public void checkTermination(Context ctxt) {
Expr no_annos = dropAnnos(ctxt).defExpandTop(ctxt);
if (no_annos.construct == FUN_TERM || no_annos.construct == CONST) return;
if (no_annos.construct != TERM_APP)
handleError(
ctxt,
"We are checking termination of a term application where"
+ " dropping\nannotations gives an unexpected form of expression."
+ "1. the term application: "
+ toString(ctxt)
+ "\n2. with annotations dropped: "
+ no_annos.toString(ctxt));
TermApp t = (TermApp) ((TermApp) no_annos).spineForm(ctxt, true, true, true);
TermApp anno_t = (TermApp) spineForm(ctxt, false, true, true);
if (ctxt.getFlag("debug_terminates")) {
ctxt.w.println(
"termTerminates checking TermApp.\n"
+ "\n1. original term, no annos: "
+ no_annos.toString(ctxt)
+ "\n2. spine form, no annos: "
+ t.toString(ctxt)
+ "\n3. spine form, with annos: "
+ anno_t.toString(ctxt)
+ "\n4. head:"
+ anno_t.head.toString(ctxt)
+ "\n5. inj:"
+ anno_t.isI(ctxt)
+ "\n5. head is ctor:"
+ (anno_t.head.construct == CONST ? ctxt.isTermCtor((Const) anno_t.head) : "false"));
ctxt.w.flush();
}
if (t.head.construct != CONST)
handleError(
ctxt,
"Checking termination, the head of an application is "
+ "not a constant.\n"
+ "1. the application in spine form: "
+ t.toString(ctxt)
+ "\n2. the head: "
+ t.head.toString(ctxt));
Const c = (Const) t.head;
boolean is_total = ctxt.isTotal(c);
if (!is_total && !ctxt.isTermCtor(c))
handleError(
ctxt,
"Checking termination, the head of an application is "
+ "neither\ndeclared total nor a term constructor.\n"
+ "1. the application in spine form: "
+ t.toString(ctxt)
+ "\n2. the head: "
+ c.toString(ctxt));
if (is_total) {
/* a little more work is needed here to check that if
totality were proved when some arguments are certain
fixed other terms, we have those arguments here. */
Collection thms = ctxt.getTotalityTheorems(c);
Iterator it = thms.iterator();
boolean problem = true;
while (it.hasNext()) {
Forall F = (Forall) it.next();
TermApp lhs = (TermApp) ((Atom) ((Exists) F.body).body).Y1;
problem = false;
for (int j = 0, jend = lhs.X.length; j < jend; j++)
if (lhs.X[j].construct != VAR)
if (!lhs.X[j].defEq(ctxt, t.X[j])) {
problem = true;
break; // out of for loop
}
if (!problem)
// we have found a matching totality theorem.
break; // out of while loop
}
if (problem) {
String s =
("Termination checking cannot find a registered totality theorem"
+ " for the\ngiven application. The number of theorems registered"
+ " for the head is "
+ (new Integer(thms.size())).toString()
+ ".\n"
+ "1. the term to termination check: "
+ t.toString());
if (thms.size() > 0) {
s = s + "2. the totality theorems registered for the head:\n";
it = thms.iterator();
while (it.hasNext()) {
Forall F = (Forall) it.next();
s = s + "-- " + F.toString(ctxt);
}
}
handleError(ctxt, s);
}
}
/* we cannot look at just t next, because terminates casts
will have been dropped computing it. */
for (int i = 0, iend = t.X.length; i < iend; i++) anno_t.X[i].checkTermination(ctxt);
}
