com.github.yin.cli.parsing.LongKeyValueParser Maven / Gradle / Ivy

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Easy to use command-line parser, which enables you to define cmdline flags directly the class they are used in.

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package com.github.yin.cli.parsing;

import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Iterators;

import java.util.Iterator;

/**
 * Parses program arguments and recognize long-format cli, each flag name argument must be followed by its value.
 * This these restrictions make it easy to build up the command-line from a script. Flag name must start with double
 * dash '--' and values may be any string. If any argument does not conform to requirement on its position, or flag is
 * not followed by a value, an {@link IllegalArgumentException}} is raised.
 *
 * Example: program --flag value --input models.txt --input scene.txt
 */
public class LongKeyValueParser {
    private final String[] args;

    public LongKeyValueParser(String[] args) {
        this.args = args;
    }

    public ImmutableMultimap parse() {
        ImmutableMultimap.Builder builder = ImmutableMultimap.builder();
        ArgumentReader reader = new ArgumentReader(args);
        while(reader.hasNext()) {
            String flag = reader.key();
            String value = reader.value();
            builder.put(flag, value);
        }
        return builder.build();
    }

    static class ArgumentReader {
        private final Iterator iterator;
        public ArgumentReader(String[] args) {
            this.iterator = Iterators.forArray(args);
        }
        public boolean hasNext() {
            return iterator.hasNext();
        }
        public String key() {
            String next = iterator.next();
            if (next.startsWith("--")) {
                return next.substring(2);
            } else {
                throw new IllegalArgumentException("Argument '" + next + "' is not a flag");
            }
        }
        public String value() {
            String next = iterator.next();
            return next;
        }
    }
}