org.jboss.logmanager.config.ValueExpression Maven / Gradle / Ivy
/*
* JBoss, Home of Professional Open Source.
*
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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 org.jboss.logmanager.config;
import java.io.File;
/**
* Represents a possible value expression. A value is said to be an expression if it matches a
* ${system.property:DEFAULT_VALUE} pattern.
*
* @author James R. Perkins
*/
public interface ValueExpression {
final ValueExpression NULL_STRING_EXPRESSION = new ValueExpression() {
@Override
public String getResolvedValue() {
return null;
}
@Override
public boolean isExpression() {
return false;
}
@Override
public String getValue() {
return null;
}
};
final ValueExpression NULL_BOOLEAN_EXPRESSION = new ValueExpression() {
@Override
public Boolean getResolvedValue() {
return null;
}
@Override
public boolean isExpression() {
return false;
}
@Override
public String getValue() {
return null;
}
};
/**
* The resolved value.
*
* If this is an {@link #isExpression() expression} the resolved value will be the value from a system property or
* the default value from the expression if the system property is not set.
*
* If this is not an {@link #isExpression() expression} the value returned will be the non-expression value
* or {@code null} if allowed for the property.
*
* @return the resolved value
*/
T getResolvedValue();
/**
* Checks whether this is an expression or not.
*
* @return {@code true} if this is an expression, otherwise {@code false}
*/
boolean isExpression();
/**
* Gets the value of the value which may or may not be an {@link #isExpression() expression}.
*
* @return the value
*/
String getValue();
@Override
String toString();
/**
* Resolves the value expression from an expression.
*
* @param the value type
*/
public interface Resolver {
/**
* Resolves the value of an expression.
*
* @param expression the expression to parse
*
* @return the value expression
*/
ValueExpression resolve(String expression);
}
public static Resolver STRING_RESOLVER = new Resolver() {
private static final int INITIAL = 0;
private static final int GOT_DOLLAR = 1;
private static final int GOT_OPEN_BRACE = 2;
private static final int RESOLVED = 3;
private static final int DEFAULT = 4;
@Override
public ValueExpression resolve(final String expression) {
if (expression == null) return NULL_STRING_EXPRESSION;
boolean isExpression = false;
final StringBuilder builder = new StringBuilder();
final char[] chars = expression.toCharArray();
final int len = chars.length;
int state = 0;
int start = -1;
int nameStart = -1;
for (int i = 0; i < len; i++) {
char ch = chars[i];
switch (state) {
case INITIAL: {
switch (ch) {
case '$': {
state = GOT_DOLLAR;
continue;
}
default: {
builder.append(ch);
continue;
}
}
// not reachable
}
case GOT_DOLLAR: {
switch (ch) {
case '$': {
builder.append(ch);
state = INITIAL;
continue;
}
case '{': {
start = i + 1;
nameStart = start;
state = GOT_OPEN_BRACE;
continue;
}
default: {
// invalid; emit and resume
builder.append('$').append(ch);
state = INITIAL;
continue;
}
}
// not reachable
}
case GOT_OPEN_BRACE: {
switch (ch) {
case ':':
case '}':
case ',': {
final String name = expression.substring(nameStart, i).trim();
if ("/".equals(name)) {
builder.append(File.separator);
state = ch == '}' ? INITIAL : RESOLVED;
continue;
} else if (":".equals(name)) {
builder.append(File.pathSeparator);
state = ch == '}' ? INITIAL : RESOLVED;
continue;
}
isExpression = true;
String val = System.getProperty(name);
if (val == null && name.startsWith("env.")) {
val = System.getenv(name);
}
if (val != null) {
builder.append(val);
state = ch == '}' ? INITIAL : RESOLVED;
continue;
} else if (ch == ',') {
nameStart = i + 1;
continue;
} else if (ch == ':') {
start = i + 1;
state = DEFAULT;
continue;
} else {
builder.append(expression.substring(start - 2, i + 1));
state = INITIAL;
continue;
}
}
default: {
continue;
}
}
// not reachable
}
case RESOLVED: {
if (ch == '}') {
state = INITIAL;
}
continue;
}
case DEFAULT: {
if (ch == '}') {
state = INITIAL;
builder.append(expression.substring(start, i));
}
continue;
}
default:
throw new IllegalStateException();
}
}
switch (state) {
case GOT_DOLLAR: {
builder.append('$');
break;
}
case DEFAULT:
case GOT_OPEN_BRACE: {
builder.append(expression.substring(start - 2));
break;
}
}
final String resolvedValue = builder.toString();
if (isExpression) {
return new ValueExpressionImpl(expression, resolvedValue);
}
return new ValueExpressionImpl(null, resolvedValue);
}
};
public static Resolver BOOLEAN_RESOLVER = new Resolver() {
@Override
public ValueExpression resolve(final String expression) {
if (expression == null) return NULL_BOOLEAN_EXPRESSION;
final ValueExpression stringResult = STRING_RESOLVER.resolve(expression);
final Boolean value = stringResult.getResolvedValue() == null ? null : Boolean.valueOf(stringResult.getResolvedValue());
return new ValueExpressionImpl(expression, value);
}
};
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy