source: josm/trunk/src/org/openstreetmap/josm/gui/mappaint/Environment.java@ 5705

// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.gui.mappaint;

import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Relation;
import org.openstreetmap.josm.gui.mappaint.mapcss.Condition.Context;
import org.openstreetmap.josm.gui.mappaint.mapcss.Selector.LinkSelector;
import org.openstreetmap.josm.tools.CheckParameterUtil;

/**
 * Environment is a data object to provide access to various "global" parameters.
 * It is used during processing of MapCSS rules and for the generation of
 * style elements.
 */
public class Environment {

    public OsmPrimitive osm;

    public MultiCascade mc;
    public String layer;
    public StyleSource source;
    private Context context = Context.PRIMITIVE;

    /**
     * If not null, this is the matching parent object if an condition or an expression
     * is evaluated in a {@link LinkSelector} (within a child selector)
     */
    public OsmPrimitive parent;
    /**
     * The same for parent selector. Only one of the 2 fields (parent or child) is not null in any environment.
     */
    public OsmPrimitive child;

    /**
     * index of node in parent way or member in parent relation. Must be != null in LINK context.
     */
    public Integer index = null;

    /**
     * Creates a new uninitialized environment
     */
    public Environment() {}

    public Environment(OsmPrimitive osm, MultiCascade mc, String layer, StyleSource source) {
        this.osm = osm;
        this.mc = mc;
        this.layer = layer;
        this.source = source;
    }

    /**
     * Creates a clone of the environment {@code other}
     * 
     * @param other the other environment. Must not be null.
     */
    public Environment(Environment other) throws IllegalArgumentException{
        CheckParameterUtil.ensureParameterNotNull(other);
        this.osm = other.osm;
        this.mc = other.mc;
        this.layer = other.layer;
        this.parent = other.parent;
        this.child = other.child;
        this.source = other.source;
        this.index = other.index;
        this.context = other.getContext();
    }

    public Environment withPrimitive(OsmPrimitive osm) {
        Environment e = new Environment(this);
        e.osm = osm;
        return e;
    }

    public Environment withParent(OsmPrimitive parent) {
        Environment e = new Environment(this);
        e.parent = parent;
        return e;
    }

    public Environment withChild(OsmPrimitive child) {
        Environment e = new Environment(this);
        e.child = child;
        return e;
    }

    public Environment withIndex(int index) {
        Environment e = new Environment(this);
        e.index = index;
        return e;
    }

    public Environment withContext(Context context) {
        Environment e = new Environment(this);
        e.context = context == null ? Context.PRIMITIVE : context;
        return e;
    }

    public Environment withLinkContext() {
        Environment e = new Environment(this);
        e.context = Context.LINK;
        return e;
    }

    public boolean isLinkContext() {
        return Context.LINK.equals(context);
    }

    public boolean hasParentRelation() {
        return parent != null && parent instanceof Relation;
    }

    /**
     * Replies the current context.
     * 
     * @return the current context
     */
    public Context getContext() {
        return context == null ? Context.PRIMITIVE : context;
    }

    public String getRole() {
        if (getContext().equals(Context.PRIMITIVE))
            return null;

        if (parent != null && parent instanceof Relation)
            return ((Relation) parent).getMember(index).getRole();
        if (child != null && osm instanceof Relation)
            return ((Relation) osm).getMember(index).getRole();
        return null;
    }

    public void clearSelectorMatchingInformation() {
        parent = null;
        child = null;
        index = null;
    }
}