/*
* Copyright 2014 Lynden, Inc.
*
* 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.lynden.gmapsfx.javascript;
import java.lang.reflect.Constructor;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import netscape.javascript.JSObject;
/**
* Base class for any Google JavaScript object.
*
* @author Rob Terpilowski
*/
public class JavascriptObject {
protected static Map<JSObject,JavascriptObject> peerRegistry = new WeakHashMap<>();
protected IJavascriptRuntime runtime;
protected JSObject jsObject;
protected static int objectCounter = 0;
protected String variableName;
/**
*/
protected JavascriptObject() {
runtime = JavascriptRuntime.getInstance();
variableName = getNextVariableName();
}
/**
*
* @param type The type of underlying Javascript object to create
*/
protected JavascriptObject(String type) {
this(type, (Object[]) null);
}
/**
* Builds a new JavascriptObject based on a string representation of the object.
* This is useful when constructing functions as objects
* @param type The type of object to build
* @param stringRepresentation A string representation of the object, which can be executed by
* the Javascript runtime.
*/
protected JavascriptObject( String type, String stringRepresentation ) {
runtime = JavascriptRuntime.getInstance();
variableName = getNextVariableName();
runtime.execute( "var " + variableName + " = " + stringRepresentation );
jsObject = runtime.execute(variableName);
peerRegistry.put(jsObject, this);
}
/**
* @param type The type of underlying Javascript object to create.
* @param args Any arguments required to create the object.
*/
protected JavascriptObject(String type, Object... args) {
runtime = JavascriptRuntime.getInstance();
variableName = getNextVariableName();
runtime.execute("var " + variableName + " = " + runtime.getConstructor(type, args));
jsObject = runtime.execute(variableName);
peerRegistry.put(jsObject, this);
}
/**
* @param type The type of underlying Javascript object to create.
* @param ary The array to be passed in.
* @param isArray boolean to indicate the an array is to be used as the parameter
* rather than breaking up into individual parameters.
*
*/
protected JavascriptObject(String type, Object[] ary, boolean isArray) {
runtime = JavascriptRuntime.getInstance();
variableName = getNextVariableName();
runtime.execute("var " + variableName + " = " + runtime.getArrayConstructor(type, ary));
jsObject = runtime.execute(variableName);
peerRegistry.put(jsObject, this);
}
/**
* Wraps a Javascript JSObject returned from a function.
*
* @param type Type of Javascript object to create.
* @param jsObject Object returned from Javascript.
*/
protected JavascriptObject(String type, JSObject jsObject) {
runtime = JavascriptRuntime.getInstance();
variableName = getNextVariableName();
this.jsObject = jsObject;
peerRegistry.put(jsObject, this);
}
/**
* Get the underlying object used by the Javascript runtime.
*
* @return The underlying Javascript object
*/
public JSObject getJSObject() {
return jsObject;
}
/**
* Gets the name of the next variable which will be the objectname plus a
* unique number
*
* @return The name of the next variable to create
*/
protected final String getNextVariableName() {
return getClass().getSimpleName() + (objectCounter++);
}
/**
* Gets the name of this variable within the Javascript runtime
*
* @return The name of this variable.
*/
public String getVariableName() {
return variableName;
}
/**
* Sets a property on this Javascript object.
*
* @param propertyName The property name
* @param propertyValue The property value.
*/
protected void setProperty(String propertyName, Object propertyValue) {
jsObject.setMember(propertyName, propertyValue);
}
/**
* Sets a property on this Javascript object for which the value is a
* Javascript object itself.
*
* @param propertyName The name of the property.
* @param propertyValue The value of the property.
*/
protected void setProperty(String propertyName, JavascriptObject propertyValue) {
jsObject.setMember(propertyName, propertyValue.getJSObject());
}
/**
* Sets a property on this Javascript object for which the value is a
* JavascriptEnum
*
* The value is set to what is returned by the getEnumValue() method on the JavascriptEnum
*
* @param propertyName The name of the property.
* @param propertyValue The value of the property.
*/
protected void setProperty(String propertyName, JavascriptEnum propertyValue) {
jsObject.setMember(propertyName, propertyValue.getEnumValue());
}
/**
* Get the specified property for this object.
*
* @param key The property name
* @return The value of the property
*/
protected Object getProperty(String key) {
return checkUndefined(jsObject.getMember(key));
}
/**
* Gets the property and casts to the appropriate type
*
* @param <T>
* @param key The property name
* @param type The property type
* @return The value of the property
*/
protected <T> T getProperty(String key, Class<T> type) {
Object returnValue = getProperty(key);
if (returnValue != null) {
return (T) returnValue;
} else {
return null;
}
}
/**
* Invokes a JavaScript function that takes no arguments.
*
* @param function The function to invoke
* @return The return value of the function call.
*/
protected Object invokeJavascript(String function) {
return checkUndefined(jsObject.call(function));
}
/**
* Invoke the specified JavaScript function in the JavaScript runtime.
*
* @param function The function to invoke
* @param args Any arguments to pass to the function
* @return The result of the function.
*/
protected Object invokeJavascript(String function, Object... args) {
Object[] jsArgs = new Object[args.length];
for (int i = 0; i < jsArgs.length; i++) {
if (args[i] instanceof JavascriptObject) {
jsArgs[i] = ((JavascriptObject) args[i]).getJSObject();
} else if (args[i] instanceof JavascriptEnum) {
jsArgs[i] = ((JavascriptEnum) args[i]).getEnumValue();
} else {
jsArgs[i] = args[i];
}
}
return checkUndefined(jsObject.call(function, (Object[]) jsArgs));
}
/**
* Invokes a JavaScript function that takes no arguments.
*
* @param <T>
* @param function The function to invoke
* @param returnType The type of object to return
* @return The result of the function.
*/
protected <T> T invokeJavascriptReturnValue(String function, Class<T> returnType) {
Object returnObject = invokeJavascript(function);
if (returnObject instanceof JSObject) {
try {
Constructor<T> constructor = returnType.getConstructor(JSObject.class);
return constructor.newInstance((JSObject) returnObject);
} catch (Exception ex) {
throw new IllegalStateException(ex);
}
} else {
return (T) returnObject;
}
}
/**
* Invoke the specified JavaScript function in the JavaScript runtime.
*
* @param <T>
* @param function The function to invoke
* @param returnType The type of object to return
* @param args Any arguments to pass to the function
* @return The result of the function.
*/
protected <T> T invokeJavascriptReturnValue(String function, Class<T> returnType, Object... args) {
Object returnObject = invokeJavascript(function, args);
if (returnObject != null) {
return (T) returnObject;
} else {
return null;
}
}
protected boolean isMemberDefined(String member) {
Object res = jsObject.getMember(member);
return (res instanceof String && ! ((String) res).equals("undefined"));
}
/** JSObject will return the String "undefined" at certain times, so we
* need to make sure we're not getting a value that looks valid, but isn't.
*
* @param val The value from Javascript to be checked.
* @return Either null or the value passed in.
*/
protected Object checkUndefined(Object val) {
if (val instanceof String && ((String) val).equals("undefined")) {
return null;
}
return val;
}
/** Checks a returned Javascript value where we expect a boolean but could
* get null.
*
* @param val The value from Javascript to be checked.
* @param def The default return value, which can be null.
* @return The actual value, or if null, returns false.
*/
protected Boolean checkBoolean(Object val, Boolean def) {
return (val == null) ? def : (Boolean) val;
}
protected Integer checkInteger(Object val, Integer def) {
return (val == null) ? def : (Integer) val;
}
}