org.apache.metron.stellar.common.shell.specials.MagicDefineGlobal.java Source code

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Here is the source code for org.apache.metron.stellar.common.shell.specials.MagicDefineGlobal.java

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/*
 *  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.
 *
 */
package org.apache.metron.stellar.common.shell.specials;

import org.apache.commons.lang3.StringUtils;
import org.apache.metron.stellar.common.StellarAssignment;
import org.apache.metron.stellar.common.shell.StellarShellExecutor;
import org.apache.metron.stellar.common.shell.StellarResult;

import java.util.function.Function;

import static org.apache.commons.lang3.StringUtils.startsWith;
import static org.apache.commons.lang3.StringUtils.trimToEmpty;
import static org.apache.metron.stellar.common.shell.StellarResult.error;
import static org.apache.metron.stellar.common.shell.StellarResult.success;

/**
 * Allows a variable to be defined (or redefined) a within the global configuration.
 *
 *   %define newVar := newValue
 */
public class MagicDefineGlobal implements SpecialCommand {

    public static final String MAGIC_DEFINE = "%define";

    @Override
    public String getCommand() {
        return MAGIC_DEFINE;
    }

    @Override
    public Function<String, Boolean> getMatcher() {
        return (input) -> startsWith(trimToEmpty(input), MAGIC_DEFINE);
    }

    @Override
    public StellarResult execute(String command, StellarShellExecutor executor) {

        // grab the expression in '%define <assign-expression>'
        String assignExpr = StringUtils.trimToEmpty(command.substring(MAGIC_DEFINE.length()));
        if (StringUtils.length(assignExpr) < 1) {
            return error(MAGIC_DEFINE + " missing assignment expression");
        }

        // the expression must be an assignment
        if (!StellarAssignment.isAssignment(assignExpr)) {
            return error(MAGIC_DEFINE + " expected assignment expression");
        }

        // execute the expression
        StellarAssignment expr = StellarAssignment.from(assignExpr);
        StellarResult result = executor.execute(expr.getStatement());

        // execution must be successful
        if (!result.isSuccess()) {
            return error(MAGIC_DEFINE + " expression execution failed");
        }

        // expression should have a result
        if (!result.getValue().isPresent()) {
            return error(MAGIC_DEFINE + " expression produced no result");
        }

        // alter the global configuration
        Object value = result.getValue().get();
        executor.getGlobalConfig().put(expr.getVariable(), value);

        return success(value);
    }
}