python-dolfin 1.0.0-7 / usr / share / pyshared / dolfin / compilemodules / subdomains.py

"This module provides functionality for compilation of strings as dolfin SubDomains."

# Copyright (C) 2008-2008 Martin Sandve Alnes
#
# This file is part of DOLFIN.
#
# DOLFIN is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# DOLFIN 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.
#
# First added:  2008-07-01
# Last changed: 2011-04-18

import re
import os
import hashlib
import instant

# Import local compile_extension_module
from dolfin.compilemodules.compilemodule import (compile_extension_module,
                                                 expression_to_code_fragments,
                                                 math_header)

__all__ = ["compile_subdomains",]

_map_args = ["x", "y"]

_subdomain_template = """
class %(classname)s: public SubDomain
{
public:
%(members)s

  %(classname)s()
  {
%(constructor)s
  }

  /// Return true for points inside the sub domain
  bool inside(const Array<double>& x, bool on_boundary) const
  {
    %(inside)s
  }

};
"""

# TODO: Support implementation of map as well
"""
  /// Map coordinate x in domain H to coordinate y in domain G (used for periodic boundary conditions)
  void map(const Array<double>& x, Array<double>& y) const
  {
    %(map)s
  }
"""

def expression_to_subdomain(expr, classname):
    """
    Generate code for a :py:class:`SubDomain <dolfin.cpp.SubDomain>`
    subclass for a single expression.
    """

    # Assure we have a simple string expression
    assert isinstance(expr, str)

    # Extract code fragments from the expr and defaults
    fragments, members = expression_to_code_fragments(\
        [expr], ["x", "on_boundary","DOLFIN_EPS"])
    
    # Generate code for inside()
    insidecode = "  return %s;" % expr
    
    # Generate code for map()
    #mapcode = "..."

    # Connect the code fragments using the function template code
    fragments["classname"] = classname
    fragments["inside"]    = insidecode
    #fragments["map"]       = mapcode
    code = _subdomain_template % fragments
    return code, members

def compile_subdomain_code(code, classnames = None):
    # Autodetect classnames:

    _classnames = re.findall(r"class[ ]+([\w]+).*", code)

    # Just a little assertion for safety:
    if classnames is None:
        classnames = _classnames
    else:
        assert all(a == b for (a,b) in zip(classnames, _classnames))

    # Complete the code
    code = math_header + \
"""
namespace dolfin
{
""" + code + \
"""
}
"""

    # Compile the extension module
    compiled_module = compile_extension_module(\
                                code,
                                dolfin_module_import=["common","mesh","function"])

    # Construct instances of the compiled subdomain classes
    subdomains = [getattr(compiled_module, name)() for name in classnames]
    return subdomains

def compile_subdomains(expressions):
    """
    Compile C++ string expressions into
    :py:class:`SubDomain <dolfin.cpp.SubDomain>` instances.

    *Arguments*
        expressions
            a string or a list of strings containing expressions
            in C++ syntax.

    If ``expressions`` is a 'str', it is interpreted as a C++ string
    with complete implementations of subclasses of
    :py:class:`SubDomain <dolfin.cpp.SubDomain>`.
    The compiled subdomains returned will be in the same order
    as they are defined in this code.

    If it is a list, each item of the list is interpreted as
    a logical 'inside' expression, and the compiled subdomains
    returned will be in the same order as they occur in this list.

    If an expression string contains a name, it is assumed to
    be a scalar variable name, and is added as a public member
    of the generated subdomain.

    The exceptions are set in the
    variable dolfin.compile_subdomains._builtins.

    *Examples of usage*

        .. code-block:: python

            left  = compile_subdomains("x[0] == 0")
            right = compile_subdomains("x[1] == 1")

        or equivalently using a list of strings

        .. code-block:: python

            bc = compile_subdomains(["x[0] == 0", "x[1] == 1"])

    """

    #, which contains:
    #    %s
    #""" % "\n".join("        " + b for b in _builtins)
    if not isinstance(expressions, (list, str)):
        raise TypeError, "expected a list of 'str' or a 'str'"
    if isinstance(expressions, str):
        expressions = [expressions]
    if not all(isinstance(expr, str) for expr in expressions):
        raise TypeError, "expected a list of 'str' or a 'str'"
    all_code = []
    all_members = []
    classnames = []
    for i, expr in enumerate(expressions):
        classname = "SubDomain_" + hashlib.md5(expr).hexdigest()
        code, members = expression_to_subdomain(expr, classname)
        all_code.append(code)
        all_members.append(members)
        classnames.append(classname)
    subdomains = compile_subdomain_code("\n".join(all_code), classnames)

    # FIXME: Use all_members to add some handling of defaults
    if len(subdomains) == 1:
        return subdomains[0]
    return subdomains


if __name__ == "__main__":
    subdomains = compile_subdomains(["x[0] >= 1.0-DOLFIN_EPS", "on_boundary && x[1] < xlen+DOLFIN_EPS"])
    print subdomains