.exception != null) return;

                // Convert the string to a number,
                // and push on the stack.

                Integer n = null;

                if (ctx.NTHSTR() != null) {
                        n = new Integer(stripEndLetters(ctx.NTHSTR().getText()));
                }
                else if (ctx.FIRST() != null) {
                        n = 1;
                }
                else if (ctx.SECOND() != null) {
                        n = 2;
                }
                else if (ctx.THIRD() != null) {
                        n = 3;
                }
                else if (ctx.FOURTH() != null) {
                        n = 4;
                }

                stack.push(n);
        }

        @Override
        public void exitStrMonth(StrMonthContext ctx) {
                if (ctx.exception != null) return;

                // Convert the month name to a number,
                // and push on the stack.

                TerminalNode monthNode = ctx.MONTH();

                if (monthNode == null) {
                        monthNode = ctx.SHORTMONTH();
                }

                String monthStr = monthNode.getText();

                stack.push(DateUtils.getMonthByName(monthStr));
        }

        @Override
        public void exitStrSeason(StrSeasonContext ctx) {
                if (ctx.exception != null) return;

                // Convert the season to a quarter number,
                // and push on the stack.

                Integer quarter = null;

                if (ctx.WINTER() != null) {
                        quarter = 1;
                }
                else if (ctx.SPRING() != null) {
                        quarter = 2;
                }
                else if (ctx.SUMMER() != null) {
                        quarter = 3;
                }
                else if (ctx.FALL() != null) {
                        quarter = 4;
                }

                stack.push(quarter);
        }

        @Override
        public void exitAllOrPartOf(AllOrPartOfContext ctx) {
                if (ctx.exception != null) return;

                // If a part was specified, it will have been
                // pushed on the stack in exitPartOf(). If not,
                // push null on the stack.

                if (ctx.partOf() == null) {
                        stack.push(null);
                }
        }

        @Override
        public void exitPartOf(PartOfContext ctx) {
                if (ctx.exception != null) return;

                // Convert the token to a Part,
                // and push on the stack.

                Part part = null;

                if (ctx.EARLY() != null) {
                        part = Part.EARLY;
                }
                else if (ctx.MIDDLE() != null) {
                        part = Part.MIDDLE;
                }
                else if (ctx.LATE() != null) {
                        part = Part.LATE;
                }

                stack.push(part);
        }

        @Override
        public void exitEra(EraContext ctx) {
                if (ctx.exception != null) return;

                // Convert the token to an Era,
                // and push on the stack.

                Era era = null;

                if (ctx.BC() != null) {
                        era = Era.BCE;
                }
                else if (ctx.AD() != null) {
                        era = Era.CE;
                }

                stack.push(era);
        }

        @Override
        public void exitNumDayOfMonth(NumDayOfMonthContext ctx) {
                if (ctx.exception != null) return;

                // Convert the numeric string to an Integer,
                // and push on the stack.

                Integer dayOfMonth = new Integer(ctx.NUMBER().getText());

                if (dayOfMonth == 0 || dayOfMonth > 31) {
                        throw new StructuredDateFormatException("unexpected day of month '" + ctx.NUMBER().getText() + "'");
                }

                stack.push(dayOfMonth);
        }

        @Override
        public void exitNum(NumContext ctx) {
                if (ctx.exception != null) return;

                // Convert the numeric string to an Integer,
                // and push on the stack.

                Integer num = new Integer(ctx.NUMBER().getText());

                stack.push(num);
        }

        @Override
        public void exitUnknownDate(UnknownDateContext ctx) {
                if (ctx.exception != null) return;

                // Dummy dates
                stack.push(new Date());
                stack.push(new Date());
        }

        protected String getErrorMessage(RecognitionException re) {
                String message = "";

                Parser recognizer = (Parser) re.getRecognizer();
                TokenStream tokens = recognizer.getInputStream();

                if (re instanceof NoViableAltException) {
                        NoViableAltException e = (NoViableAltException) re;
                        Token startToken = e.getStartToken();
                        String input = (startToken.getType() == Token.EOF ) ? "end of text" : quote(tokens.getText(startToken, e.getOffendingToken()));

                        message = "no viable date format found at " + input;
                }
                else if (re instanceof InputMismatchException) {
                        InputMismatchException e = (InputMismatchException) re;
                        message = "did not expect " + getTokenDisplayString(e.getOffendingToken()) + " while looking for " +
                                  e.getExpectedTokens().toString(recognizer.getTokenNames());
                }
                else if (re instanceof FailedPredicateException) {
                        FailedPredicateException e = (FailedPredicateException) re;
                        String ruleName = recognizer.getRuleNames()[recognizer.getContext().getRuleIndex()];

                        message = "failed predicate " + ruleName + ": " + e.getMessage();
                }

                return message;
        }

        protected String quote(String text) {
                return "'" + text + "'";
        }

        protected String getTokenDisplayString(Token token) {
                String string;

                if (token == null) {
                        string = "[no token]";
                }
                else {
                        String text = token.getText();

                        if (text == null) {
                                if (token.getType() == Token.EOF ) {
                                        string = "end of text";
                                }
                                else {
                                        string = "[" + token.getType() + "]";
                                }
                        }
                        else {
                                string = quote(text);
                        }
                }

                return string;
        }

        protected String stripEndLetters(String input) {
                return input.replaceAll("[^\\d]+$", "");
        }

        public static void main(String[] args) {
                StructuredDateEvaluator evaluator = new ANTLRStructuredDateEvaluator();

                for (String displayDate : args) {
                        try {
                                evaluator.evaluate(displayDate);
                        } catch (StructuredDateFormatException e) {
                                e.printStackTrace();
                        }
                }
        }
}