private Statement ParseUsing(TokenSet followers)
//^ requires this.currentToken == Token.Using;
//^ ensures followers[this.currentToken] || this.currentToken == Token.EndOfFile;
{
SourceLocationBuilder slb = new SourceLocationBuilder(this.scanner.SourceLocationOfLastScannedToken);
this.GetNextToken();
if (Parser.IdentifierOrNonReservedKeyword[this.currentToken]) {
this.HandleError(Error.SyntaxError, "(");
this.GetNextToken();
if (this.currentToken == Token.Semicolon)
this.GetNextToken();
slb.UpdateToSpan(this.scanner.SourceLocationOfLastScannedToken);
EmptyStatement es = new EmptyStatement(false, slb);
this.SkipTo(followers);
return es;
}
this.Skip(Token.LeftParenthesis);
Statement resourceAcquisition = this.ParseExpressionStatementOrDeclaration(false, false, followers|Token.RightParenthesis|Parser.StatementStart, false);
//^ assert resourceAcquisition is ExpressionStatement || resourceAcquisition is LocalDeclarationsStatement;
this.Skip(Token.RightParenthesis);
Statement body = this.ParseStatement(followers);
slb.UpdateToSpan(body.SourceLocation);
Statement result = new ResourceUseStatement(resourceAcquisition, body, slb);
//^ assume followers[this.currentToken] || this.currentToken == Token.EndOfFile;
return result;
}
/// <summary>
/// Looking for the pattern:
/// IDisposable<T> variable = e;
/// try {
/// using_body
/// } finally {
/// if (variable != null) {
/// variable.Dispose();
/// }
/// }
/// The type of the variable is *not* actually IDisposable, but some
/// type that implements IDisposable.
/// The assignment might be a local-declaration statement or else it
/// might be an assignment statement.
/// </summary>
public override void TraverseChildren(IBlockStatement block)
{
Contract.Assume(block is BlockStatement);
var decompiledBlock = (BlockStatement)block;
var statements = decompiledBlock.Statements;
for (int i = 2; i < statements.Count; ++i)
{
var tryFinally = statements[i] as TryCatchFinallyStatement;
if (tryFinally == null)
{
continue;
}
var finallyBody = tryFinally.FinallyBody;
if (finallyBody == null)
{
continue;
}
var finallyStatements = finallyBody.Statements;
if (tryFinally.CatchClauses.Any())
{
continue;
}
ILocalDefinition variable;
IStatement resourceAcquisition;
var variableDeclaration = statements[i - 2] as ILocalDeclarationStatement;
if (variableDeclaration == null)
{
var es = statements[i - 2] as IExpressionStatement;
if (es == null)
{
continue;
}
var assign = es.Expression as IAssignment;
if (assign == null)
{
continue;
}
if (assign.Target.Instance != null)
{
continue;
}
var loc = assign.Target.Definition as ILocalDefinition;
if (loc == null)
{
continue;
}
variable = loc;
resourceAcquisition = es;
}
else
{
variable = variableDeclaration.LocalVariable;
resourceAcquisition = variableDeclaration;
}
// finally block either looks like:
// variable.Dispose();
// or
// if (variable != null) variable.Dispose();
// or
// iDisposableLocalVar := variable as IDisposable;
// if (iDisposableLocalVar != null) iDisposableLocalVar.Dispose();
var c = finallyStatements.Count();
if (c == 1)
{
var expression = finallyStatements.Single() as IExpressionStatement;
var isDispose = this.MatchMethodCall(expression.Expression, variable, "Dispose");
if (!isDispose)
{
continue;
}
}
else if (c == 3 || c == 4)
{
IBoundExpression be;
ILocalDefinition iDisposableVariable = variable;
var index = 0;
if (c == 4)
{
var es = finallyStatements.ElementAt(index++) as IExpressionStatement;
if (es == null)
{
continue;
}
var assignment = es.Expression as IAssignment;
if (assignment == null)
{
continue;
}
var castIfPossible = assignment.Source as ICastIfPossible;
if (castIfPossible == null)
{
continue;
}
if (!TypeHelper.TypesAreEquivalent(castIfPossible.TargetType, this.IDisposable))
{
continue;
}
be = castIfPossible.ValueToCast as IBoundExpression;
if (be == null)
{
continue;
}
if (be.Instance != null)
{
continue;
}
if (be.Definition != variable)
{
continue;
}
if (assignment.Target.Instance != null)
{
continue;
}
iDisposableVariable = assignment.Target.Definition as ILocalDefinition;
if (iDisposableVariable == null)
{
continue;
}
}
var conditional = finallyStatements.ElementAt(index++) as IConditionalStatement;
if (conditional == null)
{
continue;
}
var expressionStatement = finallyStatements.ElementAt(index++) as IExpressionStatement;
if (expressionStatement == null)
{
continue;
}
var lableledStatement = finallyStatements.ElementAt(index++) as ILabeledStatement;
if (lableledStatement == null)
{
continue;
}
var equality = conditional.Condition as IEquality;
if (equality == null)
{
continue;
}
be = equality.LeftOperand as IBoundExpression;
if (be == null)
{
continue;
}
if (be.Instance != null)
{
continue;
}
if (be.Definition != iDisposableVariable)
{
continue;
}
if (!(conditional.FalseBranch is IEmptyStatement))
{
continue;
}
var gotoStatement = conditional.TrueBranch as IGotoStatement;
if (gotoStatement == null)
{
continue;
}
if (gotoStatement.TargetStatement != lableledStatement)
{
continue;
}
var methodCall = expressionStatement.Expression as IMethodCall;
if (methodCall == null)
{
continue;
}
var ct = methodCall.MethodToCall.ContainingType;
if (!TypeHelper.TypesAreEquivalent(ct, this.IDisposable))
{
continue;
}
}
else
{
continue;
}
var resourceUse = new ResourceUseStatement()
{
Locations = tryFinally.Locations,
ResourceAcquisitions = resourceAcquisition,
Body = tryFinally.TryBody
};
statements[i] = resourceUse;
statements.RemoveAt(i - 2);
i--;
}
base.TraverseChildren(block);
}