lava.io
Class ConsoleCommandShell

java.lang.Object
  |
  +--lava.io.ConsoleCommandShell

public class ConsoleCommandShell

extends java.lang.Object

Console-based command interface.

Details: A ConsoleCommandShell interacts with the user by issuing prompts and parsing the user's responses. When instructed, this class writes a prompt to the console, waits for the user to type a line of text, and then begins parsing the line. Each line is divided into substrings, which are returned one at a time during subsequent method calls. By convention, the first substring is called the "command," while all additional substrings on the same line are called "parameters."

The algorithm used by this class to parse input lines is similar to the algorithms used in common command-line shells, such as in a Unix or MS-DOS shell. For example:

• Multiple words typed on a line are parsed into individual parameters.
• Multiple words are treated as a single parameter when the words are enclosed by quotes.
• Some characters in quoted strings are interpreted differently when preceded by a backslash.
• Long responses can be split into multiple lines by ending intermediate lines with a backslash.*

*This feature will be implemented in a future release.

This class depends heavily on the ConsoleDialog class, particularly on ConsoleDialog.query_words. It is worthwhile to consult the documentation for that class in order to better understand the behavior of this class.

Version:

1999.05.04

Author:

Sharky

Field Summary

java.lang.String

prompt Prompt sent to the user to indicate that a line of text (i.e., a command) is requested.

Constructor Summary

ConsoleCommandShell(ConsoleDialog console, java.lang.String prompt)
Initializes a new ConsoleCommandShell with the specified prompt.

Method Summary

java.lang.String	getCommand() Outputs the command prompt to the console, waits for a response, parses it, and then returns the command (i.e., the first word of the response).
java.lang.String	getParam() Returns the next parameter from the most recently parsed command line.
int	paramsRemaining() Returns the number of parameters that remain to be read.
void	writeln(java.lang.String s)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

prompt

public java.lang.String prompt

Prompt sent to the user to indicate that a line of text (i.e., a command) is requested.

Constructor Detail

ConsoleCommandShell

public ConsoleCommandShell(ConsoleDialog console,
                           java.lang.String prompt)

Initializes a new ConsoleCommandShell with the specified prompt.

Parameters:

the - prompt

Method Detail

getCommand

public java.lang.String getCommand()
                            throws java.io.IOException

Outputs the command prompt to the console, waits for a response, parses it, and then returns the command (i.e., the first word of the response).

Returns:

the command, or null if a blank line was entered

Throws:

java.io.IOException - if an I/O error occurs

getParam

public java.lang.String getParam()
                          throws java.io.IOException

Returns the next parameter from the most recently parsed command line. This method should not be called before get_command.

Returns:

the next parameter, or null if there are no more words on the current line

Throws:

java.io.IOException - if an I/O error occurs

paramsRemaining

public int paramsRemaining()

Returns the number of parameters that remain to be read.

Returns:

number of parameters remaining to be read

writeln

public void writeln(java.lang.String s)
             throws java.io.IOException