/**
* Logback: the reliable, generic, fast and flexible logging framework.
* Copyright (C) 1999-2009, QOS.ch. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation.
*/
package ch.qos.logback.core.pattern.parser;
import java.util.List;
import java.util.ArrayList;
import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.pattern.util.IEscapeUtil;
import ch.qos.logback.core.pattern.util.RegularEscapeUtil;
/**
* <p>Return a steady stream of tokens. <p/>
*
* <p>The returned tokens are one of:
* LITERAL, '%', FORMAT_MODIFIER, KEYWWORD, OPTION, LEFT_PARENTHESIS, and
* RIGHT_PARENTHESIS.</p>
*
* <p>The '\' character is used as escape. It can be used to escape '_', '%', '(' and
* '('.<p>
*
* <p>Note that there is no EOS token returned.</p>
*/
class TokenStream {
private static final char ESCAPE_CHAR = '\\';
private static final char PERCENT_CHAR = CoreConstants.PERCENT_CHAR;
private static final char LEFT_PARENTHESIS = '(';
private static final char RIGHT_PARENTHESIS = ')';
private static final char CURLY_LEFT = '{';
private static final char CURLY_RIGHT = '}';
private static final int LITERAL_STATE = 0;
private static final int FORMAT_MODIFIER_STATE = 1;
private static final int KEYWORD_STATE = 2;
private static final int OPTION_STATE = 3;
final String pattern;
final int patternLength;
final IEscapeUtil escapeUtil;
int state = LITERAL_STATE;
int pointer = 0;
// this variant should be used for testing purposes only
TokenStream(String pattern) {
this(pattern, new RegularEscapeUtil());
}
TokenStream(String pattern, IEscapeUtil escapeUtil) {
if(pattern == null) {
throw new NullPointerException("null pattern string not allowed");
}
this.pattern = pattern;
patternLength = pattern.length();
this.escapeUtil = escapeUtil;
}
List tokenize() throws ScanException {
List<Token> tokenList = new ArrayList<Token>();
StringBuffer buf = new StringBuffer();
while (pointer < patternLength) {
char c = pattern.charAt(pointer);
pointer++;
switch (state) {
case LITERAL_STATE:
switch (c) {
case ESCAPE_CHAR:
escape("%()", buf);
break;
case PERCENT_CHAR:
addValuedToken(Token.LITERAL, buf, tokenList);
tokenList.add(Token.PERCENT_TOKEN);
state = FORMAT_MODIFIER_STATE;
break;
case RIGHT_PARENTHESIS:
if (buf.length() >= 1 && buf.charAt(buf.length() - 1) == '\\') {
buf.deleteCharAt(buf.length() - 1);
buf.append(RIGHT_PARENTHESIS);
} else {
addValuedToken(Token.LITERAL, buf, tokenList);
tokenList.add(Token.RIGHT_PARENTHESIS_TOKEN);
}
break;
default:
buf.append(c);
}
break;
//
case FORMAT_MODIFIER_STATE:
if (c == LEFT_PARENTHESIS) {
addValuedToken(Token.FORMAT_MODIFIER, buf, tokenList);
tokenList.add(Token.LEFT_PARENTHESIS_TOKEN);
state = LITERAL_STATE;
} else if (Character.isJavaIdentifierStart(c)) {
addValuedToken(Token.FORMAT_MODIFIER, buf, tokenList);
state = KEYWORD_STATE;
buf.append(c);
} else {
buf.append(c);
}
break;
case OPTION_STATE:
switch (c) {
case CURLY_RIGHT:
addValuedToken(Token.OPTION, buf, tokenList);
state = LITERAL_STATE;
break;
case ESCAPE_CHAR:
escape("%{}", buf);
break;
default:
buf.append(c);
}
break;
case KEYWORD_STATE:
if (c == CURLY_LEFT) {
addValuedToken(Token.KEYWORD, buf, tokenList);
state = OPTION_STATE;
} else if (Character.isJavaIdentifierPart(c)) {
buf.append(c);
} else if (c == PERCENT_CHAR) {
addValuedToken(Token.KEYWORD, buf, tokenList);
tokenList.add(Token.PERCENT_TOKEN);
state = FORMAT_MODIFIER_STATE;
} else {
addValuedToken(Token.KEYWORD, buf, tokenList);
if (c == RIGHT_PARENTHESIS) {
// if c is a right parenthesis, then add it as such
tokenList.add(Token.RIGHT_PARENTHESIS_TOKEN);
} else if (c == ESCAPE_CHAR) {
if ((pointer < patternLength)) {
char next = pattern.charAt(pointer++);
escapeUtil.escape("%()", buf, next, pointer);
}
} else {
buf.append(c);
}
state = LITERAL_STATE;
}
break;
default:
}
}
// EOS
switch (state) {
case LITERAL_STATE:
addValuedToken(Token.LITERAL, buf, tokenList);
break;
case KEYWORD_STATE:
tokenList.add(new Token(Token.KEYWORD, buf.toString()));
buf.setLength(0);
break;
case FORMAT_MODIFIER_STATE:
case OPTION_STATE:
throw new ScanException("Unexpected end of pattern string");
}
return tokenList;
}
void escape(String escapeChars, StringBuffer buf) {
if ((pointer < patternLength)) {
char next = pattern.charAt(pointer++);
escapeUtil.escape(escapeChars, buf, next, pointer);
}
}
private void addValuedToken(int type, StringBuffer buf, List<Token> tokenList) {
if (buf.length() > 0) {
tokenList.add(new Token(type, buf.toString()));
buf.setLength(0);
}
}
}