protected override ICode VisitIf(StmtIf s)
{
if (!VisitorFindContinuations.Any(s))
{
// 'If' contains no continuations, so no distribution can be done
return(s);
}
if (VisitorOnlyStatements.Only(s, Stmt.NodeType.If, Stmt.NodeType.Continuation) && this.ifInfo == null)
{
// 'If' only contains continuations, so no distribution can be done
// Must visit base method to find contained continuations
return(base.VisitIf(s));
}
bool finalise = false;
if (this.ifInfo == null)
{
finalise = true;
this.ifInfo = new IfInfo();
}
this.ifInfo.Conditions.Push(s.Condition);
var then = this.Visit(s.Then);
this.ifInfo.Conditions.Pop();
this.ifInfo.Conditions.Push(this.ctx.ExprGen.NotAutoSimplify(s.Condition));
var @else = this.Visit(s.Else);
this.ifInfo.Conditions.Pop();
if (then != s.Then || @else != s.Else)
{
var @if = new StmtIf(s.Ctx, s.Condition, (Stmt)then, (Stmt)@else);
if (finalise && this.ifInfo.AddToIf.Any())
{
var ifStmts = this.ifInfo.AddToIf.GroupBy(x => x.Item1.To, x => x.Item2).Select(x =>
new StmtIf(s.Ctx, x.Aggregate((a, b) => this.ctx.ExprGen.Or(a, b)),
this.ifInfo.AddToIf.First(y => y.Item1.To == x.Key).Item1, null)
);
var stmts = new Stmt[] { @if }.Concat(ifStmts).ToArray();
this.ifInfo = null;
return(new StmtBlock(s.Ctx, stmts));
}
else
{
if (finalise)
{
this.ifInfo = null;
}
return(@if);
}
}
else
{
// In this case, no continuations will have been found, so there cannot be any conditions to add
if (finalise)
{
this.ifInfo = null;
}
return(s);
}
}
protected override ICode VisitContinuation(StmtContinuation s)
{
// TODO: Why is this de-recursing blocks in continuations? Why doesn't it just derecurse itself (if possible)???
if (s.To.StmtType != Stmt.NodeType.Block)
{
return(base.VisitContinuation(s));
}
if (!this.seen.Add(s.To))
{
return(base.VisitContinuation(s));
}
var block = (StmtBlock)s.To;
foreach (var stmt in block.Statements)
{
if (stmt.StmtType == Stmt.NodeType.Continuation)
{
// Continuation not inside 'if'
var sCont = (StmtContinuation)stmt;
if (sCont.To == block)
{
// Recursive, so derecurse with no condition on loop
var body = new StmtBlock(s.Ctx, block.Statements.TakeWhile(x => x != stmt).ToArray());
var replaceWith = new StmtDoLoop(s.Ctx, body, new ExprLiteral(s.Ctx, true, s.Ctx.Boolean));
this.replaces.Add(s.To, replaceWith);
return(base.VisitContinuation(s));
}
}
if (stmt.StmtType == Stmt.NodeType.If)
{
// Continuation only statement within 'if' with only a 'then' clause
var sIf = (StmtIf)stmt;
if (sIf.Else == null && sIf.Then.StmtType == Stmt.NodeType.Continuation)
{
var sThen = (StmtContinuation)sIf.Then;
if (sThen.To == block)
{
// Recursive, so derecurse
var condition = sIf.Condition;
var bodyStmts = block.Statements.TakeWhile(x => x != stmt).ToArray();
var bodyLast = bodyStmts.LastOrDefault();
var body = new StmtBlock(s.Ctx, bodyStmts);
var loop = new StmtDoLoop(s.Ctx, body, condition);
var afterLoop = block.Statements.SkipWhile(x => x != stmt).Skip(1).ToArray();
if (VisitorFindContinuations.Get(new StmtBlock(s.Ctx, afterLoop)).Any(x => x.To == block))
{
// Cannot de-recurse yet, must wait for continuations to be merged
return(base.VisitContinuation(s));
}
Stmt replaceWith;
if (afterLoop.Any())
{
var loopAndAfter = new[] { loop }.Concat(afterLoop).ToArray();
replaceWith = new StmtBlock(s.Ctx, loopAndAfter);
}
else
{
replaceWith = loop;
}
this.replaces.Add(s.To, replaceWith);
return(base.VisitContinuation(s));
}
}
}
if (VisitorFindContinuations.Any(stmt))
{
// Another continuation present, cannot derecurse
break;
}
}
return(base.VisitContinuation(s));
}
protected override ICode VisitSwitch(StmtSwitch s)
{
// If switch statement contains no continuations then it doesn't need processing
if (!VisitorFindContinuations.Any(s))
{
return(base.VisitSwitch(s));
}
var ctx = s.Ctx;
// If any cases go to the same continuation as the default case, remove them
if (s.Default != null && s.Default.StmtType == Stmt.NodeType.Continuation)
{
var defaultCont = (StmtContinuation)s.Default;
var sameAsDefault = s.Cases
.Where(x => x.Stmt != null && x.Stmt.StmtType == Stmt.NodeType.Continuation && ((StmtContinuation)x.Stmt).To == defaultCont.To)
.ToArray();
if (sameAsDefault.Any())
{
var cases = s.Cases.Except(sameAsDefault);
return(new StmtSwitch(ctx, s.Expr, cases, s.Default));
}
}
// If multiple case statements all go the same continuation, then put them consecutively
var groupedByTo = s.Cases
.Where(x => x.Stmt != null && x.Stmt.StmtType == Stmt.NodeType.Continuation)
.GroupBy(x => ((StmtContinuation)x.Stmt).To)
.Where(x => x.Count() >= 2)
.ToArray();
if (groupedByTo.Any())
{
var cases = s.Cases.Except(groupedByTo.SelectMany(x => x));
var combinedCases = groupedByTo.SelectMany(x => {
var same = x.ToArray();
var last = same.Last();
var sameCases = same.Take(same.Length - 1).Select(y => new StmtSwitch.Case(y.Value, null))
.Concat(new StmtSwitch.Case(last.Value, last.Stmt));
return(sameCases);
});
var allCases = cases.Concat(combinedCases).ToArray();
return(new StmtSwitch(ctx, s.Expr, allCases, s.Default));
}
Func <Stmt, IEnumerable <StmtContinuation> > getSingleFinalContinuation = stmt => {
if (stmt == null)
{
return(Enumerable.Empty <StmtContinuation>());
}
var contCount = VisitorFindContinuations.Get(stmt).Count();
if (contCount == 0)
{
// Case contains return or throw
return(Enumerable.Empty <StmtContinuation>());
}
if (contCount == 1)
{
if (stmt.StmtType == Stmt.NodeType.Continuation)
{
return(new[] { (StmtContinuation)stmt });
}
if (stmt.StmtType == Stmt.NodeType.Block)
{
var stmtBlock = (StmtBlock)stmt;
var last = stmtBlock.Statements.LastOrDefault();
if (last != null && last.StmtType == Stmt.NodeType.Continuation)
{
return(new[] { (StmtContinuation)last });
}
}
}
return(new StmtContinuation[] { null });
};
var conts = s.Cases.Select(x => x.Stmt).Concat(s.Default).SelectMany(x => getSingleFinalContinuation(x)).ToArray();
if (conts.All(x => x != null))
{
// If all cases end with a continuation to the same stmt, then put that stmt after the switch and remove all continuations
if (conts.AllSame(x => x.To))
{
Func <Stmt, Stmt> removeCont = stmt => {
if (stmt == null)
{
return(null);
}
switch (stmt.StmtType)
{
case Stmt.NodeType.Continuation:
return(new StmtBreak(ctx));
case Stmt.NodeType.Block:
var sBlock = (StmtBlock)stmt;
var stmts = sBlock.Statements.ToArray();
if (stmts.Last().StmtType == Stmt.NodeType.Continuation)
{
stmts = stmts.Take(stmts.Length - 1).Concat(new StmtBreak(ctx)).ToArray();
return(new StmtBlock(ctx, stmts));
}
else
{
return(stmt);
}
default:
return(stmt);
}
};
var cases = s.Cases.Select(x => new StmtSwitch.Case(x.Value, removeCont(x.Stmt))).ToArray();
var @switch = new StmtSwitch(ctx, s.Expr, cases, removeCont(s.Default));
return(new StmtBlock(ctx, @switch, conts[0]));
}
else if (this.lastChance)
{
// HACK: Change it into multiple if statements
var multiValues = new List <int>();
var converted = s.Cases.Aggregate(s.Default, (@else, @case) => {
multiValues.Add(@case.Value);
if (@case.Stmt == null)
{
return(@else);
}
else
{
var cond = multiValues.Aggregate((Expr)ctx.Literal(false), (expr, caseValue) => {
return(ctx.ExprGen.Or(expr, ctx.ExprGen.Equal(s.Expr, ctx.Literal(caseValue))));
});
multiValues.Clear();
var @if = new StmtIf(ctx, cond, @case.Stmt, @else);
return(@if);
}
});
return(converted);
}
// If some cases end in a continuation that itself ends in a continuation that other cases end with
// then use an extra variable to store whether to execute the intermediate code
// TODO: This is too specific, need a more general-purpose solution to the problem where cases
// don't all end by going to the same place
//var contTos = conts.Select(x => x.To).Distinct().ToArray();
//var finalContTos = contTos.Select(x => getSingleFinalContinuation(x).Select(y => y.NullThru(z => z.To))).SelectMany(x => x).ToArray();
//if (!finalContTos.Any(x => x == null)) {
// // All continuations are fully substituted
// var distinctFinalContTos = finalContTos.Distinct().ToArray();
// if (distinctFinalContTos.Length == 1) {
// var selector = ctx.Local(ctx.Int32);
// var inIfCont = contTos.Single(x => x != distinctFinalContTos[0]);
// var inIf = new StmtContinuation(ctx, inIfCont, false);
// var afterIf = new StmtContinuation(ctx, distinctFinalContTos[0], false);
// var allCasesTo = new StmtBlock(ctx,
// new StmtIf(ctx, ctx.ExprGen.Equal(selector, ctx.Literal(1)), inIf, null),
// afterIf);
// Func<Stmt, Stmt> adjustCont = stmt => {
// var cont = VisitorFindContinuations.Get(stmt).Single();
// var newCont = new StmtContinuation(ctx, allCasesTo, false);
// var contChanged = (Stmt)VisitorReplace.V(stmt, cont, newCont);
// var sValue = cont.To == inIf.To ? 1 : 0;
// var withSelectorSet = new StmtBlock(ctx,
// new StmtAssignment(ctx, selector, ctx.Literal(sValue)),
// contChanged);
// return withSelectorSet;
// };
// var cases = s.Cases.Select(x => new StmtSwitch.Case(x.Value, adjustCont(x.Stmt))).ToArray();
// var @switch = new StmtSwitch(ctx, s.Expr, cases, adjustCont(s.Default));
// return @switch;
// } else {
// throw new NotImplementedException();
// }
//}
}
return(base.VisitSwitch(s));
}
