gnu.util.Option Maven / Gradle / Ivy
Show all versions of escher Show documentation
package gnu.util;
import java.util.Vector;
/**
* Primitive command-line option parsing.
*
* Only long option is supported, for clarity and easy parsing. GNU long
* option requires a equal sign "=" between the option name and option
* value. No equal sign is required (allowed) here, for clarity and easy
* parsing, again.
*
*
Usual approach to option parsing such as that in GNU
* getopt may not be the best in Java because Java does not
* support pointer needed for uniform argument type and pass-by-reference.
* Instead this library uses "explicit method call per option". By this
* type checking can be strictly enforced and return value can be directly
* assigned to the desired variable. No boxing of primitive types or
* un-boxing of wrapper classes will take place. Moreover, instead of
* combining arrays of option table, option can be specified in super
* classes and subclasses easily. One caveat is that option values cannot
* be used in initializations of class member variables because parsing
* takes place outside constructors. For instance, {@link
* gnu.x11.Application} cannot initialize and create a window member
* variable because parsing is not done yet and Display may
* not be initialized; a window can be created only after all parsings.
*/
public class Option {
public String [] args;
public boolean noisy;
public StringBuffer spec = new StringBuffer ();
public StringBuffer invalid_names = new StringBuffer ();
public Vector valid_names = new Vector ();
public Option (String [] args) {
this.args = args;
noisy = booleann ("noisy-option-parser",
"show working of option parsing", false);
}
/**
* Print "about" and list possible options. This method
* should be called only once after all options are specified.
*
*
Note that this package is under GNU Public License, and thus all
* programs using this package MUST be under GNU Public License.
*/
public void about (Object object, String version, String description,
String author, String url, String usage, String extra) {
String name = object.getClass ().getName ();
System.out.println ("\n" + name + " (" + version + ") - " + description
+ ".\nCopyright (C) " + author
+ ". Under GNU Public License.\n" + url
+ ".\n\nUsage: java " + name + " " + usage
+ "\n\nPossible options:\n"
+ spec + extra);
spec = null; // help garbage collection
}
public void add_spec (String name, String type, String description,
String default_value, String return_value) {
spec.append (" --" + name + " [" + type + "] " + description
+ " (" + default_value + ")\n");
valid_names.add ("--" + name);
if (noisy) System.out.println (name + " --> " + return_value);
}
public boolean booleann (String name, String description,
boolean default_value) {
boolean retval = default_value;
try {
String opt = option (name);
if (opt != null && opt.equals ("true")) retval = true;
if (opt != null && opt.equals ("false")) retval = false;
} catch (RuntimeException e) {
invalid_names.append (name + ", ");
// fall through
}
add_spec (name, "boolean", description,
String.valueOf (default_value), String.valueOf (retval));
return retval;
}
public double doublee (String name, String description,
double default_value) {
double retval = default_value;
try {
String opt = option (name);
if (opt != null) retval = Double.parseDouble (opt);
} catch (RuntimeException e) {
invalid_names.append (name + ", ");
// fall through
}
add_spec (name, "double", description,
String.valueOf (default_value), String.valueOf (retval));
return retval;
}
public int enumerate (String name, String description,
String [] enum_strings, int default_value) {
int retval = default_value;
try {
String opt = option (name);
boolean successful = false;
if (opt != null) {
for (int i=0; i 2;
if (any) {
invalid_names.delete (n-2, n); // delete last ", "
System.out.println ("\nInvalid options: " + invalid_names);
System.out.println ("Try --help for a list of valid options.");
}
invalid_names = null; // help garbage collection
valid_names = null; // help garbage collection
return any;
}
public int intt (String name, String description,
int default_value) {
int retval = default_value;
try {
String opt = option (name);
if (opt != null) retval = Integer.parseInt (opt);
} catch (RuntimeException e) {
invalid_names.append (name + ", ");
// fall through
}
add_spec (name, "int", description,
String.valueOf (default_value), String.valueOf (retval));
return retval;
}
public int intt (String name, String description,
int default_value, int low, int high) {
int retval = default_value;
try {
String opt = option (name);
if (opt != null) retval = Integer.parseInt (opt);
} catch (RuntimeException e) {
invalid_names.append (name + ", ");
// fall through
}
String full_description = description + " from " + low + " to " + high;
retval = Math.clamp (retval, low, high);
add_spec (name, "int", description,
String.valueOf (default_value), String.valueOf (retval));
return retval;
}
public long longg (String name, String description,
long default_value) {
long retval = default_value;
try {
String opt = option (name);
if (opt != null) retval = Long.parseLong (opt);
} catch (RuntimeException e) {
invalid_names.append (name + ", ");
// fall through
}
add_spec (name, "long", description,
String.valueOf (default_value), String.valueOf (retval));
return retval;
}
public String option (String name) {
int index = index (name);
if (index == -1 || index == args.length-1) return null;
return args [index+1];
}
public boolean flag (String name, String description) {
boolean retval = index (name) != -1;
add_spec (name, "flag", description, "absent",
retval ? "present" : "absent");
return retval;
}
public float scale (String name, String description,
float default_value) {
return floatt (name, description, default_value, 0.0f, 1.0f);
}
public String string (String name, String description,
String default_value) {
String retval = default_value;
try {
String opt = option (name);
if (opt != null) retval = opt;
} catch (RuntimeException e) {
invalid_names.append (name + ", ");
// fall through
}
add_spec (name, "String", description, default_value, retval);
return retval;
}
}