LineString.java

/*
 * Copyright 2013 Filippo De Luca - me@filippodeluca.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.github.filosganga.geogson.model;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.Iterables.transform;
import static com.google.common.collect.Lists.newArrayList;

import com.github.filosganga.geogson.model.positions.LinearPositions;
import com.github.filosganga.geogson.model.positions.SinglePosition;
import com.google.common.collect.ImmutableList;

/**
 * Specialization of LinearGeometry composed at least by 2 points.
 *
 * JeoGson reference: @see http://geojson.org/geojson-spec.html#linestring.
 */
public class LineString extends LinearGeometry {

    private static final long serialVersionUID = 1L;

    public LineString(LinearPositions positions) {
        super(checkPositions(positions));
    }

    private static LinearPositions checkPositions(LinearPositions toCheck) {
        checkArgument(toCheck.size() >= 2, "LineString must be composed by a minimum of 2 points.");

        return toCheck;
    }

    /**
     * Creates a LineString from the given points.
     *
     * @param points Sequence of Point composed at least by 2 points.
     * @return a LineString
     */
    public static LineString of(Point... points) {
        return LineString.of(ImmutableList.copyOf(newArrayList(points)));
    }

    /**
     * Creates a LineString from the given points.
     *
     * @param points Iterable of Point at least by 2 points.
     * @return a LineString
     */
    public static LineString of(Iterable<Point> points) {
        return new LineString(new LinearPositions(transform(points, positionsFn(SinglePosition.class))));
    }

    @Override
    public Type type() {
        return Type.LINE_STRING;
    }

    /**
     * Return if this LineString:
     *  - Is composed by at least 4 points
     *  - The first and the last Point are the same.
     *
     * For more details @see http://geojson.org/geojson-spec.html#linestring.
     *
     * @return true if this Linestring is closed false otherwise.
     */
    public boolean isClosed() {
        return positions().isClosed();
    }

}