Read misc.loglevel from RFC 5424's severity table

data-import/loglevel.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Rebuild data/misc/loglevel.tsv from RFC 5424's severity table.
+
+    data-import/loglevel.py [--source URL_OR_FILE] [--cache DIR] [--out FILE]
+
+Table 2 is the whole set, read between the facility table's caption and its own. The
+RFC describes both tables for informational purposes, so a severity is what an
+originator writes rather than something a collector rejects.
+"""
+import argparse
+import re
+import sys
+from pathlib import Path
+
+import source
+import tsv
+
+SOURCE = "https://www.rfc-editor.org/rfc/rfc5424.txt"
+OUT = Path(__file__).resolve().parent.parent / "data" / "misc" / "loglevel.tsv"
+CACHE = Path(__file__).resolve().parent / "cache"
+COLUMNS = ["code", "severity"]
+TABLE = re.compile(r"Table 1\.\s+Syslog Message Facilities(.*?)Table 2\.\s+Syslog Message Severities", re.S)
+ROW = re.compile(r"^ +(\d) +([A-Z][a-z]+): ", re.M)
+EXPECTED = 8
+
+
+def rows(text):
+    table = TABLE.search(text)
+    if not table:
+        sys.exit("the RFC holds no text between the facility and the severity caption; its tables have moved")
+    for code, severity in ROW.findall(table.group(1)):
+        yield {"code": code, "severity": severity}
+
+
+def main():
+    p = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    p.add_argument("--cache", default=str(CACHE))
+    p.add_argument("--source", default=SOURCE)
+    p.add_argument("--out", default=str(OUT))
+    a = p.parse_args()
+    table = sorted(rows(source.fetch(a.source, a.cache, "rfc5424.txt").decode("utf-8")), key=lambda r: r["code"])
+    codes = [r["code"] for r in table]
+    if codes != [str(i) for i in range(EXPECTED)]:
+        sys.exit(f"the severity table numbers {codes}, not 0 through {EXPECTED - 1}")
+    tsv.write(a.out, COLUMNS, table)
+
+
+if __name__ == "__main__":
+    main()