scripts: no need for pytz to generate tz list

code/scripts/format_tzdata.py

@@ -1,10 +1,19 @@
 import argparse
 import mmap
 import os
-import pytz
+import pathlib
 import re
 import sys
 
+from importlib import resources
+
+import tzdata  # https://tzdata.readthedocs.io/en/latest/
+
+
+def tzdata_version():
+    return f"Generated with *{tzdata.IANA_VERSION=} {tzdata.__version__=}*"
+
+
 def maybe_fix_value(value):
     return re.sub(r"<[^>]*>", "UNK", value)
 
@@ -27,11 +36,27 @@ def utc_alias(zone):
     )
 
 
-def zones(root):
+def tzdata_resource_from_name(name):
+    pair = name.rsplit("/", 1)
+    if len(pair) == 1:
+        return resources.files("tzdata.zoneinfo") / pair[0]
+
+    return resources.files(f'tzdata.zoneinfo.{pair[0].replace("/", ".")}') / pair[1]
+
+
+def make_zones_list(zones):
+    with open(zones, "r") as f:
+        zones = [zone.strip() for zone in f.readlines()]
+
+    return zones
+
+
+def make_zones(args):
     out = []
 
-    for zone in pytz.all_timezones_set:
-        with open(os.path.join(root, zone), "rb") as f:
+    for zone in make_zones_list(args.zones):
+        target = tzdata_resource_from_name(zone)
+        with tzdata_resource_from_name(zone).open("rb") as f:
             magic = f.read(4)
             if magic != b"TZif":
                 continue
@@ -50,7 +75,7 @@ def zones(root):
     return out
 
 
-def table(zones):
+def markdown(zones):
     utcs = []
     rows = []
 
@@ -79,16 +104,40 @@ def table(zones):
     print()
     print("---")
     print()
-    print(f"Generated with *{pytz.OLSON_VERSION=} {pytz.VERSION=}*")
+    print(tzdata_version())
+
+
+def header(zones):
+    print(f"// ! ! ! DO NOT EDIT, AUTOMATICALLY GENERATED ! ! !")
+    print(f"// {tzdata_version()}")
+    print()
+    print("#pragma once")
+    print()
+    for name, value in zones:
+        print(f'#define\tTZ_{name.replace("/", "_")}\tPSTR("{value}")')
 
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--format",
+        default="markdown",
+        choices=["markdown", "header"],
+    )
+    parser.add_argument(
+        "--zones",
+        help="Zone names, one per line",
+        default=os.path.join(os.path.dirname(tzdata.__file__), "zones"),
+    )
     parser.add_argument(
         "--root",
         help="Where do we get raw zoneinfo files from",
-        default=os.path.join(os.path.dirname(pytz.__file__), "zoneinfo"),
+        default=os.path.join(os.path.dirname(tzdata.__file__), "zoneinfo"),
     )
     args = parser.parse_args()
 
-    table(zones(args.root))
+    zones = make_zones(args)
+    if args.format == "markdown":
+        markdown(zones)
+    elif args.format == "header":
+        header(zones)