descriptor.py

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# -*- python -*-
#                           Package   : omniidl
# descriptor.py             Created on: 2000/08/23
#			    Author    : David Scott (djs)
#
#    Copyright (C) 1999-2000 AT&T Laboratories Cambridge
#
#  This file is part of omniidl.
#
#  omniidl 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., 59 Temple Place - Suite 330, Boston, MA
#  02111-1307, USA.
#
# Description:
#   Produce internal descriptors
#

# $Id: descriptor.py,v 1.1.4.6 2003/10/23 11:55:12 dgrisby Exp $
# $Log: descriptor.py,v $
# Revision 1.1.4.6  2003/10/23 11:55:12  dgrisby
# Fix hex_word for Python 1.5.2.
#
# Revision 1.1.4.5  2003/08/21 15:06:03  dgrisby
# Avoid spurious Python 2.3 complaints about unsigned long integers.
#
# Revision 1.1.4.4  2001/06/08 17:12:12  dpg1
# Merge all the bug fixes from omni3_develop.
#
# Revision 1.1.4.3  2001/03/26 11:11:54  dpg1
# Python clean-ups. Output routine optimised.
#
# Revision 1.1.4.2  2001/03/13 10:34:01  dpg1
# Minor Python clean-ups
#
# Revision 1.1.4.1  2000/10/12 15:37:47  sll
# Updated from omni3_1_develop.
#
# Revision 1.1.2.1  2000/09/14 16:03:02  djs
# Remodularised C++ descriptor name generator
# Bug in listing all inherited interfaces if one is a forward
# repoID munging function now handles #pragma ID in bootstrap.idl
# Naming environments generating code now copes with new IDL AST types
# Modified type utility functions
# Minor tidying
#

from omniidl import idlvisitor, idlast
from omniidl_be.cxx import config, id, ast
import string

# All descriptors are of the form:
#  TAG _ PREFIX _ BASE
# TAG:    groups descriptors by type (eg context, call descriptor, callback)
# PREFIX: derived from a hash of the first callable in the IDL
# BASE:   counter added  to guarantee uniqueness

# There are two categories of descriptors.
#  o Signature dependent (where there is only one instance per operation
#    signature, which can be shared by multiple interfaces) eg normal
#    call descriptors.
#  o Interface & operation dependent eg local callback functions


def __init__(ast):
    global prefix, counter, signature_descriptors, iface_descriptors

    prefix  = ""
    counter = 0

    # Descriptors keyed by signature alone
    signature_descriptors = {}

    # Descriptors keyed by interface and operation name (a two level
    # hashtable)
    iface_descriptors = {}

    # initialise the prefix
    HV = HashVisitor()
    ast.accept(HV)

def call_descriptor(signature):
    return private_prefix + "_cd_" + get_signature_descriptor(signature)

def context_descriptor(signature):
    return private_prefix + "_ctx_" + get_signature_descriptor(signature)

def local_callback_fn(iname, operation_name, signature):
    return private_prefix + "_lcfn_" +\
       get_interface_operation_descriptor(iname, operation_name, signature)


####################################################################
## Internals

private_prefix = config.state['Private Prefix']

# Walks over the AST, finds the first callable and creates the prefix hash
class HashVisitor(idlvisitor.AstVisitor):

    def __init__(self):
        self.base_initialised = 0
    
    def visitAST(self, node):
        for declaration in node.declarations():
            if self.base_initialised:
                return
            if ast.shouldGenerateCodeForDecl(declaration):
                declaration.accept(self)

    def visitModule(self, node):
        for definition in node.definitions():
            if self.base_initialised:
                return
            definition.accept(self)

    def visitInterface(self, node):
        if node.callables() != []:
            name = node.scopedName()

            # Use an op first if available
            for c in node.callables():
                if isinstance(c, idlast.Operation):
                    self.initialise_base(name + [c.identifier()])
                    return

            # Use first attribute
            self.initialise_base(name + [node.callables()[0].identifiers()[0]])

    # Knuth-style string -> int hash
    def initialise_base(self, name):
        if self.base_initialised: return
        self.base_initialised = 1
        
        string_seed = id.Name(name).guard()
    
        # equivalent to >> only without sign extension
        # (python uses 2's complement signed arithmetic)
        def rshift(x, distance):
            sign_bit = x & 0x80000000L
            # remove the sign bit to make it unsigned
            x = x & 0x7fffffffL
            # perform shift (thinks number is unsigned, no extension)
            x = x >> distance
            # add sign bit back in
            if sign_bit:
                x = x | (1 << (32 - distance -1))
            return x

        def lshift(x, distance):
            # same as non-sign extended case
            return (x << distance) & 0xffffffffL

        high = low = 0L
        for char in string_seed:
            tmp  = rshift((high & 0xfe000000L), 25)
            high = (lshift(high, 7)) ^ (rshift((low & 0xfe000000L), 25))
            low  = lshift(low, 7) ^ tmp
            low  = low ^ (ord(char))

        high = list(hex_word(high))
        low  = list(hex_word(low))

        high.reverse()
        low.reverse()
        
        global prefix
        prefix = string.join(high + low, "")


# Return a unique PREFIX + BASE
def unique():
    global counter
    clist = list(hex_word(counter))
    clist.reverse()

    name = prefix + "_" + string.join(clist, "")
    counter = counter + 1
    
    return name


def get_signature_descriptor(signature):
    global signature_descriptors
    
    if not signature_descriptors.has_key(signature):
        signature_descriptors[signature] = unique()

    return signature_descriptors[signature]

def get_interface_operation_descriptor(iname, operation_name, signature):
    global iface_descriptors

    assert isinstance(iname, id.Name)

    key = iname.hash()
    if not iface_descriptors.has_key(key):
        iface_descriptors[key] = {}

    iface_table = iface_descriptors[key]
    
    key = signature + "/" + operation_name
    if iface_table.has_key(key):
        return iface_table[key]
    
    descriptor = unique()
    iface_table[key] = descriptor
    return descriptor


# Takes an int and returns the int in hex, without leading 0x and with
# 0s padding. Can't use %08x because Python 1.5.2 can't do it with
# longs >= 2**31.

def hex_word(x):
    s = hex(x)[2:]
    if s[-1] == "L":
        s = s[:-1]
    return string.zfill(s, 8)