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StringTemplate is a java template engine for generating source code, web pages, emails, or any other formatted text output. StringTemplate is particularly good at multi-targeted code generators, multiple site skins, and internationalization/localization. It evolved over years of effort developing jGuru.com. StringTemplate also powers the ANTLR 3 and 4 code generator. Its distinguishing characteristic is that unlike other engines, it strictly enforces model-view separation. Strict separation makes websites and code generators more flexible and maintainable; it also provides an excellent defense against malicious template authors.

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/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.stringtemplate.v4.misc;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
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") ) {
                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 {
            // In Spring Boot context the URL can be like this:
            // jar:file:/path/to/myapp.jar!/BOOT-INF/lib/mylib.jar!/org/foo/templates/g.stg
            // This url cannot be processed using standard URLClassLoader
            URLConnection con = url.openConnection();
            InputStream is = con.getInputStream();
            try {
                is.close();
            } catch (Throwable e) {
                // Closing the input stream may throw an exception. See bug below. Most probabaly it was
                // the true reason for this commit: 
                // https://github.com/antlr/stringtemplate4/commit/21484ed46f1b20b2cdaec49f9d5a626fb26a493c             
                // https://bugs.openjdk.java.net/browse/JDK-8080094
//              e.printStackTrace();
            }
            return true;
        }
        catch (IOException ioe) {
            return false;
        }
    }

    /**
     * Given {@code index} into string {@code s}, compute the line and char
     * position in line.
     */
    public static Coordinate getLineCharPosition(String s, int index) {
        int line = 1;
        int charPos = 0;
        int p = 0;
        while ( p < index ) { // don't care about s[index] itself; count before
            if ( s.charAt(p)=='\n' ) { line++; charPos=0; }
            else charPos++;
            p++;
        }

        return new Coordinate(line,charPos);
    }
}