Question

I am brand-new to Irony (I studied BNF at uni about 10 years ago), and am starting by creating a quasi-real coordinate parser.

Below is the grammar class (full code at https://github.com/spadger/notam-visualiser) that I believed should have been able to parse input

70 50' 44" N 1 13' 66" E

However, when I run it in the grammar explorer, I get a syntax error at 1:4 "expected: space"

Can you see what is wrong with my code?

Thanks,

Jon

[Language("Simple non-real coordinates", "0.1", "A grammar to parse an imaginary coordinate system")]
public class CoordinateGrammar : Grammar
{
    //70 50' 44" N 1 13' 66" E
    public CoordinateGrammar()
    {
        #region Terminals
        var integer = new NumberLiteral("integer", NumberOptions.IntOnly);
        var space = ToTerm(" ", "space");
        var point = ToTerm(".", "dot");
        var lat = ToTerm("N", "north") | ToTerm("S", "south");
        var lon = ToTerm("E", "east") | ToTerm("W", "west");
        var minuteMarker = ToTerm("'", "minute");
        var secondMarker = ToTerm("\"", "second");
        #endregion

        #region Non-Terminals
        var decimalAmount = new NonTerminal("decimalAmount", typeof(DecimalAmountNode));
        var minute = new NonTerminal("minute", typeof(MinuteNode));
        var second = new NonTerminal("second", typeof(SecondNode));

        var imperialMagnitude = new NonTerminal("decimalMagnitude", typeof (ImperialMagnitudeNode));

        var imperialLatitude = new NonTerminal("imperialLatitude", typeof (ImperialLatitudeNode));
        var imperialLongitude = new NonTerminal("imperialLongitude", typeof (ImperialLongitudeNode));
        var imperialCoordinate = new NonTerminal("imperialCoordinate", typeof(ImperialCoordinateNode));
        #endregion

        #region Rules
        decimalAmount.Rule = integer | integer + point + integer;

        minute.Rule = integer + minuteMarker;
        second.Rule = integer + secondMarker;
        imperialMagnitude.Rule = integer + space + minute + space + second;
        imperialLatitude.Rule = imperialMagnitude + space + lat;
        imperialLongitude.Rule = imperialMagnitude + space + lon;
        imperialCoordinate.Rule = imperialLatitude + space + imperialLongitude;
        #endregion

        Root = imperialCoordinate;
    }
}
Was it helpful?

Solution

Fixed it!

I was manually expecting spaces, but the grammar was already configured (by default) to treat the 'space' character as a white-space marker. Updating the non-termanal rules to below fixed my problem.

decimalAmount.Rule = integer | integer + point + integer;

minute.Rule = integer + minuteMarker;
second.Rule = integer + secondMarker;
imperialMagnitude.Rule = integer + minute + second;
imperialLatitude.Rule = imperialMagnitude + lat;
imperialLongitude.Rule = imperialMagnitude + lon;
imperialCoordinate.Rule = imperialLatitude + imperialLongitude;
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