style: Tweak regen_atoms.py.

Specifically, give all the string templates the ''' form, and give them all
`_TEMPLATE` suffixes. This requires slightly changing the newline handling.

Bug: 1449787
Reviewed-by: emilio

components/style/gecko/regen_atoms.py

@@ -15,14 +15,6 @@
 
 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\(([^,]*),[^"]*"([^"]*)",\s*(0x[0-9a-f]+),\s*([^,]*),\s*([^)]*)\)',
@@ -144,73 +136,90 @@ def __exit__(self, type, value, traceback):
             self.close()
 
 
-IMPORTS = ("\nuse gecko_bindings::structs::nsStaticAtom;"
-           "\nuse string_cache::Atom;\n\n")
+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:]
+
+IMPORTS = '''
+use gecko_bindings::structs::nsStaticAtom;
+use string_cache::Atom;
 
-ATOM_TEMPLATE = ("            #[link_name = \"{link_name}\"]\n"
-                 "            pub static {name}: *mut {type};")
+'''
+
+UNSAFE_STATIC = '''
+#[inline(always)]
+pub unsafe fn atom_from_static(ptr: *mut nsStaticAtom) -> Atom {
+    Atom::from_static(ptr)
+}
+'''
 
-UNSAFE_STATIC = ("#[inline(always)]\n"
-                 "pub unsafe fn atom_from_static(ptr: *mut nsStaticAtom) -> Atom {\n"
-                 "    Atom::from_static(ptr)\n"
-                 "}\n\n")
+ATOM_TEMPLATE = '''
+            #[link_name = \"{link_name}\"]
+            pub static {name}: *mut {type};
+'''[1:]
 
-CFG_IF = '''
+CFG_IF_TEMPLATE = '''
 cfg_if! {{
     if #[cfg(not(target_env = "msvc"))] {{
         extern {{
-{gnu}
+{gnu}\
         }}
     }} else if #[cfg(target_pointer_width = "64")] {{
         extern {{
-{msvc64}
+{msvc64}\
         }}
     }} else {{
         extern {{
-{msvc32}
+{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 _) }}'
-                 ' }}}};')
+RULE_TEMPLATE = '''
+("{atom}") =>
+    {{{{
+        #[allow(unsafe_code)] #[allow(unused_unsafe)]
+        unsafe {{ $crate::string_cache::atom_macro::atom_from_static ($crate::string_cache::atom_macro::{name} as *mut _) }}
+    }}}};
+'''[1:]
 
-MACRO = '''
+MACRO_TEMPLATE = '''
 #[macro_export]
 macro_rules! atom {{
-{}
+{body}\
 }}
 '''
 
 
 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])
+        return ''.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("pub enum {} {{}}\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))
+        f.write(CFG_IF_TEMPLATE.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)))
+        f.write(MACRO_TEMPLATE.format(body=''.join(macro_rules)))
 
 
 def write_pseudo_elements(atoms, target_filename):