/** Desugar a generalized While clause. */
@Override
public Node forWhile(While w) {
GeneratorClause g = w.getTestExpr();
if (g.getBind().size() > 0) {
// while binds <- expr do body end
// desugars to
// while __whileCond(expr, fn (binds) => body) do end
ArrayList<Expr> args = new ArrayList<Expr>(2);
args.add(g.getInit());
args.add(bindsAndBody(g, w.getBody()));
Expr cond =
ExprFactory.make_RewriteFnApp(
NodeUtil.getSpan(g),
WHILECOND_NAME,
ExprFactory.makeTupleExpr(NodeUtil.getSpan(w), args));
w = ExprFactory.makeWhile(NodeUtil.getSpan(w), cond);
}
return (Expr) super.forWhile(w);
}
/**
* Add an if clause to a (potentially) pre-existing else clause. The else clase can be null, or
* can be an if expression.
*/
private Expr addIfClause(IfClause c, Expr elsePart) {
GeneratorClause g = c.getTestClause();
if (g.getBind().size() > 0) {
// if binds <- expr then body else elsePart end desugars to
// __cond(expr, fn (binds) => body, elsePart)
ArrayList<Expr> args = new ArrayList<Expr>(3);
args.add(g.getInit());
args.add(bindsAndBody(g, c.getBody()));
if (elsePart != null) args.add(thunk(elsePart));
return (Expr)
recur(
ExprFactory.make_RewriteFnApp(
NodeUtil.getSpan(c),
COND_NAME,
ExprFactory.makeTupleExpr(NodeUtil.getSpan(c), args)));
}
// if expr then body else elsePart end is preserved
// (but we replace elif chains by nesting).
if (elsePart == null) {
return (Expr) super.forIf(ExprFactory.makeIf(NodeUtil.getSpan(c), c));
} else {
return (Expr)
super.forIf(ExprFactory.makeIf(NodeUtil.getSpan(c), c, ExprFactory.makeBlock(elsePart)));
}
}
private Expr cleanupOpExpr(OpExpr opExp) {
FunctionalRef ref = opExp.getOp();
List<Expr> args = opExp.getArgs();
if (args.size() <= 1) return opExp;
IdOrOp name = ref.getNames().get(0);
if (!(name instanceof Op)) return bug(name, "The name field of OpRef should be Op.");
Op qop = (Op) name;
if (OprUtil.isEnclosing(qop)) return opExp;
if (OprUtil.isUnknownFixity(qop))
return bug(opExp, "The operator fixity is unknown: " + ((Op) qop).getText());
boolean prefix = OprUtil.hasPrefixColon(qop);
boolean suffix = OprUtil.hasSuffixColon(qop);
if (!prefix && !suffix) return opExp;
qop = OprUtil.noColon(qop);
Iterator<Expr> i = args.iterator();
Expr res = i.next();
Span sp = NodeUtil.getSpan(opExp);
for (Expr arg : Iter.iter(i)) {
if (prefix) {
res = thunk(res);
}
if (suffix) {
arg = thunk(arg);
}
res = ExprFactory.makeOpExpr(sp, qop, res, arg);
}
return res;
}
/**
* @param loc Containing context
* @param gens Generators in generator list
* @return single generator equivalent to the generator list Desugars as follows: body, empty =>
* body body, x <- exp, gs => exp.loop(fn x => body, gs)
*/
Expr visitLoop(Span span, List<GeneratorClause> gens, Expr body) {
for (int i = gens.size() - 1; i >= 0; i--) {
GeneratorClause g = gens.get(i);
Expr loopBody = bindsAndBody(g, body);
body =
ExprFactory.makeMethodInvocation(NodeUtil.getSpan(g), g.getInit(), LOOP_NAME, loopBody);
}
// System.out.println("Desugared to "+body.toStringVerbose());
return (Expr) recur(body);
}
@Override
public Node forSubscriptExpr(SubscriptExpr that) {
if (!Shell.getAssignmentPreDesugaring()) {
return super.forSubscriptExpr(that);
} else {
// Rewrite a subscript expression into a method call (pretty straightforward)
Expr obj = that.getObj();
List<Expr> subs = that.getSubs();
Option<Op> op = that.getOp();
List<StaticArg> staticArgs = that.getStaticArgs();
if (!op.isSome()) bug(that, "Subscript operator expected");
Op knownOp = op.unwrap();
Expr result =
ExprFactory.makeMethodInvocation(
that,
obj,
knownOp,
staticArgs,
ExprFactory.makeTupleExpr(NodeUtil.getSpan(knownOp), subs));
return (Expr) recur(result);
}
}
private Expr visitAccumulator(
Span span,
List<GeneratorClause> gens,
Op op,
Expr body,
List<StaticArg> staticArgs,
boolean isParen) {
body = visitGenerators(span, gens, body);
/**
* * If the accumulation is a nested reduction like BIG OP [ys <- gg] BIG OT <| f y | y <- ys |>
* , visitGenerators returns a tuple of ((BIG OT, f), gg) (this should be refactored, though)
*/
Expr res;
if (body instanceof FnExpr) {
Expr opexp = ExprFactory.makeOpExpr(span, op, staticArgs);
res =
ExprFactory.make_RewriteFnApp(
span, BIGOP_NAME, ExprFactory.makeTupleExpr(span, opexp, body));
} else if (body instanceof TupleExpr) {
/**
* * For BIG OP [ys <- gg] BIG OT <| f y | y <- ys |> The nested reduction is replaced with
* __bigOperator2(BIG OP, BIG OT, gg)
*
* <p>This is similar to forOpExpr(OpExpr that) .
*
* <p>by Kento
*/
// a tuple of the inner Accumulator (op, body) and the gg
TupleExpr tuple = (TupleExpr) body;
TupleExpr innerAccumTuple = (TupleExpr) tuple.getExprs().get(0);
Expr opexpI = (Expr) innerAccumTuple.getExprs().get(0);
Expr innerBody = (Expr) innerAccumTuple.getExprs().get(1);
Expr opexpO = ExprFactory.makeOpExpr(span, op, staticArgs);
Expr gg = tuple.getExprs().get(1);
res =
ExprFactory.make_RewriteFnApp(
span, BIGOP2_NAME, ExprFactory.makeTupleExpr(span, opexpO, opexpI, gg, innerBody));
} else res = bug(body, "Function expressions or tuple expressions are expected.");
if (isParen) res = ExprFactory.makeInParentheses(res);
return (Expr) recur(res);
}
@Override
public Node forAmbiguousMultifixOpExpr(AmbiguousMultifixOpExpr that) {
// If there is a colon at all, the operator is no longer ambiguous:
// It must be infix.
IdOrOp name = that.getInfix_op().getNames().get(0);
if (!(name instanceof Op)) return bug(name, "The name field of OpRef should be Op.");
Op op_name = (Op) name;
boolean prefix = OprUtil.hasPrefixColon(op_name);
boolean suffix = OprUtil.hasSuffixColon(op_name);
if (prefix || suffix) {
OpExpr new_op =
ExprFactory.makeOpExpr(
NodeUtil.getSpan(that),
NodeUtil.isParenthesized(that),
NodeUtil.getExprType(that),
that.getInfix_op(),
that.getArgs());
return recur(new_op);
} else {
return super.forAmbiguousMultifixOpExpr(that);
}
}
@Override
public Node forAssignment(Assignment that) {
// System.out.println("PreDesugar entry");
// Here there are three sorts of rewrite to consider:
// (a) If this is a compound assignment, rewrite to use ordinary assignment.
// (b) If the lhs is a tuple, rewrite into a set of individual assignments.
// (c) If the lhs is a subscript expression, rewrite to a method call.
List<Lhs> lhs = that.getLhs();
Option<FunctionalRef> assignOp = that.getAssignOp();
Expr rhs = that.getRhs();
List<CompoundAssignmentInfo> assignmentInfos = that.getAssignmentInfos();
if (!Shell.getAssignmentPreDesugaring()) {
// System.out.println("Did not PreDesugar");
return super.forAssignment(that);
} else if (assignOp.isSome() || lhs.size() > 1) {
// System.out.println("Compound/tuple PreDesugar");
// Compound and/or tuple assignment
// The basic idea is to transform `(a, b.field, c[sub1,sub2]) := e` into
// `do (ta, tb, tc, tsub1, tsub2, (t1, t2, t3)) = (a, b, c, sub1, sub2, e)
// a := t1; tb.field := t2; tc[tsub1, tsub2] := t3 end`
// (TODO) Unfortunately, currently we don't handle nested binding tuples.
// For now, we'll just transform it into
// `do (ta, tb, tc, tsub1, tsub2) = (a, b, c, sub1, sub2)
// (t1, t2, t3) = e
// a := t1; tb.field := t2; tc[tsub1, tsub2] := t3 end`
// which merely loses a bit of potential parallelism.
// We omit the first tuple binding if the tuple is empty.
// If it is a compound assignment `(a, b.field, c[sub1,sub2]) OP= e`, it becomes
// `do (ta, tb, tc, tsub1, tsub2) = (a, b, c, sub1, sub2)
// (t1, t2, t3) = (ta, tb, tc[tsub1, tsub2]) OP e
// a := t1; tb.field := t2; tc[tsub1, tsub2] := t3 end`
List<LValue> exprLValues = Useful.list();
List<LValue> otherLValues = Useful.list();
List<Expr> otherExprs = Useful.list();
List<Expr> assignments = Useful.list();
boolean isCompound = assignOp.isSome();
List<Expr> accesses = Useful.list();
Span thatSpan = NodeUtil.getSpan(that);
for (Lhs lh : lhs) {
Span lhSpan = NodeUtil.getSpan((Expr) lh);
Id tempId = DesugarerUtil.gensymId(lhSpan, "e");
VarRef tempVar = ExprFactory.makeVarRef(lhSpan, tempId);
exprLValues = Useful.snoc(exprLValues, NodeFactory.makeLValue(lhSpan, tempId));
if (lh instanceof SubscriptExpr) {
SubscriptExpr lhsub = (SubscriptExpr) lh;
Expr obj = lhsub.getObj();
Span objSpan = NodeUtil.getSpan(obj);
List<Expr> subs = lhsub.getSubs();
Id baseTempId = DesugarerUtil.gensymId(objSpan, "b");
VarRef baseTempVar = ExprFactory.makeVarRef(objSpan, baseTempId);
otherLValues = Useful.snoc(otherLValues, NodeFactory.makeLValue(objSpan, baseTempId));
otherExprs = Useful.snoc(otherExprs, obj);
List<Expr> subTempVars = Useful.list();
for (Expr sub : lhsub.getSubs()) {
Span subSpan = NodeUtil.getSpan(sub);
Id subTempId = DesugarerUtil.gensymId(subSpan, "s");
subTempVars = Useful.snoc(subTempVars, ExprFactory.makeVarRef(subSpan, subTempId));
otherLValues = Useful.snoc(otherLValues, NodeFactory.makeLValue(subSpan, subTempId));
}
otherExprs = Useful.concat(otherExprs, subs);
SubscriptExpr newLhs =
ExprFactory.makeSubscriptExpr(
NodeUtil.getSpan(lhsub),
baseTempVar,
subTempVars,
lhsub.getOp(),
lhsub.getStaticArgs());
if (isCompound) accesses = Useful.snoc(accesses, newLhs);
assignments =
Useful.snoc(assignments, ExprFactory.makeAssignment(thatSpan, newLhs, tempVar));
} else if (lh instanceof FieldRef) {
FieldRef lhref = (FieldRef) lh;
Expr obj = lhref.getObj();
Span objSpan = NodeUtil.getSpan(obj);
Id objTempId = DesugarerUtil.gensymId(objSpan, "o");
VarRef objTempVar = ExprFactory.makeVarRef(objSpan, objTempId);
otherLValues = Useful.snoc(otherLValues, NodeFactory.makeLValue(objSpan, objTempId));
otherExprs = Useful.snoc(otherExprs, obj);
FieldRef newLhs =
ExprFactory.makeFieldRef(NodeUtil.getSpan(lhref), objTempVar, lhref.getField());
if (isCompound) accesses = Useful.snoc(accesses, newLhs);
assignments =
Useful.snoc(assignments, ExprFactory.makeAssignment(thatSpan, newLhs, tempVar));
} else if (lh instanceof VarRef) {
VarRef lhvar = (VarRef) lh;
Span varSpan = NodeUtil.getSpan(lhvar);
Id varTempId = DesugarerUtil.gensymId(varSpan, "v");
VarRef varTempVar = ExprFactory.makeVarRef(varSpan, varTempId);
otherLValues = Useful.snoc(otherLValues, NodeFactory.makeLValue(varSpan, varTempId));
otherExprs = Useful.snoc(otherExprs, lhvar);
if (isCompound) accesses = Useful.snoc(accesses, varTempVar);
assignments =
Useful.snoc(assignments, ExprFactory.makeAssignment(thatSpan, lhvar, tempVar));
} else {
bug(that, "Malformed assignment LHS");
}
}
Expr result = ExprFactory.makeBlock(thatSpan, assignments);
if (otherExprs.size() > 0) {
Expr otherRhs = ExprFactory.makeMaybeTupleExpr(thatSpan, otherExprs);
result = ExprFactory.makeLocalVarDecl(thatSpan, otherLValues, otherRhs, result);
}
Expr newRhs =
isCompound
? ExprFactory.makeOpExpr(
NodeUtil.spanTwo(assignOp.unwrap(), rhs),
assignOp.unwrap(),
ExprFactory.makeMaybeTupleExpr(thatSpan, accesses),
rhs)
: rhs;
result = ExprFactory.makeLocalVarDecl(thatSpan, exprLValues, newRhs, result);
return (Expr) recur(result);
} else if (lhs.get(0) instanceof SubscriptExpr) {
// System.out.println("PreDesugar single subscript expr");
// Subscripted assignment
SubscriptExpr lhExpr = (SubscriptExpr) lhs.get(0);
Expr obj = lhExpr.getObj();
List<Expr> subs = lhExpr.getSubs();
Option<Op> op = lhExpr.getOp();
List<StaticArg> staticArgs = lhExpr.getStaticArgs();
if (!op.isSome()) bug(lhExpr, "Subscript operator expected");
Op knownOp = op.unwrap();
Expr result =
ExprFactory.makeMethodInvocation(
that,
obj,
NodeFactory.makeOp(knownOp, knownOp.getText() + ":="),
staticArgs,
ExprFactory.makeTupleExpr(NodeUtil.spanTwo(knownOp, rhs), Useful.cons(rhs, subs)));
return (Expr) recur(result);
} else {
// System.out.println("PreDesugar single expr of class " + lhs.get(0).getClass().getName());
return super.forAssignment(that);
}
}
@Override
public Node forFor(For f) {
Block df = f.getBody();
Do doBlock = ExprFactory.makeDo(NodeUtil.getSpan(df), Useful.list(df));
return visitLoop(NodeUtil.getSpan(f), f.getGens(), doBlock);
}
private static Expr thunk(Expr e) {
return ExprFactory.makeFnExpr(NodeUtil.getSpan(e), Collections.<Param>emptyList(), e);
}
@Override
public Node forOpExpr(OpExpr that) {
FunctionalRef op_result = (FunctionalRef) recur(that.getOp());
/**
* * For BIG OP <| BIG OT <| f y | y <- ys |> | ys <- gg |> Is this case, BIG <||> is being
* removed. The nested reduction is replaced with __bigOperator2(BIG OP, BIG OT, gg)
*
* <p>by Kento
*/
String str = op_result.toString();
String theListEnclosingOperatorName = "BIG <| BIG |>";
String someBigOperatorName = "BIG";
// make sure the body is of application of some big operator
if ((str.length() >= someBigOperatorName.length()
&& str.substring(0, someBigOperatorName.length()).equals(someBigOperatorName))) {
// make sure that BIG OP (Accumulator (BIG <||>, gs))
if (that.getArgs().size() == 1
&& that.getArgs().get(0) instanceof Accumulator
&& ((Accumulator) that.getArgs().get(0))
.getAccOp()
.toString()
.equals(theListEnclosingOperatorName)) {
Accumulator acc = (Accumulator) that.getArgs().get(0);
Expr body = visitGenerators(NodeUtil.getSpan(acc), acc.getGens(), acc.getBody());
/**
* * If the accumulation is a nested reduction like <| BIG OT <| f y | y <- ys |> | ys <- gg
* |> , visitGenerators returns a tuple of ((BIG OT, f), gg) (this should be refactored,
* though) In this case, the nested reduction is replaced with __bigOperator2
*/
if (body instanceof TupleExpr) {
// a tuple of the inner Accumulator (op, body) and the gg
TupleExpr tuple = (TupleExpr) body;
TupleExpr innerAccumTuple = (TupleExpr) tuple.getExprs().get(0);
Expr opexpI = (Expr) innerAccumTuple.getExprs().get(0);
Expr innerBody = (Expr) innerAccumTuple.getExprs().get(1);
FunctionalRef ref = (FunctionalRef) op_result;
IdOrOp name = ref.getNames().get(0);
// make sure the operator is actually an operator
if (!(name instanceof Op)) return null;
Expr opexpO =
ExprFactory.makeOpExpr(NodeUtil.getSpan(that), (Op) name, ref.getStaticArgs());
Expr gg = tuple.getExprs().get(1);
Expr res =
ExprFactory.make_RewriteFnApp(
NodeUtil.getSpan(that),
BIGOP2_NAME,
ExprFactory.makeTupleExpr(NodeUtil.getSpan(body), opexpO, opexpI, gg, innerBody));
return (Expr) recur(res);
}
}
}
List<Expr> args_result = recurOnListOfExpr(that.getArgs());
OpExpr new_op;
if (op_result == that.getOp() && args_result == that.getArgs()) {
new_op = that;
} else {
new_op =
ExprFactory.makeOpExpr(
NodeUtil.getSpan(that),
NodeUtil.isParenthesized(that),
NodeUtil.getExprType(that),
op_result,
args_result);
}
return cleanupOpExpr(new_op);
}
