Class ErrorMessages

src/main/java/wyc/util/ErrorMessages.java:53–598

Contains global constants mapping syntax errors to their error messages. The purpose of this class is bring all syntax error messages into one place, such that: It's easy to change error messages, and be sure the changes are applied universally. It's easy to reflect on the

 *
 */
public class ErrorMessages {

	public interface Message {
		public String getMessage(Tuple<Syntactic.Item> context);

		/**
		 * Determine whether an actual error message was generated from this template
		 * (or not).
		 *
		 * @param message
		 * @return
		 */
		public boolean match(String message);
	}

	/**
	 * A static message is a single message which, once created, never changes.
	 *
	 * @author David J. Pearce
	 *
	 */
	private static final class StaticMessage implements Message {
		private final String message;

		public StaticMessage(String message) {
			this.message = message;
		}

		@Override
		public String getMessage(Tuple<Syntactic.Item> context) {
			return message;
		}

		@Override
		public boolean match(String message) {
			return this.message.equals(message);
		}
	}

	/**
	 * A multi-part message is a dynamic message which is created based upon the
	 * context in which it exists.
	 *
	 * @author David J. Pearce
	 *
	 */
	private static final class MultiPartMessage implements Message {
		private final String[] parts;

		public MultiPartMessage(String... parts) {
			this.parts = parts;
		}

		@Override
		public boolean match(String message) {
			return message.startsWith(parts[0]) || parts[0].startsWith(message);
		}