uk.ac.starlink.task

Class LineEnvironment

java.lang.Object

uk.ac.starlink.task.LineEnvironment

All Implemented Interfaces:

Environment

Direct Known Subclasses:

LineTableEnvironment

public class LineEnvironment
extends Object
implements Environment

Execution environment for use from the command line. Arguments are supplied as LineWord objects.

Since:

27 Nov 2006

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static char	INDIRECTION_CHAR
static int	NUM_TRIES

Constructor Summary

Constructors

Constructor and Description
LineEnvironment() Constructs a LineEnvironment without any additional initialisation.
LineEnvironment(String[] args, Parameter<?>[] params) Constructs a new LineEnvironment, initialising it with a set of command line arguments.

Method Summary

Modifier and Type	Method and Description
void	acquireValue(Parameter<?> param) Obtains a legal value for a given parameter from the environment and sets the parameter's value accordingly.
void	checkParameters(Parameter<?>[] params) Checks that this environment's values are compatible with the given list of parameters.
void	clearValue(Parameter<?> par) Clears a value for a given parameter.
String[]	getAssignments() Returns an array of strings, one for each parameter assignment which was actually used (via acquireValue(uk.ac.starlink.task.Parameter<?>)) for this environment.
PrintStream	getErrorStream() Returns an output stream into which error or logging output from a task can be written.
boolean	getInteractive() Determines whether we are running interactively.
String[]	getNames() Returns an array of parameter names which have been specified.
PrintStream	getOutputStream() Returns an output stream into which text output from a task can be written.
String	getParamHelp(Parameter<?> param) Returns the help string for a given parameter.
boolean	getPromptAll() Determines whether all parameters which haven't received explicit values on the command line should be prompted for.
String[]	getUnused() Returns a string containing any words of the input argument list which were never queried by the application to find their value.
boolean	isHidden(Parameter<?> param) Determines whether a parameter is "hidden", that is its value should not be revealed to prying eyes.
boolean	paramNameMatches(String envName, Parameter<?> param) Indicates whether a parameter name supplied from the environment is a reference to a given parameter.
void	setErrorStream(PrintStream err) Sets the destination stream for standard error.
void	setInteractive(boolean interactive) Sets whether we are running interactively or not.
void	setOutputStream(PrintStream out) Sets the destination stream for standard out.
void	setPromptAll(boolean prompt) Sets whether all parameters which haven't received explicit values on the command line should be prompted for.
void	setWords(LineWord[] words) Sets the words supplying the parameter values for this environment.

Methods inherited from class java.lang.Object

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

Field Detail

INDIRECTION_CHAR

public static final char INDIRECTION_CHAR

See Also:

Constant Field Values

NUM_TRIES

public static final int NUM_TRIES

See Also:

Constant Field Values

Constructor Detail

LineEnvironment

public LineEnvironment()

Constructs a LineEnvironment without any additional initialisation. A subsequent call of setWords(uk.ac.starlink.task.LineWord[]) must be made before it is interrogated for values.

LineEnvironment

public LineEnvironment(String[] args,
                       Parameter<?>[] params)
                throws UsageException

Constructs a new LineEnvironment, initialising it with a set of command line arguments. These are checked against a set of parameters. The arguments must be of the form name=value, or just value for positional arguments. If any of these refer to parameters not in the params list, an exception will be thrown.

Parameters:

args - command-line arguments

params - parameters that args provide values for

Throws:

UsageException

Method Detail

setWords

public void setWords(LineWord[] words)

Sets the words supplying the parameter values for this environment.

Parameters:

words - list of words

getParamHelp

public String getParamHelp(Parameter<?> param)

Returns the help string for a given parameter. This should be supplied in ready-to-use form, that is formatted for a suitable screen width etc.

Parameters:

param - parameter

Returns:

formatted documentation for param

isHidden

public boolean isHidden(Parameter<?> param)

Determines whether a parameter is "hidden", that is its value should not be revealed to prying eyes. The default implementation returns false.

Parameters:

param - param

Returns:

true if param is hidden type

checkParameters

public void checkParameters(Parameter<?>[] params)
                     throws UsageException

Checks that this environment's values are compatible with the given list of parameters. If any of the values does not appear to be a spcecification of one of the listed parameters a UsageException will be thrown.

Parameters:

params - parameter list

Throws:

UsageException

getNames

public String[] getNames()

Description copied from interface: Environment

Returns an array of parameter names which have been specified. The result is not necessarily an exhaustive list of all parameters whose values can be retrieved from this environment, since an interactive environment may be able to prompt the user for values, but it can give a list of values provided explicitly or without interactive prompts.

Specified by:

getNames in interface Environment

Returns:

array of names of known supplied parameters

setInteractive

public void setInteractive(boolean interactive)

Sets whether we are running interactively or not. Only if this attribute is true will any attempt be made to prompt the user for responses etc. Default is true.

Parameters:

interactive - whether we are running interactively

getInteractive

public boolean getInteractive()

Determines whether we are running interactively. Only if this attribute is true will any attempt be made to prompt the user for responses etc. Default is true.

Returns:

whether we are running interactively

setPromptAll

public void setPromptAll(boolean prompt)

Sets whether all parameters which haven't received explicit values on the command line should be prompted for. Default is false. Only makes sense if we're running interatively.

Parameters:

prompt - whether to prompt for everything

getPromptAll

public boolean getPromptAll()

Determines whether all parameters which haven't received explicit values on the command line should be prompted for. Default is false.

Returns:

whether to prompt for everything

clearValue

public void clearValue(Parameter<?> par)

Description copied from interface: Environment

Clears a value for a given parameter.

Specified by:

clearValue in interface Environment

Parameters:

par - the Parameter whose value is to be cleared

setOutputStream

public void setOutputStream(PrintStream out)

Sets the destination stream for standard out.

Parameters:

out - output stream

setErrorStream

public void setErrorStream(PrintStream err)

Sets the destination stream for standard error.

Parameters:

err - error stream

getOutputStream

public PrintStream getOutputStream()

Description copied from interface: Environment

Returns an output stream into which text output from a task can be written. This would correspond to standard output for a terminal-based application.

Specified by:

getOutputStream in interface Environment

Returns:

a stream for text output

getErrorStream

public PrintStream getErrorStream()

Description copied from interface: Environment

Returns an output stream into which error or logging output from a task can be written. This would correspodnd to standard error for a terminal-based application.

Specified by:

getErrorStream in interface Environment

Returns:

a stream for error output

acquireValue

public void acquireValue(Parameter<?> param)
                  throws TaskException

Description copied from interface: Environment

Obtains a legal value for a given parameter from the environment and sets the parameter's value accordingly.

This environment should obtain a value for the parameter par in whatever way it sees fit, and must then call par's Parameter.setValueFromString(uk.ac.starlink.task.Environment, java.lang.String) method so that the parameter knows what its new value is. If the setValueFromString call throws a ParameterValueException the environment may try to get another value (for instance by re-prompting the user) or may give up and re-throw the exception.

Specified by:

acquireValue in interface Environment

Parameters:

param - the Parameter whose value is to be obtained and set

Throws:

TaskException

getUnused

public String[] getUnused()

Returns a string containing any words of the input argument list which were never queried by the application to find their value. Such unused words probably merit a warning, since they may for instance be misspelled versions of real parameters.

Returns:

array of unused words

getAssignments

public String[] getAssignments()

Returns an array of strings, one for each parameter assignment which was actually used (via acquireValue(uk.ac.starlink.task.Parameter<?>)) for this environment.

Returns:

array of parameter assignment strings

paramNameMatches

public boolean paramNameMatches(String envName,
                                Parameter<?> param)

Indicates whether a parameter name supplied from the environment is a reference to a given parameter.

The implementation in the LineEnvironment class performs case-insensitive matching against the param.getName(). This behaviour may be overridden by subclasses to change the environment's behaviour.

Parameters:

envName - parameter name from environment

param - parameter

Returns:

true iff envName is considered to name param