public override int Compile(FunctionContext context)
{
context.Position(Token);
var stack = 0;
var caseLabels = new List <LabelOperand>(Branches.Count);
var caseEnd = context.MakeLabel("caseEnd");
LabelOperand caseDefault = null;
BlockExpression defaultBlock = null;
for (var i = 0; i < Branches.Count; i++)
{
var label = context.MakeLabel("caseBranch_" + i);
caseLabels.Add(label);
var conditions = Branches[i].Conditions;
if (conditions.Any(c => c == null))
{
caseDefault = label;
if (conditions.Count == 1)
{
defaultBlock = Branches[i].Block;
}
}
}
var emptyDefault = caseDefault == null;
if (emptyDefault)
{
caseDefault = context.MakeLabel("caseDefault");
}
context.PushScope();
context.Statement(Expression);
stack += Expression.Compile(context);
var flattenedBranches = FlattenBranches(Branches, caseLabels, caseDefault);
BuildTables(flattenedBranches, caseDefault, out var tables, out var rest);
foreach (var table in tables)
{
var start = table.Entries[0].Value;
var labels = table.Entries.Select(e => e.Label).ToList();
stack += context.Dup();
stack += context.JumpTable(start, labels);
}
foreach (var entry in rest)
{
stack += context.Dup();
stack += entry.Condition.Compile(context);
stack += context.BinaryOperation(TokenType.EqualTo);
stack += context.JumpTrue(entry.Label);
}
stack += context.Jump(caseDefault);
context.PushLoop(null, caseEnd);
for (var i = 0; i < Branches.Count; i++)
{
var branchStack = stack;
var branch = Branches[i];
branchStack += context.Bind(caseLabels[i]);
branchStack += context.Drop();
branchStack += branch.Block.Compile(context);
branchStack += context.Jump(caseEnd);
CheckStack(branchStack, 0);
}
// only bind if we need a default block
if (emptyDefault || defaultBlock != null)
{
stack += context.Bind(caseDefault);
}
// always drop the switch value
stack += context.Drop();
if (defaultBlock != null)
{
stack += defaultBlock.Compile(context);
}
context.PopLoop();
stack += context.Bind(caseEnd);
context.PopScope();
CheckStack(stack, 0);
return(stack);
}