source: domaineditor/src/main/java/geniusweb/domaineditor/model/NumberValueSetModel.java@ 52

package geniusweb.domaineditor.model;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;

import geniusweb.issuevalue.NumberValueSet;
import geniusweb.issuevalue.ValueSet;
import tudelft.utilities.immutablelist.Range;
import tudelft.utilities.listener.DefaultListenable;
import tudelft.utilities.logging.Reporter;
import tudelft.utilities.mvc.model.BasicModel;
import tudelft.utilities.mvc.model.ListModel;
import tudelft.utilities.mvc.model.NumberModel;
import tudelft.utilities.mvc.model.events.Changed;
import tudelft.utilities.mvc.model.events.Event;

/**
 * Model for a {@link NumberValueSet}
 *
 */
public class NumberValueSetModel extends DefaultListenable<Event>
                implements ValueSetModel {

        private final NumberModel low, high, step;
        protected final Reporter log;

        public NumberValueSetModel(NumberModel lowv, NumberModel highv,
                        NumberModel stepv, Reporter log) {
                this.low = lowv;
                this.high = highv;
                this.step = stepv;
                this.log = log;

                check();

                // 'this' refers to surrounding class inside lambda.
                low.addListener((e) -> check());
                high.addListener((e) -> check());
                step.addListener((e) -> check());
        }

        private void check() throws IllegalStateException {
                if (low.getValue().compareTo(high.getValue()) > 0)
                        throw new IllegalStateException("low must be <= high");
                if (step.getValue().compareTo(BigDecimal.ZERO) <= 0)
                        throw new IllegalStateException("step must be >0");
                notifyListeners(new Changed(this, null));
        }

        /*
         * Default, bit arbitrary values.
         */
        public NumberValueSetModel(Reporter log) {
                this(new NumberModel(BigDecimal.ZERO, log),
                                new NumberModel(BigDecimal.TEN, log),
                                new NumberModel(BigDecimal.ONE, log), log);
        }

        @Override
        public String toString() {
                return "(" + low + high + step + ")";
        }

        public NumberModel getLow() {
                return low;
        }

        public NumberModel getHigh() {
                return high;

        }

        public NumberModel getStep() {
                return step;
        }

        @Override
        public BasicModel first() {
                return low;
        }

        @Override
        public ListModel getList() {
                /**
                 * Return a ListModel backed up by the original set. It contains the
                 * possible values in the range.
                 */
                return new MyListModel(this);
        }

        @Override
        public NumberValueSet getCurrentValue() throws IllegalStateException {
                return new NumberValueSet(
                                new Range(low.getValue(), high.getValue(), step.getValue()));
        }

        @Override
        public void setCurrentValue(ValueSet obj) throws IllegalArgumentException {
                if (!(obj instanceof NumberValueSet))
                        throw new IllegalArgumentException(
                                        "Argument must be a NumberValueSet but got " + obj);
                NumberValueSet nv = (NumberValueSet) obj;
                // order of change is important, avoiding illegal ranges:
                // if low must be increased, change high first.
                // if high must be decreased, change low first.
                // otherwise the change order is irrelevant.
                if (nv.getRange().getLow().compareTo(low.getValue()) > 0) {
                        high.setValue(nv.getRange().getHigh());
                        low.setValue(nv.getRange().getLow());
                } else {
                        low.setValue(nv.getRange().getLow());
                        high.setValue(nv.getRange().getHigh());
                }
                step.setValue(nv.getRange().getStep());
        }

}

/**
 * A ListModel view of this object. Editing is not supported.
 *
 */
class MyListModel extends DefaultListenable<Event>
                implements ListModel<NumberModel> {

        private NumberValueSetModel numvalset;
        /**
         * A "cache" Map with the actual values from the range. Although
         * NumberModels, they really should not be edited. This map ensures we
         * return the SAME NumberModel every time a value from the range is
         * selected.
         */
        private final transient Map<BigDecimal, NumberModel> itemsCache = new HashMap<>();

        public MyListModel(NumberValueSetModel valset) {
                this.numvalset = valset;
                valset.addListener((e) -> notifyListeners(e));
        }

        @Override
        public NumberModel get(int n) {
                BigDecimal val = numvalset.getCurrentValue().getRange().get(n);
                if (!itemsCache.containsKey(val))
                        itemsCache.put(val, new NumberModel(val, numvalset.log));
                return itemsCache.get(val);
        }

        @Override
        public int getSize() {
                return numvalset.getCurrentValue().getRange().size().intValue();
        }

        @Override
        public void remove(NumberModel value) {
                throw new UnsupportedOperationException();
        }

        @Override
        public void add(NumberModel value) {
                throw new UnsupportedOperationException();
        }

        @Override
        public boolean contains(Object o) {
                return o instanceof NumberModel && numvalset.getCurrentValue()
                                .getRange().contains(((NumberModel) o).getValue());
        }

}