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