private bool ExtractFromClump(StatementList contractClump, Method method, GatherLocals gatherLocals,
RequiresList Preconditions, EnsuresList Postconditions, RequiresList validations,
EnsuresList modelPostconditions, SourceContext defaultContext, Method originalMethod,
Block contractInitializer, ref HelperMethods.StackDepthTracker dupStackTracker)
{
// set the state so that the contract clump is used for extraction (as opposed to the method body as it used to)
StatementList stmts = contractClump;
int beginning = 0;
int n = stmts.Count;
int seginning = HelperMethods.FindNextRealStatement(((Block) stmts[beginning]).Statements, 0);
bool endContractFound = false;
bool postConditionFound = false;
SourceContext currentSourceContext;
for (int i = beginning; i < n; i++)
{
Block b = (Block) stmts[i];
if (b == null) continue;
for (int j = 0, m = b.Statements == null ? 0 : b.Statements.Count; j < m; j++)
{
if (dupStackTracker.IsValid && dupStackTracker.Depth >= 0)
{
b.Statements[j] = dupStackTracker.Visit(b.Statements[j]);
}
Statement s = b.Statements[j];
if (s == null) continue;
Block currentClump;
Throw t = null;
t = s as Throw;
Method calledMethod = HelperMethods.IsMethodCall(s);
if ((t != null ||
(calledMethod != null &&
calledMethod.DeclaringType != null &&
calledMethod.DeclaringType != this.contractNodes.ContractClass &&
HelperMethods.IsVoidType(calledMethod.ReturnType) &&
!this.contractNodes.IsContractOrValidatorOrAbbreviatorMethod(calledMethod))))
{
// Treat throw statements as (part of) a precondition
// don't accept "throw ..." unless it comes in the "precondition section"
// then treat the current clump as a precondition, but need to massage it a bit:
// all branches to the block just after the throw should be modified to be branches to
// a new manufactured block that sets a fresh local to "true". The
// throw itself should be changed to set the same local to "false". That way the
// clump can be treated as the value of precondition (because the branch polarity has
// already been negated as part of the code gen).
// This test was supposed to be a sanity check that the current block contained
// only "throw ..." or else "nop; throw ...". But I've also seen "ThrowHelper.Throw(...); nop",
// so I'm just going to comment this out for now.
//if (!((m == 1 && j == 0) || (m == 2 && j == 1))) {
// Preconditions = new RequiresList();
// Postconditions = new EnsuresList();
// return; // throw new ExtractorException();
//}
Expression exception;
// The clump being extracted may contain code/blocks that represent (part of)
// the expression that is being thrown (if the original throw expression had
// control flow in it from boolean expressions and/or ternary expressions).
b.Statements[j] = null; // wipe out throw statement
currentClump = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
int currentClumpLength = i - beginning + 1;
// there better be a next block because that must have been the target for all of the branches
// that didn't cause the throw to happen
if (!(i < n - 1))
{
this.HandleError(method, 1027, "Malformed contract.", s.SourceContext);
return false;
}
Block nextBlock = (Block) stmts[i + 1]; // cast succeeds because body is clump
Local valueOfPrecondition = new Local(Identifier.For("_preConditionHolds"), SystemTypes.Boolean);
Block preconditionHolds = new Block(new StatementList(new AssignmentStatement(valueOfPrecondition, Literal.True)));
ReplaceBranchTarget rbt = new ReplaceBranchTarget(nextBlock, preconditionHolds);
rbt.VisitBlock(currentClump);
int ILOffset;
CountPopExpressions cpe = new CountPopExpressions();
currentSourceContext = s.SourceContext;
cpe.Visit(s);
if (0 < cpe.PopOccurrences)
{
// then there is a set of blocks that represent the exception: the Reader
// was not able to decompile it back into an expression. Extract the set
// from the current clump and make it into a block expression
// Find the last block that has a branch to "preconditionHolds". After that are all of the blocks
// that represent the evaluation of the exception
int branchBlockIndex = currentClumpLength - 2;
// can't be the current block: that has the throw in it
while (0 <= branchBlockIndex)
{
Block possibleBranchBlock = currentClump.Statements[branchBlockIndex] as Block;
Branch br = possibleBranchBlock.Statements[possibleBranchBlock.Statements.Count - 1] as Branch;
if (br != null && br.Target == preconditionHolds)
{
break;
}
branchBlockIndex--;
}
if (branchBlockIndex < 0)
{
this.HandleError(method, 1028, "Malformed exception constructor in contract.", defaultContext);
return false;
}
Block exceptionBlock =
new Block(HelperMethods.ExtractClump(currentClump.Statements, branchBlockIndex + 1, 0,
currentClumpLength - 1,
((Block) currentClump.Statements[currentClumpLength - 1]).Statements.Count - 1));
exceptionBlock.Statements.Add(new ExpressionStatement(t.Expression));
SourceContext sctx = ((Block) exceptionBlock.Statements[0]).Statements[0].SourceContext;
if (sctx.IsValid)
{
currentSourceContext = sctx;
}
else
{
SourceContext tmp;
bool foundContext = HelperMethods.GetLastSourceContext(exceptionBlock.Statements, out tmp);
if (foundContext)
currentSourceContext = tmp;
}
if (!CheckClump(method, gatherLocals, currentSourceContext, exceptionBlock)) return false;
exception = new BlockExpression(exceptionBlock, SystemTypes.Exception);
ILOffset = t.ILOffset;
}
else
{
currentSourceContext = s.SourceContext;
if (t != null)
{
// then the statement is "throw ..."
exception = t.Expression;
ILOffset = t.ILOffset;
}
else
{
ExpressionStatement throwHelperCall = s as ExpressionStatement;
Debug.Assert(throwHelperCall != null);
exception = throwHelperCall.Expression;
ILOffset = s.ILOffset;
}
exception.SourceContext = currentSourceContext;
SourceContext tmp;
bool foundContext = HelperMethods.GetLastSourceContext(currentClump.Statements, out tmp);
if (foundContext)
currentSourceContext = tmp;
}
Block returnValueOfPrecondition = new Block(new StatementList(new ExpressionStatement(valueOfPrecondition)));
Statement extraAssumeFalse = this.ExtraAssumeFalseOnThrow();
Block preconditionFails =
new Block(new StatementList(new AssignmentStatement(valueOfPrecondition, Literal.False),
extraAssumeFalse, new Branch(null, returnValueOfPrecondition, true, false, false)));
//Block preconditionFails = new Block(new StatementList(new AssignmentStatement(valueOfPrecondition, Literal.False), new Branch(null, returnValueOfPrecondition, true, false, false)));
currentClump.Statements.Add(preconditionFails); // replace throw statement
currentClump.Statements.Add(preconditionHolds);
currentClump.Statements.Add(returnValueOfPrecondition);
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, currentClump)) return false;
BlockExpression be = new BlockExpression(currentClump, SystemTypes.Boolean);
be.SourceContext = currentSourceContext;
var ro = new RequiresOtherwise(be, exception);
ro.ILOffset = ILOffset;
ro.SourceContext = currentSourceContext;
if (postConditionFound)
{
HandleError(originalMethod, 1013, "Precondition found after postcondition.", currentSourceContext);
return false;
}
validations.Add(ro);
var req = new RequiresPlain(be, FindExceptionThrown.Find(exception));
req.IsFromValidation = true;
req.ILOffset = ro.ILOffset;
req.SourceContext = ro.SourceContext;
Preconditions.Add(req);
}
else
{
if (contractNodes.IsContractMethod(calledMethod))
{
// Treat calls to contract methods
if (endContractFound)
{
HandleError(originalMethod, 1012, "Contract call found after prior EndContractBlock.", s.SourceContext);
break;
}
if (contractNodes.IsEndContract(calledMethod))
{
endContractFound = true;
continue;
}
MethodCall mc = ((ExpressionStatement) s).Expression as MethodCall;
Expression arg = mc.Operands[0];
arg.SourceContext = s.SourceContext;
MethodContractElement mce;
currentSourceContext = s.SourceContext;
Expression condition;
if (beginning == i && seginning == j)
{
// Deal with the simple case: the reader decompiled the call into a single statement
condition = arg;
}
else
{
b.Statements[j] = new ExpressionStatement(arg);
// construct a clump from
// methodBody.Statements[beginning].Statements[seginning] to
// methodBody.Statements[i].Statements[j]
currentClump = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
if (!currentSourceContext.IsValid)
{
// then a good source context has not been found yet. Grovel around in the clump
// to see if there is a better one
SourceContext sctx;
if (HelperMethods.FindContext(currentClump, currentSourceContext, out sctx))
currentSourceContext = sctx;
}
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, currentClump))
return false;
BlockExpression be = new BlockExpression(currentClump);
condition = be;
}
condition.SourceContext = currentSourceContext;
if (contractNodes.IsPlainPrecondition(calledMethod))
{
var req = new RequiresPlain(condition);
contractNodes.IsRequiresWithException(calledMethod, out req.ExceptionType);
mce = req;
}
else if (this.contractNodes.IsPostcondition(calledMethod))
{
mce = new EnsuresNormal(condition);
}
else if (contractNodes.IsExceptionalPostcondition(calledMethod))
{
EnsuresExceptional ee = new EnsuresExceptional(condition);
// Extract the type of exception.
ee.Type = calledMethod.TemplateArguments[0];
mce = ee;
}
else
{
throw new InvalidOperationException("Cannot recognize contract method");
}
mce.SourceContext = currentSourceContext;
mce.ILOffset = mc.ILOffset;
if (1 < mc.Operands.Count)
{
var candidate = SanitizeUserMessage(method, mc.Operands[1], currentSourceContext);
mce.UserMessage = candidate;
}
if (2 < mc.Operands.Count)
{
Literal lit = mc.Operands[2] as Literal;
if (lit != null)
{
mce.SourceConditionText = lit;
}
}
// determine Model status
mce.UsesModels = CodeInspector.UsesModel(mce.Assertion, this.contractNodes);
// Check context rules
switch (mce.NodeType)
{
case NodeType.RequiresPlain:
if (postConditionFound)
{
this.HandleError(originalMethod, 1014, "Precondition found after postcondition.", currentSourceContext);
return false;
}
if (mce.UsesModels)
{
this.HandleError(originalMethod, 1073, "Preconditions may not refer to model members.", currentSourceContext);
return false;
}
var rp = (RequiresPlain) mce;
Preconditions.Add(rp);
validations.Add(rp); // also add to the internal validation list
break;
// TODO: check visibility of post conditions based on visibility of possible implementation
case NodeType.EnsuresNormal:
case NodeType.EnsuresExceptional:
Ensures ensures = (Ensures) mce;
if (mce.UsesModels)
{
if (this.IncludeModels)
{
modelPostconditions.Add(ensures);
}
}
else
{
Postconditions.Add(ensures);
}
postConditionFound = true;
break;
}
}
else if (ContractNodes.IsValidatorMethod(calledMethod))
{
// Treat calls to Contract validators
if (endContractFound)
{
this.HandleError(originalMethod, 1012,
"Contract call found after prior EndContractBlock.", s.SourceContext);
break;
}
MethodCall mc = ((ExpressionStatement) s).Expression as MethodCall;
var memberBinding = (MemberBinding) mc.Callee;
currentSourceContext = s.SourceContext;
Statement validation;
Block validationPrefix;
if (beginning == i && seginning == j)
{
// Deal with the simple case: the reader decompiled the call into a single statement
validation = s;
validationPrefix = null;
}
else
{
// The clump may contain multiple statements ending in the validator call.
// to extract the code as Requires<E>, we need to keep the statements preceeding
// the validator call, as they may contain local initialization etc. These should go
// into the first Requires<E> that the validator expands to. This way, if there are
// no Requires<E> expanded from the validator, then the statements can be omitted.
// At the same time, the statements won't be duplicated when validations are emitted.
//
// If the validator call contains any pops, then the extraction must fail saying it
// is too complicated.
// must null out statement with call before extract clump
b.Statements[j] = null; // we have a copy in mc, s
validationPrefix = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
if (!currentSourceContext.IsValid)
{
// then a good source context has not been found yet. Grovel around in the clump
// to see if there is a better one
SourceContext sctx;
if (HelperMethods.FindContext(validationPrefix, currentSourceContext, out sctx))
currentSourceContext = sctx;
}
if (CountPopExpressions.Count(mc) > 0)
{
this.HandleError(method, 1071,
"Arguments to contract validator call are too complicated. Please simplify.",
currentSourceContext);
return false;
}
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, validationPrefix))
return false;
validation = new Block(new StatementList(validationPrefix, s));
validation.SourceContext = currentSourceContext;
}
var ro = new RequiresOtherwise(null, new BlockExpression(new Block(new StatementList(validation))));
validations.Add(ro);
CopyValidatorContracts(
method, calledMethod, memberBinding.TargetObject, mc.Operands,
Preconditions, currentSourceContext, validationPrefix);
}
else if (ContractNodes.IsAbbreviatorMethod(calledMethod))
{
// Treat calls to Contract abbreviators
if (endContractFound)
{
this.HandleError(originalMethod, 1012, "Contract call found after prior EndContractBlock.", s.SourceContext);
break;
}
MethodCall mc = ((ExpressionStatement) s).Expression as MethodCall;
var memberBinding = (MemberBinding) mc.Callee;
currentSourceContext = s.SourceContext;
if (beginning == i && seginning == j)
{
// Deal with the simple case: the reader decompiled the call into a single statement
// nothing to do. All is in the call and its arguments
}
else
{
// The clump may contain multiple statements ending in the abbreviator call.
// We need to keep the statements preceeding the abbreviator call and add them to the
// contract initializer block. The reason we cannot add them to the first expansion contract
// of the abbreviator is that the abbreviator may give rise to closure initialization which will
// be hoisted into the closure initializer block. This closure initializer may refer to the
// locals initialized by the present statement sequence, so it must precede it.
//
// If the abbreviator call contains any pops, then the extraction must fail saying it
// is too complicated.
// grab prefix of clump minus last call statement.
// must null out current call statement before we extract clump (ow. it stays in body)
b.Statements[j] = null;
currentClump = new Block(HelperMethods.ExtractClump(stmts, beginning, seginning, i, j));
if (!currentSourceContext.IsValid)
{
// then a good source context has not been found yet. Grovel around in the clump
// to see if there is a better one
SourceContext sctx;
if (HelperMethods.FindContext(currentClump, currentSourceContext, out sctx))
currentSourceContext = sctx;
}
if (CountPopExpressions.Count(mc) > 0)
{
this.HandleError(method, 1070,
"Arguments to contract abbreviator call are too complicated. Please simplify.",
currentSourceContext);
return false;
}
if (!CheckClump(originalMethod, gatherLocals, currentSourceContext, currentClump))
return false;
if (HelperMethods.IsNonTrivial(currentClump))
{
contractInitializer.Statements.Add(currentClump);
}
}
CopyAbbreviatorContracts(method, calledMethod, memberBinding.TargetObject, mc.Operands,
Preconditions, Postconditions, currentSourceContext, validations, contractInitializer);
}
else
{
// important to continue here and accumulate blocks/statements for next contract!
if (i == beginning && j == seginning && s.NodeType == NodeType.Nop)
{
// nop following contract is often associated with previous code, so skip it
seginning = j + 1;
}
continue;
}
}
// Re-initialize current state after contract has been found
beginning = i;
seginning = j + 1;
//seginning = HelperMethods.FindNextRealStatement(((Block)stmts[i]).Statements, j + 1);
if (seginning < 0) seginning = 0;
//b = (Block)stmts[i]; // IMPORTANT! Need this to keep "b" in sync
}
}
if (this.verbose)
{
Console.WriteLine("\tNumber of Preconditions: " + Preconditions.Count);
Console.WriteLine("\tNumber of Postconditions: " + Postconditions.Count);
}
return true;
}
// 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 void ProcessClosureClass(Method method, TypeNode closure, bool isAsync)
{
Contract.Requires(method != null);
Contract.Requires(closure != null);
Method movenext = closure.GetMethod(StandardIds.MoveNext);
if (movenext == null) return;
movenext.IsAsync = isAsync;
if (movenext.Body == null) return;
if (movenext.Body.Statements == null) return;
SourceContext defaultSourceContext;
Block contractInitializerBlock = new Block(new StatementList());
HelperMethods.StackDepthTracker dupStackTracker = new HelperMethods.StackDepthTracker();
AssumeBlock originalContractPosition;
StatementList contractClump = GetContractClumpFromMoveNext(method, movenext, contractNodes,
contractInitializerBlock.Statements, out defaultSourceContext, ref dupStackTracker,
out originalContractPosition);
if (contractClump != null)
{
// Look for bad stuff
BadStuff(method, contractClump, defaultSourceContext);
// 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();
// Make sure that the entire contract section is closed.
if (!CheckClump(movenext, gatherLocals, currentMethodSourceContext, new Block(contractClump)))
{
movenext.ClearBody();
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();
RequiresList Preconditions = new RequiresList();
EnsuresList Postconditions = new EnsuresList();
RequiresList Validations = new RequiresList();
EnsuresList modelPostconditions = new EnsuresList();
EnsuresList asyncPostconditions = null;
// REVIEW: What should we do with the Validations in this case? Should we map them to the enumerator method? Maybe not, since without
// rewriting this won't happen.
if (!ExtractFromClump(contractClump, movenext, gatherLocals, Preconditions, Postconditions, Validations,
modelPostconditions, defaultSourceContext, method, contractInitializerBlock, ref dupStackTracker))
{
movenext.ClearBody();
return;
}
if (isAsync)
{
asyncPostconditions = SplitAsyncEnsures(ref Postconditions, method);
}
try
{
// Next is to attach the preconditions to method (instead of movenext)
// To do so, we have to duplicate the expressions and statements in Precondition, Postcondition and contractInitializerBlock
Duplicator dup = new Duplicator(closure.DeclaringModule, method.DeclaringType);
var origPreconditions = Preconditions;
var origValidations = Validations;
var origcontractInitializerBlock = contractInitializerBlock;
Preconditions = dup.VisitRequiresList(Preconditions);
Postconditions = dup.VisitEnsuresList(Postconditions);
Validations = dup.VisitRequiresList(Validations);
contractInitializerBlock = dup.VisitBlock(contractInitializerBlock);
asyncPostconditions = dup.VisitEnsuresList(asyncPostconditions);
var mapClosureExpToOriginal = BuildMappingFromClosureToOriginal(closure, movenext, method);
Preconditions = mapClosureExpToOriginal.Apply(Preconditions);
Postconditions = mapClosureExpToOriginal.Apply(Postconditions);
Validations = mapClosureExpToOriginal.Apply(Validations);
contractInitializerBlock = mapClosureExpToOriginal.Apply(contractInitializerBlock);
asyncPostconditions = mapClosureExpToOriginal.Apply(asyncPostconditions);
//MemberList members = FindClosureMembersInContract(closure, movenext);
// MakeClosureAccessibleToOriginalMethod(closure, members);
if (method.Contract == null)
method.Contract = new MethodContract(method);
method.Contract.Requires = Preconditions;
method.Contract.Validations = Validations;
// Postconditions are sanity checked here, because Result<T> must be compared against the
// return type of the original method. It is most conveniently done after the type substitution.
// TODO: refactor the checking part altogether out of ExtractFromClump.
method.Contract.Ensures = Postconditions;
method.Contract.ModelEnsures = modelPostconditions;
method.Contract.ContractInitializer = contractInitializerBlock;
method.Contract.AsyncEnsures = asyncPostconditions;
// Following replacement causes some weird issues for complex preconditions (like x != null && x.Length > 0)
// when CCRewriter is used with /publicsurface or Preconditions only.
// This fix could be temporal and proper fix would be applied in the future.
// After discussion this issue with original CC authors (Mike Barnett and Francesco Logozzo),
// we decided that this fix is safe and lack of Assume statement in the MoveNext method will not affect
// customers (neither CCRewriter customers nor CCCheck customers).
// If this assumption would not be true in the future, proper fix should be applied.
// put requires as assumes into movenext method at original position
// ReplaceRequiresWithAssumeInMoveNext(origPreconditions, originalContractPosition);
// no postPreamble to initialize, as method is not a ctor
}
finally
{
// this is done in caller!!!
//// normalize contract by forcing IsPure to look at attributes and removing contract it is empty
//var contract = method.Contract;
//var isPure = contract.IsPure;
//if (!isPure && contract.RequiresCount == 0 && contract.EnsuresCount == 0 && contract.ModelEnsuresCount == 0 && contract.ValidationsCount == 0 && contract.AsyncEnsuresCount == 0)
//{
// method.Contract = null;
//} else
//{
// // turn helper method calls to Result, OldValue, ValueAtReturn into proper AST nodes.
// this.extractionFinalizer.VisitMethodContract(method.Contract);
//}
}
}
}
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;
}
public CheckLocals(GatherLocals gatherLocals)
{
this.gatherLocals = gatherLocals;
}
public CheckLocals(GatherLocals gatherLocals)
{
this.gatherLocals = gatherLocals;
}
