io.undertow.attribute.PredicateContextAttribute Maven / Gradle / Ivy

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 * 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 io.undertow.attribute;

import java.util.Map;

import io.undertow.predicate.Predicate;
import io.undertow.server.HttpServerExchange;

/**
 * @author Stuart Douglas
 */
public class PredicateContextAttribute implements ExchangeAttribute {

    private final String name;

    public PredicateContextAttribute(final String name) {
        this.name = name;
    }

    @Override
    public String readAttribute(final HttpServerExchange exchange) {
        Map context = exchange.getAttachment(Predicate.PREDICATE_CONTEXT);
        if (context != null) {
            Object object = context.get(name);
            return object == null ? null : object.toString();
        }
        return null;
    }

    @Override
    public void writeAttribute(final HttpServerExchange exchange, final String newValue) throws ReadOnlyAttributeException {
        Map context = exchange.getAttachment(Predicate.PREDICATE_CONTEXT);
        if (context != null) {
            context.put(name, newValue);
        }
    }

    @Override
    public String toString() {
        return "${" + name + "}";
    }

    public static final class Builder implements ExchangeAttributeBuilder {

        @Override
        public String name() {
            return "Predicate context variable";
        }

        @Override
        public ExchangeAttribute build(final String token) {
            if (token.startsWith("${") && token.endsWith("}") && token.length() > 3) {
                return new PredicateContextAttribute(token.substring(2, token.length() - 1));
            } else if (token.startsWith("$")) {
                return new PredicateContextAttribute(token.substring(1, token.length()));
            }
            return null;
        }

        @Override
        public int priority() {
            return 0;
        }
    }
}