TypeParser.java

/**
 * Copyright (c) 2014-2017 by the respective copyright holders.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.eclipse.smarthome.core.types;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;

/**
 * This is a helper class that helps parsing a string into an Eclipse SmartHome type (state or command).
 *
 * @author Kai Kreuzer - Initial contribution and API
 *
 */
public final class TypeParser {

    /**
     * No instances allowed.
     */
    private TypeParser() {
    }

    private static final String CORE_LIBRARY_PACKAGE = "org.eclipse.smarthome.core.library.types.";

    /**
     * Parses a string into a type.
     *
     * @param typeName name of the type, for example StringType.
     * @param input input string to parse.
     * @return Parsed type or null, if the type couldn't be parsed.
     */
    public static Type parseType(String typeName, String input) {
        try {
            Class<?> stateClass = Class.forName(CORE_LIBRARY_PACKAGE + typeName);
            Method valueOfMethod = stateClass.getMethod("valueOf", String.class);
            return (Type) valueOfMethod.invoke(stateClass, input);
        } catch (ClassNotFoundException e) {
        } catch (NoSuchMethodException e) {
        } catch (IllegalAccessException e) {
        } catch (InvocationTargetException e) {
        }
        return null;
    }

    /**
     * <p>
     * Determines a state from a string. Possible state types are passed as a parameter. Note that the order matters
     * here; the first type that accepts the string as a valid value, will be used for the state.
     * </p>
     * <p>
     * Example: The type list is OnOffType.class,StringType.class. The string "ON" is now accepted by the OnOffType and
     * thus OnOffType.ON will be returned (and not a StringType with value "ON").
     * </p>
     *
     * @param types possible types of the state to consider
     * @param s the string to parse
     * @return the corresponding State instance or <code>null</code>
     */
    public static State parseState(List<Class<? extends State>> types, String s) {
        for (Class<? extends Type> type : types) {
            try {
                Method valueOf = type.getMethod("valueOf", String.class);
                State state = (State) valueOf.invoke(type, s);
                if (state != null) {
                    return state;
                }
            } catch (NoSuchMethodException e) {
            } catch (IllegalArgumentException e) {
            } catch (IllegalAccessException e) {
            } catch (InvocationTargetException e) {
            }
        }
        return null;
    }

    /**
     * <p>
     * Determines a command from a string. Possible command types are passed as a parameter. Note that the order matters
     * here; the first type that accepts the string as a valid value, will be used for the command.
     * </p>
     * <p>
     * Example: The type list is OnOffType.class,StringType.class. The string "ON" is now accepted by the OnOffType and
     * thus OnOffType.ON will be returned (and not a StringType with value "ON").
     * </p>
     *
     * @param types possible types of the command to consider
     * @param s the string to parse
     * @return the corresponding Command instance or <code>null</code>
     */
    public static Command parseCommand(List<Class<? extends Command>> types, String s) {
        for (Class<? extends Command> type : types) {
            try {
                Method valueOf = type.getMethod("valueOf", String.class);
                Command value = (Command) valueOf.invoke(type, s);
                if (value != null) {
                    return value;
                }
            } catch (NoSuchMethodException e) {
            } catch (IllegalArgumentException e) {
            } catch (IllegalAccessException e) {
            } catch (InvocationTargetException e) {
            }
        }
        return null;
    }
}