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);
}
protected override ICode VisitSwitch(StmtSwitch s) {
this.NewLine();
this.js.Append("switch (");
this.Visit(s.Expr);
this.js.Append(") {");
foreach (var @case in s.Cases) {
this.NewLine();
this.js.AppendFormat("case {0}:", @case.Value);
this.indent++;
this.Visit(@case.Stmt);
this.indent--;
}
if (s.Default != null) {
this.NewLine();
this.js.Append("default:");
this.indent++;
this.Visit(s.Default);
this.indent--;
}
this.NewLine();
this.js.Append("}");
return s;
}
private void BuildBlock(IEnumerable<Instruction> insts, Instruction startOfNextPart) {
var inst0 = insts.First();
var instN = insts.Last();
// Any instruction in the method could target this block
var blockStarts = this.methodBlockStarts
.Where(x => x.Offset >= inst0.Offset && x.Offset <= instN.Offset)
.ToArray();
// For each block create a StmtCil, with the correct ending.
// Endings that require a expression have them set to null; they will be filled in during CIL decoding
for (int i = 0; i < blockStarts.Length; i++) {
var start = blockStarts[i];
var end = i == blockStarts.Length - 1 ? insts.Last() : blockStarts[i + 1].Previous;
var blockInsts = start.GetRange(end);
Stmt blockEndStmt;
var code = end.OpCode.Code;
switch (end.OpCode.FlowControl) {
case FlowControl.Cond_Branch:
if (code == Code.Switch) {
var cases = ((Instruction[])end.Operand).Select(x => new StmtContinuation(this.ctx, x, false)).ToArray();
foreach (var @case in cases) {
this.mappable.Add(@case);
}
var @default = new StmtContinuation(this.ctx, end.Next, false);
this.mappable.Add(@default);
blockEndStmt = new StmtSwitch(this.ctx, new ExprVarInstResult(this.ctx, end, this.ctx.Int32),
cases.Select((x, value) => new StmtSwitch.Case(value, x)).ToArray(),
@default);
} else {
var ifTrue = new StmtContinuation(this.ctx, (Instruction)end.Operand, false);
var ifFalse = new StmtContinuation(this.ctx, end.Next, false);
this.mappable.Add(ifTrue);
this.mappable.Add(ifFalse);
blockEndStmt = new StmtIf(this.ctx, new ExprVarInstResult(this.ctx, end, this.ctx.Boolean), ifTrue, ifFalse);
}
break;
case FlowControl.Branch:
var leaveProtectedRegion = code == Code.Leave || code == Code.Leave_S;
blockEndStmt = new StmtContinuation(this.ctx, (Instruction)end.Operand, leaveProtectedRegion);
this.mappable.Add((StmtContinuation)blockEndStmt);
break;
case FlowControl.Next:
case FlowControl.Call:
blockEndStmt = new StmtContinuation(this.ctx, end.Next, false);
this.mappable.Add((StmtContinuation)blockEndStmt);
break;
case FlowControl.Return:
switch (code) {
case Code.Endfinally:
blockEndStmt = new StmtContinuation(this.ctx, startOfNextPart, true);
this.mappable.Add((StmtContinuation)blockEndStmt);
break;
case Code.Ret:
blockEndStmt = new StmtContinuation(this.ctx, this.endBlock, false);
blockInsts = start == end ? Enumerable.Empty<Instruction>() : start.GetRange(end.Previous); // Remove 'ret' from statements
break;
default:
blockEndStmt = null;
break;
}
break;
case FlowControl.Throw:
blockEndStmt = null;
break;
default:
throw new NotImplementedException("Cannot handle: " + end.OpCode.FlowControl);
}
var block = new StmtCil(this.ctx, blockInsts, blockEndStmt);
this.blockMap.Add(start, new List<Stmt> { block });
}
}
