public override void TraverseChildren(IBlockStatement block) {
base.TraverseChildren(block);
Contract.Assume(block is BlockStatement);
var decompiledBlock = (BlockStatement)block;
var statements = decompiledBlock.Statements;
for (int i = 0; i < statements.Count-1; i++) {
var switchInstruction = statements[i] as SwitchInstruction;
if (switchInstruction == null) continue;
SwitchStatement result = new SwitchStatement();
result.Expression = switchInstruction.switchExpression;
statements[i] = result;
for (int j = 0, n = switchInstruction.SwitchCases.Count; j < n; j++) {
CompileTimeConstant caseLabel = new CompileTimeConstant() { Value = j, Type = this.host.PlatformType.SystemInt32 };
var gotoCaseBody = switchInstruction.SwitchCases[j];
Contract.Assume(gotoCaseBody != null);
SwitchCase currentCase = new SwitchCase() { Expression = caseLabel };
result.Cases.Add(currentCase);
if (j < n-1) {
Contract.Assume(switchInstruction.SwitchCases[j+1] != null);
if (gotoCaseBody.TargetStatement == switchInstruction.SwitchCases[j+1].TargetStatement) continue;
}
currentCase.Body.Add(gotoCaseBody);
}
if (i == statements.Count-1) return;
Contract.Assert(i+1 <= statements.Count);
var gotoStatement = statements[i+1] as IGotoStatement;
if (gotoStatement != null) {
SwitchCase defaultCase = new SwitchCase() { }; // Default case is represented by a dummy Expression.
defaultCase.Body.Add(statements[i + 1]);
statements.RemoveAt(i + 1);
result.Cases.Add(defaultCase);
}
}
}
/// <summary>
/// Get the mutable copy of a switch case.
/// </summary>
/// <param name="swithCase"></param>
/// <returns></returns>
public virtual SwitchCase GetMutableCopy(ISwitchCase swithCase)
{
object cachedValue;
if (this.cache.TryGetValue(swithCase, out cachedValue))
return (SwitchCase)cachedValue;
var result = new SwitchCase(swithCase);
// Probably not necessary, no two switch cases are shared.
this.cache.Add(swithCase, result);
this.cache.Add(result, result);
return result;
}
/// <summary>
/// Visits the specified switch case.
/// </summary>
/// <param name="switchCase">The switch case.</param>
/// <returns></returns>
protected virtual ISwitchCase DeepCopy(SwitchCase switchCase)
{
if (!switchCase.IsDefault)
switchCase.Expression = (ICompileTimeConstant)Substitute(switchCase.Expression);
switchCase.Body = this.Substitute(switchCase.Body);
return switchCase;
}
/// <summary>
/// Build the state machine.
///
/// We start from state 0. For each yield return, we assign a unique state, which we call continueing state. For a yield return
/// assigned with state x, we move the state machine from the previous state to x. Whenever we see a yield break, we transit
/// the state to -1.
///
/// When we return from state x, we jump to a label that is inserted right after the previous yield return (that is assigned with state x).
/// </summary>
private BlockStatement BuildStateMachine(IteratorClosureInformation iteratorClosure, BlockStatement oldBody, Dictionary<int, ILabeledStatement> stateEntries) {
// Switch on cases. StateEntries, which have been computed previously, map a state number (for initial and continuing states) to a label that has been inserted
// right after the associated yield return.
BlockStatement result = new BlockStatement();
var returnFalse = new ReturnStatement() { Expression = new CompileTimeConstant() { Value = false, Type = this.host.PlatformType.SystemBoolean } };
var returnFalseLabel = new LabeledStatement() { Label = this.host.NameTable.GetNameFor("return false"), Statement = returnFalse };
List<ISwitchCase> cases = new List<ISwitchCase>();
foreach (int i in stateEntries.Keys) {
SwitchCase c = new SwitchCase() {
Expression = new CompileTimeConstant() { Type = this.host.PlatformType.SystemInt32, Value = i },
Body = new List<IStatement>(),
};
c.Body.Add(new GotoStatement() { TargetStatement = stateEntries[i] });
cases.Add(c);
}
// Default case.
SwitchCase defaultCase = new SwitchCase();
defaultCase.Body.Add(new GotoStatement() { TargetStatement = returnFalseLabel });
cases.Add(defaultCase);
SwitchStatement switchStatement = new SwitchStatement() {
Cases = cases,
Expression = new BoundExpression() { Type = this.host.PlatformType.SystemInt32, Instance = new ThisReference(), Definition = iteratorClosure.StateFieldReference }
};
result.Statements.Add(switchStatement);
result.Statements.Add(oldBody);
result.Statements.Add(returnFalseLabel);
return result;
}
private void DecompileSwitch(List<IStatement> statements, int i)
{
if (i >= statements.Count-1) return;
SwitchInstruction/*?*/ switchInstruction = statements[i] as SwitchInstruction;
if (switchInstruction == null) return;
SwitchStatement result = new SwitchStatement();
result.Expression = switchInstruction.switchExpression;
statements[i] = result;
for (int j = 0, n = switchInstruction.switchCases.Count; j < n; j++) {
CompileTimeConstant caseLabel = new CompileTimeConstant() { Value = j, Type = this.platformType.SystemInt32 };
var gotoCaseBody = switchInstruction.switchCases[j];
SwitchCase currentCase = new SwitchCase() { Expression = caseLabel };
result.Cases.Add(currentCase);
if (j < n-1 && gotoCaseBody.TargetStatement == switchInstruction.switchCases[j+1].TargetStatement) continue;
currentCase.Body.Add(gotoCaseBody);
}
if (i == statements.Count-1) return;
var gotoStatement = statements[i+1] as IGotoStatement;
if (gotoStatement != null) {
SwitchCase defaultCase = new SwitchCase() { }; // Default case is represented by a dummy Expression.
defaultCase.Body.Add(statements[i + 1]);
statements.RemoveAt(i + 1);
result.Cases.Add(defaultCase);
}
}
/// <summary>
/// Rewrites the children of the given switch case.
/// </summary>
public virtual void RewriteChildren(SwitchCase switchCase)
{
if (!switchCase.IsDefault)
switchCase.Expression = this.Rewrite((CompileTimeConstant)switchCase.Expression);
switchCase.Body = this.Rewrite(switchCase.Body);
}
/// <summary>
/// Visits the specified switch case.
/// </summary>
/// <param name="switchCase">The switch case.</param>
/// <returns></returns>
public virtual ISwitchCase Visit(ISwitchCase switchCase)
{
SwitchCase mutableSwitchCase = switchCase as SwitchCase;
if (!this.copyOnlyIfNotAlreadyMutable || mutableSwitchCase == null)
mutableSwitchCase = new SwitchCase(switchCase);
return Visit(mutableSwitchCase);
}
/// <summary>
/// Visits the specified switch case.
/// </summary>
/// <param name="switchCase">The switch case.</param>
/// <returns></returns>
public virtual ISwitchCase Visit(SwitchCase switchCase)
{
if (!switchCase.IsDefault)
switchCase.Expression = Visit(switchCase.Expression);
switchCase.Body = Visit(switchCase.Body);
return switchCase;
}
