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

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Here is the source code for org.apache.metron.stellar.common.shell.specials.DocCommand.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.shell.StellarShellExecutor;
import org.apache.metron.stellar.common.shell.StellarResult;
import org.apache.metron.stellar.dsl.StellarFunctionInfo;

import java.util.Optional;
import java.util.Spliterator;
import java.util.function.Function;
import java.util.stream.StreamSupport;

import static org.apache.metron.stellar.common.shell.StellarResult.error;
import static org.apache.metron.stellar.common.shell.StellarResult.success;

/**
 * A special command that allows a user to request doc string
 * about a Stellar function.
 *
 * For example `?TO_STRING` will output the docs for the function `TO_STRING`
 */
public class DocCommand implements SpecialCommand {

    public static final String DOC_PREFIX = "?";

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

    @Override
    public Function<String, Boolean> getMatcher() {
        return (input) -> StringUtils.startsWith(input, DOC_PREFIX);
    }

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

        // expect ?functionName
        String functionName = StringUtils.substring(command, 1);

        // grab any docs for the given function
        Spliterator<StellarFunctionInfo> fnIterator = executor.getFunctionResolver().getFunctionInfo()
                .spliterator();
        Optional<StellarFunctionInfo> functionInfo = StreamSupport.stream(fnIterator, false)
                .filter(info -> StringUtils.equals(functionName, info.getName())).findFirst();

        if (functionInfo.isPresent()) {
            result = success(docFormat(functionInfo.get()));
        } else {
            result = error(String.format("No docs available for function '%s'", functionName));
        }

        return result;
    }

    /**
     * Formats the Stellar function info object into a readable string.
     * @param info The stellar function info object.
     * @return A readable string.
     */
    private String docFormat(StellarFunctionInfo info) {
        StringBuffer docString = new StringBuffer();

        // name
        docString.append(info.getName() + "\n");

        // description
        docString.append(String.format("Description: %-60s\n\n", info.getDescription()));

        // params
        if (info.getParams().length > 0) {
            docString.append("Arguments:\n");
            for (String param : info.getParams()) {
                docString.append(String.format("\t%-60s\n", param));
            }
            docString.append("\n");
        }

        // returns
        docString.append(String.format("Returns: %-60s\n", info.getReturns()));

        return docString.toString();
    }
}