Jso.java

// Copyright 2012 Google Inc. All Rights Reserved.
//
// 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 org.eclipse.che.ide.collections;

import org.eclipse.che.ide.collections.js.JsoArray;
import com.google.gwt.core.client.JavaScriptObject;

/**
 * Utility class for JavaScriptObject construction and serialization. We try to
 * keep all the nasty typesystem cludge with working with JavaScriptObject maps
 * confined in this class. We rely on identical method body coalescing to keep
 * the code small.
 * <p/>
 * TODO: Using the builder pattern like this for constructing JSOs
 * on the client will cause a lot of boundary crossings. Revisit this as a
 * potential perf optimization if we find ourselve spending a lot of time
 * building objects for serialization.
 */
public class Jso extends JavaScriptObject implements JsonObject {

    public static Jso create() {
        return JavaScriptObject.createObject().cast();
    }

    /** Deserializes a JSON String and returns an overlay type. */
    public static native <T extends Jso> T deserialize(String jsonString) /*-{
        return JSON.parse(jsonString);
    }-*/;

    /** Serializes a JsonObject into a String. */
    public static native String serialize(JavaScriptObject jso) /*-{
        return JSON.stringify(jso);
    }-*/;

    protected Jso() {
    }

    @Override
    public native final JsonObject addField(String key, boolean value) /*-{
        this[key] = value;
        return this;
    }-*/;

    @Override
    public native final JsonObject addField(String key, double value) /*-{
        this[key] = value;
        return this;
    }-*/;

    @Override
    public native final JsonObject addField(String key, int value) /*-{
        this[key] = value;
        return this;
    }-*/;

    @Override
    public final JsonObject addField(String key, Array<?> value) {
        // Delegate to the JS impl
        return addField(key, (Object)value);
    }

    @Override
    public final JsonObject addField(String key, JsonObject value) {
        // Delegate to the JS impl
        return addField(key, (Object)value);
    }

    public native final Jso addField(String key, Object value) /*-{
        this[key] = value;
        return this;
    }-*/;

    @Override
    public native final Jso addField(String key, String value) /*-{
        this[key] = value;
        return this;
    }-*/;

    public native final Jso addNullField(String key) /*-{
        this[key] = null;
        return this;
    }-*/;

    public native final Jso addUndefinedField(String key) /*-{
        this[key] = undefined;
        return this;
    }-*/;

    public native final Jso deleteField(String key) /*-{
        delete this[key];
    }-*/;

    @Override
    public final JsoArray<JsonObject> getArrayField(String key) {
        return ((Jso)getObjectField(key)).cast();
    }

    @Override
    public final boolean getBooleanField(String key) {
        return getBooleanFieldImpl(key);
    }

    /**
     * @return evaluated boolean value (casted to a boolean). This is useful for
     *         "optional" boolean fields to treat {@code undefined} values as
     *         {@code false}
     */
    public final native boolean getFieldCastedToBoolean(String key) /*-{
        return !!this[key];
    }-*/;

    @Override
    public final int getIntField(String key) {
        return getIntFieldImpl(key);
    }

    @Override
    public final double getDoubleField(String key) {
        return getFieldCastedToNumber(key);
    }

    /**
     * Evaluates a given property to an integer number. The {@code undefined} and
     * {@code null} key values will be casted to zero.
     *
     * @return evaluated integer value (casted to integer)
     */
    public final int getFieldCastedToInteger(String key) {
        return (int)getFieldCastedToNumber(key);
    }

    /**
     * Evaluates a given property to a number. The {@code undefined} and
     * {@code null} key values will be casted to zero.
     *
     * @return evaluated number value (casted to number)
     */
    private native double getFieldCastedToNumber(String key) /*-{
        return +(this[key] || 0);
    }-*/;

    public native final JavaScriptObject getJsObjectField(String key) /*-{
        return this[key];
    }-*/;

    /*
     * GWT dev mode adds a __gwt_ObjectId property to all objects. We have to call
     * hasOwnProperty (which is overridden by GWT) when using for(in) loops to verify
     * that the key is actually a property of the object, and not the __gwt_ObjectId
     * set by Chrome dev mode.
     */
    @Override
    public native final JsoArray<String> getKeys() /*-{
        keys = [];
        for (key in this) {
            if (Object.prototype.hasOwnProperty.call(this, key)) {
                keys.push(key);
            }
        }
        return keys;
    }-*/;

    public native final boolean isEmpty() /*-{
        for (key in this) {
            if (Object.prototype.hasOwnProperty.call(this, key)) {
                return false;
            }
        }
        return true;
    }-*/;

    @Override
    public native final JsonObject getObjectField(String key) /*-{
        return this[key];
    }-*/;

    public native final Object getJavaObjectField(String key) /*-{
        return this[key];
    }-*/;

    @Override
    public native final String getStringField(String key) /*-{
        return this[key];
    }-*/;

    /** @return evaluated string value (casted to string) */
    public final native String getFieldCastedToString(String key) /*-{
        return "" + this[key];
    }-*/;

    /**
     * Checks to see if the specific key is present as a field/property on the
     * Jso.
     * <p/>
     * You should guard calls to primitive type getters with this or else you
     * might blow up at runtime (attempting to pass null as a return value for a
     * primitive type).
     *
     * @param key
     * @return whether or not
     */
    public native final boolean hasOwnProperty(String key) /*-{
        return this.hasOwnProperty(key);
    }-*/;

    public final String serialize() {
        return Jso.serialize(this);
    }

    private native boolean getBooleanFieldImpl(String key) /*-{
        return this[key];
    }-*/;

    private native int getIntFieldImpl(String key) /*-{
        return this[key];
    }-*/;

    /** Removes the GWT development/hosted mode property "__gwt_ObjectId". */
    public final void removeGwtObjectId() {
        deleteField("__gwt_ObjectId");
    }
}