Quelle JspReader.java Sprache: JAVA

/*
* 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 org.apache.jasper.JasperException;
import org.apache.jasper.JspCompilationContext;
import org.apache.jasper.runtime.ExceptionUtils;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.Jar;

/**
* 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 final Log log = LogFactory.getLog(JspReader.class); // must not be static

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

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

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

 /**
 * Constructor.
 *
 * @param ctxt The compilation context
 * @param fname The file name
 * @param encoding The file encoding
 * @param jar ?
 * @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
 */
 JspReader(JspCompilationContext ctxt,
 String fname,
 String encoding,
 Jar jar,
 ErrorDispatcher err)
 throws JasperException, FileNotFoundException, IOException {

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

 /**
 * Constructor: same as above constructor but with initialized reader
 * to the file given.
 *
 * @param ctxt The compilation context
 * @param fname The file name
 * @param reader A reader for the JSP source file
 * @param err The error dispatcher
 *
 * @throws JasperException If an error occurs parsing the JSP file
 */
 JspReader(JspCompilationContext ctxt,
 String fname,
 InputStreamReader reader,
 ErrorDispatcher err)
 throws JasperException {

 this.context = ctxt;
 this.err = err;

 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();
 current = new Mark(this, caw.toCharArray(), fname);
 } catch (Throwable ex) {
 ExceptionUtils.handleThrowable(ex);
 log.error(Localizer.getMessage("jsp.error.file.cannot.read", fname), ex);
 err.jspError("jsp.error.file.cannot.read", fname);
 } finally {
 if (reader != null) {
 try {
 reader.close();
 } catch (Exception any) {
 if(log.isDebugEnabled()) {
 log.debug("Exception closing reader: ", any);
 }
 }
 }
 }
 }

 /**
 * @return JSP compilation context with which this JspReader is
 * associated
 */
 JspCompilationContext getJspCompilationContext() {
 return context;
 }

 /**
 * Checks if the current file has more input.
 *
 * @return True if more reading is possible
 */
 boolean hasMoreInput() {
 return current.cursor < current.stream.length;
 }

 int nextChar() {
 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;
 }

 /**
 * A faster approach than calling {@link #mark()} & {@link #nextChar()}.
 * However, this approach is only safe if the mark is only used within the
 * JspReader.
 */
 private int nextChar(Mark mark) {
 if (!hasMoreInput()) {
 return -1;
 }

 int ch = current.stream[current.cursor];

 mark.init(current, true);

 current.cursor++;

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

 /**
 * Search the given character, If it was found, then mark the current cursor
 * and the cursor point to next character.
 */
 private Boolean indexOf(char c, Mark mark) {
 if (!hasMoreInput()) {
 return null;
 }

 int end = current.stream.length;
 int ch;
 int line = current.line;
 int col = current.col;
 int i = current.cursor;
 for(; i < end; i ++) {
 ch = current.stream[i];

 if (ch == c) {
 mark.update(i, line, col);
 }
 if (ch == '\n') {
 line++;
 col = 0;
 } else {
 col++;
 }
 if (ch == c) {
 current.update(i+1, line, col);
 return Boolean.TRUE;
 }
 }
 current.update(i, line, col);
 return Boolean.FALSE;
 }

 /**
 * 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) {
 Mark oldstart = mark();
 reset(start);
 CharArrayWriter caw = new CharArrayWriter();
 while (!markEquals(stop)) {
 caw.write(nextChar());
 }
 caw.close();
 setCurrent(oldstart);
 return caw.toString();
 }

 /**
 * Read ahead one character without moving the cursor.
 *
 * @return The next character or -1 if no further input is available
 */
 int peekChar() {
 return peekChar(0);
 }

 /**
 * Read ahead the given number of characters without moving the cursor.
 *
 * @param readAhead The number of characters to read ahead. NOTE: This is
 * zero based.
 *
 * @return The requested character or -1 if the end of the input is reached
 * first
 */
 int peekChar(int readAhead) {
 int target = current.cursor + readAhead;
 if (target < current.stream.length) {
 return current.stream[target];
 }
 return -1;
 }

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

 /**
 * This method avoids a call to {@link #mark()} when doing comparison.
 */
 private boolean markEquals(Mark another) {
 return another.equals(current);
 }

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

 /**
 * Similar to {@link #reset(Mark)} but no new Mark will be created.
 * Therefore, the parameter mark must NOT be used in other places.
 */
 private void setCurrent(Mark mark) {
 current = mark;
 }

 /**
 * search the stream for a match to a string
 * @param string The string to match
 * @return true is one is found, the current position
 * in stream is positioned after the search string, 
 * false otherwise, position in stream unchanged.
 */
 boolean matches(String string) {
 int len = string.length();
 int cursor = current.cursor;
 int streamSize = current.stream.length;
 if (cursor + len < streamSize) { //Try to scan in memory
 int line = current.line;
 int col = current.col;
 int ch;
 int i = 0;
 for(; i < len; i ++) {
 ch = current.stream[i+cursor];
 if (string.charAt(i) != ch) {
 return false;
 }
 if (ch == '\n') {
 line ++;
 col = 0;
 } else {
 col++;
 }
 }
 current.update(i+cursor, line, col);
 } else {
 Mark mark = mark();
 int ch = 0;
 int i = 0;
 do {
 ch = nextChar();
 if (((char) ch) != string.charAt(i++)) {
 setCurrent(mark);
 return false;
 }
 } while (i < len);
 }
 return true;
 }

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

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

 setCurrent(mark);
 return false;
 }

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

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

 setCurrent(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) {
 Mark mark = mark();

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

 return result;
 }

 int skipSpaces() {
 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 limit The String to match.
 * @return A non-null <code>Mark</code> instance (positioned immediately
 * before the search string) if found, null
 * otherwise.
 */
 Mark skipUntil(String limit) {
 Mark ret = mark();
 int limlen = limit.length();
 char firstChar = limit.charAt(0);
 Boolean result = null;
 Mark restart = null;

 skip:
 while((result = indexOf(firstChar, ret)) != null) {
 if (result.booleanValue()) {
 if (restart != null) {
 restart.init(current, true);
 } else {
 restart = mark();
 }
 for (int i = 1 ; i < limlen ; i++) {
 if (peekChar() == limit.charAt(i)) {
 nextChar();
 } else {
 current.init(restart, true);
 continue skip;
 }
 }
 return ret;
 }
 }
 return null;
 }

 /**
 * Skip until the given string is matched in the stream, but ignoring
 * chars initially escaped by a '\' and any EL expressions.
 * When returned, the context is positioned past the end of the match.
 *
 * @param limit The String to match.
 * @param ignoreEL <code>true</code> if something that looks like EL should
 * not be treated as EL.
 * @return A non-null <code>Mark</code> instance (positioned immediately
 * before the search string) if found, null
 * otherwise.
 */
 Mark skipUntilIgnoreEsc(String limit, boolean ignoreEL) {
 Mark ret = mark();
 int limlen = limit.length();
 int ch;
 int prev = 'x'; // Doesn't matter
 char firstChar = limit.charAt(0);
 skip:
 for (ch = nextChar(ret) ; ch != -1 ; prev = ch, ch = nextChar(ret)) {
 if (ch == '\\' && prev == '\\') {
 ch = 0; // Double \ is not an escape char anymore
 } else if (prev == '\\') {
 continue;
 } else if (!ignoreEL && (ch == '$' || ch == '#') && peekChar() == '{' ) {
 // Move beyond the '{'
 nextChar();
 skipELExpression();
 } else if (ch == firstChar) {
 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</code> instance (positioned immediately
 * before the ETag) if found, null otherwise.
 */
 Mark skipUntilETag(String tag) {
 Mark ret = skipUntil(" + tag);
 if (ret != null) {
 skipSpaces();
 if (nextChar() != '>') {
 ret = null;
 }
 }
 return ret;
 }

 /**
 * Parse ELExpressionBody that is a body of ${} or #{} expression. Initial
 * reader position is expected to be just after '${' or '#{' characters.
 * 
 * In case of success, this method returns <code>Mark</code> for the last
 * character before the terminating '}' and reader is positioned just after
 * the '}' character. If no terminating '}' is encountered, this method
 * returns <code>null</code>.
 * 
 * Starting with EL 3.0, nested paired {}s are supported.
 *
 * @return Mark for the last character of EL expression or <code>null</code>
 */
 Mark skipELExpression() {
 // ELExpressionBody.
 // Starts with "#{" or "${". Ends with "}".
 // May contain quoted "{", "}", '{', or '}' and nested "{...}"
 Mark last = mark();
 boolean singleQuoted = false;
 boolean doubleQuoted = false;
 int nesting = 0;
 int currentChar;
 do {
 currentChar = nextChar(last);
 while (currentChar == '\\' && (singleQuoted || doubleQuoted)) {
 // skip character following '\' within quotes
 // No need to update 'last', as neither of these characters
 // can be the closing '}'.
 nextChar();
 currentChar = nextChar();
 }
 if (currentChar == -1) {
 return null;
 }
 if (currentChar == '"' && !singleQuoted) {
 doubleQuoted = !doubleQuoted;
 } else if (currentChar == '\'' && !doubleQuoted) {
 singleQuoted = !singleQuoted;
 } else if (currentChar == '{' && !doubleQuoted && !singleQuoted) {
 nesting++;
 } else if (currentChar =='}' && !doubleQuoted && !singleQuoted) {
 // Note: This also matches the terminating '}' at which point
 // nesting will be set to -1 - hence the test for
 // while (currentChar != '}' || nesting > -1 ||...) below
 // to continue the loop until the final '}' is detected
 nesting--;
 }
 } while (currentChar != '}' || singleQuoted || doubleQuoted || nesting > -1);

 return last;
 }

 final boolean isSpace() {
 // 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 true accept quoted strings.
 */
 String parseToken(boolean quoted) throws JasperException {
 StringBuilder StringBuilder = new StringBuilder();
 skipSpaces();
 StringBuilder.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();
 }
 StringBuilder.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();
 }
 }
 StringBuilder.append((char) ch);
 } while (!isDelimiter());
 }
 }

 return StringBuilder.toString();
 }

 /**
 * 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</code>.
 *
 * @return A boolean.
 */
 private boolean isDelimiter() {
 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() == '>'))) {
 setCurrent(mark);
 return true;
 } else {
 setCurrent(mark);
 return false;
 }
 }
 return false;
 } else {
 return true;
 }
 }
}

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