JavaScriptUtils.java

/*
 Copyright (c) 2014 Ahomé Innovation Technologies. 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 com.ait.toolkit.node.core;

import com.ait.toolkit.node.core.node.util.Util;
import com.google.gwt.core.client.JavaScriptException;
import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.core.client.JsArrayInteger;
import com.google.gwt.core.client.JsArrayMixed;
import com.google.gwt.core.client.JsArrayString;

/**
 * JavaScript utility methods
 * 
 * 
 */
public class JavaScriptUtils {

	public static native JavaScriptObject getProperty(JavaScriptObject parent,
			String propertyName) /*-{
									return parent[propertyName];
									}-*/;

	public static native JavaScriptObject undefined() /*-{
														return undefined;
														}-*/;

	public static native void throwJavaScriptObject(JavaScriptObject err) /*-{
																			throw err;
																			}-*/;

	public static JsArrayInteger toIntegerArray(byte... bytes) {
		JsArrayInteger ret = JavaScriptObject.createArray().cast();
		for (byte byt : bytes) {
			ret.push(byt);
		}
		return ret;
	}

	public static JsArrayString toStringArray(String... strings) {
		JsArrayString ret = JavaScriptObject.createArray().cast();
		for (String string : strings) {
			ret.push(string);
		}
		return ret;
	}

	public static void addToArray(JsArrayMixed array, Object value) {
		if (value == null) {
			array.push((JavaScriptObject) null);
		} else if (value instanceof Boolean) {
			array.push((Boolean) value);
		} else if (value instanceof Integer) {
			array.push((Integer) value);
		} else if (value instanceof Double) {
			array.push((Double) value);
		} else if (value instanceof Float) {
			array.push((Float) value);
		} else if (value instanceof Byte) {
			array.push((Byte) value);
		} else if (value instanceof Character) {
			array.push((Character) value);
		} else if (value instanceof Short) {
			array.push((Short) value);
		} else if (value instanceof String) {
			array.push((String) value);
		} else if (value instanceof JavaScriptObject) {
			array.push((JavaScriptObject) value);
		} else {
			array.push("" + value);
		}
	}

	public static JsArrayMixed toMixedArray(Object... values) {
		JsArrayMixed ret = JavaScriptObject.createArray().cast();
		for (Object value : values) {
			addToArray(ret, value);
		}
		return ret;
	}

	public static StringBuilder appendException(Throwable throwable,
			StringBuilder builder) {
		return appendException(throwable, true, builder);
	}

	private static StringBuilder appendException(Throwable throwable,
			boolean topLevel, StringBuilder builder) {
		if (topLevel) {
			builder.append("Exception: ").append(throwable).append('\n');
		} else {
			builder.append("Caused by: ").append(throwable).append('\n');
		}
		if (throwable instanceof JavaScriptException) {
			if (throwable.getStackTrace().length == 0) {
				throwable.fillInStackTrace();
			}
			builder.append("    JS Error: ")
					.append(Util.get().inspect(
							((JavaScriptException) throwable).getException(),
							true)).append('\n');
		}
		StackTraceElement[] stackTraceElements = throwable.getStackTrace();
		if (stackTraceElements != null && stackTraceElements.length > 0) {
			for (StackTraceElement stackTraceElement : stackTraceElements) {
				builder.append("    ").append(stackTraceElement).append('\n');
			}
		} else {
			builder.append("[no stacktrace]\n");
		}
		if (throwable.getCause() != null && throwable.getCause() != throwable) {
			return appendException(throwable.getCause(), false, builder);
		} else {
			return builder;
		}
	}

	/**
	 * Unescape JS strings and return them, surrounded by single quotes.
	 * Specifically, this unescapes \b, \f, \n, \0, \r, \t, and single quotes.
	 * 
	 * @param string
	 *            The string to unescape
	 * @return The unescaped string
	 */
	public static String unescapeJavaScriptString(String string) {
		StringBuilder ret = new StringBuilder(string.length()).append('\'');
		for (int i = 0; i < string.length(); i++) {
			char chr = string.charAt(i);
			switch (chr) {
			case '\b':
				ret.append("\\b");
				break;
			case '\f':
				ret.append("\\f");
				break;
			case '\n':
				ret.append("\\n");
				break;
			case '\0':
				// TODO: does this even work?
				ret.append("\\0");
				break;
			case '\r':
				ret.append("\\r");
				break;
			case '\t':
				ret.append("\\t");
				break;
			case '\'':
				ret.append("\\'");
				break;
			default:
				ret.append(chr);
			}
		}
		return ret.append('\'').toString();
	}

	private JavaScriptUtils() {
	}
}