Struts example source code file (JspReader.java)

This example Struts source code file (JspReader.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

chararraywriter, errordispatcher, exception, exception, filenotfoundexception, io, jar, jasperexception, jasperexception, jspcompilationcontext, jspreader, mark, mark, net, network, string, string, stringbuffer, util

The Struts JspReader.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.struts2.jasper.compiler;

import java.io.CharArrayWriter;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import java.util.Vector;
import java.util.jar.JarFile;
import java.net.URL;
import java.net.MalformedURLException;

import org.apache.struts2.jasper.JasperException;
import org.apache.struts2.jasper.JspCompilationContext;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

/**
 * JspReader is an input buffer for the JSP parser. It should allow
 * unlimited lookahead and pushback. It also has a bunch of parsing
 * utility methods for understanding htmlesque thingies.
 *
 * @author Anil K. Vijendran
 * @author Anselm Baird-Smith
 * @author Harish Prabandham
 * @author Rajiv Mordani
 * @author Mandar Raje
 * @author Danno Ferrin
 * @author Kin-man Chung
 * @author Shawn Bayern
 * @author Mark Roth
 */

class JspReader {

    /**
     * Logger.
     */
    private Log log = LogFactory.getLog(JspReader.class);

    /**
     * The current spot in the file.
     */
    private Mark current;

    /**
     * What is this?
     */
    private String master;

    /**
     * The list of source files.
     */
    private List sourceFiles;

    /**
     * The current file ID (-1 indicates an error or no file).
     */
    private int currFileId;

    /**
     * Seems redundant.
     */
    private int size;

    /**
     * The compilation context.
     */
    private JspCompilationContext context;

    /**
     * The Jasper error dispatcher.
     */
    private ErrorDispatcher err;

    /**
     * Set to true when using the JspReader on a single file where we read up
     * to the end and reset to the beginning many times.
     * (as in ParserController.figureOutJspDocument()).
     */
    private boolean singleFile;

    /**
     * Constructor.
     *
     * @param ctxt The compilation context
     * @param fname The file name
     * @param encoding The file encoding
     * @param jarFile ?
     * @param err The error dispatcher
     * @throws JasperException If a Jasper-internal error occurs
     * @throws FileNotFoundException If the JSP file is not found (or is unreadable)
     * @throws IOException If an IO-level error occurs, e.g. reading the file
     */
    public JspReader(JspCompilationContext ctxt,
                     String fname,
                     String encoding,
                     JarFile jarFile,
                     ErrorDispatcher err)
            throws JasperException, FileNotFoundException, IOException {

        this(ctxt, fname, encoding,
             JspUtil.getReader(fname, encoding, jarFile, ctxt, err),
             err);
    }

    /**
     * Constructor: same as above constructor but with initialized reader
     * to the file given.
     */
    public JspReader(JspCompilationContext ctxt,
                     String fname,
                     String encoding,
                     InputStreamReader reader,
                     ErrorDispatcher err)
            throws JasperException, FileNotFoundException {

        this.context = ctxt;
        this.err = err;
        sourceFiles = new Vector();
        currFileId = 0;
        size = 0;
        singleFile = false;
        pushFile(fname, encoding, reader);
    }

    /**
     * @return JSP compilation context with which this JspReader is 
     * associated
     */
    JspCompilationContext getJspCompilationContext() {
        return context;
    }
    
    /**
     * Returns the file at the given position in the list.
     *
     * @param fileid The file position in the list
     * @return The file at that position, if found, null otherwise
     */
    String getFile(final int fileid) {
        return (String) sourceFiles.get(fileid);
    }
       
    /**
     * Checks if the current file has more input.
     *
     * @return True if more reading is possible
     * @throws JasperException if an error occurs
     */ 
    boolean hasMoreInput() throws JasperException {
        if (current.cursor >= current.stream.length) {
            if (singleFile) return false; 
            while (popFile()) {
                if (current.cursor < current.stream.length) return true;
            }
            return false;
        }
        return true;
    }
    
    int nextChar() throws JasperException {
        if (!hasMoreInput())
            return -1;
        
        int ch = current.stream[current.cursor];

        current.cursor++;
        
        if (ch == '\n') {
            current.line++;
            current.col = 0;
        } else {
            current.col++;
        }
        return ch;
    }

    /**
     * Back up the current cursor by one char, assumes current.cursor > 0,
     * and that the char to be pushed back is not '\n'.
     */
    void pushChar() {
        current.cursor--;
        current.col--;
    }

    String getText(Mark start, Mark stop) throws JasperException {
        Mark oldstart = mark();
        reset(start);
        CharArrayWriter caw = new CharArrayWriter();
        while (!stop.equals(mark()))
            caw.write(nextChar());
        caw.close();
        reset(oldstart);
        return caw.toString();
    }

    int peekChar() throws JasperException {
        if (!hasMoreInput())
            return -1;
        return current.stream[current.cursor];
    }

    Mark mark() {
        return new Mark(current);
    }

    void reset(Mark mark) {
        current = new Mark(mark);
    }

    boolean matchesIgnoreCase(String string) throws JasperException {
        Mark mark = mark();
        int ch = 0;
        int i = 0;
        do {
            ch = nextChar();
            if (Character.toLowerCase((char) ch) != string.charAt(i++)) {
                reset(mark);
                return false;
            }
        } while (i < string.length());
        reset(mark);
        return true;
    }

    /**
     * search the stream for a match to a string
     * @param string The string to match
     * @return <strong>true is one is found, the current position
     *         in stream is positioned after the search string, <strong>
     *               false</strong> otherwise, position in stream unchanged.
     */
    boolean matches(String string) throws JasperException {
        Mark mark = mark();
        int ch = 0;
        int i = 0;
        do {
            ch = nextChar();
            if (((char) ch) != string.charAt(i++)) {
                reset(mark);
                return false;
            }
        } while (i < string.length());
        return true;
    }

    boolean matchesETag(String tagName) throws JasperException {
        Mark mark = mark();

        if (!matches("</" + tagName))
            return false;
        skipSpaces();
        if (nextChar() == '>')
            return true;

        reset(mark);
        return false;
    }

    boolean matchesETagWithoutLessThan(String tagName)
        throws JasperException
    {
       Mark mark = mark();

       if (!matches("/" + tagName))
           return false;
       skipSpaces();
       if (nextChar() == '>')
           return true;

       reset(mark);
       return false;
    }


    /**
     * Looks ahead to see if there are optional spaces followed by
     * the given String.  If so, true is returned and those spaces and
     * characters are skipped.  If not, false is returned and the
     * position is restored to where we were before.
     */
    boolean matchesOptionalSpacesFollowedBy( String s )
        throws JasperException
    {
        Mark mark = mark();

        skipSpaces();
        boolean result = matches( s );
        if( !result ) {
            reset( mark );
        }

        return result;
    }

    int skipSpaces() throws JasperException {
        int i = 0;
        while (hasMoreInput() && isSpace()) {
            i++;
            nextChar();
        }
        return i;
    }

    /**
     * Skip until the given string is matched in the stream.
     * When returned, the context is positioned past the end of the match.
     *
     * @param s The String to match.
     * @return A non-null <code>Mark instance (positioned immediately
     *         before the search string) if found, <strong>null
     *         otherwise.
     */
    Mark skipUntil(String limit) throws JasperException {
        Mark ret = null;
        int limlen = limit.length();
        int ch;

    skip:
        for (ret = mark(), ch = nextChar() ; ch != -1 ;
                 ret = mark(), ch = nextChar()) {
            if (ch == limit.charAt(0)) {
                Mark restart = mark();
                for (int i = 1 ; i < limlen ; i++) {
                    if (peekChar() == limit.charAt(i))
                        nextChar();
                    else {
                        reset(restart);
                        continue skip;
                    }
                }
                return ret;
            }
        }
        return null;
    }

    /**
     * Skip until the given string is matched in the stream, but ignoring
     * chars initially escaped by a '\'.
     * When returned, the context is positioned past the end of the match.
     *
     * @param s The String to match.
     * @return A non-null <code>Mark instance (positioned immediately
     *         before the search string) if found, <strong>null
     *         otherwise.
     */
    Mark skipUntilIgnoreEsc(String limit) throws JasperException {
        Mark ret = null;
        int limlen = limit.length();
        int ch;
        int prev = 'x';        // Doesn't matter
        
    skip:
        for (ret = mark(), ch = nextChar() ; ch != -1 ;
                 ret = mark(), prev = ch, ch = nextChar()) {            
            if (ch == '\\' && prev == '\\') {
                ch = 0;                // Double \ is not an escape char anymore
            }
            else if (ch == limit.charAt(0) && prev != '\\') {
                for (int i = 1 ; i < limlen ; i++) {
                    if (peekChar() == limit.charAt(i))
                        nextChar();
                    else
                        continue skip;
                }
                return ret;
            }
        }
        return null;
    }
    
    /**
     * Skip until the given end tag is matched in the stream.
     * When returned, the context is positioned past the end of the tag.
     *
     * @param tag The name of the tag whose ETag (</tag>) to match.
     * @return A non-null <code>Mark instance (positioned immediately
     *               before the ETag) if found, <strong>null otherwise.
     */
    Mark skipUntilETag(String tag) throws JasperException {
        Mark ret = skipUntil("</" + tag);
        if (ret != null) {
            skipSpaces();
            if (nextChar() != '>')
                ret = null;
        }
        return ret;
    }

    final boolean isSpace() throws JasperException {
        // Note: If this logic changes, also update Node.TemplateText.rtrim()
        return peekChar() <= ' ';
    }

    /**
     * Parse a space delimited token.
     * If quoted the token will consume all characters up to a matching quote,
     * otherwise, it consumes up to the first delimiter character.
     *
     * @param quoted If <strong>true accept quoted strings.
     */
    String parseToken(boolean quoted) throws JasperException {
        StringBuffer stringBuffer = new StringBuffer();
        skipSpaces();
        stringBuffer.setLength(0);
        
        if (!hasMoreInput()) {
            return "";
        }

        int ch = peekChar();
        
        if (quoted) {
            if (ch == '"' || ch == '\'') {

                char endQuote = ch == '"' ? '"' : '\'';
                // Consume the open quote: 
                ch = nextChar();
                for (ch = nextChar(); ch != -1 && ch != endQuote;
                         ch = nextChar()) {
                    if (ch == '\\') 
                        ch = nextChar();
                    stringBuffer.append((char) ch);
                }
                // Check end of quote, skip closing quote:
                if (ch == -1) {
                    err.jspError(mark(), "jsp.error.quotes.unterminated");
                }
            } else {
                err.jspError(mark(), "jsp.error.attr.quoted");
            }
        } else {
            if (!isDelimiter()) {
                // Read value until delimiter is found:
                do {
                    ch = nextChar();
                    // Take care of the quoting here.
                    if (ch == '\\') {
                        if (peekChar() == '"' || peekChar() == '\'' ||
                               peekChar() == '>' || peekChar() == '%')
                            ch = nextChar();
                    }
                    stringBuffer.append((char) ch);
                } while (!isDelimiter());
            }
        }

        return stringBuffer.toString();
    }

    void setSingleFile(boolean val) {
        singleFile = val;
    }


    /**
     * Gets the URL for the given path name.
     *
     * @param path Path name
     *
     * @return URL for the given path name.
     *
     * @exception MalformedURLException if the path name is not given in 
     * the correct form
     */
    URL getResource(String path) throws MalformedURLException {
        return context.getResource(path);
    }


    /**
     * Parse utils - Is current character a token delimiter ?
     * Delimiters are currently defined to be =, >, <, ", and ' or any
     * any space character as defined by <code>isSpace.
     *
     * @return A boolean.
     */
    private boolean isDelimiter() throws JasperException {
        if (! isSpace()) {
            int ch = peekChar();
            // Look for a single-char work delimiter:
            if (ch == '=' || ch == '>' || ch == '"' || ch == '\''
                    || ch == '/') {
                return true;
            }
            // Look for an end-of-comment or end-of-tag:                
            if (ch == '-') {
                Mark mark = mark();
                if (((ch = nextChar()) == '>')
                        || ((ch == '-') && (nextChar() == '>'))) {
                    reset(mark);
                    return true;
                } else {
                    reset(mark);
                    return false;
                }
            }
            return false;
        } else {
            return true;
        }
    }

    /**
     * Register a new source file.
     * This method is used to implement file inclusion. Each included file
     * gets a unique identifier (which is the index in the array of source
     * files).
     *
     * @return The index of the now registered file.
     */
    private int registerSourceFile(final String file) {
        if (sourceFiles.contains(file)) {
            return -1;
        }

        sourceFiles.add(file);
        this.size++;

        return sourceFiles.size() - 1;
    }
    

    /**
     * Unregister the source file.
     * This method is used to implement file inclusion. Each included file
     * gets a uniq identifier (which is the index in the array of source
     * files).
     *
     * @return The index of the now registered file.
     */
    private int unregisterSourceFile(final String file) {
        if (!sourceFiles.contains(file)) {
            return -1;
        }

        sourceFiles.remove(file);
        this.size--;
        return sourceFiles.size() - 1;
    }

    /**
     * Push a file (and its associated Stream) on the file stack.  THe
     * current position in the current file is remembered.
     */
    private void pushFile(String file, String encoding, 
                           InputStreamReader reader) 
                throws JasperException, FileNotFoundException {

        // Register the file
        String longName = file;

        int fileid = registerSourceFile(longName);

        if (fileid == -1) {
            // Bugzilla 37407: http://issues.apache.org/bugzilla/show_bug.cgi?id=37407
            if(reader != null) {
                try {
                    reader.close();
                } catch (Exception any) {
                    if(log.isDebugEnabled()) {
                        log.debug("Exception closing reader: ", any);
                    }
                }
            }

            err.jspError("jsp.error.file.already.registered", file);
        }

        currFileId = fileid;

        try {
            CharArrayWriter caw = new CharArrayWriter();
            char buf[] = new char[1024];
            for (int i = 0 ; (i = reader.read(buf)) != -1 ;)
                caw.write(buf, 0, i);
            caw.close();
            if (current == null) {
                current = new Mark(this, caw.toCharArray(), fileid, 
                                   getFile(fileid), master, encoding);
            } else {
                current.pushStream(caw.toCharArray(), fileid, getFile(fileid),
                                   longName, encoding);
            }
        } catch (Throwable ex) {
            log.error("Exception parsing file ", ex);
            // Pop state being constructed:
            popFile();
            err.jspError("jsp.error.file.cannot.read", file);
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (Exception any) {
                    if(log.isDebugEnabled()) {
                        log.debug("Exception closing reader: ", any);
                    }
                }
            }
        }
    }

    /**
     * Pop a file from the file stack.  The field "current" is retored
     * to the value to point to the previous files, if any, and is set
     * to null otherwise.
     * @return true is there is a previous file on the stack.
     *         false otherwise.
     */
    private boolean popFile() throws JasperException {

        // Is stack created ? (will happen if the Jsp file we're looking at is
        // missing.
        if (current == null || currFileId < 0) {
            return false;
        }

        // Restore parser state:
        String fName = getFile(currFileId);
        currFileId = unregisterSourceFile(fName);
        if (currFileId < -1) {
            err.jspError("jsp.error.file.not.registered", fName);
        }

        Mark previous = current.popStream();
        if (previous != null) {
            master = current.baseDir;
            current = previous;
            return true;
        }
        // Note that although the current file is undefined here, "current"
        // is not set to null just for convience, for it maybe used to
        // set the current (undefined) position.
        return false;
    }
}