https://github.com/docopt/docopt.java
Java port of docopt
https://github.com/docopt/docopt.java
Last synced: about 1 year ago
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Java port of docopt
- Host: GitHub
- URL: https://github.com/docopt/docopt.java
- Owner: docopt
- License: mit
- Created: 2014-07-20T15:33:31.000Z (almost 12 years ago)
- Default Branch: master
- Last Pushed: 2016-10-10T15:03:39.000Z (over 9 years ago)
- Last Synced: 2024-05-09T19:19:23.890Z (about 2 years ago)
- Language: Java
- Size: 238 KB
- Stars: 157
- Watchers: 17
- Forks: 18
- Open Issues: 9
-
Metadata Files:
- Readme: README.rst
- License: LICENSE
Awesome Lists containing this project
README
``docopt.java`` is a Java port of docopt
======================================================================
Isn't it awesome how ``Apache Commons CLI`` and the dozens of other Java command
line parsers generate help messages based on your code?!
*Hell no!* You know what's awesome? It's when the option parser *is*
generated based on the beautiful help message that you write yourself!
This way you don't need to write this stupid repeatable parser-code,
and instead can write only the help message--*the way you want it*.
**docopt.java** helps you create most beautiful command-line interfaces
*easily*:
.. code:: java
import java.util.Map;
import org.docopt.Docopt;
public final class NavalFate {
private static final String doc =
"Naval Fate.\n"
+ "\n"
+ "Usage:\n"
+ " naval_fate ship new ...\n"
+ " naval_fate ship move [--speed=]\n"
+ " naval_fate ship shoot \n"
+ " naval_fate mine (set|remove) [--moored | --drifting]\n"
+ " naval_fate (-h | --help)\n"
+ " naval_fate --version\n"
+ "\n"
+ "Options:\n"
+ " -h --help Show this screen.\n"
+ " --version Show version.\n"
+ " --speed= Speed in knots [default: 10].\n"
+ " --moored Moored (anchored) mine.\n"
+ " --drifting Drifting mine.\n"
+ "\n";
public static void main(String[] args) {
Map opts =
new Docopt(doc).withVersion("Naval Fate 2.0").parse(args);
System.out.println(opts);
}
}
Differences from the reference implementation
======================================================================
- Because Java does not support optional or named arguments, this port uses the
Builder pattern to configure the parser instead of a simple method call.
- Because Java does not provide a way (native) way to read a class's Javadoc,
there is no idiomatic way to supply the ``doc`` or ``version`` arguments.
This implementation provides convenience methods to read these values from
streams (e.g. files within the JAR) in addition to accepting String arguments.
- Because Java does not provide a way to get command line arguments other than
in a ``main`` method, the ``argv`` parameter is required.
- Exiting the application when parsing arguments has been made optional. See the
``withExit`` method.
Installation
======================================================================
You can build a JAR using `Maven http://maven.apache.org/` and include it as a
dependency in your project. **docopt.java** is not currently available from Maven
central.
Alternatevely, you can just copy the ``org.docopt`` package into your project--it
is self-contained.
**docopt.java** is tested with Java 6 and Java 7.
API
======================================================================
.. code:: java
import org.docopt.Docopt;
.. code:: java
public Docopt(String doc)
``Docopt`` takes one required argument:
- ``doc`` is a ``String`` that contains a **help message** that will be parsed to
create the option parser. The simple rules of how to write such a
help message are given in next sections. Here is a quick example of
such a string:
.. code:: java
static final String doc =
"Usage: my_program [-hso FILE] [--quiet | --verbose] [INPUT ...]\n"
+ "\n"
+ "-h --help show this\n"
+ "-s --sorted sorted output\n"
+ "-o FILE specify output file [default: ./test.txt]\n"
+ "--quiet print less text\n"
+ "--verbose print more text\n"
+ "\n";
.. code:: java
public Docopt(String doc)
public Docopt(InputStream doc)
public Docopt(InputStream doc, Charset charset)
Constructs an option parser from the ``doc`` argument or throws a
``DocoptLanguageError`` if it is malformed. If ``doc`` is an ``InputStream``,
the stream is read using the specified ``CharSet`` (``UTF-8`` by default).
.. code:: java
public Map parse(List argv)
public Map parse(String... argv)
``parse`` takes one required argument:
- ``argv`` is an argument vector. The vector may be given as a ``List`` or as an
array of ``Strings``. *Note that calling this method with no argument is
equivalent to a giving an empty array!*
The **return** value is a ``Map`` with options, arguments, and commands as keys,
spelled exactly like in your help message. Long versions of options are given
priority. For example, if you invoke the top example as::
naval_fate.py ship Guardian move 100 150 --speed=15
the return ``Map`` will be:
.. code:: java
{--version=false, remove=false,
--speed=15, ship=true,
=[Guardian], set=false,
=150, =100,
--moored=false, new=false,
--drifting=false, shoot=false,
mine=false, --help=false,
move=true}
.. code:: java
public Docopt withHelp(boolean help)
``withHelp`` takes one required argument:
- ``help``, by default ``true``, specifies whether the parser should
automatically print the help message (supplied as ``doc``) and
terminate, in case ``-h`` or ``--help`` option is encountered
(options should exist in usage pattern, more on that below). If you
want to handle ``-h`` or ``--help`` options manually (as other
options), invoke ``withHelp(false)``.
Note, when ``docopt`` is set to automatically handle the ``-h`` and
``--help`` options, you still need to mention them in usage pattern for this
to work. Also, for your users to know about them.
.. code:: java
public Docopt withVersion(String version)
- ``version``, by default ``null``, specifies the version of your program. If
supplied, then, (assuming ``--version`` option is mentioned in usage pattern)
when parser encounters the ``--version`` option, it will print the supplied
version and terminate.
Note, when ``docopt`` is set to automatically handle the ``--version``
option, you still need to mention it in usage pattern for this to work.
Also, for your users to know about them.
.. code:: java
public Docopt withOptionsFirst(boolean optionsFirst)
- ``optionsFirst``, by default ``false``. If set to ``true`` will
disallow mixing options and positional argument. I.e. after first
positional argument, all arguments will be interpreted as positional
even if the look like options. This can be used for strict
compatibility with POSIX, or if you want to dispatch your arguments
to other programs.
.. code:: java
public Docopt withExit(boolean exit)
- ``exit``, by default ``true``. If set to ``false`` will cause ``parse`` to
throw a ``DocoptExit`` exception instead of terminating the application.
Help message format
======================================================================
Help message consists of 2 parts:
- Usage pattern, e.g.::
Usage: my_program [-hso FILE] [--quiet | --verbose] [INPUT ...]
- Option descriptions, e.g.::
-h --help show this
-s --sorted sorted output
-o FILE specify output file [default: ./test.txt]
--quiet print less text
--verbose print more text
Their format is described below; other text is ignored.
Usage pattern format
----------------------------------------------------------------------
**Usage pattern** is a substring of ``doc`` that starts with
``usage:`` (case *insensitive*) and ends with a *visibly* empty line.
Minimum example:
.. code:: java
static final String USAGE = "Usage: my_program";
The first word after ``usage:`` is interpreted as your program's name.
You can specify your program's name several times to signify several
exclusive patterns:
.. code:: java
static final String USAGE =
"Usage: my_program FILE\n" +
" my_program COUNT FILE";
Each pattern can consist of the following elements:
- ****, **ARGUMENTS**. Arguments are specified as either
upper-case words, e.g. ``my_program CONTENT-PATH`` or words
surrounded by angular brackets: ``my_program ``.
- **--options**. Options are words started with dash (``-``), e.g.
``--output``, ``-o``. You can "stack" several of one-letter
options, e.g. ``-oiv`` which will be the same as ``-o -i -v``. The
options can have arguments, e.g. ``--input=FILE`` or ``-i FILE`` or
even ``-iFILE``. However it is important that you specify option
descriptions if you want your option to have an argument, a default
value, or specify synonymous short/long versions of the option (see
next section on option descriptions).
- **commands** are words that do *not* follow the described above
conventions of ``--options`` or ```` or ``ARGUMENTS``,
plus two special commands: dash "``-``" and double dash "``--``"
(see below).
Use the following constructs to specify patterns:
- **[ ]** (brackets) **optional** elements. e.g.: ``my_program
[-hvqo FILE]``
- **( )** (parens) **required** elements. All elements that are *not*
put in **[ ]** are also required, e.g.: ``my_program
--path= ...`` is the same as ``my_program
(--path= ...)``. (Note, "required options" might be not
a good idea for your users).
- **|** (pipe) **mutually exclusive** elements. Group them using **(
)** if one of the mutually exclusive elements is required:
``my_program (--clockwise | --counter-clockwise) TIME``. Group
them using **[ ]** if none of the mutually-exclusive elements are
required: ``my_program [--left | --right]``.
- **...** (ellipsis) **one or more** elements. To specify that
arbitrary number of repeating elements could be accepted, use
ellipsis (``...``), e.g. ``my_program FILE ...`` means one or
more ``FILE``-s are accepted. If you want to accept zero or more
elements, use brackets, e.g.: ``my_program [FILE ...]``. Ellipsis
works as a unary operator on the expression to the left.
- **[options]** (case sensitive) shortcut for any options. You can
use it if you want to specify that the usage pattern could be
provided with any options defined below in the option-descriptions
and do not want to enumerate them all in usage-pattern.
- "``[--]``". Double dash "``--``" is used by convention to separate
positional arguments that can be mistaken for options. In order to
support this convention add "``[--]``" to your usage patterns.
- "``[-]``". Single dash "``-``" is used by convention to signify that
``stdin`` is used instead of a file. To support this add "``[-]``"
to your usage patterns. "``-``" acts as a normal command.
If your pattern allows to match argument-less option (a flag) several
times::
Usage: my_program [-v | -vv | -vvv]
then number of occurrences of the option will be counted. I.e.
``args['-v']`` will be ``2`` if program was invoked as ``my_program
-vv``. Same works for commands.
If your usage patterns allows to match same-named option with argument
or positional argument several times, the matched arguments will be
collected into a list::
Usage: my_program --path=...
I.e. invoked with ``my_program file1 file2 --path=./here
--path=./there`` the returned dict will contain ``args[''] ==
['file1', 'file2']`` and ``args['--path'] == ['./here', './there']``.
Option descriptions format
----------------------------------------------------------------------
**Option descriptions** consist of a list of options that you put
below your usage patterns.
It is necessary to list option descriptions in order to specify:
- synonymous short and long options,
- if an option has an argument,
- if option's argument has a default value.
The rules are as follows:
- Every line in ``doc`` that starts with ``-`` or ``--`` (not counting
spaces) is treated as an option description, e.g.::
Options:
--verbose # GOOD
-o FILE # GOOD
Other: --bad # BAD, line does not start with dash "-"
- To specify that option has an argument, put a word describing that
argument after space (or equals "``=``" sign) as shown below. Follow
either or UPPER-CASE convention for options'
arguments. You can use comma if you want to separate options. In
the example below, both lines are valid, however you are recommended
to stick to a single style.::
-o FILE --output=FILE # without comma, with "=" sign
-i , --input # with comma, without "=" sing
- Use two spaces to separate options with their informal description::
--verbose More text. # BAD, will be treated as if verbose option had
# an argument "More", so use 2 spaces instead
-q Quit. # GOOD
-o FILE Output file. # GOOD
--stdout Use stdout. # GOOD, 2 spaces
- If you want to set a default value for an option with an argument,
put it into the option-description, in form ``[default:
]``::
--coefficient=K The K coefficient [default: 2.95]
--output=FILE Output file [default: test.txt]
--directory=DIR Some directory [default: ./]
- If the option is not repeatable, the value inside ``[default: ...]``
will be interpreted as string. If it *is* repeatable, it will be
splited into a list on whitespace::
Usage: my_program [--repeatable= --repeatable=]
[--another-repeatable=]...
[--not-repeatable=]
# will be ['./here', './there']
--repeatable= [default: ./here ./there]
# will be ['./here']
--another-repeatable= [default: ./here]
# will be './here ./there', because it is not repeatable
--not-repeatable= [default: ./here ./there]
Changelog
======================================================================
**docopt.java** follows `semantic versioning `_.
- 0.6.0 Initial port based on version 0.6.1 of the `reference implementation
`_. All language agnostic tests pass.