Misc.java

package nebula.simpletemplate;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLConnection;
import java.util.Iterator;

public class Misc {
	public static final String newline = System.getProperty("line.separator");

	/**
	 * Makes it clear when a comparison is intended as reference equality.
	 */
	public static boolean referenceEquals(Object x, Object y) {
		return x == y;
	}

	// Seriously: why isn't this built in to java?
	public static String join(Iterator<?> iter, String separator) {
		StringBuilder buf = new StringBuilder();
		while (iter.hasNext()) {
			buf.append(iter.next());
			if (iter.hasNext()) {
				buf.append(separator);
			}
		}
		return buf.toString();
	}

	// public static String join(Object[] a, String separator, int start, int
	// stop) {
	// StringBuilder buf = new StringBuilder();
	// for (int i = start; i < stop; i++) {
	// if ( i>start ) buf.append(separator);
	// buf.append(a[i].toString());
	// }
	// return buf.toString();
	// }

	public static String strip(String s, int n) {
		return s.substring(n, s.length() - n);
	}

	// public static String stripRight(String s, int n) {
	// return s.substring(0, s.length()-n);
	// }

	/** Strip a single newline character from the front of {@code s}. */
	public static String trimOneStartingNewline(String s) {
		if (s.startsWith("\r\n")) s = s.substring(2);
		else if (s.startsWith("\n")) s = s.substring(1);
		return s;
	}

	/** Strip a single newline character from the end of {@code s}. */
	public static String trimOneTrailingNewline(String s) {
		if (s.endsWith("\r\n")) s = s.substring(0, s.length() - 2);
		else if (s.endsWith("\n")) s = s.substring(0, s.length() - 1);
		return s;
	}

	/**
	 * Given, say, {@code file:/tmp/test.jar!/org/foo/templates/main.stg}
	 * convert to {@code file:/tmp/test.jar!/org/foo/templates}
	 */
	public static String stripLastPathElement(String f) {
		int slash = f.lastIndexOf('/');
		if (slash < 0) return f;
		return f.substring(0, slash);
	}

	public static String getFileNameNoSuffix(String f) {
		if (f == null) return null;
		f = getFileName(f);
		return f.substring(0, f.lastIndexOf('.'));
	}

	public static String getFileName(String fullFileName) {
		if (fullFileName == null) return null;
		File f = new File(fullFileName); // strip to simple name
		return f.getName();
	}

	public static String getParent(String name) {
		// System.out.println("getParent("+name+")="+p);
		if (name == null) return null;
		int lastSlash = name.lastIndexOf('/');
		if (lastSlash > 0) return name.substring(0, lastSlash);
		if (lastSlash == 0) return "/";
		// System.out.println("getParent("+name+")="+p);
		return "";
	}

	public static String getPrefix(String name) {
		if (name == null) return "/";
		String parent = getParent(name);
		String prefix = parent;
		if (!parent.endsWith("/")) prefix += '/';
		return prefix;
	}

	public static String replaceEscapes(String s) {
		s = s.replaceAll("\n", "\\\\n");
		s = s.replaceAll("\r", "\\\\r");
		s = s.replaceAll("\t", "\\\\t");
		return s;
	}

	/**
	 * Replace >\> with >> in s. Replace \>> unless prefix of \>>> with >>. Do
	 * NOT replace if it's <\\>
	 */
	public static String replaceEscapedRightAngle(String s) {
		StringBuilder buf = new StringBuilder();
		int i = 0;
		while (i < s.length()) {
			char c = s.charAt(i);
			if (c == '<' && s.substring(i).startsWith("<\\\\>")) {
				buf.append("<\\\\>");
				i += "<\\\\>".length();
				continue;
			}
			if (c == '>' && s.substring(i).startsWith(">\\>")) {
				buf.append(">>");
				i += ">\\>".length();
				continue;
			}
			if (c == '\\' && s.substring(i).startsWith("\\>>") && !s.substring(i).startsWith("\\>>>")) {
				buf.append(">>");
				i += "\\>>".length();
				continue;
			}
			buf.append(c);
			i++;
		}
		return buf.toString();
	}

	public static boolean urlExists(URL url) {
		try {
			URLConnection connection = url.openConnection();
			if (connection instanceof JarURLConnection) {
				JarURLConnection jarURLConnection = (JarURLConnection) connection;
				URLClassLoader urlClassLoader = new URLClassLoader(new URL[] { jarURLConnection.getJarFileURL() });
				try {
					return urlClassLoader.findResource(jarURLConnection.getEntryName()) != null;
				} finally {
					// urlClassLoader.close();
				}
			}

			InputStream is = url.openStream();
			is.close();
			return true;
		} catch (IOException ioe) {
			return false;
		}
	}

}