jspreader.java

业界著名的tomcat服务器的最新6.0的源代码。

/*
 * 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.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.jasper.JasperException;
import org.apache.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</strong> 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</code> instance (positioned immediately