/*
* 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));
}
/** @see jaskell.compiler.JaskellVisitor#visit(Let) */
public Object visit(Let a) {
Type ret = a.getType();
if (ret != null) return ret;
// visit definitions
Iterator it = a.getBindings().entrySet().iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
String name = (String) entry.getKey();
Expression def = (Expression) entry.getValue();
log.finer("Visiting " + name);
def.setType((Type) def.visit(this));
}
// visit body
ret = (Type) a.getBody().visit(this);
a.setType(ret);
// return type of body
return ret;
}