roast
Class CommandLine

java.lang.Object
  |
  +--roast.CommandLine

public class CommandLine

extends java.lang.Object

A CommandLine object parses an array of Unix-style command-line arguments according to a user-supplied specification.

define terms: flag, flag argument, suffix argument

State variables
errorMessage: String
flagArgs: set of (flag: String, arg: String)
suffixArgs: array of String

Field Summary

static java.lang.String	DUPLICATEFLAG
static java.lang.String	INVALIDFLAG
static java.lang.String	INVALIDFLAGARG
static java.lang.String	MISSINGFLAGARG
static java.lang.String	REQUIREDFLAGMISSING

Constructor Summary

CommandLine(FlagSpec[] flagSpec, java.lang.String[] args)
Parses an array of command line flags and arguments.

Method Summary

java.lang.String	getErrorMessage() Gets the error message if the command line was not successfully parsed.
java.lang.String	getFlagArg(java.lang.String flagName) Gets value of named flag.
java.lang.String[]	getSuffixArgs() Gets suffix arguments arguments present in args.
boolean	isArgPresent(java.lang.String flagName) Determines whether the named flag is present in args.

Methods inherited from class java.lang.Object

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

Field Detail

DUPLICATEFLAG

public static final java.lang.String DUPLICATEFLAG

MISSINGFLAGARG

public static final java.lang.String MISSINGFLAGARG

INVALIDFLAGARG

public static final java.lang.String INVALIDFLAGARG

INVALIDFLAG

public static final java.lang.String INVALIDFLAG

REQUIREDFLAGMISSING

public static final java.lang.String REQUIREDFLAGMISSING

Constructor Detail

CommandLine

public CommandLine(FlagSpec[] flagSpec,
                   java.lang.String[] args)
            throws ParameterException

Parses an array of command line flags and arguments.

Precondition

ArgType does not throw an exception

Exceptions

if flagSpec or args contains a null entry
or args has an entry that is ""
or flagSpec has two entries with the same flag name then
throw ParameterException

Transitions

 i = 0
 errorMessage = ""
 while i < 0..args.length && errorMessage == ""
 	if args[i] has a leading "-" // flags
 		if flagSpec has an entry F such that F.name == args[i] 
 			if flagArgs has an entry with name args[i]
 				errorMessage = DUPLICATEFLAG+args[i]
 			else if F.argRequired
 				if i == args.length-1
 					errorMessage = MISSINGFLAGARG+args[i]
 				else if !F.argType.isValid(args[i+1])
 					errorMessage = INVALIDFLAGARG+args[i+1]
 				else
 					add (args[i],args[i+1]) to flagArgs
 					i = i+2
 			else
 				add (args[i],null) to flagArgs
 				i = i+1
 		else
 			errorMessage = INVALIDFLAG+args[i]
 	else // begin suffix arguments
 		if there is a required flag F in flagSpec not in flagArgs
 			errorMessage = REQUIREDFLAGMISSING+F.name
 		else
 			copy args[i..args.length-1] to suffixArgs
 

Method Detail

getErrorMessage

public java.lang.String getErrorMessage()

Gets the error message if the command line was not successfully parsed.

Output

errorMessage or null if no error occurred

isArgPresent

public boolean isArgPresent(java.lang.String flagName)

Determines whether the named flag is present in args.

Output

exists (flagName,x) in flagArgs, where x is any value (may be null)

getFlagArg

public java.lang.String getFlagArg(java.lang.String flagName)

Gets value of named flag.

Output

arg such that (flagName, arg) is in flagArgs
null if an error occurred during parsing

getSuffixArgs

public java.lang.String[] getSuffixArgs()

Gets suffix arguments arguments present in args.

Output

suffixArgs, may contain zero elements
null if an error occurred during parsing