package org.apache.lucene.queryParser.standard.parser;
/**
* 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.
*/
import java.util.Locale;
import org.apache.lucene.messages.MessageImpl;
import org.apache.lucene.queryParser.core.messages.QueryParserMessages;
import org.apache.lucene.queryParser.core.parser.EscapeQuerySyntax;
import org.apache.lucene.queryParser.core.util.UnescapedCharSequence;
/**
*/
public class EscapeQuerySyntaxImpl implements EscapeQuerySyntax {
private static final char[] wildcardChars = { '*', '?' };
private static final String[] escapableTermExtraFirstChars = { "+", "-", "@" };
private static final String[] escapableTermChars = { "\"", "<", ">", "=",
"!", "(", ")", "^", "[", "{", ":", "]", "}", "~" };
// TODO: check what to do with these "*", "?", "\\"
private static final String[] escapableQuotedChars = { "\"" };
private static final String[] escapableWhiteChars = { " ", "\t", "\n", "\r",
"\f", "\b", "\u3000" };
private static final String[] escapableWordTokens = { "AND", "OR", "NOT",
"TO", "WITHIN", "SENTENCE", "PARAGRAPH", "INORDER" };
private static final CharSequence escapeChar(CharSequence str, Locale locale) {
if (str == null || str.length() == 0)
return str;
CharSequence buffer = str;
// regular escapable Char for terms
for (int i = 0; i < escapableTermChars.length; i++) {
buffer = replaceIgnoreCase(buffer, escapableTermChars[i].toLowerCase(),
"\\", locale);
}
// First Character of a term as more escaping chars
for (int i = 0; i < escapableTermExtraFirstChars.length; i++) {
if (buffer.charAt(0) == escapableTermExtraFirstChars[i].charAt(0)) {
buffer = "\\" + buffer.charAt(0)
+ buffer.subSequence(1, buffer.length());
break;
}
}
return buffer;
}
private final CharSequence escapeQuoted(CharSequence str, Locale locale) {
if (str == null || str.length() == 0)
return str;
CharSequence buffer = str;
for (int i = 0; i < escapableQuotedChars.length; i++) {
buffer = replaceIgnoreCase(buffer, escapableTermChars[i].toLowerCase(),
"\\", locale);
}
return buffer;
}
private static final CharSequence escapeTerm(CharSequence term, Locale locale) {
if (term == null)
return term;
// Escape single Chars
term = escapeChar(term, locale);
term = escapeWhiteChar(term, locale);
// Escape Parser Words
for (int i = 0; i < escapableWordTokens.length; i++) {
if (escapableWordTokens[i].equalsIgnoreCase(term.toString()))
return "\\" + term;
}
return term;
}
/**
* replace with ignore case
*
* @param string
* string to get replaced
* @param sequence1
* the old character sequence in lowercase
* @param escapeChar
* the new character to prefix sequence1 in return string.
* @return the new String
*/
private static CharSequence replaceIgnoreCase(CharSequence string,
CharSequence sequence1, CharSequence escapeChar, Locale locale) {
if (escapeChar == null || sequence1 == null || string == null)
throw new NullPointerException();
// empty string case
int count = string.length();
int sequence1Length = sequence1.length();
if (sequence1Length == 0) {
StringBuilder result = new StringBuilder((count + 1)
* escapeChar.length());
result.append(escapeChar);
for (int i = 0; i < count; i++) {
result.append(string.charAt(i));
result.append(escapeChar);
}
return result.toString();
}
// normal case
StringBuilder result = new StringBuilder();
char first = sequence1.charAt(0);
int start = 0, copyStart = 0, firstIndex;
while (start < count) {
if ((firstIndex = string.toString().toLowerCase(locale).indexOf(first,
start)) == -1)
break;
boolean found = true;
if (sequence1.length() > 1) {
if (firstIndex + sequence1Length > count)
break;
for (int i = 1; i < sequence1Length; i++) {
if (string.toString().toLowerCase(locale).charAt(firstIndex + i) != sequence1
.charAt(i)) {
found = false;
break;
}
}
}
if (found) {
result.append(string.toString().substring(copyStart, firstIndex));
result.append(escapeChar);
result.append(string.toString().substring(firstIndex,
firstIndex + sequence1Length));
copyStart = start = firstIndex + sequence1Length;
} else {
start = firstIndex + 1;
}
}
if (result.length() == 0 && copyStart == 0)
return string;
result.append(string.toString().substring(copyStart));
return result.toString();
}
/**
* escape all tokens that are part of the parser syntax on a given string
*
* @param str
* string to get replaced
* @param locale
* locale to be used when performing string compares
* @return the new String
*/
private static final CharSequence escapeWhiteChar(CharSequence str,
Locale locale) {
if (str == null || str.length() == 0)
return str;
CharSequence buffer = str;
for (int i = 0; i < escapableWhiteChars.length; i++) {
buffer = replaceIgnoreCase(buffer, escapableWhiteChars[i].toLowerCase(),
"\\", locale);
}
return buffer;
}
public CharSequence escape(CharSequence text, Locale locale, Type type) {
if (text == null || text.length() == 0)
return text;
// escape wildcards and the escape char (this has to be perform before
// anything else)
// since we need to preserve the UnescapedCharSequence and escape the
// original escape chars
if (text instanceof UnescapedCharSequence) {
text = ((UnescapedCharSequence) text).toStringEscaped(wildcardChars);
} else {
text = new UnescapedCharSequence(text).toStringEscaped(wildcardChars);
}
if (type == Type.STRING) {
return escapeQuoted(text, locale);
} else {
return escapeTerm(text, locale);
}
}
/**
* Returns a String where the escape char has been removed, or kept only once
* if there was a double escape.
*
* Supports escaped unicode characters, e. g. translates <code>A</code> to
* <code>A</code>.
*
*/
public static UnescapedCharSequence discardEscapeChar(CharSequence input)
throws ParseException {
// Create char array to hold unescaped char sequence
char[] output = new char[input.length()];
boolean[] wasEscaped = new boolean[input.length()];
// The length of the output can be less than the input
// due to discarded escape chars. This variable holds
// the actual length of the output
int length = 0;
// We remember whether the last processed character was
// an escape character
boolean lastCharWasEscapeChar = false;
// The multiplier the current unicode digit must be multiplied with.
// E. g. the first digit must be multiplied with 16^3, the second with
// 16^2...
int codePointMultiplier = 0;
// Used to calculate the codepoint of the escaped unicode character
int codePoint = 0;
for (int i = 0; i < input.length(); i++) {
char curChar = input.charAt(i);
if (codePointMultiplier > 0) {
codePoint += hexToInt(curChar) * codePointMultiplier;
codePointMultiplier >>>= 4;
if (codePointMultiplier == 0) {
output[length++] = (char) codePoint;
codePoint = 0;
}
} else if (lastCharWasEscapeChar) {
if (curChar == 'u') {
// found an escaped unicode character
codePointMultiplier = 16 * 16 * 16;
} else {
// this character was escaped
output[length] = curChar;
wasEscaped[length] = true;
length++;
}
lastCharWasEscapeChar = false;
} else {
if (curChar == '\\') {
lastCharWasEscapeChar = true;
} else {
output[length] = curChar;
length++;
}
}
}
if (codePointMultiplier > 0) {
throw new ParseException(new MessageImpl(
QueryParserMessages.INVALID_SYNTAX_ESCAPE_UNICODE_TRUNCATION));
}
if (lastCharWasEscapeChar) {
throw new ParseException(new MessageImpl(
QueryParserMessages.INVALID_SYNTAX_ESCAPE_CHARACTER));
}
return new UnescapedCharSequence(output, wasEscaped, 0, length);
}
/** Returns the numeric value of the hexadecimal character */
private static final int hexToInt(char c) throws ParseException {
if ('0' <= c && c <= '9') {
return c - '0';
} else if ('a' <= c && c <= 'f') {
return c - 'a' + 10;
} else if ('A' <= c && c <= 'F') {
return c - 'A' + 10;
} else {
throw new ParseException(new MessageImpl(
QueryParserMessages.INVALID_SYNTAX_ESCAPE_NONE_HEX_UNICODE, c));
}
}
}