flabbergast.ReflectedFrame Maven / Gradle / Ivy

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package flabbergast;

import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;

/**
 * A Frame wrapper over a Java object.
 */
public class ReflectedFrame extends Frame {

    private final Object backing;

    private final TreeMap attributes;
    public interface Transform {
        Object invoke(T src);
    }

    public static  ReflectedFrame create(TaskMaster task_master, T backing,
                                            Map> accessors) {
        TreeMap attributes = new TreeMap();
        for (Entry> entry : accessors.entrySet()) {
            Object result = entry.getValue().invoke(backing);
            if (result == null) {
                result = Unit.NULL;
            } else if (result instanceof Boolean || result instanceof Double
                       || result instanceof Long || result instanceof Frame
                       || result instanceof Stringish
                       || result instanceof Template || result instanceof Unit) {
            } else if (result instanceof String) {
                result = new SimpleStringish((String) result);
            } else {
                throw new ClassCastException("Value for " + entry.getKey()
                                             + " is non-Flabbergast type "
                                             + result.getClass().getSimpleName() + ".");
            }
            attributes.put(entry.getKey(), result);
        }
        return new ReflectedFrame(task_master, new JavaSourceReference(),
                                  backing, attributes);
    }

    private ReflectedFrame(TaskMaster task_master, SourceReference source_ref,
                           Object backing, TreeMap attributes) {
        super(task_master, source_ref, null, null);
        this.backing = backing;
        this.attributes = attributes;
    }

    @Override
    public int count() {
        return attributes.size();
    }

    /**
     * Access the functions in the frames. Frames should not be mutated, but
     * this policy is not enforced by this class; it must be done in the calling
     * code.
     */
    @Override
    public Object get(String name) {
        return attributes.containsKey(name) ? attributes.get(name) : null;
    }

    public Object getBacking() {
        return backing;
    }

    /**
     * Check if an attribute name is present in the frame.
     */
    @Override
    public boolean has(String name) {
        return attributes.containsKey(name);
    }

    @Override
    public Iterator iterator() {
        return attributes.keySet().iterator();
    }

    public void set(String name, Object value) {
        if (attributes.containsKey(name)) {
            throw new IllegalArgumentException();
        }
        attributes.put(name, value);
    }
}