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package bjc.utils.cli;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Arrays;
import java.util.Scanner;
/**
* Runs a CLI interface from the provided set of streams.
*
* @author ben
*/
public class CLICommander {
/* The streams used for input and normal/error output. */
private final InputStream input;
private final OutputStream output;
private final OutputStream error;
/* The command mode to start execution in. */
private CommandMode initialMode;
/**
* Create a new CLI interface powered by streams.
*
* @param input
* The stream to get user input from.
*
* @param output
* The stream to send normal output to.
*
* @param error
* The stream to send error output to.
*/
public CLICommander(final InputStream input, final OutputStream output, final OutputStream error) {
if (input == null) throw new NullPointerException("Input stream must not be null");
else if (output == null) throw new NullPointerException("Output stream must not be null");
else if (error == null) throw new NullPointerException("Error stream must not be null");
this.input = input;
this.output = output;
this.error = error;
}
/** Start handling commands from the given input stream. */
public void runCommands() {
/* Setup output streams. */
final PrintStream normalOutput = new PrintStream(output);
final PrintStream errorOutput = new PrintStream(error);
/*
* Set up input streams.
*
* We're suppressing the warning about a potentially leaked
* resource because we might use the input stream multiple
* times.
*/
@SuppressWarnings("resource")
final Scanner inputSource = new Scanner(input);
/*
* The mode currently being used to handle commands.
*
* Used to preserve the initial mode, so that a mode can be
* invoked more than once.
*/
CommandMode currentMode = initialMode;
/* The number of the command we are executing. */
int comno = 1;
/*
* Process commands until we're told to stop, by the mode being
* set to null.
*/
while (currentMode != null) {
/*
* Print out the command prompt.
*
* Use a custom prompt if one is specified.
*/
if (currentMode.isCustomPromptEnabled()) {
normalOutput.print(currentMode.getCustomPrompt());
} else {
normalOutput.printf("%s (%d)>> ", currentMode.getName(), comno);
comno += 1;
}
/* Read in a command. */
final String currentLine = inputSource.nextLine();
/* Handle commands we can handle in this mode. */
if (currentMode.canHandle(currentLine)) {
final String[] commandTokens = currentLine.split(" ");
String[] commandArgs = null;
final int argCount = commandTokens.length;
/* Parse args if they are present. */
if (argCount > 1) {
commandArgs = Arrays.copyOfRange(commandTokens, 1, argCount);
}
/* Process command. */
currentMode = currentMode.process(commandTokens[0], commandArgs);
} else {
errorOutput.printf("Error: Unrecognized command '%s' (no. %d)\n",
currentLine, comno);
}
}
normalOutput.printf("Exiting now (ran %d commands).\n", comno);
}
/**
* Set the initial command mode to use.
*
* @param initialMode
* The initial command mode to use.
*/
public void setInitialCommandMode(final CommandMode initialMode) {
if (initialMode == null) throw new NullPointerException("Initial mode must be non-null");
this.initialMode = initialMode;
}
}
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