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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.

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/*
 * #%L
 * SciJava Common shared library for SciJava software.
 * %%
 * Copyright (C) 2009 - 2017 Board of Regents of the University of
 * Wisconsin-Madison, Broad Institute of MIT and Harvard, Max Planck
 * Institute of Molecular Cell Biology and Genetics, University of
 * Konstanz, and KNIME GmbH.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * #L%
 */

package org.scijava.parse;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.scijava.parse.eval.DefaultEvaluator;
import org.scijava.plugin.Plugin;
import org.scijava.service.AbstractService;
import org.scijava.service.Service;
import org.scijava.util.ObjectArray;

/**
 * Default service for parsing strings.
 * 
 * @author Curtis Rueden
 */
@Plugin(type = Service.class)
public class DefaultParseService extends AbstractService implements
	ParseService
{

	@Override
	public Items parse(final String arg, final boolean strict) {
		if (arg == null) throw new NullPointerException("arg must not be null");
		return new ItemsList(arg, strict);
	}

	// -- Helper classes --

	/**
	 * {@link Items} implementation backed by the
	 * SciJava
	 * Expression Parser.
	 */
	private static class ItemsList extends ObjectArray implements Items {

		public ItemsList(final String arg, final boolean strict) {
			super(Item.class);
			parseItems(arg, strict);
		}

		@Override
		public Map asMap() {
			final LinkedHashMap map =
				new LinkedHashMap<>();
			for (final Item item : this) {
				map.put(item.name(), item.value());
			}
			return map;
		}

		@Override
		public boolean isMap() {
			for (final Item item : this) {
				if (item.name() == null) return false;
			}
			return true;
		}

		@Override
		public boolean isList() {
			for (final Item item : this) {
				if (item.name() != null) return false;
			}
			return true;
		}

		private void parseItems(final String arg, final boolean strict) {
			final DefaultEvaluator e = new DefaultEvaluator();
			e.setStrict(strict);
			final Object result = e.evaluate("(" + arg + ")");
			if (result == null) {
				throw new IllegalStateException("Error parsing string: '" + arg + "'");
			}
			final List list;
			if (result instanceof List) list = (List) result;
			else list = Collections.singletonList(result);

			for (final Object o : list) {
				final String name;
				final Object value;
				if (o instanceof Variable) {
					final Variable v = (Variable) o;
					name = v.getToken();
					value = e.value(v);
				}
				else {
					name = null;
					value = o;
				}
				add(new Item() {

					@Override
					public String name() {
						return name;
					}

					@Override
					public Object value() {
						return value;
					}

				});
			}
		}

	}

}