private Pred TranslateLoopExpr(LNode expr, Context ctx)
{
Symbol type = expr.Name;
bool? greedy = null;
bool g;
expr = expr.Args[0];
if ((g = expr.Calls(_Greedy, 1)) || expr.Calls(_Nongreedy, 1))
{
greedy = g;
expr = expr.Args[0];
}
BranchMode branchMode;
Pred subpred = BranchToPred(expr, out branchMode, ctx);
if (branchMode != BranchMode.None)
{
_sink.Write(Severity.Warning, expr, "'default' and 'error' only apply when there are multiple arms (a|b, a/b)");
}
if (type == _Star)
{
return(new Alts(expr, LoopMode.Star, subpred, greedy));
}
else if (type == _Plus)
{
return(new Seq(subpred, new Alts(expr, LoopMode.Star, subpred.Clone(), greedy), expr));
}
else // type == _Opt
{
return(new Alts(expr, LoopMode.Opt, subpred, greedy));
}
}
public override Pred Clone()
{
Gate clone = (Gate)base.Clone();
clone.Predictor = Predictor.Clone();
clone.Match = Match.Clone();
return(clone);
}
public override Pred Clone()
{
Gate clone = (Gate)base.Clone();
clone._predictor = _predictor.Clone();
clone._match = _match.Clone();
return(clone);
}
private Pred TranslateLoopExpr(LNode expr, Context ctx)
{
Symbol type = expr.Name;
bool? greedy = null;
bool g;
expr = expr.Args[0];
if ((g = expr.Calls(_Greedy, 1)) || expr.Calls(_Nongreedy, 1))
{
greedy = g;
expr = expr.Args[0];
}
BranchMode branchMode;
Pred subpred = BranchToPred(expr, out branchMode, ctx);
if (branchMode == BranchMode.ErrorContinue || branchMode == BranchMode.ErrorExit)
{
_sink.Error(expr, "'error' only applies when there are multiple arms (a|b, a/b)");
}
Pred clone = type == _Plus?subpred.Clone() : null;
Alts alts = new Alts(expr, type == _Opt ? LoopMode.Opt : LoopMode.Star, clone ?? subpred, greedy);
if (branchMode == BranchMode.Default)
{
alts.DefaultArm = 0;
}
if (clone != null)
{
return(new Seq(subpred, alts, expr));
}
else
{
return(alts);
}
}
Pred NodeToPredCore(LNode expr, Context ctx = Context.Rule)
{
if (expr.IsCall)
{
bool slash = false, not;
if (expr.Calls(S.Tuple))
{
// sequence: (a, b, c)
if (expr.Calls(S.Tuple, 1))
{
return(NodeToPred(expr.Args[0], ctx));
}
return(ArgsToSeq(expr, ctx));
}
else if (expr.Calls(S.Braces))
{
// Just code: use an empty sequence
var seq = new Seq(expr);
seq.PostAction = RemoveBraces(expr);
return(seq);
}
else if (expr.Calls(S.OrBits, 2) || (slash = expr.Calls(S.Div, 2)))
{
// alternatives: a | b, a || b, a / b
LNode lhs = expr.Args[0], rhs = expr.Args[1];
BranchMode lhsMode, rhsMode;
Pred left = BranchToPred(lhs, out lhsMode, ctx);
Pred right = BranchToPred(rhs, out rhsMode, ctx);
return(Pred.Or(left, right, slash, expr, lhsMode, rhsMode, _sink));
}
else if (expr.Calls(_Star, 1) || expr.Calls(_Plus, 1) || expr.Calls(_Opt, 1))
{
// loop (a+, a*) or optional (a?)
Symbol type = expr.Name;
bool? greedy = null;
bool g;
expr = expr.Args[0];
if ((g = expr.Calls(_Greedy, 1)) || expr.Calls(_Nongreedy, 1))
{
greedy = g;
expr = expr.Args[0];
}
BranchMode branchMode;
Pred subpred = BranchToPred(expr, out branchMode, ctx);
if (branchMode != BranchMode.None)
{
_sink.Write(Severity.Warning, expr, "'default' and 'error' only apply when there are multiple arms (a|b, a/b)");
}
if (type == _Star)
{
return(new Alts(expr, LoopMode.Star, subpred, greedy));
}
else if (type == _Plus)
{
return(new Seq(subpred, new Alts(expr, LoopMode.Star, subpred.Clone(), greedy), expr));
}
else // type == _Opt
{
return(new Alts(expr, LoopMode.Opt, subpred, greedy));
}
}
else if (expr.Calls(_Gate, 1) || expr.Calls(_EqGate, 1))
{
// => foo (LES-based parser artifact)
return(new Gate(expr, new Seq(F._Missing),
NodeToPred(expr.Args[0], Context.GateRight))
{
IsEquivalency = expr.Calls(_EqGate)
});
}
else if (expr.Calls(_Gate, 2) || expr.Calls(_EqGate, 2))
{
if (ctx == Context.GateLeft)
{
_sink.Write(Severity.Error, expr, "Cannot use a gate in the left-hand side of another gate");
}
return(new Gate(expr, NodeToPred(expr.Args[0], Context.GateLeft),
NodeToPred(expr.Args[1], Context.GateRight))
{
IsEquivalency = expr.Calls(_EqGate)
});
}
else if ((not = expr.Calls(_AndNot, 1)) || expr.Calls(_And, 1))
{
expr = expr.Args[0];
var subpred = AutoNodeToPred(expr, Context.And);
LNode subexpr = subpred as LNode;
bool local = false;
if (subexpr != null && (subpred = subexpr.WithoutAttrNamed(_Local)) != subexpr)
{
local = true;
}
return(new AndPred(expr, subpred, not, local));
}
else if (expr.Calls(S.NotBits, 1))
{
var subpred = NodeToPred(expr.Args[0], ctx);
if (subpred is TerminalPred)
{
var term = (TerminalPred)subpred;
term.Set = term.Set.Inverted().WithoutEOF();
return(term);
}
else
{
_sink.Write(Severity.Error, expr,
"The set-inversion operator ~ can only be applied to a single terminal, not a '{0}'", subpred.GetType().Name);
return(subpred);
}
}
else if (expr.Name.Name.EndsWith("=") && expr.ArgCount == 2)
{
var lhs = expr.Args[0];
var pred = NodeToPred(expr.Args[1], ctx);
if (expr.Calls(S.AddSet))
{
pred.ResultSaver = result => F.Call(F.Dot(lhs, _Add), result);
}
else if (expr.Calls(S.QuickBindSet))
{
pred.ResultSaver = result => F.Call(S.Var, F._Missing, F.Call(S.Assign, lhs, result));
}
else
{
pred.ResultSaver = result => F.Call(expr.Target, lhs, result);
}
return(pred);
}
}
// expr is an Id, literal, or non-special call
Rule rule;
if (!expr.IsLiteral && _rules.TryGetValue(expr.Name, out rule))
{
//int ruleArgc = rule.Basis.Args[2].ArgCount;
//if (expr.ArgCount > ruleArgc) // don't complain about too few args, in case there are default args (I'm too lazy to check)
// _sink.Write(MessageSink.Error, expr, "Rule '{0}' takes {1} arguments ({2} given)", rule.Name, ruleArgc, expr.ArgCount);
return(new RuleRef(expr, rule)
{
Params = expr.Args
});
}
string errorMsg = null;
Pred terminal = _helper.CodeToPred(expr, ref errorMsg);
if (terminal == null)
{
errorMsg = errorMsg ?? "LLLPG: unrecognized expression";
terminal = new TerminalPred(expr, _helper.EmptySet);
_sink.Write(Severity.Error, expr, errorMsg);
}
else if (errorMsg != null)
{
_sink.Write(Severity.Warning, expr, errorMsg);
}
return(terminal);
}