juzu.impl.router.regex.Literal Maven / Gradle / Ivy
/*
* Copyright 2013 eXo Platform SAS
*
* Licensed 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 juzu.impl.router.regex;
import java.io.IOException;
/** @author Julien Viet */
public class Literal {
/**
* Return true if the char should be escaped. Note that the implementation sometime may escape the char although the
* context in which it is used would not require its escape.
*
* @param c the char to test
* @return true when the char should be escaped.
*/
public static boolean isEscaped(char c) {
return c >= '(' && c <= '+' // ()*+
|| c == '?'
|| c == '{'
|| c == '}'
|| c == '|'
|| c == '$'
|| c == '&'
|| c == '^'
|| c == '-'
|| c == '.'
|| c == '['
|| c == ']'
|| c == '\\';
}
/**
* Return the char value as a string literal in a regexp. Note that the implementation does not tries to optimize the
* value with respect to the AST context, (for instance (?) would be fine as (?) but it will rewritten as (\?).
*
* @param value the value
* @return the escaped string
*/
public String getEscape(char value) {
switch (value) {
case '|':
return "\\|";
case '&':
return "\\&";
case '$':
return "\\$";
case '^':
return "\\^";
case '-':
return "\\-";
case '.':
return "\\.";
case '?':
return "\\?";
case '+':
return "\\+";
case '*':
return "\\*";
case '[':
return "\\[";
case ']':
return "\\]";
case '(':
return "\\(";
case ')':
return "\\)";
case '{':
return "\\{";
case '}':
return "\\}";
case '\\':
return "\\\\";
default:
return Character.toString(value);
}
}
public static void escapeTo(char value, Appendable appendable) throws IOException, NullPointerException {
if (appendable == null) {
throw new NullPointerException();
}
if (isEscaped(value)) {
appendable.append('\\');
}
appendable.append(value);
}
}