org.argeo.cms/src/org/argeo/cms/cli/DescribedCommand.java

   1 package org.argeo.cms.cli;
   2
   3 import java.io.StringWriter;
   4 import java.util.Arrays;
   5 import java.util.List;
   6 import java.util.function.Function;
   7
   8 import org.apache.commons.cli.CommandLine;
   9 import org.apache.commons.cli.DefaultParser;
  10 import org.apache.commons.cli.Options;
  11 import org.apache.commons.cli.ParseException;
  12
  13 /** A command that can be described. */
  14 public interface DescribedCommand<T> extends Function<List<String>, T> {
  15         default Options getOptions() {
  16                 return new Options();
  17         }
  18
  19         String getDescription();
  20
  21         default String getUsage() {
  22                 return null;
  23         }
  24
  25         default String getExamples() {
  26                 return null;
  27         }
  28
  29         default CommandLine toCommandLine(List<String> args) {
  30                 try {
  31                         DefaultParser parser = new DefaultParser();
  32                         return parser.parse(getOptions(), args.toArray(new String[args.size()]));
  33                 } catch (ParseException e) {
  34                         throw new CommandArgsException(e);
  35                 }
  36         }
  37
  38         /** In order to implement quickly a main method. */
  39         public static void mainImpl(DescribedCommand<?> command, String[] args) {
  40                 try {
  41                         Object output = command.apply(Arrays.asList(args));
  42                         System.out.println(output);
  43                         System.exit(0);
  44                 } catch (IllegalArgumentException e) {
  45                         StringWriter out = new StringWriter();
  46                         HelpCommand.printHelp(command, out);
  47                         System.err.println(out.toString());
  48                         System.exit(1);
  49                 } catch (Exception e) {
  50                         e.printStackTrace();
  51                         System.exit(1);
  52                 }
  53         }
  54
  55 }