122 lines
3.3 KiB
Python
122 lines
3.3 KiB
Python
# -*- coding: utf-8 -*-
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'''
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A dialect of Joy in Python.
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Joy is a programming language created by Manfred von Thun that is easy to
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use and understand and has many other nice properties. This Python script
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is an interpreter for a dialect of Joy that attempts to stay very close
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to the spirit of Joy but does not precisely match the behaviour of the
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original version(s) written in C. A Tkinter GUI is provided as well.
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Copyright © 2014, 2016, 2017 Simon Forman
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This file is part of Joypy.
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Joypy is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Joypy is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Joypy. If not see <http://www.gnu.org/licenses/>.
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§ joy()
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The basic joy() function is quite straightforward. It iterates through a
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sequence of terms which are either literals (strings, numbers, sequences)
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or functions. Literals are put onto the stack and functions are
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executed.
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Every Joy function is an unary mapping from stacks to stacks. Even
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literals are considered to be functions that accept a stack and return a
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new stack with the literal value on top.
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Exports:
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joy(stack, expression, dictionary, viewer=None)
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run(text, stack, dictionary, viewer=None)
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repl(stack=(), dictionary=())
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'''
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from __future__ import print_function
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try:
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input = raw_input
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except NameError:
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pass
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from traceback import print_exc, format_exc
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from .parser import text_to_expression, ParseError, Symbol
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from .utils.stack import stack_to_string
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from .utils.pretty_print import TracePrinter
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def joy(stack, expression, dictionary, viewer=None):
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'''
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Evaluate the Joy expression on the stack.
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'''
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while expression:
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if viewer: viewer(stack, expression)
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term, expression = expression
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if isinstance(term, Symbol):
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term = dictionary[term]
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stack, expression, dictionary = term(stack, expression, dictionary)
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else:
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stack = term, stack
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if viewer: viewer(stack, expression)
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return stack, expression, dictionary
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def run(text, stack, dictionary, viewer=None):
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'''
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Return the stack resulting from running the Joy code text on the stack.
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'''
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expression = text_to_expression(text)
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return joy(stack, expression, dictionary, viewer)
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def repl(stack=(), dictionary=None):
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'''
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Read-Evaluate-Print Loop
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Accept input and run it on the stack, loop.
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'''
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if dictionary is None:
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dictionary = {}
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try:
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while True:
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print()
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print(stack_to_string(stack), '<-top')
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print()
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try:
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text = input('joy? ')
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except (EOFError, KeyboardInterrupt):
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break
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viewer = TracePrinter()
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try:
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stack, _, dictionary = run(text, stack, dictionary, viewer.viewer)
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except:
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exc = format_exc() # Capture the exception.
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viewer.print_() # Print the Joy trace.
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print('-' * 73)
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print(exc) # Print the original exception.
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else:
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viewer.print_()
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except:
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print_exc()
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print()
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return stack
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