Perform type-checking in CI

.github/workflows/ci.yml

@@ -3,14 +3,14 @@ on: [push, pull_request]
 
 jobs:
   build:
-
     runs-on: ubuntu-18.04
     strategy:
       matrix:
-        python-version: [2.7, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, pypy2, pypy3]
+        python-version: [2.7, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, pypy2, pypy3]
 
     steps:
-    - uses: actions/checkout@v2
+    - name: Check out code
+      uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with:
@@ -33,3 +33,29 @@ jobs:
          git status
          exit 1
         fi
+
+  typecheck:
+    runs-on: ubuntu-18.04
+    strategy:
+      matrix:
+        python-version: [3.5, 3.6, 3.7, 3.8, 3.9]
+
+    steps:
+    - name: Check out code
+      uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install protobuf mypy
+    - name: Add typing imports
+      run: |
+        for file in $(find . -name \*.py); do
+          printf '%s\n%s\n' "from typing import Callable, Dict, List, Optional, Sequence, Set" "$(cat $file)" >$file
+        done
+    - name: Run mypy
+      run: |
+        (cd python && mypy phonenumbers --exclude phonenumbers/pb2 --show-error-codes)

python/phonenumbers/carrierdata/__init__.py

@@ -18,7 +18,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-CARRIER_DATA = {}
+CARRIER_DATA = {}  #  # type: Dict[str, Sequence[str]]
 from .data0 import data
 CARRIER_DATA.update(data)
 from .data1 import data

python/phonenumbers/geodata/__init__.py

@@ -18,7 +18,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-GEOCODE_DATA = {}
+GEOCODE_DATA = {}  #  # type: Dict[str, Sequence[str]]
 from .data0 import data
 GEOCODE_DATA.update(data)
 from .data1 import data

python/phonenumbers/phonemetadata.py

@@ -254,23 +254,24 @@ class PhoneMetadata(UnicodeMixin, ImmutableMixin):
     # The modificiation involves loading data from a file, so we cannot just
     # rely on the GIL.
     _metadata_lock = threading.Lock()
-    # If a region code is a key in this dict, metadata for that region is available.
+    # If a region code (ISO 3166-1 alpha 2) is a key in this dict, metadata for that region is available.
     # The corresponding value of the map is either:
     #   - a function which loads the region's metadata
     #   - None, to indicate that the metadata is already loaded
-    _region_available = {}  # ISO 3166-1 alpha 2 => function or None
+    _region_available = {}  # type: Dict[str, Optional[Callable[[str], None]]]
     # Likewise for short number metadata.
-    _short_region_available = {}  # ISO 3166-1 alpha 2 => function or None
-    # Likewise for non-geo country calling codes.
-    _country_code_available = {}  # country calling code (as int) => function or None
+    _short_region_available = {}  # type: Dict[str, Optional[Callable[[str], None]]]
+    # Likewise for non-geo country calling codes (indexed by country calling code as int)
+    _country_code_available = {}  # type: Dict[str, Optional[Callable[[int], None]]]
 
-    _region_metadata = {}  # ISO 3166-1 alpha 2 => PhoneMetadata
-    _short_region_metadata = {}  # ISO 3166-1 alpha 2 => PhoneMetadata
+    # PhoneMetadata indexed by ISO 3166-1 alpha 2.
+    _region_metadata = {}  # type: Dict[str, PhoneMetadata]
+    _short_region_metadata = {}  # type: Dict[str, PhoneMetadata]
     # A mapping from a country calling code for a non-geographical entity to
     # the PhoneMetadata for that country calling code. Examples of the country
     # calling codes include 800 (International Toll Free Service) and 808
     # (International Shared Cost Service).
-    _country_code_metadata = {}  # country calling code (as int) => PhoneMetadata
+    _country_code_metadata = {}  # type: Dict[int, PhoneMetadata]
 
     @classmethod
     def metadata_for_region(kls, region_code, default=None):

python/phonenumbers/phonenumberutil.py

@@ -516,9 +516,9 @@ class ValidationResult(object):
 
 
 # Derived data structures
-SUPPORTED_REGIONS = set()
-COUNTRY_CODES_FOR_NON_GEO_REGIONS = set()
-_NANPA_REGIONS = set()
+SUPPORTED_REGIONS = set()  # type: Set[str]
+COUNTRY_CODES_FOR_NON_GEO_REGIONS = set()  # type: Set[int]
+_NANPA_REGIONS = set()  # type: Set[str]
 
 
 def _regenerate_derived_data():

python/phonenumbers/timezone.py

@@ -49,7 +49,7 @@
     if (os.path.basename(sys.argv[0]) == "buildmetadatafromxml.py" or
         os.path.basename(sys.argv[0]) == "buildprefixdata.py"):
         prnt("Failed to import generated data (but OK as during autogeneration)", file=sys.stderr)
-        TIMEZONE_DATA = {'4411': u('Europe/London')}
+        TIMEZONE_DATA = {'4411': (u('Europe/London'),)}
         TIMEZONE_LONGEST_PREFIX = 4
     else:
         raise

python/phonenumbers/tzdata/__init__.py

@@ -18,7 +18,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-TIMEZONE_DATA = {}
+TIMEZONE_DATA = {}  #  # type: Dict[str, Sequence[str]]
 from .data0 import data
 TIMEZONE_DATA.update(data)
 del data

python/phonenumbers/unicode_util.py

@@ -72,7 +72,6 @@
 """
 import bisect
 import unicodedata
-
 from .util import UnicodeMixin, unicod, u
 
 
@@ -159,8 +158,10 @@ def __unicode__(self):
 class Block(object):
     """Description of the possible Unicode blocks"""
 
-    _RANGES = {}  # lower end of range => _BlockRange object
-    _RANGE_KEYS = None  # sorted list of _RANGES.keys()
+    # Map lower end of range to _BlockRange object
+    _RANGES = {}  # type: Dict[int, _BlockRange]
+    # Sorted list of _RANGES.keys()
+    _RANGE_KEYS = None  # type: Optional[List[int]]
 
     # Taken from http://www.unicode.org/Public/UNIDATA/Blocks.txt
     BASIC_LATIN = _BlockRange(0x0000, 0x007F, _RANGES)

python/tests/testcarrierdata/__init__.py

@@ -18,7 +18,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-CARRIER_DATA = {}
+CARRIER_DATA = {}  #  # type: Dict[str, Sequence[str]]
 from .data0 import data
 CARRIER_DATA.update(data)
 del data

python/tests/testgeodata/__init__.py

@@ -18,7 +18,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-GEOCODE_DATA = {}
+GEOCODE_DATA = {}  #  # type: Dict[str, Sequence[str]]
 from .data0 import data
 GEOCODE_DATA.update(data)
 del data

python/tests/testtzdata/__init__.py

@@ -18,7 +18,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-TIMEZONE_DATA = {}
+TIMEZONE_DATA = {}  #  # type: Dict[str, Sequence[str]]
 from .data0 import data
 TIMEZONE_DATA.update(data)
 del data

tools/python/buildprefixdata.py

@@ -192,7 +192,7 @@ def output_prefixdata_code(prefixdata, outfilename, module_prefix, varprefix, pe
         else:
             prnt(PREFIXDATA_FILE_PROLOG % {'module': module_prefix}, file=outfile)
         prnt(COPYRIGHT_NOTICE, file=outfile)
-        prnt("%s_DATA = {}" % varprefix, file=outfile)
+        prnt("%s_DATA = {}  #  # type: Dict[str, Sequence[str]]" % varprefix, file=outfile)
         for chunk_num in range(total_chunks):
             prnt("from .data%d import data" % chunk_num, file=outfile)
             prnt("%s_DATA.update(data)" % varprefix, file=outfile)