Synnefo » snf-ganeti » ganeti-local

#!/usr/bin/python

#

# Copyright (C) 2011, 2012 Google Inc.

#

# 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; either version 2 of the License, or

# (at your option) any later version.

#

# 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 GNU

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""Script for converting Python constants to Haskell code fragments.

"""

import re

import types

from ganeti import compat

from ganeti import constants

from ganeti import luxi

#: Constant name regex

CONSTANT_RE = re.compile("^[A-Z][A-Z0-9_-]+$")

#: Private name regex

PRIVATE_RE = re.compile("^__.+__$")

#: The type of regex objects

RE_TYPE = type(CONSTANT_RE)

def NameRules(name):

  """Converts the upper-cased Python name to Haskell camelCase.

  """

  name = name.replace("-", "_")

  elems = name.split("_")

  return elems[0].lower() + "".join(e.capitalize() for e in elems[1:])

def StringValueRules(value):

  """Converts a string value from Python to Haskell.

  """

  value = value.encode("string_escape") # escapes backslashes

  value = value.replace("\"", "\\\"")

  return value

def DictKeyName(dict_name, key_name):

  """Converts a dict plus key name to a full name.

  """

  return"%s_%s" % (dict_name, str(key_name).upper())

def HaskellTypeVal(value):

  """Returns the Haskell type and value for a Python value.

  Note that this only work for 'plain' Python types.

  @returns: (string, string) or None, if we can't determine the type.

  """

  if isinstance(value, basestring):

    return ("String", "\"%s\"" % StringValueRules(value))

  elif isinstance(value, int):

    return ("Int", "%d" % value)

  elif isinstance(value, long):

    return ("Integer", "%d" % value)

  elif isinstance(value, float):

    return ("Double", "%f" % value)

  else:

    return None

def IdentifyOrigin(all_items, value):

  """Tries to identify a constant name from a constant's value.

  This uses a simple algorithm: is there a constant (and only one)

  with the same value? If so, then it returns that constants' name.

  @note: it is recommended to use this only for tuples/lists/sets, and

      not for individual (top-level) values

  @param all_items: a dictionary of name/values for the current module

  @param value: the value for which we try to find an origin

  """

  found = [name for (name, v) in all_items.items() if v is value]

  if len(found) == 1:

    return found[0]

  else:

    return None

def FormatListElems(all_items, pfx_name, ovals, tvals):

  """Formats a list's elements.

  This formats the elements as either values or, if we find all

  origins, as names.

  @param all_items: a dictionary of name/values for the current module

  @param pfx_name: the prefix name currently used

  @param ovals: the list of actual (Python) values

  @param tvals: the list of values we want to format in the Haskell form

  """

  origins = [IdentifyOrigin(all_items, v) for v in ovals]

  if compat.all(x is not None for x in origins):

    values = [NameRules(pfx_name + origin) for origin in origins]

  else:

    values = tvals

  return ", ".join(values)

def ConvertVariable(prefix, name, value, all_items):

  """Converts a given variable to Haskell code.

  @param prefix: a prefix for the Haskell name (useful for module

      identification)

  @param name: the Python name

  @param value: the value

  @param all_items: a dictionary of name/value for the module being

      processed

  @return: a list of Haskell code lines

  """

  lines = []

  if prefix:

    pfx_name = prefix + "_"

    fqn = prefix + "." + name

  else:

    pfx_name = ""

    fqn = name

  hs_name = NameRules(pfx_name + name)

  hs_typeval = HaskellTypeVal(value)

  if (isinstance(value, types.ModuleType) or callable(value) or

      PRIVATE_RE.match(name)):

    # no sense in marking these, as we don't _want_ to convert them; the

    # message in the next if block is for datatypes we don't _know_

    # (yet) how to convert

    pass

  elif not CONSTANT_RE.match(name):

    lines.append("-- Skipped %s %s, not constant" % (fqn, type(value)))

  elif hs_typeval is not None:

    # this is a simple value

    (hs_type, hs_val) = hs_typeval

    lines.append("-- | Converted from Python constant %s" % fqn)

    lines.append("%s :: %s" % (hs_name, hs_type))

    lines.append("%s = %s" % (hs_name, hs_val))

  elif isinstance(value, dict):

    if value:

      lines.append("-- Following lines come from dictionary %s" % fqn)

      for k in sorted(value.keys()):

        lines.extend(ConvertVariable(prefix, DictKeyName(name, k),

                                     value[k], all_items))

  elif isinstance(value, tuple):

    tvs = [HaskellTypeVal(elem) for elem in value]

    if compat.all(e is not None for e in tvs):

      ttypes = ", ".join(e[0] for e in tvs)

      tvals = FormatListElems(all_items, pfx_name, value, [e[1] for e in tvs])

      lines.append("-- | Converted from Python tuple %s" % fqn)

      lines.append("%s :: (%s)" % (hs_name, ttypes))

      lines.append("%s = (%s)" % (hs_name, tvals))

    else:

      lines.append("-- Skipped tuple %s, cannot convert all elements" % fqn)

  elif isinstance(value, (list, set, frozenset)):

    # Lists and frozensets are handled the same in Haskell: as lists,

    # since lists are immutable and we don't need for constants the

    # high-speed of an actual Set type. However, we can only convert

    # them if they have the same type for all elements (which is a

    # normal expectation for constants, our code should be well

    # behaved); note that this is different from the tuples case,

    # where we always (for some values of always) can convert

    tvs = [HaskellTypeVal(elem) for elem in value]

    if compat.all(e is not None for e in tvs):

      ttypes, tvals = zip(*tvs)

      uniq_types = set(ttypes)

      if len(uniq_types) == 1:

        values = FormatListElems(all_items, pfx_name, value, tvals)

        lines.append("-- | Converted from Python list or set %s" % fqn)

        lines.append("%s :: [%s]" % (hs_name, uniq_types.pop()))

        lines.append("%s = [%s]" % (hs_name, values))

      else:

        lines.append("-- | Skipped list/set %s, is not homogeneous" % fqn)

    else:

      lines.append("-- | Skipped list/set %s, cannot convert all elems" % fqn)

  elif isinstance(value, RE_TYPE):

    tvs = HaskellTypeVal(value.pattern)

    assert tvs is not None

    lines.append("-- | Converted from Python RE object %s" % fqn)

    lines.append("%s :: %s" % (hs_name, tvs[0]))

    lines.append("%s = %s" % (hs_name, tvs[1]))

  else:

    lines.append("-- Skipped %s, %s not handled" % (fqn, type(value)))

  return lines

def Convert(module, prefix):

  """Converts the constants to Haskell.

  """

  lines = [""]

  all_items = dict((name, getattr(module, name)) for name in dir(module))

  for name in sorted(all_items.keys()):

    value = all_items[name]

    new_lines = ConvertVariable(prefix, name, value, all_items)

    if new_lines:

      lines.extend(new_lines)

      lines.append("")

  return "\n".join(lines)

def main():

  print Convert(constants, "")

  print Convert(luxi, "luxi")

if __name__ == "__main__":

  main()