void MatchExpr(out ElaExpression exp)
{
scanner.InjectBlock();
bindings.Push(unit);
while (!(la.kind == 0 || la.kind == 29)) {SynErr(77); Get();}
Expect(29);
var match = new ElaMatch(t);
exp = match;
var block = default(ElaEquationSet);
var cexp = default(ElaExpression);
Expr(out cexp);
match.Expression = cexp;
Expect(34);
BindingChain(out block);
match.Entries = block;
bindings.Pop();
EndBlock();
}
//Used to compile a 'match' expression.
private void CompileMatchExpression(ElaMatch n, LabelMap map, Hints hints)
{
CompileExpression(n.Expression, map, Hints.None, n);
AddLinePragma(n);
CompileSimpleMatch(n.Entries.Equations, map, hints, n.Expression);
if ((hints & Hints.Left) == Hints.Left)
AddValueNotUsed(n);
}
private ElaExpression ValidateDoBlock(ElaExpression exp)
{
if (exp.Type == ElaNodeType.Juxtaposition && ((ElaJuxtaposition)exp).Parameters[0] == null)
{
var ext = ((ElaJuxtaposition)exp).Parameters[1];
var ctx = default(ElaContext);
if (ext.Type == ElaNodeType.Context)
{
ctx = (ElaContext)ext;
ext = ctx.Expression;
}
var eqt = new ElaJuxtaposition { Spec = true };
eqt.SetLinePragma(exp.Line, exp.Column);
eqt.Target = new ElaNameReference(t) { Name = ">>=" };
eqt.Parameters.Add(ext);
var jux = new ElaJuxtaposition();
jux.SetLinePragma(exp.Line, exp.Column);
jux.Target = new ElaNameReference { Name = "point" };
jux.Parameters.Add(new ElaUnitLiteral());
eqt.Parameters.Add(new ElaLambda { Left = new ElaPlaceholder(), Right = jux });
if (ctx != null)
{
ctx.Expression = eqt;
exp = ctx;
}
else
exp = eqt;
}
var root = exp;
while (true)
{
if (exp.Type == ElaNodeType.Juxtaposition)
{
var juxta = (ElaJuxtaposition)exp;
if (juxta.Parameters.Count == 2)
{
juxta.Parameters[0] = Reduce(juxta.Parameters[0], juxta);
juxta.Parameters[1] = Reduce(juxta.Parameters[1], juxta);
exp = juxta.Parameters[1];
}
else
break;
}
else if (exp.Type == ElaNodeType.LetBinding)
{
var lb = (ElaLetBinding)exp;
lb.Expression = Reduce(lb.Expression, lb);
exp = lb.Expression;
}
else if (exp.Type == ElaNodeType.Lambda)
{
var lb = (ElaLambda)exp;
lb.Right = Reduce(lb.Right, lb);
if (lb.Left.Type != ElaNodeType.NameReference &&
lb.Left.Type != ElaNodeType.Placeholder)
{
var em = new ElaMatch();
em.SetLinePragma(lb.Left.Line, lb.Left.Column);
em.Expression = new ElaNameReference { Name = "$x01" };
em.Entries = new ElaEquationSet();
var eq1 = new ElaEquation();
eq1.SetLinePragma(lb.Left.Line, lb.Left.Column);
eq1.Left = lb.Left;
eq1.Right = lb.Right;
em.Entries.Equations.Add(eq1);
var eq2 = new ElaEquation();
eq2.SetLinePragma(lb.Left.Line, lb.Left.Column);
eq2.Left = new ElaNameReference { Name = "$x02" };
var errExp = new ElaJuxtaposition();
errExp.SetLinePragma(lb.Left.Line, lb.Left.Column);
errExp.Target = new ElaNameReference { Name = "failure" };
errExp.Parameters.Add(new ElaNameReference { Name = "$x02" });
eq2.Right = errExp;
em.Entries.Equations.Add(eq2);
lb.Left = new ElaNameReference { Name = "$x01" };
lb.Right = em;
exp = lb;
}
else
exp = lb.Right;
}
else
break;
}
var ret = new ElaLazyLiteral { Expression = root };
ret.SetLinePragma(root.Line, root.Column);
return ret;
}
