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- import sys
- import marshal
- import contextlib
- import dis
- from distutils.version import StrictVersion
-
- from ._imp import find_module, PY_COMPILED, PY_FROZEN, PY_SOURCE
- from . import _imp
-
-
- __all__ = [
- 'Require', 'find_module', 'get_module_constant', 'extract_constant'
- ]
-
-
- class Require:
- """A prerequisite to building or installing a distribution"""
-
- def __init__(
- self, name, requested_version, module, homepage='',
- attribute=None, format=None):
-
- if format is None and requested_version is not None:
- format = StrictVersion
-
- if format is not None:
- requested_version = format(requested_version)
- if attribute is None:
- attribute = '__version__'
-
- self.__dict__.update(locals())
- del self.self
-
- def full_name(self):
- """Return full package/distribution name, w/version"""
- if self.requested_version is not None:
- return '%s-%s' % (self.name, self.requested_version)
- return self.name
-
- def version_ok(self, version):
- """Is 'version' sufficiently up-to-date?"""
- return self.attribute is None or self.format is None or \
- str(version) != "unknown" and version >= self.requested_version
-
- def get_version(self, paths=None, default="unknown"):
- """Get version number of installed module, 'None', or 'default'
-
- Search 'paths' for module. If not found, return 'None'. If found,
- return the extracted version attribute, or 'default' if no version
- attribute was specified, or the value cannot be determined without
- importing the module. The version is formatted according to the
- requirement's version format (if any), unless it is 'None' or the
- supplied 'default'.
- """
-
- if self.attribute is None:
- try:
- f, p, i = find_module(self.module, paths)
- if f:
- f.close()
- return default
- except ImportError:
- return None
-
- v = get_module_constant(self.module, self.attribute, default, paths)
-
- if v is not None and v is not default and self.format is not None:
- return self.format(v)
-
- return v
-
- def is_present(self, paths=None):
- """Return true if dependency is present on 'paths'"""
- return self.get_version(paths) is not None
-
- def is_current(self, paths=None):
- """Return true if dependency is present and up-to-date on 'paths'"""
- version = self.get_version(paths)
- if version is None:
- return False
- return self.version_ok(version)
-
-
- def maybe_close(f):
- @contextlib.contextmanager
- def empty():
- yield
- return
- if not f:
- return empty()
-
- return contextlib.closing(f)
-
-
- def get_module_constant(module, symbol, default=-1, paths=None):
- """Find 'module' by searching 'paths', and extract 'symbol'
-
- Return 'None' if 'module' does not exist on 'paths', or it does not define
- 'symbol'. If the module defines 'symbol' as a constant, return the
- constant. Otherwise, return 'default'."""
-
- try:
- f, path, (suffix, mode, kind) = info = find_module(module, paths)
- except ImportError:
- # Module doesn't exist
- return None
-
- with maybe_close(f):
- if kind == PY_COMPILED:
- f.read(8) # skip magic & date
- code = marshal.load(f)
- elif kind == PY_FROZEN:
- code = _imp.get_frozen_object(module, paths)
- elif kind == PY_SOURCE:
- code = compile(f.read(), path, 'exec')
- else:
- # Not something we can parse; we'll have to import it. :(
- imported = _imp.get_module(module, paths, info)
- return getattr(imported, symbol, None)
-
- return extract_constant(code, symbol, default)
-
-
- def extract_constant(code, symbol, default=-1):
- """Extract the constant value of 'symbol' from 'code'
-
- If the name 'symbol' is bound to a constant value by the Python code
- object 'code', return that value. If 'symbol' is bound to an expression,
- return 'default'. Otherwise, return 'None'.
-
- Return value is based on the first assignment to 'symbol'. 'symbol' must
- be a global, or at least a non-"fast" local in the code block. That is,
- only 'STORE_NAME' and 'STORE_GLOBAL' opcodes are checked, and 'symbol'
- must be present in 'code.co_names'.
- """
- if symbol not in code.co_names:
- # name's not there, can't possibly be an assignment
- return None
-
- name_idx = list(code.co_names).index(symbol)
-
- STORE_NAME = 90
- STORE_GLOBAL = 97
- LOAD_CONST = 100
-
- const = default
-
- for byte_code in dis.Bytecode(code):
- op = byte_code.opcode
- arg = byte_code.arg
-
- if op == LOAD_CONST:
- const = code.co_consts[arg]
- elif arg == name_idx and (op == STORE_NAME or op == STORE_GLOBAL):
- return const
- else:
- const = default
-
-
- def _update_globals():
- """
- Patch the globals to remove the objects not available on some platforms.
-
- XXX it'd be better to test assertions about bytecode instead.
- """
-
- if not sys.platform.startswith('java') and sys.platform != 'cli':
- return
- incompatible = 'extract_constant', 'get_module_constant'
- for name in incompatible:
- del globals()[name]
- __all__.remove(name)
-
-
- _update_globals()
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