/*
* Copyright (C) 2011 eXo Platform SAS.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.exoplatform.web.controller.regexp;
import java.util.NoSuchElementException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
*/
class Lexer {
/** /. */
private static final Pattern QUANTIFIER_PATTERN = Pattern.compile("^\\{([0-9]+)" + "(?:" + "(,)([0-9]+)?" + ")?\\}$");
/** /. */
private static final Pattern OCTAL_PATTERN = Pattern.compile("^[0-7]|[0-7][0-7]|[0-3][0-7][0-7]$");
/** /. */
private final Stream stream;
/** /. */
private int ccDepth;
/** /. */
private Kind next;
/** /. */
private String token;
/** /. */
private Kind previous;
Lexer(Stream stream) {
this.stream = stream;
this.ccDepth = 0;
this.next = null;
this.previous = null;
this.token = null;
}
Lexer(CharSequence seq) {
this(new Stream(seq));
}
int getIndex() {
return stream.getIndex();
}
void reset() {
this.stream.reset();
this.ccDepth = 0;
this.next = null;
this.previous = null;
this.token = null;
}
String getToken() {
return token;
}
boolean isDone() {
return !stream.hasNext();
}
boolean hasNext() throws SyntaxException {
if (next == null) {
if (stream.hasNext()) {
Kind kind;
char c = stream.next();
switch (c) {
case '^':
kind = Kind.BEGIN;
token = "^";
break;
case '$':
kind = Kind.END;
token = "$";
break;
case '.':
kind = Kind.ANY;
token = ".";
break;
case '-':
if (ccDepth > 0) {
if (stream.hasNext(']')) {
kind = Kind.LITERAL;
token = "-";
} else if (previous == Kind.CC_OPEN) {
kind = Kind.LITERAL;
token = "-";
} else if (previous == Kind.HYPHEN) {
kind = Kind.LITERAL;
token = "-";
} else {
kind = Kind.HYPHEN;
token = "-";
}
} else {
kind = Kind.LITERAL;
token = "-";
}
break;
case '|':
kind = Kind.OR;
token = "|";
break;
case '[': {
kind = Kind.CC_OPEN;
if (stream.next('^')) {
token = "[^";
} else {
token = "[";
}
ccDepth++;
break;
}
case ']':
if (ccDepth > 0) {
if (previous == Kind.CC_OPEN) {
kind = Kind.LITERAL;
token = "]";
} else {
kind = Kind.CC_CLOSE;
token = "]";
ccDepth--;
}
} else {
kind = Kind.LITERAL;
token = "]";
}
break;
case '&':
if (stream.next('&')) {
kind = Kind.CC_AND;
token = "&&";
} else {
kind = Kind.LITERAL;
token = "&";
}
break;
case '\\': {
if (stream.hasNext()) {
c = stream.peek();
if (c == '0') {
StringBuilder sb = new StringBuilder().append(stream.next());
Character matched = null;
while (true) {
if (stream.hasNext()) {
sb.append(stream.peek());
Matcher matcher = OCTAL_PATTERN.matcher(sb);
if (matcher.matches()) {
matched = (char) Integer.parseInt(sb.toString(), 8);
stream.next();
} else {
break;
}
} else {
break;
}
}
if (matched != null) {
kind = Kind.LITERAL;
token = Character.toString(matched);
} else {
throw new SyntaxException();
}
} else if (c == 'x') {
stream.next();
if (stream.hasNext(1)) {
String s = "" + stream.next() + stream.next();
try {
kind = Kind.LITERAL;
token = Character.toString((char) Integer.parseInt(s, 16));
} catch (NumberFormatException e) {
throw new SyntaxException();
}
} else {
throw new SyntaxException();
}
} else if (c == 'u') {
stream.next();
if (stream.hasNext(3)) {
String s = "" + stream.next() + stream.next() + stream.next() + stream.next();
try {
kind = Kind.LITERAL;
token = Character.toString((char) Integer.parseInt(s, 16));
} catch (NumberFormatException e) {
throw new SyntaxException();
}
} else {
throw new SyntaxException();
}
} else if (Character.isLetterOrDigit(c)) {
throw new SyntaxException();
} else {
stream.next();
kind = Kind.LITERAL;
token = "" + c;
}
} else {
throw new SyntaxException();
}
break;
}
case '(': {
if (ccDepth == 0) {
StringBuilder sb = new StringBuilder("(");
if (stream.hasNext('?')) {
if (stream.hasNext(1, ')')) {
// Do nothing
} else {
stream.next();
sb.append('?');
if (stream.hasNext(':') || stream.hasNext('=') || stream.hasNext('!')) {
sb.append(stream.next());
} else if (stream.next('<')) {
sb.append('<');
if (stream.hasNext('=') || stream.hasNext('!')) {
sb.append(stream.next());
} else {
throw new SyntaxException();
}
} else {
throw new SyntaxException();
}
}
}
kind = Kind.GROUP_OPEN;
token = sb.toString();
} else {
kind = Kind.LITERAL;
token = "(";
}
break;
}
case '?':
if (previous == Kind.GROUP_OPEN) {
kind = Kind.LITERAL;
token = "?";
} else if (previous == Kind.QUANTIFIER) {
kind = Kind.QUANTIFIER_MODE;
token = "?";
} else {
kind = Kind.QUANTIFIER;
token = "?";
}
break;
case '+':
if (previous == Kind.QUANTIFIER) {
kind = Kind.QUANTIFIER_MODE;
token = "+";
} else {
kind = Kind.QUANTIFIER;
token = "+";
break;
}
break;
case '*':
kind = Kind.QUANTIFIER;
token = "*";
break;
case '{': {
if (ccDepth == 0) {
StringBuilder sb = new StringBuilder("{");
while (stream.hasNext()) {
c = stream.next();
sb.append(c);
if (c == '}') {
break;
}
}
if (QUANTIFIER_PATTERN.matcher(sb).matches()) {
kind = Kind.QUANTIFIER;
token = sb.toString();
} else {
throw new SyntaxException();
}
} else {
kind = Kind.LITERAL;
token = "{";
}
break;
}
case ')':
if (ccDepth == 0) {
kind = Kind.GROUP_CLOSE;
token = ")";
} else {
kind = Kind.LITERAL;
token = ")";
}
break;
default:
kind = Kind.LITERAL;
token = "" + c;
break;
}
next = kind;
}
}
return next != null;
}
boolean next(Kind expected) throws SyntaxException {
if (hasNext() && expected == next) {
previous = next();
next = null;
return true;
}
return false;
}
Kind next() throws SyntaxException {
if (!hasNext()) {
throw new NoSuchElementException();
}
previous = next;
next = null;
return previous;
}
}