private bool TryGetSimpleCaseStatementType(SwitchCase theCase, out StatementType statementType, out string gotoLabel)
{
gotoLabel = null;
statementType = StatementType.None;
if (theCase.Body.Statements.Count != 1 || !string.IsNullOrEmpty(theCase.Body.Statements[0].Label))
{
return false;
}
Statement statement = theCase.Body.Statements[0];
if (statement is GotoStatement)
{
statementType = StatementType.Goto;
gotoLabel = (statement as GotoStatement).TargetLabel;
}
else if (statement is BreakStatement)
{
statementType = StatementType.Break;
}
else if (statement is ContinueStatement)
{
statementType = StatementType.Continue;
}
return statementType != StatementType.None;
}
public void AddCase(SwitchCase @case)
{
cases.Add(@case);
@case.Parent = this;
needsRefreshing = true;
}
/// <summary>
/// Contains the logic for moving a goto inside the case of switch statement. For more information
/// see Chapter "2.2.2 Inward-movement Transformations : Moving a goto into a switch statement" from
/// <see cref="Taming Control Flow A Structured Approach to Eliminating Goto Statements.pdf"/>.
/// </summary>
/// <param name="gotoStatement">The goto statement to be moved in.</param>
/// <param name="switchCase">The switch case that contains the target of the goto statement.</param>
/// <param name="label">The label of the target.</param>
private void MoveInCase(IfStatement gotoStatement, SwitchCase switchCase, string label)
{
VariableReferenceExpression conditionVariable = new VariableReferenceExpression(GetLabelVariable(label), null);
BlockStatement containingBlock = GetOuterBlock(gotoStatement);
SwitchStatement switchStatement = switchCase.Parent as SwitchStatement;
int gotoIndex = containingBlock.Statements.IndexOf(gotoStatement);
int switchIndex = containingBlock.Statements.IndexOf(switchStatement);
/// Generate variable and extract the switch condition
string switchVariableName = "switch" + switchStatement.ConditionBlock.First.Offset;
TypeReference switchVariableType = GetSwitchType(switchStatement);
VariableDefinition switchVariable = new VariableDefinition(switchVariableName, switchVariableType);
switchVariables.Add(switchVariable);
VariableReferenceExpression switchVarEx = new VariableReferenceExpression(switchVariable, null);
ExtractConditionIntoVariable(switchVarEx, switchStatement, containingBlock);
BlockStatement thenBlock = CollectStatements(gotoIndex + 1, switchIndex + 1, containingBlock);
BlockStatement elseBlock = new BlockStatement();
/// Adds swCond = caseCond; in the last part of else.
BinaryExpression assignSwitchVariable = new BinaryExpression(BinaryOperator.Assign, switchVarEx.CloneExpressionOnly(), GetCaseConditionExpression(switchCase), typeSystem, null);
elseBlock.AddStatement(new ExpressionStatement(assignSwitchVariable));
IfStatement precedingIf = new IfStatement(new UnaryExpression(UnaryOperator.LogicalNot, conditionVariable, null), thenBlock, elseBlock);
/// Attach new if and move the goto conditional.
/// Attach it only if the then block is not empty.
if (precedingIf.Then.Statements.Count != 0)
{
containingBlock.AddStatementAt(gotoIndex, precedingIf);
}
containingBlock.Statements.Remove(gotoStatement);
switchCase.Body.AddStatementAt(0, gotoStatement);
}
/// <summary>
/// Gets the condition that is representing the supplied case.
/// </summary>
/// <param name="switchCase">The switch case, whose condition is being needed.</param>
/// <returns>Returns expression, evaluating so that the switch jumps to <paramref name="switchCase"/>.</returns>
private Expression GetCaseConditionExpression(SwitchCase switchCase)
{
if (switchCase is ConditionCase)
{
return (switchCase as ConditionCase).Condition;
}
else
{
/// SwitchCase is the default case
SwitchStatement switchStatement = switchCase.Parent as SwitchStatement;
//TypeReference switchType = GetSwitchType(switchCase.Parent as SwitchStatement);
/// this could possibly be long instead of int, but this case should be quite rare
int result = 1;
foreach (SwitchCase @case in switchStatement.Cases)
{
if (@case is DefaultCase)
{
continue;
}
result += (int)(((@case as ConditionCase).Condition as LiteralExpression).Value);
}
return GetLiteralExpression(result);
}
}
public CaseGotoStatement(GotoStatement transformedGoto, SwitchCase targetedCase) : base(transformedGoto.Label, transformedGoto.UnderlyingSameMethodInstructions)
{
this.TargetedSwitchCase = targetedCase;
}
/// <summary>
/// Copy-constructor for cloning purposes.
/// </summary>
/// <param name="toClone">The statement to clone.</param>
private CaseGotoStatement(CaseGotoStatement toClone, IEnumerable<Instruction> instructions) : base(toClone.Label, instructions)
{
this.TargetedSwitchCase = toClone.TargetedSwitchCase;
}
public CaseGotoStatement(GotoStatement transformedGoto, SwitchCase targetedCase)
{
base(transformedGoto.get_Label(), transformedGoto.get_UnderlyingSameMethodInstructions());
this.set_TargetedSwitchCase(targetedCase);
return;
}