Small Uncomplicated Plugin Extensible Reliable Shell in PYthon

About

SUPERSPY is a implementation of a shell and programming language written completely in Python. It is meant as a replacement of the builtin cmd module which allows scripting and advanced flow control functions.

[SUPERSPY DEMO] >>> i = 4 + 3
[SUPERSPY DEMO] >>> spam 3
SPAM
SPAM
SPAM
[SUPERSPY DEMO] >>> while i {
[SUPERSPY DEMO] >>>     printnl i
[SUPERSPY DEMO] >>>     printnl " to go: "
[SUPERSPY DEMO] >>>     joke
[SUPERSPY DEMO] >>>     i = i - 1
[SUPERSPY DEMO] >>> }
7.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!
6.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!
5.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!
4.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!
3.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!
2.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!
1.0 to go: Wenn ist das Nunstück git und Slotermeyer? Ja! Beiherhund das Oder die Flipperwaldt gersput!

joke and spam here are funktions easily defined in Python code:

from superspy import ast, language

@language.register_function('joke', 0)
class Joke(ast.Function):
    funniest_joke_in_the_world = 'Wenn ist das Nunstück git und Slotermeyer?'\
        'Ja! Beiherhund das Oder die Flipperwaldt gersput!'
    def execute(self):
        print(self.funniest_joke_in_the_world)

@language.register_function('spam')
class Spam(ast.Function):
    def execute(self):
        for _ in range(int(self.argument.execute())):
            print('SPAM')

It also allows for the execution of entire scripts:

printnl "COMPUTE FACTORIAL OF: "
base = getnum
base_backup = base

factorial = 1
while base {
    factorial = factorial * base
    base = base - 1
}

printnl base_backup
printnl "! = "
print factorial

Getting started

Superspy is meant to, in true Python fashion, be very easy to use.

Prerequisites

Superspy was developed in Python 3.7. Older versions cannot be guaranteed to work.

If you get it working on an older version please let me know!

Installing

Setup manually from this repository or just type

pip3 install superspy

Basic usage

To understand how to run a script from file check out the file_factorial script and its corresponding factorial script, that also illustrates basic language functionality.

To learn how to run an interactive shell check out the shell_demo script, that is being exanded upon by the plugin_demo and its example implementation of a plugin.

Superspy Language

Superspy is primarily a shell language, however it uses braces. Commands can be separated by lines or semicolons. Superspy supports strings and numbers, which are always stored as float.

Variables can be used in a similar way to Python:

a = 5
b = 2 * a

Basic Arithmetic and Logic is also supported, in (mostly) the correct order of operations (see the Bugfixes section of the Roadmap:

b = 2 * a - 3 / 4
c = a == 9.25
d = a != 10

Basic IO is also supported:

my_num_from_input = getnum
my_str_from_input = getstr
printnl "Your inputed number was"
printnl my_num_from_input
printnl " and your string was "
print my_str_from_input

Here printnl means Print No Lline, since the normal print has a line break. Also dis prints the entire token tree and should be used for debugging.

However, one of the primary reasons for Superspy's existence is the Flow Control:

while base != 0 {
    factorial = factorial * base
    base = base - 1
}
if factorial == 120 {
    print "Your number was 5"
} else {
    print "Your number was not 5"
}

For further features, that are not mentioned in the (roadmap)[#Roadmap], like running scripts from a shell, please create an issue (or even a pull request)!

Python

The way a new Ast/Interpreter is created will get further simplified in the future.

Currently you have to create a Language object, because a custom language might be defined. Then a CodeSource object has to be defined to be created to feed that Ast lines. Those can for example come from a file, string, or shell. Finally an Ast object, that does all the parsing and interpreting has to be created and executed.

from superspy import ast, code_source, language

# Run file
lang = language.SuperSpyLanguage()
source = code_source.FileSource(f'path/to/my/script.spy')
my_ast = ast.Ast(source, lang)
exit_code = my_ast.complete_run()

# Run shell
lang = language.SuperSpyLanguage(['path/to/my/plugin/folder']) # Plugin folder can be left out
source = code_source.ShellSource()
my_ast = ast.Ast(source, lang)
my_ast.error_mode = ast.ErrorMode.PRINT
exit_code = my_ast.complete_run(run_after_each_line=True)

Advanced Usage

The complete_run method is an abstraction for something similar to this:

my_ast.build_token_list()
my_ast.guess_variables()
my_ast.build_token_tree()
my_ast.interpret()
exit_code: int = my_ast.get_exit_code()

It can obviously be executed manually in this order and then customized any way. Everything is open source and the source code is hopefully documented very clearly, so if there are any questions of how something is implemented by default you check out the source code.

To implement custom functions available inside the language specify a plugin search path with custom python files inside. Check out the plugin_demo example and its example implementation of a plugin.

from superspy import language

@language.register_function('my_function_name_inside_the_shell', number_of_arguments)
class MyFunction(ast.Function):
    def execute(self):
        # Run code

Rationale

This module was created because I wanted scripting functionality inside the cmd module, that was not there. I have also been toying around with creating my own programming language for a few years and never got around to it. But most of all I needed a distraction during the exams this year.

Roadmap

Language

• More math functions
  • Trigonometry (sin, cos, tan, atan, ...)
  • Exponential (pow, log)
  • Constants (e, tau, pi, phi)
• More flow control
  • elif/elsif/elseif/else if
  • for
  • catch
  • break
• Logical operators (and, or, xor)
• Parentheses
• arrays
• help
• script executability
• functions

Implementation

• Full drop in cmd replacement
• Single line shell creation without having to define a language and source first
• Ability to define commands in the main script before creating alanguage object

Bugfixes

• Order of Operations: Make 3 - 1 - 1 not equal 3.

Other

• Integrate with
  • TravisCI
  • codecov.io
  • Read the docs
  • lgtm

Contributing

If you want to contribute, please feel free to suggest features or implement some from the (roadmap)[#Roadmap], other ones that are still lacking, or bugfixes.

Also please encounter any issues and bugs you might find!

Authors

• Currently this entire project is just by me.

License

The project is licensed under the MIT-License.

Acknowledgments

• This project uses the module PluginBase for loading language syntax python files, which makes my job so much easier.
• Thank you also to all the people who have supported me in this endeavor.

Thanks for reading this to the end.

GNU Terry Pratchett