// Ensures:
// Preconditions != null
// && ForAll{Requires r in Preconditions;
// r.Condition is BlockExpression
// && r.Condition.Type == Void
// && IsClump(r.Condition.Block.Statements)
// Postconditions != null
// && ForAll{Ensures e in Posconditions;
// e.PostCondition is BlockExpression
// && e.PostCondition.Type == Void
// && IsClump(e.PostCondition.Block.Statements)
// (In addition, each Requires is a RequiresPlain when the contract
// call is Contract.Requires and is a RequiresOtherwise when the
// contract call is Critical.Requires. In the latter case, the
// ThrowException is filled in correctly.)
//
/// <summary>
///
/// </summary>
/// <param name="method"></param>
/// <param name="Preconditions"></param>
/// <param name="Postconditions"></param>
/// <param name="Validations"></param>
/// <param name="contractInitializerBlock">used to store extra closure initializations from abbrevs and validators</param>
public void CheapAndDirty(
Method method,
ref RequiresList Preconditions,
ref EnsuresList Postconditions,
ref RequiresList Validations,
ref EnsuresList modelPostConditions,
Block contractInitializerBlock,
ref HelperMethods.StackDepthTracker dupStackTracker)
{
if (this.verbose)
{
Console.WriteLine("Method : " + method.FullName);
}
if (method == null || method.Body == null || method.Body.Statements == null ||
method.Body.Statements.Count <= 0)
{
return;
}
Block methodBody = method.Body;
int n = methodBody.Statements.Count;
int beginning = 0;
while (beginning < n && methodBody.Statements[beginning] is PreambleBlock)
{
beginning++;
}
int lastBlockContainingContract;
int lastStatementContainingContract;
bool anyContractCall = FindLastBlockWithContracts(methodBody.Statements, beginning,
out lastBlockContainingContract, out lastStatementContainingContract);
// Make sure any locals in the contracts are disjoint from the locals in the rest of the body
// can use the same one throughout
GatherLocals gatherLocals = new GatherLocals();
SourceContext lastContractSourceContext = method.SourceContext;
if (!anyContractCall)
{
if (this.verbose)
{
Console.WriteLine("\tNo contracts found");
}
// still need to check for bad other contract calls in method body
goto CheckBody;
}
Block lastBlock = methodBody.Statements[lastBlockContainingContract] as Block;
lastContractSourceContext = lastBlock.SourceContext;
// probably not a good context, what to do if one can't be found?
if (lastBlock.Statements != null && 0 <= lastStatementContainingContract &&
lastStatementContainingContract < lastBlock.Statements.Count)
{
lastContractSourceContext = lastBlock.Statements[lastStatementContainingContract].SourceContext;
}
// Make sure contract section is not in any try-catch region
TrivialHashtable<int> block2Index = new TrivialHashtable<int>(methodBody.Statements.Count);
for (int i = 0, nn = methodBody.Statements.Count; i < nn; i++)
{
if (methodBody.Statements[i] == null) continue;
block2Index[methodBody.Statements[i].UniqueKey] = i;
}
// Check each exception handler and see if any overlap with the contract section
for (int i = 0, nn = method.ExceptionHandlers == null ? 0 : method.ExceptionHandlers.Count; i < nn; i++)
{
ExceptionHandler eh = method.ExceptionHandlers[i];
if (eh == null) continue;
if (((int) block2Index[eh.BlockAfterTryEnd.UniqueKey]) < beginning ||
lastBlockContainingContract < ((int) block2Index[eh.TryStartBlock.UniqueKey]))
{
continue; // can't overlap
}
this.HandleError(method, 1024, "Contract section within try block.", lastContractSourceContext);
return;
}
// Extract <beginning,0> to <lastBlockContainingContract,lastStatmentContainingContract>
StatementList contractClump = HelperMethods.ExtractClump(methodBody.Statements, beginning, 0,
lastBlockContainingContract, lastStatementContainingContract);
// Look for bad stuff
BadStuff(method, contractClump, lastContractSourceContext);
// Make sure that the entire contract section is closed.
if (!CheckClump(method, gatherLocals, currentMethodSourceContext, new Block(contractClump)))
{
return;
}
// Checking that had the side effect of populating the hashtable, but now each contract will be individually visited.
// That process needs to start with a fresh table.
gatherLocals.Locals = new TrivialHashtable();
Preconditions = new RequiresList();
Postconditions = new EnsuresList();
Validations = new RequiresList();
modelPostConditions = new EnsuresList();
if (!ExtractFromClump(
contractClump, method, gatherLocals, Preconditions, Postconditions, Validations,
modelPostConditions, lastContractSourceContext, method, contractInitializerBlock, ref dupStackTracker))
{
return;
}
CheckBody:
// Check "real" method body for use of any locals used in contracts
// var checkMethodBody = new CheckForBadContractStuffInMethodBody(gatherLocals, this.CallErrorFound, method);
var checkMethodBody = new CheckLocals(gatherLocals);
checkMethodBody.Visit(methodBody);
if (!this.fSharp && checkMethodBody.reUseOfExistingLocal != null)
{
SourceContext sc = lastContractSourceContext;
this.HandleError(method, 1025,
"After contract block, found use of local variable '" +
checkMethodBody.reUseOfExistingLocal.Name.Name + "' defined in contract block", sc);
}
}
private bool CheckClump(Method method, GatherLocals gatherLocals, SourceContext sctx, Block clump)
{
if (!HelperMethods.ClumpIsClosed(clump.Statements))
{
this.contractNodes.CallErrorFound(new Error(1017,
"Malformed contract section in method '" + method.FullName + "'", sctx));
return false;
// throw new ExtractorException();
}
TypeNode t = method.DeclaringType;
bool IsContractTypeForSomeOtherType = t == null
? false
: HelperMethods.GetTypeFromAttribute(t, ContractNodes.ContractClassForAttributeName) != null;
// We require that a contract class implement the interface it is holding contracts for. In addition, the methods in that class must be explicit
// interface implementations. This creates a problem when the contracts need to refer to other methods in the interface. The "this" reference has
// the wrong type: it needs to be the interface type. Writing an explicit cast before every reference is painful. It is better to allow the user
// to create a local variable of the interface type and assign it before the contracts. This can't cause a problem with the local being used later
// in the method body, because methods in contract classes don't have method bodies, just contracts. So don't check for re-use of locals for such
// methods.
//
// Example of above comment
//[ContractClass(typeof(ContractForJ))]
//interface J{
// bool M(int x);
// [Pure]
// bool P { get; }
//}
//[ContractClassFor(typeof(J))]
//class ContractForJ : J{
// bool J.M(int x) {
// J jThis = this;
// Contract.Requires(x != 3);
// Contract.Requires(jThis.P);
// Contract.Ensures(x != 5 || !jThis.P);
// return default(bool);
// }
// bool J.P {
// get {
// Contract.Ensures(Contract.Result<bool>());
// return default(bool);
// }
// }
//}
if (!IsContractTypeForSomeOtherType)
{
// First, make sure the clump doesn't use any locals that were used
// in any previous contract, need a new instance each time
CheckLocals checkLocals = new CheckLocals(gatherLocals);
checkLocals.Visit(clump);
if (!this.fSharp && checkLocals.reUseOfExistingLocal != null)
{
this.HandleError(method, 1040,
"Reuse of existing local variable '" + checkLocals.reUseOfExistingLocal.Name.Name +
"' in contract.", sctx);
return false;
}
// If that test passes, then add in the locals used in the clump into the table of locals that have been used
gatherLocals.Visit(clump);
}
return true;
}
