package org.daisy.pipeline.nlp;
   
   import java.io.IOException;
   
   /**
    * Categorize input strings. Two modes are possible:
    * 
    * - FULL_MATCH: try to categorize the whole input
    * 
   * - PREFIX_MATCH: try to categorize the longest prefix match
   */
  public abstract class TextCategorizer {
  	protected MatchMode mMatchMode = MatchMode.FULL_MATCH;
  
  	public enum Category {
  		COMMON,
  		UNKNOWN,
  		PROPER_NOUN,
  		PROPER_NOUN_PLACE,
  		PROPER_NOUN_NAME,
  		ABBREVIATION,
  		ACRONYM,
  		PUNCTUATION,
  		EMAIL_ADDR,
  		WEB_LINK,
  		QUANTITY,
  		ORDINAL,
  		TIME,
  		QUOTE,
  		DATE,
  		SPACE,
  		CURRENCY,
  		DIMENSIONS,
  		MEASURE,
  		PHONE_NUMBER,
  		RANGE,
  		IDENTIFIER,
  		NUMBERING_ITEM
  	};
  
  	public static boolean isProperNoun(Category c) {
  		switch (c) {
  		case PROPER_NOUN:
  		case PROPER_NOUN_PLACE:
  		case PROPER_NOUN_NAME:
  			return true;
  		default:
  			return false;
  		}
  	}
  
  	public static boolean isSpeakable(Category c) {
  		switch (c) {
  		case SPACE:
  		case PUNCTUATION:
  		case QUOTE:
  			return false;
  		default:
  			return true;
  		}
  	}
  
  	public static class CategorizedWord {
  		public Category category;
  		public String word;
  	}
  
  	public enum MatchMode {
  		FULL_MATCH,
  		PREFIX_MATCH
  	}
  
  	public void init(MatchMode mode) throws IOException {
  		mMatchMode = mode;
  	}
  
  	/**
  	 * Called after init()
  	 */
  	public abstract void compile();
  
  	public abstract void resetContext();
  
  	/**
  	 * Can return false before returning true, but not the other way around.
  	 */
  	public abstract boolean threadsafe();
  
  	/**
  	 * Both the fullcase and lower case versions are provided to prevent us from
  	 * performing the conversion everytime.
  	 * 
  	 * @param fullcase fullcase version of the string to match
  	 * @param lowercase lowercase version of the string to match
  	 * @return null if the word cannot be categorized, otherwise the
  	 *         CategorizedWord will the contain the longest match (i.e. a
  	 *         substring of @param fullcase) depending on the match mode.
  	 */
  	public abstract CategorizedWord categorize(String fullcase, String lowercase);
 }