author Nika Layzell <>
Tue, 25 Sep 2018 17:34:53 +0200
changeset 504874 e0f95dd96d5458f60980f1e8b3f846beed6e5817
parent 504105 b6c97b4db60a1d8169a3e798a248144ab2973506
child 542190 9c5b3c7e1ca2240f765d62466cc917ad778407ef
permissions -rw-r--r--
Bug 1448426 - Wrap windows.h to avoid problematic define statements, r=froydnj,glandium By default, windows.h exposes a large number of problematic define statements which are UpperCamelCase, such as a define from `CreateWindow` to `CreateWindow{A,W}`. As many of these names are generic (e.g. CreateFile, CreateWindow), they can mess up Gecko code that may legitimately have its own methods with the same names. The header also defines some traditional SCREAMING_SNAKE_CASE defines which can mess up our code by conflicting with local values. This patch adds a simple code generator which generates wrappers for these defines, and uses them to wrap the windows.h wrapper using the `stl_wrappers` mechanism, allowing us to use windows.h in more places. Differential Revision:

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at

import re
import textwrap
import string
from system_header_util import header_path

comment_re = re.compile(r'//[^\n]*\n|/\*.*\*/', re.S)
decl_re = re.compile(r'''^(.+)\s+        # type
                         (\w+)\s*        # name
                         (?:\((.*)\))?$  # optional param tys
                         ''', re.X | re.S)

def read_decls(filename):
    """Parse & yield C-style decls from an input file"""
    with open(filename, 'r') as fd:
        # Strip comments from the source text.
        text = comment_re.sub('',

        # Parse individual declarations.
        raw_decls = [d.strip() for d in text.split(';') if d.strip()]
        for raw in raw_decls:
            match = decl_re.match(raw)
            if match is None:
                raise "Invalid decl: %s" % raw

            ty, name, params = match.groups()
            if params is not None:
                params = [a.strip() for a in params.split(',') if a.strip()]
            yield ty, name, params

def generate(fd, consts_path, unicodes_path, template_path, compiler):
    # Parse the template
    with open(template_path, 'r') as template_fd:
        template = string.Template(

    decls = ''

    # Each constant should be saved to a temporary, and then re-assigned to a
    # constant with the correct name, allowing the value to be determined by
    # the actual definition.
    for ty, name, args in read_decls(consts_path):
        assert args is None, "parameters in const decl!"

        decls += textwrap.dedent("""
            #ifdef {name}
            constexpr {ty} _tmp_{name} = {name};
            #undef {name}
            constexpr {ty} {name} = _tmp_{name};
            """.format(ty=ty, name=name))

    # Each unicode declaration defines a static inline function with the
    # correct types which calls the 'A' or 'W'-suffixed versions of the
    # function. Full types are required here to ensure that '0' to 'nullptr'
    # coersions are preserved.
    for ty, name, args in read_decls(unicodes_path):
        assert args is not None, "argument list required for unicode decl"

        # Parameter & argument string list
        params = ', '.join('%s a%d' % (ty, i) for i, ty in enumerate(args))
        args = ', '.join('a%d' % i for i in range(len(args)))

        decls += textwrap.dedent("""
            #ifdef {name}
            #undef {name}
            static inline {ty} WINAPI
            #ifdef UNICODE
              return {name}W({args});
              return {name}A({args});
            """.format(ty=ty, name=name, params=params, args=args))

    path = header_path('windows.h', compiler)

    # Write out the resulting file
    fd.write(template.substitute(header_path=path, decls=decls))