path: root/lib/spack/llnl/util/lang.py

##############################################################################
# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
# Produced at the Lawrence Livermore National Laboratory.
#
# This file is part of Spack.
# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
# LLNL-CODE-647188
#
# For details, see https://scalability-llnl.github.io/spack
# Please also see the LICENSE file for our notice and the LGPL.
#
# This program 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) version 2.1 dated February 1999.
#
# This program 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 terms and
# conditions of the GNU General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##############################################################################
import os
import re
import sys
import functools
import inspect

# Ignore emacs backups when listing modules
ignore_modules = [r'^\.#', '~$']


def index_by(objects, *funcs):
    """Create a hierarchy of dictionaries by splitting the supplied
       set of objects on unique values of the supplied functions.
       Values are used as keys.  For example, suppose you have four
       objects with attributes that look like this:

           a = Spec(name="boost",    compiler="gcc",   arch="bgqos_0")
           b = Spec(name="mrnet",    compiler="intel", arch="chaos_5_x86_64_ib")
           c = Spec(name="libelf",   compiler="xlc",   arch="bgqos_0")
           d = Spec(name="libdwarf", compiler="intel", arch="chaos_5_x86_64_ib")

           list_of_specs = [a,b,c,d]
           index1 = index_by(list_of_specs, lambda s: s.arch, lambda s: s.compiler)
           index2 = index_by(list_of_specs, lambda s: s.compiler)

       ``index1'' now has two levels of dicts, with lists at the
       leaves, like this:

           { 'bgqos_0'           : { 'gcc' : [a], 'xlc' : [c] },
             'chaos_5_x86_64_ib' : { 'intel' : [b, d] }
           }

       And ``index2'' is a single level dictionary of lists that looks
       like this:

           { 'gcc'    : [a],
             'intel'  : [b,d],
             'xlc'    : [c]
           }

       If any elemnts in funcs is a string, it is treated as the name
       of an attribute, and acts like getattr(object, name).  So
       shorthand for the above two indexes would be:

           index1 = index_by(list_of_specs, 'arch', 'compiler')
           index2 = index_by(list_of_specs, 'compiler')
    """
    if not funcs:
        return objects

    f = funcs[0]
    if isinstance(f, basestring):
        f = lambda x: getattr(x, funcs[0])

    result = {}
    for o in objects:
        key = f(o)
        if key not in result:
            result[key] = [o]
        else:
            result[key].append(o)

    for key, objects in result.items():
        result[key] = index_by(objects, *funcs[1:])

    return result


def partition_list(elements, predicate):
    """Partition a list into two lists, the first containing elements
       for which the predicate evaluates to true, the second containing
       those for which it is false.
    """
    trues = []
    falses = []
    for elt in elements:
        if predicate(elt):
            trues.append(elt)
        else:
            falses.append(elt)
    return trues, falses


def caller_locals():
    """This will return the locals of the *parent* of the caller.
       This allows a fucntion to insert variables into its caller's
       scope.  Yes, this is some black magic, and yes it's useful
       for implementing things like depends_on and provides.
    """
    stack = inspect.stack()
    try:
        return stack[2][0].f_locals
    finally:
        del stack


def get_calling_package_name():
    """Make sure that the caller is a class definition, and return
       the module's name.  This is useful for getting the name of
       spack packages from inside a relation function.
    """
    stack = inspect.stack()
    try:
        # get calling function name (the relation)
        relation = stack[1][3]

        # Make sure locals contain __module__
        caller_locals = stack[2][0].f_locals
    finally:
        del stack

    if not '__module__' in caller_locals:
        raise ScopeError(relation)

    module_name = caller_locals['__module__']
    base_name = module_name.split('.')[-1]
    return base_name


def attr_required(obj, attr_name):
    """Ensure that a class has a required attribute."""
    if not hasattr(obj, attr_name):
        tty.die("No required attribute '%s' in class '%s'"
                % (attr_name, obj.__class__.__name__))


def attr_setdefault(obj, name, value):
    """Like dict.setdefault, but for objects."""
    if not hasattr(obj, name):
        setattr(obj, name, value)
    return getattr(obj, name)


def has_method(cls, name):
    for base in inspect.getmro(cls):
        if base is object:
            continue
        if name in base.__dict__:
            return True
    return False


def memoized(obj):
    """Decorator that caches the results of a function, storing them
       in an attribute of that function."""
    cache = obj.cache = {}
    @functools.wraps(obj)
    def memoizer(*args, **kwargs):
        if args not in cache:
            cache[args] = obj(*args, **kwargs)
        return cache[args]
    return memoizer


def list_modules(directory, **kwargs):
    """Lists all of the modules, excluding __init__.py, in a
       particular directory.  Listed packages have no particular
       order."""
    list_directories = kwargs.setdefault('directories', True)

    for name in os.listdir(directory):
        if name == '__init__.py':
            continue

        path = os.path.join(directory, name)
        if list_directories and os.path.isdir(path):
            init_py = os.path.join(path, '__init__.py')
            if os.path.isfile(init_py):
                yield name

        elif name.endswith('.py'):
            if not any(re.search(pattern, name) for pattern in ignore_modules):
                yield re.sub('.py$', '', name)


def key_ordering(cls):
    """Decorates a class with extra methods that implement rich comparison
       operations and __hash__.  The decorator assumes that the class
       implements a function called _cmp_key().  The rich comparison operations
       will compare objects using this key, and the __hash__ function will
       return the hash of this key.

       If a class already has __eq__, __ne__, __lt__, __le__, __gt__, or __ge__
       defined, this decorator will overwrite them.  If the class does not
       have a _cmp_key method, then this will raise a TypeError.
    """
    def setter(name, value):
        value.__name__ = name
        setattr(cls, name, value)

    if not has_method(cls, '_cmp_key'):
        raise TypeError("'%s' doesn't define _cmp_key()." % cls.__name__)

    setter('__eq__', lambda s,o: o is not None and s._cmp_key() == o._cmp_key())
    setter('__lt__', lambda s,o: o is not None and s._cmp_key() <  o._cmp_key())
    setter('__le__', lambda s,o: o is not None and s._cmp_key() <= o._cmp_key())

    setter('__ne__', lambda s,o: o is None or s._cmp_key() != o._cmp_key())
    setter('__gt__', lambda s,o: o is None or s._cmp_key() >  o._cmp_key())
    setter('__ge__', lambda s,o: o is None or s._cmp_key() >= o._cmp_key())

    setter('__hash__', lambda self: hash(self._cmp_key()))

    return cls


@key_ordering
class HashableMap(dict):
    """This is a hashable, comparable dictionary.  Hash is performed on
       a tuple of the values in the dictionary."""
    def _cmp_key(self):
        return tuple(sorted(self.values()))


    def copy(self):
        """Type-agnostic clone method.  Preserves subclass type."""
        # Construct a new dict of my type
        T = type(self)
        clone = T()

        # Copy everything from this dict into it.
        for key in self:
            clone[key] = self[key].copy()
        return clone


def in_function(function_name):
    """True if the caller was called from some function with
       the supplied Name, False otherwise."""
    stack = inspect.stack()
    try:
        for elt in stack[2:]:
            if elt[3] == function_name:
                return True
        return False
    finally:
        del stack