129 lines
3.4 KiB
Python
129 lines
3.4 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright © 2016 Simon Forman
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#
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# This file is part of Thun.
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#
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# Thun 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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#
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# Thun 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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#
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# You should have received a copy of the GNU General Public License
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# along with Thun. If not see <http://www.gnu.org/licenses/>.
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#
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'''
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Pretty printing support, e.g.::
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Joy? 23 18 * 99 +
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. 23 18 mul 99 add
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23 . 18 mul 99 add
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23 18 . mul 99 add
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414 . 99 add
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414 99 . add
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513 .
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513 <-top
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joy?
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On each line the stack is printed with the top to the right, then a ``.`` to
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represent the current locus of processing, then the pending expression to the
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left.
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'''
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# (Kinda clunky and hacky. This should be swapped out in favor of much
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# smarter stuff.)
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from __future__ import print_function
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from builtins import object
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from traceback import print_exc
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from .stack import expression_to_string, stack_to_string
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from ..joy import joy
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from ..library import inscribe, FunctionWrapper
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@inscribe
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@FunctionWrapper
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def trace(stack, expression, dictionary):
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'''Evaluate a Joy expression on a stack and print a trace.
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This function is just like the `i` combinator but it also prints a
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trace of the evaluation
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:param stack stack: The stack.
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:param stack expression: The expression to evaluate.
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:param dict dictionary: A ``dict`` mapping names to Joy functions.
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:rtype: (stack, (), dictionary)
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'''
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tp = TracePrinter()
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quote, stack = stack
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try:
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s, _, d = joy(stack, quote, dictionary, tp.viewer)
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except:
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tp.print_()
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print('-' * 73)
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raise
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else:
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tp.print_()
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return s, expression, d
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class TracePrinter(object):
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'''
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This is what does the formatting. You instantiate it and pass the ``viewer()``
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method to the :py:func:`joy.joy.joy` function, then print it to see the
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trace.
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'''
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def __init__(self):
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self.history = []
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def viewer(self, stack, expression):
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'''
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Record the current stack and expression in the TracePrinter's history.
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Pass this method as the ``viewer`` argument to the :py:func:`joy.joy.joy` function.
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:param stack quote: A stack.
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:param stack expression: A stack.
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'''
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self.history.append((stack, expression))
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def __str__(self):
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return '\n'.join(self.go())
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def go(self):
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'''
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Return a list of strings, one for each entry in the history, prefixed
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with enough spaces to align all the interpreter dots.
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This method is called internally by the ``__str__()`` method.
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:rtype: list(str)
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'''
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max_stack_length = 0
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lines = []
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for stack, expression in self.history:
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stack = stack_to_string(stack)
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expression = expression_to_string(expression)
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n = len(stack)
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if n > max_stack_length:
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max_stack_length = n
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lines.append((n, '%s . %s' % (stack, expression)))
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return [ # Prefix spaces to line up '.'s.
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(' ' * (max_stack_length - length) + line)
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for length, line in lines
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]
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def print_(self):
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try:
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print(self)
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except:
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print_exc()
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print('Exception while printing viewer.')
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