/*
* If we visit a nested abstraction, we just launch a new lift operation on
* this abstraction using current context as namespace and returns an
* Application object
*
* @see jaskell.compiler.JaskellVisitor#visit(jaskell.compiler.core.Abstraction)
*/
public Object visit(Abstraction a) {
if (!lift) {
/* top level abstractions */
lift = true;
a.setBody((Expression) a.getBody().visit(this));
return a;
}
/* first visit body */
a.setBody((Expression) a.getBody().visit(this));
/* retrieve outer LocalBindings */
Set captured = new HashSet();
CaptureCollector cc = new CaptureCollector(captured);
a.visit(cc);
/* return the newly computed abstraction as an application spine */
String vname;
try {
vname = lift(a, captured);
Expression ex = applyLifted(vname, captured);
ex.setParent(a.getParent());
return ex;
} catch (SymbolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return null;
}
}
/*
* Definitions in the let block are lifted to top-level and the corresponding
* references in the body are replaced by new definitions.
*
* @see jaskell.compiler.JaskellVisitor#visit(jaskell.compiler.core.Let)
*/
public Object visit(Let let) {
HashMap subst = new HashMap(); /* substitution map */
Set lambdas = new HashSet(); /* newly created toplevels ? */
Iterator it = let.getBindings().entrySet().iterator();
/* first lift all definitions in this let */
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
String name = (String) entry.getKey();
Expression e = (Expression) entry.getValue();
/* reset lift flag */
lift = false;
Expression ndef = (Expression) e.visit(this);
ndef.setParent(let);
/* lift new definition */
Set captured = new HashSet();
CaptureCollector cc = new CaptureCollector(captured);
ndef.visit(cc);
String vname;
try {
vname = lift(ndef, captured);
lambdas.add(vname);
/*
* store new application spine in a map for later substitution
*/
subst.put(name, applyLifted(vname, captured));
} catch (SymbolException e1) {
e1.printStackTrace();
}
}
/* second, replace old occurences in new definitions */
it = lambdas.iterator();
while (it.hasNext()) {
String n = (String) it.next();
Expression e;
try {
e = (Expression) ns.resolve(n);
ns.rebind(n, (Expression) e.visit(new Substitution(subst)));
} catch (SymbolException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
/* thirs, replace occurences in body of let and return it */
return let.getBody().visit(new Substitution(subst));
}