servo/components/style/gecko/regen_atoms.py

#!/usr/bin/env python

# 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 http://mozilla.org/MPL/2.0/.

import re
import os
import sys

from io import BytesIO

GECKO_DIR = os.path.dirname(__file__.replace('\\', '/'))
sys.path.insert(0, os.path.join(os.path.dirname(GECKO_DIR), "properties"))

import build

PRELUDE = """
/* 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 http://mozilla.org/MPL/2.0/. */

/* Autogenerated file created by components/style/gecko/regen_atoms.py, DO NOT EDIT DIRECTLY */
"""[1:]   # NOQA: E501


# Matches lines like `GK_ATOM(foo, "foo", 0x12345678, nsStaticAtom, PseudoElementAtom)`.
PATTERN = re.compile('^GK_ATOM\(([^,]*),[^"]*"([^"]*)",\s*(0x[0-9a-f]+),\s*([^,]*),\s*([^)]*)\)',
                     re.MULTILINE)
FILE = "include/nsGkAtomList.h"
CLASS = "nsGkAtoms"


def gnu_symbolify(ident):
    return "_ZN{}{}{}{}E".format(len(CLASS), CLASS, len(ident), ident)


def msvc64_symbolify(ident, ty):
    return "?{}@{}@@2PEAV{}@@EA".format(ident, CLASS, ty)


def msvc32_symbolify(ident, ty):
    # Prepend "\x01" to avoid LLVM prefixing the mangled name with "_".
    # See https://github.com/rust-lang/rust/issues/36097
    return "\\x01?{}@{}@@2PAV{}@@A".format(ident, CLASS, ty)


def map_atom(ident):
    if ident in {"box", "loop", "match", "mod", "ref",
                 "self", "type", "use", "where", "in"}:
        return ident + "_"
    return ident


class Atom:
    def __init__(self, ident, value, hash, ty, atom_type):
        self.ident = "{}_{}".format(CLASS, ident)
        self.original_ident = ident
        self.value = value
        self.hash = hash
        # The Gecko type: "nsStaticAtom", "nsICSSPseudoElement", or "nsIAnonBoxPseudo"
        self.ty = ty
        # The type of atom: "Atom", "PseudoElement", "NonInheritingAnonBox",
        # or "InheritingAnonBox"
        self.atom_type = atom_type
        if self.is_pseudo() or self.is_anon_box():
            self.pseudo_ident = (ident.split("_", 1))[1]
        if self.is_anon_box():
            assert self.is_inheriting_anon_box() or self.is_non_inheriting_anon_box()

    def gnu_symbol(self):
        return gnu_symbolify(self.original_ident)

    def msvc32_symbol(self):
        return msvc32_symbolify(self.original_ident, self.ty)

    def msvc64_symbol(self):
        return msvc64_symbolify(self.original_ident, self.ty)

    def type(self):
        return self.ty

    def capitalized_pseudo(self):
        return self.pseudo_ident[0].upper() + self.pseudo_ident[1:]

    def is_pseudo(self):
        return self.atom_type == "PseudoElementAtom"

    def is_anon_box(self):
        return self.is_non_inheriting_anon_box() or self.is_inheriting_anon_box()

    def is_non_inheriting_anon_box(self):
        return self.atom_type == "NonInheritingAnonBoxAtom"

    def is_inheriting_anon_box(self):
        return self.atom_type == "InheritingAnonBoxAtom"

    def is_tree_pseudo_element(self):
        return self.value.startswith(":-moz-tree-")


def collect_atoms(objdir):
    atoms = []
    path = os.path.abspath(os.path.join(objdir, FILE))
    print("cargo:rerun-if-changed={}".format(path))
    with open(path) as f:
        content = f.read()
        for result in PATTERN.finditer(content):
            atoms.append(Atom(result.group(1), result.group(2), result.group(3),
                              result.group(4), result.group(5)))
    return atoms


class FileAvoidWrite(BytesIO):
    """File-like object that buffers output and only writes if content changed."""
    def __init__(self, filename):
        BytesIO.__init__(self)
        self.name = filename

    def write(self, buf):
        if isinstance(buf, unicode):
            buf = buf.encode('utf-8')
        BytesIO.write(self, buf)

    def close(self):
        buf = self.getvalue()
        BytesIO.close(self)
        try:
            with open(self.name, 'rb') as f:
                old_content = f.read()
                if old_content == buf:
                    print("{} is not changed, skip".format(self.name))
                    return
        except IOError:
            pass
        with open(self.name, 'wb') as f:
            f.write(buf)

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        if not self.closed:
            self.close()


IMPORTS = ("\nuse gecko_bindings::structs::nsStaticAtom;"
           "\nuse string_cache::Atom;\n\n")

ATOM_TEMPLATE = ("            #[link_name = \"{link_name}\"]\n"
                 "            pub static {name}: *mut {type};")

UNSAFE_STATIC = ("#[inline(always)]\n"
                 "pub unsafe fn atom_from_static(ptr: *mut nsStaticAtom) -> Atom {\n"
                 "    Atom::from_static(ptr)\n"
                 "}\n\n")

CFG_IF = '''
cfg_if! {{
    if #[cfg(not(target_env = "msvc"))] {{
        extern {{
{gnu}
        }}
    }} else if #[cfg(target_pointer_width = "64")] {{
        extern {{
{msvc64}
        }}
    }} else {{
        extern {{
{msvc32}
        }}
    }}
}}
'''

RULE_TEMPLATE = ('("{atom}") =>\n  '
                 '{{{{ '
                 '#[allow(unsafe_code)] #[allow(unused_unsafe)]'
                 'unsafe {{ $crate::string_cache::atom_macro::atom_from_static'
                 '($crate::string_cache::atom_macro::{name} as *mut _) }}'
                 ' }}}};')

MACRO = '''
#[macro_export]
macro_rules! atom {{
{}
}}
'''


def write_atom_macro(atoms, file_name):
    def get_symbols(func):
        return '\n'.join([ATOM_TEMPLATE.format(name=atom.ident,
                                               link_name=func(atom),
                                               type=atom.type()) for atom in atoms])

    with FileAvoidWrite(file_name) as f:
        f.write(PRELUDE)
        f.write(IMPORTS)

        for ty in sorted(set([atom.type() for atom in atoms])):
            if ty != "nsStaticAtom":
                f.write("pub enum {} {{}}\n\n".format(ty))

        f.write(UNSAFE_STATIC)

        gnu_symbols = get_symbols(Atom.gnu_symbol)
        msvc32_symbols = get_symbols(Atom.msvc32_symbol)
        msvc64_symbols = get_symbols(Atom.msvc64_symbol)
        f.write(CFG_IF.format(gnu=gnu_symbols, msvc32=msvc32_symbols, msvc64=msvc64_symbols))

        macro_rules = [RULE_TEMPLATE.format(atom=atom.value, name=atom.ident) for atom in atoms]
        f.write(MACRO.format('\n'.join(macro_rules)))


def write_pseudo_elements(atoms, target_filename):
    pseudos = []
    for atom in atoms:
        if atom.type() == "nsICSSPseudoElement" or atom.type() == "nsICSSAnonBoxPseudo":
            pseudos.append(atom)

    pseudo_definition_template = os.path.join(GECKO_DIR, "pseudo_element_definition.mako.rs")
    print("cargo:rerun-if-changed={}".format(pseudo_definition_template))
    contents = build.render(pseudo_definition_template, PSEUDOS=pseudos)

    with FileAvoidWrite(target_filename) as f:
        f.write(contents)


def generate_atoms(dist, out):
    atoms = collect_atoms(dist)
    write_atom_macro(atoms, os.path.join(out, "atom_macro.rs"))
    write_pseudo_elements(atoms, os.path.join(out, "pseudo_element_definition.rs"))


if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: {} dist out".format(sys.argv[0]))
        exit(2)
    generate_atoms(sys.argv[1], sys.argv[2])