/// <summary>
/// Determines the last default item in the list of switch items.
/// </summary>
/// <returns>The last default item or a <b>null</b> reference if there is no default item.</returns>
private DefaultItem GetLastDefaultItem()
{
DefaultItem result = null;
foreach (SwitchItem item in switchItems)
{
DefaultItem di = item as DefaultItem;
if (di != null)
{
result = di;
}
}
return(result);
}
/// <summary>
/// Visit switch-default item.
/// Visit case body.
/// </summary>
/// <param name="x"></param>
virtual public void VisitDefaultItem(DefaultItem x)
{
VisitSwitchItem(x);
}
/// <summary>
/// Visit switch-default item.
/// Visit case body.
/// </summary>
/// <param name="x"></param>
virtual public void VisitDefaultItem(DefaultItem x)
{
VisitSwitchItem(x);
}
/// <include file='Doc/Nodes.xml' path='doc/method[@name="Emit"]/*'/>
internal override void Emit(CodeGenerator /*!*/ codeGenerator)
{
Statistics.AST.AddNode("SwitchStmt");
ILEmitter il = codeGenerator.IL;
// Note:
// SwitchStmt is now implemented in the most general (and unefficient) way. The whole switch
// is understood as a series of if-elseif-else statements.
Label exit_label = il.DefineLabel();
bool fall_through = false;
Label fall_through_label = il.DefineLabel();
Label last_default_label = il.DefineLabel();
DefaultItem last_default = GetLastDefaultItem();
LocalBuilder branch_to_lastdefault = null;
if (last_default != null)
{
branch_to_lastdefault = il.DeclareLocal(Types.Bool[0]);
il.LdcI4(0);
il.Stloc(branch_to_lastdefault);
}
codeGenerator.BranchingStack.BeginLoop(exit_label, exit_label,
codeGenerator.ExceptionBlockNestingLevel);
// marks a sequence point containing the discriminator evaluation:
codeGenerator.MarkSequencePoint(
switchValue.Position.FirstLine,
switchValue.Position.FirstColumn,
switchValue.Position.LastLine,
switchValue.Position.LastColumn + 1);
// Evaluate condition value and store the result into local variable
codeGenerator.EmitBoxing(switchValue.Emit(codeGenerator));
LocalBuilder condition_value = il.DeclareLocal(Types.Object[0]);
il.Stloc(condition_value);
foreach (SwitchItem item in switchItems)
{
item.MarkSequencePoint(codeGenerator);
// switch item is either CaseItem ("case xxx:") or DefaultItem ("default") item:
CaseItem case_item = item as CaseItem;
if (case_item != null)
{
Label false_label = il.DefineLabel();
// PhpComparer.Default.CompareEq(<switch expr. value>,<case value>);
/*changed to static method*/ //il.Emit(OpCodes.Ldsfld, Fields.PhpComparer_Default);
codeGenerator.EmitCompareEq(
cg => { cg.IL.Ldloc(condition_value); return(PhpTypeCode.Object); },
cg => case_item.EmitCaseValue(cg));
// IF (!STACK) GOTO false_label;
il.Emit(OpCodes.Brfalse, false_label);
if (fall_through == true)
{
il.MarkLabel(fall_through_label, true);
fall_through = false;
}
case_item.EmitStatements(codeGenerator);
if (fall_through == false)
{
fall_through_label = il.DefineLabel();
fall_through = true;
}
il.Emit(OpCodes.Br, fall_through_label);
il.MarkLabel(false_label, true);
}
else
{
DefaultItem default_item = (DefaultItem)item;
// Only the last default branch defined in source code is used.
// So skip default while testing "case" items at runtime.
Label false_label = il.DefineLabel();
il.Emit(OpCodes.Br, false_label);
if (default_item == last_default)
{
il.MarkLabel(last_default_label, false);
}
if (fall_through == true)
{
il.MarkLabel(fall_through_label, true);
fall_through = false;
}
default_item.EmitStatements(codeGenerator);
if (fall_through == false)
{
fall_through_label = il.DefineLabel();
fall_through = true;
}
il.Emit(OpCodes.Br, fall_through_label);
il.MarkLabel(false_label, true);
}
}
// If no case branch matched, branch to last default case if any is defined
if (last_default != null)
{
// marks a sequence point containing the condition evaluation or skip of the default case:
codeGenerator.MarkSequencePoint(
last_default.Position.FirstLine,
last_default.Position.FirstColumn,
last_default.Position.LastLine,
last_default.Position.LastColumn + 1);
Debug.Assert(branch_to_lastdefault != null);
Label temp = il.DefineLabel();
// IF (!branch_to_lastdefault) THEN
il.Ldloc(branch_to_lastdefault);
il.LdcI4(0);
il.Emit(OpCodes.Bne_Un, temp);
if (true)
{
// branch_to_lastdefault = TRUE;
il.LdcI4(1);
il.Stloc(branch_to_lastdefault);
// GOTO last_default_label;
il.Emit(OpCodes.Br, last_default_label);
}
il.MarkLabel(temp, true);
// END IF;
il.ForgetLabel(last_default_label);
}
if (fall_through == true)
{
il.MarkLabel(fall_through_label, true);
}
il.MarkLabel(exit_label);
codeGenerator.BranchingStack.EndLoop();
il.ForgetLabel(exit_label);
}
