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diff --git a/build-aux/measurestack/vcg.py b/build-aux/measurestack/vcg.py
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+# build-aux/measurestack/vcg.py - Parse the "VCG" language
+#
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+import re
+import typing
+
+# pylint: disable=unused-variable
+__all__ = [
+    "VCGElem",
+    "parse_vcg",
+]
+
+# Parse the "VCG" language
+#
+# https://www.rw.cdl.uni-saarland.de/people/sander/private/html/gsvcg1.html
+#
+# The formal syntax is found at
+# ftp://ftp.cs.uni-sb.de/pub/graphics/vcg/vcg.tgz `doc/grammar.txt`.
+
+
+class VCGElem:
+    typ: str
+    lineno: int
+    attrs: dict[str, str]
+
+
+re_beg = re.compile(r"(edge|node):\s*\{\s*")
+_re_tok = r"[a-zA-Z_][a-zA-Z0-9_]*"
+_re_str = r'"(?:[^\"]|\\.)*"'
+re_attr = re.compile("(" + _re_tok + r")\s*:\s*(" + _re_tok + "|" + _re_str + r")\s*")
+re_end = re.compile(r"\}\s*$")
+re_skip = re.compile(r"(graph:\s*\{\s*title\s*:\s*" + _re_str + r"\s*|\})\s*")
+re_esc = re.compile(r"\\.")
+
+
+def parse_vcg(reader: typing.TextIO) -> typing.Iterator[VCGElem]:
+
+    for lineno, line in enumerate(reader):
+        pos = 0
+
+        def _raise(msg: str) -> typing.NoReturn:
+            nonlocal lineno
+            nonlocal line
+            nonlocal pos
+            e = SyntaxError(msg)
+            e.lineno = lineno
+            e.offset = pos
+            e.text = line
+            raise e
+
+        if re_skip.fullmatch(line):
+            continue
+
+        elem = VCGElem()
+        elem.lineno = lineno
+
+        m = re_beg.match(line, pos=pos)
+        if not m:
+            _raise("does not look like a VCG line")
+        elem.typ = m.group(1)
+        pos = m.end()
+
+        elem.attrs = {}
+        while True:
+            if re_end.match(line, pos=pos):
+                break
+            m = re_attr.match(line, pos=pos)
+            if not m:
+                _raise("unexpected character")
+            k = m.group(1)
+            v = m.group(2)
+            if k in elem.attrs:
+                _raise(f"duplicate key: {k!r}")
+            if v.startswith('"'):
+
+                def unesc(esc: re.Match[str]) -> str:
+                    match esc.group(0)[1:]:
+                        case "n":
+                            return "\n"
+                        case '"':
+                            return '"'
+                        case "\\":
+                            return "\\"
+                        case _:
+                            _raise(f"invalid escape code {esc.group(0)!r}")
+
+                v = re_esc.sub(unesc, v[1:-1])
+            elem.attrs[k] = v
+            pos = m.end()
+
+        del _raise
+        del pos
+        del line
+        del lineno
+        yield elem