Commit ded9fc28 authored by Marc-André Lureau's avatar Marc-André Lureau Committed by Markus Armbruster
Browse files

qapi: add #if/#endif helpers 



Add helpers to wrap generated code with #if/#endif lines.

A later patch wants to use QAPIGen for generating C snippets rather
than full C files with copyright headers etc.  Splice in class
QAPIGenCCode between QAPIGen and QAPIGenC.

Add a 'with' statement context manager that will be used to wrap
generator visitor methods.  The manager will check if code was
generated before adding #if/#endif lines on QAPIGenCSnippet
objects. Used in the following patches.

Signed-off-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180703155648.11933-7-marcandre.lureau@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
Signed-off-by: default avatarMarkus Armbruster <armbru@redhat.com>
parent 485d948c

scripts/qapi/common.py

+94 −4
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
# See the COPYING file in the top-level directory.



from __future__ import print_function

from contextlib import contextmanager

import errno

import os

import re
@@ -1974,6 +1975,40 @@ def guardend(name): 
                 name=guardname(name))





def gen_if(ifcond):

    ret = ''

    for ifc in ifcond:

        ret += mcgen('''

#if %(cond)s

''', cond=ifc)

    return ret





def gen_endif(ifcond):

    ret = ''

    for ifc in reversed(ifcond):

        ret += mcgen('''

#endif /* %(cond)s */

''', cond=ifc)

    return ret





def _wrap_ifcond(ifcond, before, after):

    if before == after:

        return after   # suppress empty #if ... #endif



    assert after.startswith(before)

    out = before

    added = after[len(before):]

    if added[0] == '\n':

        out += '\n'

        added = added[1:]

    out += gen_if(ifcond)

    out += added

    out += gen_endif(ifcond)

    return out





def gen_enum_lookup(name, values, prefix=None):

    ret = mcgen('''
@@ -2071,6 +2106,10 @@ class QAPIGen(object): 
    def add(self, text):

        self._body += text



    def get_content(self, fname=None):

        return (self._top(fname) + self._preamble + self._body

                + self._bottom(fname))



    def _top(self, fname):

        return ''
@@ -2091,8 +2130,7 @@ class QAPIGen(object): 
            f = open(fd, 'r+', encoding='utf-8')

        else:

            f = os.fdopen(fd, 'r+')

        text = (self._top(fname) + self._preamble + self._body

                + self._bottom(fname))

        text = self.get_content(fname)

        oldtext = f.read(len(text) + 1)

        if text != oldtext:

            f.seek(0)
@@ -2101,10 +2139,62 @@ class QAPIGen(object): 
        f.close()





class QAPIGenC(QAPIGen):

@contextmanager

def ifcontext(ifcond, *args):

    """A 'with' statement context manager to wrap with start_if()/end_if()



    def __init__(self, blurb, pydoc):

    *args: any number of QAPIGenCCode



    Example::



        with ifcontext(ifcond, self._genh, self._genc):

            modify self._genh and self._genc ...



    Is equivalent to calling::



        self._genh.start_if(ifcond)

        self._genc.start_if(ifcond)

        modify self._genh and self._genc ...

        self._genh.end_if()

        self._genc.end_if()

    """

    for arg in args:

        arg.start_if(ifcond)

    yield

    for arg in args:

        arg.end_if()





class QAPIGenCCode(QAPIGen):



    def __init__(self):

        QAPIGen.__init__(self)

        self._start_if = None



    def start_if(self, ifcond):

        assert self._start_if is None

        self._start_if = (ifcond, self._body, self._preamble)



    def end_if(self):

        assert self._start_if

        self._wrap_ifcond()

        self._start_if = None



    def _wrap_ifcond(self):

        self._body = _wrap_ifcond(self._start_if[0],

                                  self._start_if[1], self._body)

        self._preamble = _wrap_ifcond(self._start_if[0],

                                      self._start_if[2], self._preamble)



    def get_content(self, fname=None):

        assert self._start_if is None

        return QAPIGen.get_content(self, fname)





class QAPIGenC(QAPIGenCCode):



    def __init__(self, blurb, pydoc):

        QAPIGenCCode.__init__(self)

        self._blurb = blurb

        self._copyright = '\n * '.join(re.findall(r'^Copyright .*', pydoc,

                                                  re.MULTILINE))