Add classfile-api module: java.lang.classfile (JEP 484) parse, generate, transform with timing instrumentation, ASM 9.11.1 comparison, version limits, JDK 24/25/26 API diff

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b4VQVEJWetTT1dYzyJ

classfile-api/scripts/api_diff.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+"""Owner-aware diff of two `javap -public` dumps (one per JDK). Usage: api_diff.py OLD.txt NEW.txt"""
+import sys
+
+def load(p):
+    cur, d = None, {}
+    for line in open(p):
+        line = line.rstrip("\n")
+        if not line.strip():
+            continue
+        if not line.startswith(" "):
+            cur = line.rstrip(" {").split(" extends ")[0].split(" implements ")[0].rsplit(" ", 1)[-1]
+            d[cur] = {"__header__": line}
+        elif line.strip() != "}":
+            d[cur][line.strip()] = True
+    return d
+
+a, b = load(sys.argv[1]), load(sys.argv[2])
+changes = 0
+for c in sorted(set(a) | set(b)):
+    if c not in a: print(f"+ class {c}"); changes += 1; continue
+    if c not in b: print(f"- class {c}"); changes += 1; continue
+    if a[c]["__header__"] != b[c]["__header__"]:
+        print(f"~ {c}\n    was: {a[c]['__header__']}\n    now: {b[c]['__header__']}"); changes += 1
+    for m in sorted(set(a[c]) - set(b[c]) - {"__header__"}): print(f"- {c}: {m}"); changes += 1
+    for m in sorted(set(b[c]) - set(a[c]) - {"__header__"}): print(f"+ {c}: {m}"); changes += 1
+print(f"{len(a)} classes in old, {len(b)} in new, {changes} difference(s)")