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JSimpleDB classes supporting command line interfaces.
There is a newer version: 3.6.1

/*
 * Copyright (C) 2015 Archie L. Cobbs. All rights reserved.
 */

package org.jsimpledb.cli.cmd;

import java.io.PrintWriter;
import java.util.HashSet;
import java.util.Map;

import org.jsimpledb.SessionMode;
import org.jsimpledb.cli.CliSession;
import org.jsimpledb.parse.Parser;
import org.jsimpledb.parse.WordParser;
import org.jsimpledb.parse.func.AbstractFunction;
import org.jsimpledb.util.ParseContext;

@Command(modes = { SessionMode.KEY_VALUE, SessionMode.CORE_API, SessionMode.JSIMPLEDB })
public class HelpCommand extends AbstractCommand {

    private final CliSession session;

    public HelpCommand(CliSession session) {
        super("help -a:all command-or-function:cmdfunc?");
        this.session = session;
    }

    @Override
    public String getHelpSummary() {
        return "Display help information";
    }

    @Override
    public String getHelpDetail() {
        return "Displays the list of known commands and functions, or help information about a specific command or function."
          + "\nNormally only those appropriate for the current session mode are listed; use `-a' to show all.";
    }

    @Override
    protected Parser getParser(String typeName) {
        if ("cmdfunc".equals(typeName)) {
            return new WordParser("command/function") {
                @Override
                protected HashSet getWords() {
                    final HashSet names = new HashSet<>();
                    names.addAll(HelpCommand.this.session.getCommands().keySet());
                    names.addAll(HelpCommand.this.session.getFunctions().keySet());
                    return names;
                }
            };
        }
        return super.getParser(typeName);
    }

    @Override
    public CliSession.Action getAction(CliSession session, ParseContext ctx, boolean complete, Map params) {
        final boolean all = params.containsKey("all");
        final String name = (String)params.get("command-or-function");
        final SessionMode sessionMode = session.getMode();
        return new CliSession.Action() {
            @Override
            public void run(CliSession session) throws Exception {
                final PrintWriter writer = session.getWriter();
                if (name == null) {
                    writer.println((all ? "All" : "Available") + " commands:");
                    for (AbstractCommand command : session.getCommands().values()) {
                        if (all || command.getSessionModes().contains(sessionMode))
                            writer.println(String.format("%24s - %s", command.getName(), command.getHelpSummary()));
                    }
                    writer.println((all ? "All" : "Available") + " functions:");
                    for (AbstractFunction function : session.getFunctions().values()) {
                        if (all || function.getSessionModes().contains(sessionMode))
                            writer.println(String.format("%24s - %s", function.getName(), function.getHelpSummary()));
                    }
                } else {
                    final AbstractCommand command = session.getCommands().get(name);
                    if (command != null) {
                        writer.println("Usage: " + command.getUsage());
                        writer.println(command.getHelpDetail());
                        writer.println("Supported session modes: "
                          + command.getSessionModes().toString().replaceAll("\\[(.*)\\]", "$1"));
                    }
                    final AbstractFunction function = session.getFunctions().get(name);
                    if (function != null) {
                        writer.println("Usage: " + function.getUsage());
                        writer.println(function.getHelpDetail());
                        writer.println("Supported session modes: "
                          + function.getSessionModes().toString().replaceAll("\\[(.*)\\]", "$1"));
                    }
                    if (command == null && function == null)
                        writer.println("No command or function named `" + name + "' exists.");
                }
            }
        };
    }
}