loxi_utils/loxi_utils.py

# Copyright 2013, Big Switch Networks, Inc.
#
# LoxiGen is licensed under the Eclipse Public License, version 1.0 (EPL), with
# the following special exception:
#
# LOXI Exception
#
# As a special exception to the terms of the EPL, you may distribute libraries
# generated by LoxiGen (LoxiGen Libraries) under the terms of your choice, provided
# that copyright and licensing notices generated by LoxiGen are not altered or removed
# from the LoxiGen Libraries and the notice provided below is (i) included in
# the LoxiGen Libraries, if distributed in source code form and (ii) included in any
# documentation for the LoxiGen Libraries, if distributed in binary form.
#
# Notice: "Copyright 2013, Big Switch Networks, Inc. This library was generated by the LoxiGen Compiler."
#
# You may not use this file except in compliance with the EPL or LOXI Exception. You may obtain
# a copy of the EPL at:
#
# http://www.eclipse.org/legal/epl-v10.html
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# EPL for the specific language governing permissions and limitations
# under the EPL.

"""
@brief Utilities involving LOXI naming conventions

Utility functions for OpenFlow class generation

These may need to be sorted out into language specific functions
"""

import sys
import of_g
import tenjin

def class_signature(members):
    """
    Generate a signature string for a class in canonical form

    @param cls The class whose signature is to be generated
    """
    return ";".join([",".join([x["m_type"], x["name"], str(x["offset"])])
                     for x in members])

def type_dec_to_count_base(m_type):
    """
    Resolve a type declaration like uint8_t[4] to a count (4) and base_type
    (uint8_t)

    @param m_type The string type declaration to process
    """
    count = 1
    chk_ar = m_type.split('[')
    if len(chk_ar) > 1:
        count_str = chk_ar[1].split(']')[0]
        if count_str in of_g.ofp_constants:
            count = of_g.ofp_constants[count_str]
        else:
            count = int(count_str)
        base_type = chk_ar[0]
    else:
        base_type = m_type
    return count, base_type

##
# Class types:
#
# Virtual
#    A virtual class is one which does not have an explicit wire
#    representation.  For example, an inheritance super class
#    or a list type.
#
# List
#    A list of objects of some other type
#
# TLV16
#    The wire represenation starts with 16-bit type and length fields
#
# OXM
#    An extensible match object
#
# Message
#    A top level OpenFlow message
#
#

def class_is_message(cls):
    """
    Return True if cls is a message object based on info in unified
    """
    return "xid" in of_g.unified[cls]["union"] and cls != "of_header"

def class_is_tlv16(cls):
    """
    Return True if cls_name is an object which uses uint16 for type and length
    """
    if cls.find("of_action") == 0: # Includes of_action_id classes
        return True
    if cls.find("of_instruction") == 0:
        return True
    if cls.find("of_queue_prop") == 0:
        return True
    if cls.find("of_table_feature_prop") == 0:
        return True
    # *sigh*
    if cls.find("of_meter_band_stats") == 0:  # NOT A TLV
        return False
    if cls.find("of_meter_band") == 0:
        return True
    if cls.find("of_hello_elem") == 0:
        return True
    if cls == "of_match_v3":
        return True
    if cls == "of_match_v4":
        return True
    return False

def class_is_u16_len(cls):
    """
    Return True if cls_name is an object which uses initial uint16 length
    """
    return cls in ["of_group_desc_stats_entry", "of_group_stats_entry",
                   "of_flow_stats_entry", "of_bucket", "of_table_features"]

def class_is_oxm(cls):
    """
    Return True if cls_name is an OXM object
    """
    if cls.find("of_oxm") == 0:
        return True
    return False

def class_is_action(cls):
    """
    Return True if cls_name is an action object

    Note that action_id is not an action object, though it has
    the same header.  It looks like an action header, but the type
    is used to identify a kind of action, it does not indicate the
    type of the object following.
    """
    if cls.find("of_action_id") == 0:
        return False
    if cls.find("of_action") == 0:
        return True

    # For each vendor, check for vendor specific action
    for exp in of_g.experimenter_name_to_id:
        if cls.find("of_action" + exp) == 0:
            return True

    return False

def class_is_action_id(cls):
    """
    Return True if cls_name is an action object

    Note that action_id is not an action object, though it has
    the same header.  It looks like an action header, but the type
    is used to identify a kind of action, it does not indicate the
    type of the object following.
    """
    if cls.find("of_action_id") == 0:
        return True

    # For each vendor, check for vendor specific action
    for exp in of_g.experimenter_name_to_id:
        if cls.find("of_action_id_" + exp) == 0:
            return True

    return False

def class_is_instruction(cls):
    """
    Return True if cls_name is an instruction object
    """
    if cls.find("of_instruction") == 0:
        return True

    # For each vendor, check for vendor specific action
    for exp in of_g.experimenter_name_to_id:
        if cls.find("of_instruction_" + exp) == 0:
            return True

    return False

def class_is_meter_band(cls):
    """
    Return True if cls_name is an instruction object
    """
    # meter_band_stats is not a member of meter_band class hierarchy
    if cls.find("of_meter_band_stats") == 0:
        return False
    if cls.find("of_meter_band") == 0:
        return True
    return False

def class_is_hello_elem(cls):
    """
    Return True if cls_name is an instruction object
    """
    if cls.find("of_hello_elem") == 0:
        return True
    return False

def class_is_queue_prop(cls):
    """
    Return True if cls_name is a queue_prop object
    """
    if cls.find("of_queue_prop") == 0:
        return True

    # For each vendor, check for vendor specific action
    for exp in of_g.experimenter_name_to_id:
        if cls.find("of_queue_prop_" + exp) == 0:
            return True

    return False

def class_is_table_feature_prop(cls):
    """
    Return True if cls_name is a queue_prop object
    """
    if cls.find("of_table_feature_prop") == 0:
        return True
    return False

def class_is_stats_message(cls):
    """
    Return True if cls_name is a message object based on info in unified
    """

    return "stats_type" in of_g.unified[cls]["union"]

def class_is_list(cls):
    """
    Return True if cls_name is a list object
    """
    return (cls.find("of_list_") == 0)

def type_is_of_object(m_type):
    """
    Return True if m_type is an OF object type
    """
    # Remove _t from the type id and see if key for unified class
    if m_type[-2:] == "_t":
        m_type = m_type[:-2]
    return m_type in of_g.unified

def list_to_entry_type(cls):
    """
    Return the entry type for a list
    """
    slen = len("of_list_")
    return "of_" + cls[slen:]

def type_to_short_name(m_type):
    if m_type in of_g.of_base_types:
        tname = of_g.of_base_types[m_type]["short_name"]
    elif m_type in of_g.of_mixed_types:
        tname = of_g.of_mixed_types[m_type]["short_name"]
    else:
        tname = "unknown"
    return tname

def type_to_name_type(cls, member_name):
    """
    Generate the root name of a member for accessor functions, etc
    @param cls The class name
    @param member_name The member name
    """
    members = of_g.unified[cls]["union"]
    if not member_name in members:
        debug("Error:  %s is not in class %s for acc_name defn" %
              (member_name, cls))
        os.exit()

    mem = members[member_name]
    m_type = mem["m_type"]
    id = mem["memid"]
    tname = type_to_short_name(m_type)

    return "o%d_m%d_%s" % (of_g.unified[cls]["object_id"], id, tname)


def member_to_index(m_name, members):
    """
    Given a member name, return the index in the members dict
    @param m_name The name of the data member to search for
    @param members The dict of members
    @return Index if found, -1 not found

    Note we could generate an index when processing the original input
    """
    count = 0
    for d in members:
        if d["name"] == m_name:
            return count
        count += 1
    return -1

def member_base_type(cls, m_name):
    """
    Map a member to its of_ type
    @param cls The class name
    @param m_name The name of the member being gotten
    @return The of_ type of the member
    """
    rv = of_g.unified[cls]["union"][m_name]["m_type"]
    if rv[-2:] == "_t":
        return rv
    return rv + "_t"

def member_type_is_octets(cls, m_name):
    return member_base_type(cls, m_name) == "of_octets_t"

def member_returns_val(cls, m_name):
    """
    Should get accessor return a value rather than void
    @param cls The class name
    @param m_name The member name
    @return True if of_g config and the specific member allow a
    return value.  Otherwise False
    """
    m_type = of_g.unified[cls]["union"][m_name]["m_type"]
    return (config_check("get_returns") =="value" and
            m_type in of_g.of_scalar_types)

def config_check(str, dictionary = of_g.code_gen_config):
    """
    Return config value if in dictionary; else return False.
    @param str The lookup index
    @param dictionary The dict to check; use code_gen_config if None
    """

    if str in dictionary:
        return dictionary[str]

    return False

def h_file_to_define(name):
    """
    Convert a .h file name to the define used for the header
    """
    h_name = name[:-2].upper()
    h_name = "_" + h_name + "_H_"
    return h_name

def type_to_cof_type(m_type):
    if m_type in of_g.of_base_types:
        if "cof_type" in of_g.of_base_types[m_type]:
            return of_g.of_base_types[m_type]["cof_type"]
    return m_type


def member_is_scalar(cls, m_name):
    return of_g.unified[cls]["union"][m_name]["m_type"] in of_g.of_scalar_types

def type_is_scalar(m_type):
    return m_type in of_g.of_scalar_types

def skip_member_name(name):
    return name.find("pad") == 0 or name in of_g.skip_members

def enum_name(cls):
    """
    Return the name used for an enum identifier for the given class
    @param cls The class name
    """
    return cls.upper()

def class_in_version(cls, ver):
    """
    Return boolean indicating if cls is defined for wire version ver
    """

    return (cls, ver) in of_g.base_length

def instance_to_class(instance, parent):
    """
    Return the name of the class for an instance of inheritance type parent
    """
    return parent + "_" + instance

def sub_class_to_var_name(cls):
    """
    Given a subclass name like of_action_output, generate the
    name of a variable like 'output'
    @param cls The class name
    """
    pass

def class_is_var_len(cls, version):
    # Match is special case.  Only version 1.2 (wire version 3) is var
    if cls == "of_match":
        return version == 3

    return not (cls, version) in of_g.is_fixed_length

def base_type_to_length(base_type, version):
    if base_type + "_t" in of_g.of_base_types:
        inst_len = of_g.of_base_types[base_type + "_t"]["bytes"]
    else:
        inst_len = of_g.base_length[(base_type, version)]

def version_to_name(version):
    """
    Convert an integer version to the C macro name
    """
    return "OF_" + of_g.version_names[version]

##
# Is class a flow modify of some sort?

def cls_is_flow_mod(cls):
    return cls in ["of_flow_modify", "of_flow_add", "of_flow_delete",
                   "of_flow_modify_strict", "of_flow_delete_strict"]


def all_member_types_get(cls, version):
    """
    Get the members and list of types for members of a given class
    @param cls The class name to process
    @param version The version for the class
    """
    member_types = []

    if not version in of_g.unified[cls]:
        return ([], [])

    if "use_version" in of_g.unified[cls][version]:
        v = of_g.unified[cls][version]["use_version"]
        members = of_g.unified[cls][v]["members"]
    else:
        members = of_g.unified[cls][version]["members"]
    # Accumulate variables that are supported
    for member in members:
        m_type = member["m_type"]
        m_name = member["name"]
        if skip_member_name(m_name):
            continue
        if not m_type in member_types:
            member_types.append(m_type)

    return (members, member_types)

def list_name_extract(list_type):
    """
    Return the base name for a list object of the given type
    @param list_type The type of the list as appears in the input,
    for example list(of_port_desc_t).
    @return A pair, (list-name, base-type) where list-name is the
    base name for the list, for example of_list_port_desc, and base-type
    is the type of list elements like of_port_desc_t
    """
    base_type = list_type[5:-1]
    list_name = base_type
    if list_name.find("of_") == 0:
        list_name = list_name[3:]
    if list_name[-2:] == "_t":
        list_name = list_name[:-2]
    list_name = "of_list_" + list_name
    return (list_name, base_type)

def version_to_name(version):
    """
    Convert an integer version to the C macro name
    """
    return "OF_" + of_g.version_names[version]

def gen_c_copy_license(out):
    """
    Generate the top comments for copyright and license
    """
    import c_gen.util
    c_gen.util.render_template(out, '_copyright.c')

def accessor_returns_error(a_type, m_type):
    is_var_len = (not type_is_scalar(m_type)) and \
        [x for x in of_g.of_version_range if class_is_var_len(m_type[:-2], x)] != []
    if a_type == "set" and is_var_len:
        return True
    elif m_type == "of_match_t":
        return True
    else:
        return False

def render_template(out, name, path, context, prefix = None):
    """
    Render a template using tenjin.
    out: a file-like object
    name: name of the template
    path: array of directories to search for the template
    context: dictionary of variables to pass to the template
    prefix: optional prefix to use for embedding (for other languages than python)
    """
    pp = [ tenjin.PrefixedLinePreprocessor(prefix=prefix) if prefix else tenjin.PrefixedLinePreprocessor() ] # support "::" syntax
    template_globals = { "to_str": str, "escape": str } # disable HTML escaping
    engine = TemplateEngine(path=path, pp=pp)
    out.write(engine.render(name, context, template_globals))

def render_static(out, name, path):
    """
    Write out a static template.
    out: a file-like object
    name: name of the template
    path: array of directories to search for the template
    """
    # Reuse the tenjin logic for finding the template
    template_filename = tenjin.FileSystemLoader().find(name, path)
    if not template_filename:
        raise ValueError("template %s not found" % name)
    with open(template_filename) as infile:
        out.write(infile.read())

class TemplateEngine(tenjin.Engine):
    def include(self, template_name, **kwargs):
        """
        Tenjin has an issue with nested includes that use the same local variable
        names, because it uses the same context dict for each level of nesting.
        The fix is to copy the context.
        """
        frame = sys._getframe(1)
        locals  = frame.f_locals
        globals = frame.f_globals
        context = locals["_context"].copy()
        context.update(kwargs)
        template = self.get_template(template_name, context, globals)
        return template.render(context, globals, _buf=locals["_buf"])