jcommons/org.eclipse.statet.jcommons.util/src/org/eclipse/statet/jcommons/collections/CollectionUtils.java

/*=============================================================================#
 # Copyright (c) 2012, 2021 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.jcommons.collections;

import static org.eclipse.statet.jcommons.lang.NullDefaultLocation.FIELD;
import static org.eclipse.statet.jcommons.lang.NullDefaultLocation.PARAMETER;
import static org.eclipse.statet.jcommons.lang.NullDefaultLocation.RETURN_TYPE;
import static org.eclipse.statet.jcommons.lang.NullDefaultLocation.TYPE_ARGUMENT;
import static org.eclipse.statet.jcommons.lang.NullDefaultLocation.TYPE_BOUND;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.RandomAccess;

import org.eclipse.statet.jcommons.lang.NonNull;
import org.eclipse.statet.jcommons.lang.NonNullByDefault;


@NonNullByDefault
public class CollectionUtils {
	
	
	public static String toString(final List<@NonNull ?> list, final String sep) {
		final int n= list.size();
		if (n <= 0) {
			return ""; //$NON-NLS-1$
		}
		else if (n == 1) {
			return list.get(0).toString();
		}
		else if (list instanceof RandomAccess) {
			final StringBuilder sb= new StringBuilder(list.get(0).toString());
			for (int i= 1; i < n; i++) {
				sb.append(sep);
				sb.append(list.get(i).toString());
			}
			return sb.toString();
		}
		else {
			final Iterator<?> iter= list.iterator();
			final StringBuilder sb= new StringBuilder(iter.next().toString());
			for (int i= 1; i < n; i++) {
				sb.append(sep);
				sb.append(iter.next().toString());
			}
			return sb.toString();
		}
	}
	
	public static String toString(final Collection<@NonNull ?> c, final String sep) {
		if (c instanceof List) {
			return toString((List<?>) c, sep);
		}
		final int n= c.size();
		if (n <= 0) {
			return ""; //$NON-NLS-1$
		}
		else if (n == 1) {
			return c.iterator().next().toString();
		}
		else {
			final Iterator<?> iter= c.iterator();
			final StringBuilder sb= new StringBuilder(iter.next().toString());
			for (int i= 1; i < n; i++) {
				sb.append(sep);
				sb.append(iter.next().toString());
			}
			return sb.toString();
		}
	}
	
	
	@NonNullByDefault({ PARAMETER, RETURN_TYPE, FIELD, TYPE_BOUND, TYPE_ARGUMENT })
	public static ImIdentityList<String> toIdentifierList(final String[] array) {
		int count= 0;
		for (int i= 0; i < array.length; i++) {
			final String s= array[i];
			if (s != null && !s.isEmpty()) {
				array[count++]= s.intern();
			}
		}
		return ImCollections.newIdentityList(array, 0, count);
	}
	
	@NonNullByDefault({ PARAMETER, RETURN_TYPE, FIELD, TYPE_BOUND, TYPE_ARGUMENT })
	public static ImIdentitySet<String> toIdentifierSet(final String[] array) {
		int count= 0;
		for (int i= 0; i < array.length; i++) {
			final String s= array[i];
			if (s != null && !s.isEmpty()) {
				array[count++]= s.intern();
			}
		}
		return ImCollections.newIdentitySet(array, 0, count);
	}
	
}