TypeUtils.java

//Dstl (c) Crown Copyright 2017
package uk.gov.dstl.baleen.uima.utils;

import java.util.Iterator;

import org.apache.uima.cas.Type;
import org.apache.uima.cas.TypeSystem;
import org.apache.uima.jcas.JCas;
import org.apache.uima.jcas.cas.AnnotationBase;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.googlecode.concurrenttrees.radix.node.concrete.DefaultByteArrayNodeFactory;
import com.googlecode.concurrenttrees.suffix.ConcurrentSuffixTree;
import com.googlecode.concurrenttrees.suffix.SuffixTree;

import uk.gov.dstl.baleen.exceptions.BaleenException;
import uk.gov.dstl.baleen.types.semantic.Entity;

/** A collection of utility to set bridge between Uima types and Java classes.
 * 
 *
 */
public class TypeUtils {
	private static final Logger LOGGER = LoggerFactory.getLogger(TypeUtils.class);
	private TypeUtils(){
		// Private constructor for Util class
	}

	/**
	 * For a given type name, look through the type system and return the matching class.
	 * If two types of the same name (but different packages) exist, then null will be returned and the package will need to be included in the typeName.
	 *
	 * @param typeName The name of the type, optionally including the package
	 * @param jCas A JCas object containing the type system
	 * @return The class associated with that type
	 */
	public static Class<? extends AnnotationBase> getType(String typeName, JCas jCas){
		return getType(typeName, jCas.getTypeSystem());
	}

	/**
	 * For a given type name, look through the type system and return the matching class.
	 * If two types of the same name (but different packages) exist, then null will be returned and the package will need to be included in the typeName.
	 *
	 * @param typeName The name of the type, optionally including the package
	 * @param typeSystem The type system to search
	 * @return The class associated with that type
	 */
	@SuppressWarnings("unchecked")
	public static Class<AnnotationBase> getType(String typeName, TypeSystem typeSystem){
		SuffixTree<Class<AnnotationBase>> types = new ConcurrentSuffixTree<>(new DefaultByteArrayNodeFactory());

		Iterator<Type> itTypes = typeSystem.getTypeIterator();
		while(itTypes.hasNext()){
			Type t = itTypes.next();

			Class<AnnotationBase> c;
			try {
				String clazz = t.getName();
				if(clazz.startsWith("uima.")){
					continue;
				} else if(clazz.endsWith("[]")){
					clazz = clazz.substring(0, clazz.length() - 2);
				}

				Class<?> unchecked = Class.forName(clazz);

				if(AnnotationBase.class.isAssignableFrom(unchecked)){
					c = (Class<AnnotationBase>) unchecked;
					types.put(t.getName(), c);
				}else{
					LOGGER.debug("Skipping class {} that doesn't inherit from AnnotationBase");
				}
			} catch (ClassNotFoundException e) {
				LOGGER.warn("Unable to load class {} from type system", t.getName(), e);
			}
		}

		Class<AnnotationBase> ret = getClassFromType("."+typeName, types);
		if(ret == null){
			ret = getClassFromType(typeName, types);
		}
		
		if(ret == null){
			LOGGER.warn("No uniquely matching class found for type {}", typeName);
		}

		return ret;
	}
	
	private static Class<AnnotationBase> getClassFromType(String typeName, SuffixTree<Class<AnnotationBase>> types){
		Iterator<CharSequence> itMatchedTypes = types.getKeysEndingWith(typeName).iterator();
		if(!itMatchedTypes.hasNext()){
			return null;	//No match found
		}
		
		Class<AnnotationBase> ret = types.getValueForExactKey(itMatchedTypes.next());

		if(itMatchedTypes.hasNext()){
			return null;	//More than one match found
		}
		
		return ret;
	}
	
	/**
	 * Get the class of a specified type, that extends from the Entity base class
	 * 
	 * @param typeName The name of the type, optionally including the package
	 * @param jCas A JCas object containing the type system
	 * @return The class associated with that type, which will extend from Entity
	 * @throws BaleenException is thrown if a suitable class can't be found
	 */
	@SuppressWarnings("unchecked")
	public static Class<? extends Entity> getEntityClass(String typeName, JCas jCas) throws BaleenException{
		Class<? extends AnnotationBase> at = getType(typeName, jCas);
		
		if(at == null){
			throw new BaleenException("Couldn't find type '"+typeName+"'");
		}
		
		if(!Entity.class.isAssignableFrom(at)){
			throw new BaleenException("Entity type '"+typeName+"' does not inherit from Entity");
		}
		
		return (Class<? extends Entity>) at;
	}
}