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"""Compiler tools with improved interactive support.
Provides compilation machinery similar to codeop, but with caching support so
we can provide interactive tracebacks.
Authors
-------
* Robert Kern
* Fernando Perez
* Thomas Kluyver
"""
# Note: though it might be more natural to name this module 'compiler', that
# name is in the stdlib and name collisions with the stdlib tend to produce
# weird problems (often with third-party tools).
#-----------------------------------------------------------------------------
# Copyright (C) 2010-2011 The IPython Development Team.
#
# Distributed under the terms of the BSD License.
#
# The full license is in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from __future__ import print_function
# Stdlib imports
import __future__
from ast import PyCF_ONLY_AST
import codeop
import functools
import hashlib
import linecache
import operator
import time
#-----------------------------------------------------------------------------
# Constants
#-----------------------------------------------------------------------------
# Roughtly equal to PyCF_MASK | PyCF_MASK_OBSOLETE as defined in pythonrun.h,
# this is used as a bitmask to extract future-related code flags.
PyCF_MASK = functools.reduce(operator.or_,
(getattr(__future__, fname).compiler_flag
for fname in __future__.all_feature_names))
#-----------------------------------------------------------------------------
# Local utilities
#-----------------------------------------------------------------------------
def code_name(code, number=0):
""" Compute a (probably) unique name for code for caching.
This now expects code to be unicode.
"""
hash_digest = hashlib.sha1(code.encode("utf-8")).hexdigest()
# Include the number and 12 characters of the hash in the name. It's
# pretty much impossible that in a single session we'll have collisions
# even with truncated hashes, and the full one makes tracebacks too long
return '<ipython-input-{0}-{1}>'.format(number, hash_digest[:12])
#-----------------------------------------------------------------------------
# Classes and functions
#-----------------------------------------------------------------------------
class CachingCompiler(codeop.Compile):
"""A compiler that caches code compiled from interactive statements.
"""
def __init__(self):
codeop.Compile.__init__(self)
# This is ugly, but it must be done this way to allow multiple
# simultaneous ipython instances to coexist. Since Python itself
# directly accesses the data structures in the linecache module, and
# the cache therein is global, we must work with that data structure.
# We must hold a reference to the original checkcache routine and call
# that in our own check_cache() below, but the special IPython cache
# must also be shared by all IPython instances. If we were to hold
# separate caches (one in each CachingCompiler instance), any call made
# by Python itself to linecache.checkcache() would obliterate the
# cached data from the other IPython instances.
if not hasattr(linecache, '_ipython_cache'):
linecache._ipython_cache = {}
if not hasattr(linecache, '_checkcache_ori'):
linecache._checkcache_ori = linecache.checkcache
# Now, we must monkeypatch the linecache directly so that parts of the
# stdlib that call it outside our control go through our codepath
# (otherwise we'd lose our tracebacks).
linecache.checkcache = check_linecache_ipython
def ast_parse(self, source, filename='<unknown>', symbol='exec'):
"""Parse code to an AST with the current compiler flags active.
Arguments are exactly the same as ast.parse (in the standard library),
and are passed to the built-in compile function."""
return compile(source, filename, symbol, self.flags | PyCF_ONLY_AST, 1)
def reset_compiler_flags(self):
"""Reset compiler flags to default state."""
# This value is copied from codeop.Compile.__init__, so if that ever
# changes, it will need to be updated.
self.flags = codeop.PyCF_DONT_IMPLY_DEDENT
@property
def compiler_flags(self):
"""Flags currently active in the compilation process.
"""
return self.flags
def cache(self, code, number=0):
"""Make a name for a block of code, and cache the code.
Parameters
----------
code : str
The Python source code to cache.
number : int
A number which forms part of the code's name. Used for the execution
counter.
Returns
-------
The name of the cached code (as a string). Pass this as the filename
argument to compilation, so that tracebacks are correctly hooked up.
"""
name = code_name(code, number)
entry = (len(code), time.time(),
[line+'\n' for line in code.splitlines()], name)
linecache.cache[name] = entry
linecache._ipython_cache[name] = entry
return name
def check_linecache_ipython(*args):
"""Call linecache.checkcache() safely protecting our cached values.
"""
# First call the orignal checkcache as intended
linecache._checkcache_ori(*args)
# Then, update back the cache with our data, so that tracebacks related
# to our compiled codes can be produced.
linecache.cache.update(linecache._ipython_cache)
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