Source code for joy.utils.pretty_print

# -*- coding: utf-8 -*-
#
#    Copyright © 2016 Simon Forman
#
#    This file is part of Thun.
#
#    Thun is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    Thun is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with Thun.  If not see <http://www.gnu.org/licenses/>.
#
'''
Pretty printing support, e.g.::

    Joy? [23 18 * 99 +] trace
           • 23 18 mul 99 add
        23 • 18 mul 99 add
     23 18 • mul 99 add
       414 • 99 add
    414 99 • add
       513 • 

    513 <-top

    joy? 

On each line the stack is printed with the top to the left, then a
bullet symbol,``•``, to represent the current locus of processing, then
the pending expression to the right.
'''
# (Kinda clunky and hacky.  This should be swapped out in favor of much
# smarter stuff.)
from traceback import print_exc
from .stack import expression_to_string, stack_to_string
from ..joy import joy
from ..library import FunctionWrapper


[docs]@FunctionWrapper def trace(stack, expression, dictionary): '''Evaluate a Joy expression on a stack and print a trace. This function is just like the `i` combinator but it also prints a trace of the evaluation :param stack stack: The stack. :param stack expression: The expression to evaluate. :param dict dictionary: A ``dict`` mapping names to Joy functions. :rtype: (stack, (), dictionary) ''' tp = TracePrinter() quote, stack = stack try: s, _, d = joy(stack, quote, dictionary, tp.viewer) except: tp.print_() print('-' * 73) raise else: tp.print_() return s, expression, d
[docs]class TracePrinter(object): ''' This is what does the formatting. You instantiate it and pass the ``viewer()`` method to the :py:func:`joy.joy.joy` function, then print it to see the trace. ''' def __init__(self): self.history = []
[docs] def viewer(self, stack, expression): ''' Record the current stack and expression in the TracePrinter's history. Pass this method as the ``viewer`` argument to the :py:func:`joy.joy.joy` function. :param stack quote: A stack. :param stack expression: A stack. ''' self.history.append((stack, expression))
def __str__(self): return '\n'.join(self.go())
[docs] def go(self): ''' Return a list of strings, one for each entry in the history, prefixed with enough spaces to align all the interpreter dots. This method is called internally by the ``__str__()`` method. :rtype: list(str) ''' max_stack_length = 0 lines = [] for stack, expression in self.history: stack = stack_to_string(stack) expression = expression_to_string(expression) n = len(stack) if n > max_stack_length: max_stack_length = n lines.append((n, '%s%s' % (stack, expression))) for i in range(len(lines)): # Prefix spaces to line up '•'s. length, line = lines[i] lines[i] = (' ' * (max_stack_length - length) + line) return lines
def print_(self): try: print(self) except: print_exc() print('Exception while printing viewer.')