/// \brief If an overloaded operator call is a dereference of IndexVar or
/// a subscript of a the container with IndexVar as the single argument,
/// include it as a valid usage and prune the traversal.
///
/// For example, given
/// \code
/// struct Foo { int bar(); int x; };
/// vector<Foo> v;
/// void f(Foo);
/// \endcode
/// the following uses will be considered convertible:
/// \code
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
/// f(*i);
/// }
/// for (int i = 0; i < v.size(); ++i) {
/// int i = v[i] + 1;
/// }
/// \endcode
bool ForLoopIndexUseVisitor::TraverseCXXOperatorCallExpr(
CXXOperatorCallExpr *OpCall) {
switch (OpCall->getOperator()) {
case OO_Star:
if (isDereferenceOfOpCall(OpCall, IndexVar)) {
Usages.push_back(Usage(OpCall));
return true;
}
break;
case OO_Subscript:
if (OpCall->getNumArgs() != 2)
break;
if (isIndexInSubscriptExpr(Context, OpCall->getArg(1), IndexVar,
OpCall->getArg(0), ContainerExpr,
ContainerNeedsDereference)) {
Usages.push_back(Usage(OpCall));
return true;
}
break;
default:
break;
}
return VisitorBase::TraverseCXXOperatorCallExpr(OpCall);
}
//// \brief Apply the source transformations necessary to migrate the loop!
void LoopFixer::doConversion(ASTContext *Context,
const VarDecl *IndexVar,
const VarDecl *MaybeContainer,
StringRef ContainerString,
const UsageResult &Usages,
const DeclStmt *AliasDecl, const ForStmt *TheLoop,
bool ContainerNeedsDereference) {
std::string VarName;
if (Usages.size() == 1 && AliasDecl) {
const VarDecl *AliasVar = cast<VarDecl>(AliasDecl->getSingleDecl());
VarName = AliasVar->getName().str();
// We keep along the entire DeclStmt to keep the correct range here.
const SourceRange &ReplaceRange = AliasDecl->getSourceRange();
if (!CountOnly)
Replace->insert(
Replacement(Context->getSourceManager(),
CharSourceRange::getTokenRange(ReplaceRange), ""));
// No further replacements are made to the loop, since the iterator or index
// was used exactly once - in the initialization of AliasVar.
} else {
VariableNamer Namer(GeneratedDecls, &ParentFinder->getStmtToParentStmtMap(),
TheLoop, IndexVar, MaybeContainer);
VarName = Namer.createIndexName();
// First, replace all usages of the array subscript expression with our new
// variable.
for (UsageResult::const_iterator I = Usages.begin(), E = Usages.end();
I != E; ++I) {
std::string ReplaceText = I->IsArrow ? VarName + "." : VarName;
ReplacedVarRanges->insert(std::make_pair(TheLoop, IndexVar));
if (!CountOnly)
Replace->insert(
Replacement(Context->getSourceManager(),
CharSourceRange::getTokenRange(I->Range),
ReplaceText));
}
}
// Now, we need to construct the new range expresion.
SourceRange ParenRange(TheLoop->getLParenLoc(), TheLoop->getRParenLoc());
QualType AutoRefType =
Context->getLValueReferenceType(Context->getAutoDeductType());
std::string MaybeDereference = ContainerNeedsDereference ? "*" : "";
std::string TypeString = AutoRefType.getAsString();
std::string Range = ("(" + TypeString + " " + VarName + " : "
+ MaybeDereference + ContainerString + ")").str();
if (!CountOnly)
Replace->insert(Replacement(Context->getSourceManager(),
CharSourceRange::getTokenRange(ParenRange),
Range));
GeneratedDecls->insert(make_pair(TheLoop, VarName));
}
/// \brief If the unary operator is a dereference of IndexVar, include it
/// as a valid usage and prune the traversal.
///
/// For example, if container.begin() and container.end() both return pointers
/// to int, this makes sure that the initialization for `k` is not counted as an
/// unconvertible use of the iterator `i`.
/// \code
/// for (int *i = container.begin(), *e = container.end(); i != e; ++i) {
/// int k = *i + 2;
/// }
/// \endcode
bool ForLoopIndexUseVisitor::TraverseUnaryDeref(UnaryOperator *Uop) {
// If we dereference an iterator that's actually a pointer, count the
// occurrence.
if (isDereferenceOfUop(Uop, IndexVar)) {
Usages.push_back(Usage(Uop));
return true;
}
return VisitorBase::TraverseUnaryOperator(Uop);
}
/// \brief If the member expression is operator-> (overloaded or not) on
/// IndexVar, include it as a valid usage and prune the traversal.
///
/// For example, given
/// \code
/// struct Foo { int bar(); int x; };
/// vector<Foo> v;
/// \endcode
/// the following uses will be considered convertible:
/// \code
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
/// int b = i->bar();
/// int k = i->x + 1;
/// }
/// \endcode
/// though
/// \code
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
/// int k = i.insert(1);
/// }
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
/// int b = e->bar();
/// }
/// \endcode
/// will not.
bool ForLoopIndexUseVisitor::TraverseMemberExpr(MemberExpr *Member) {
const Expr *Base = Member->getBase();
const DeclRefExpr *Obj = getDeclRef(Base);
const Expr *ResultExpr = Member;
QualType ExprType;
if (const CXXOperatorCallExpr *Call =
dyn_cast<CXXOperatorCallExpr>(Base->IgnoreParenImpCasts())) {
// If operator->() is a MemberExpr containing a CXXOperatorCallExpr, then
// the MemberExpr does not have the expression we want. We therefore catch
// that instance here.
// For example, if vector<Foo>::iterator defines operator->(), then the
// example `i->bar()` at the top of this function is a CXXMemberCallExpr
// referring to `i->` as the member function called. We want just `i`, so
// we take the argument to operator->() as the base object.
if(Call->getOperator() == OO_Arrow) {
assert(Call->getNumArgs() == 1 &&
"Operator-> takes more than one argument");
Obj = getDeclRef(Call->getArg(0));
ResultExpr = Obj;
ExprType = Call->getCallReturnType();
}
}
if (Member->isArrow() && Obj && exprReferencesVariable(IndexVar, Obj)) {
if (ExprType.isNull())
ExprType = Obj->getType();
assert(ExprType->isPointerType() && "Operator-> returned non-pointer type");
// FIXME: This works around not having the location of the arrow operator.
// Consider adding OperatorLoc to MemberExpr?
SourceLocation ArrowLoc =
Lexer::getLocForEndOfToken(Base->getExprLoc(), 0,
Context->getSourceManager(),
Context->getLangOpts());
// If something complicated is happening (i.e. the next token isn't an
// arrow), give up on making this work.
if (!ArrowLoc.isInvalid()) {
Usages.push_back(Usage(ResultExpr, /*IsArrow=*/true,
SourceRange(Base->getExprLoc(), ArrowLoc)));
return true;
}
}
return TraverseStmt(Member->getBase());
}
/// \brief If we encounter an array with IndexVar as the index of an
/// ArraySubsriptExpression, note it as a consistent usage and prune the
/// AST traversal.
///
/// For example, given
/// \code
/// const int N = 5;
/// int arr[N];
/// \endcode
/// This is intended to permit
/// \code
/// for (int i = 0; i < N; ++i) { /* use arr[i] */ }
/// \endcode
/// but not
/// \code
/// for (int i = 0; i < N; ++i) { /* use notArr[i] */ }
/// \endcode
/// and further checking needs to be done later to ensure that exactly one array
/// is referenced.
bool ForLoopIndexUseVisitor::TraverseArraySubscriptExpr(
ArraySubscriptExpr *ASE) {
Expr *Arr = ASE->getBase();
if (!isIndexInSubscriptExpr(ASE->getIdx(), IndexVar))
return VisitorBase::TraverseArraySubscriptExpr(ASE);
if ((ContainerExpr && !areSameExpr(Context, Arr->IgnoreParenImpCasts(),
ContainerExpr->IgnoreParenImpCasts()))
|| !arrayMatchesBoundExpr(Context, Arr->IgnoreImpCasts()->getType(),
ArrayBoundExpr)) {
// If we have already discovered the array being indexed and this isn't it
// or this array doesn't match, mark this loop as unconvertible.
OnlyUsedAsIndex = false;
return VisitorBase::TraverseArraySubscriptExpr(ASE);
}
if (!ContainerExpr)
ContainerExpr = Arr;
Usages.push_back(Usage(ASE));
return true;
}
/// \brief If a member function call is the at() accessor on the container with
/// IndexVar as the single argument, include it as a valid usage and prune
/// the traversal.
///
/// Member calls on other objects will not be permitted.
/// Calls on the iterator object are not permitted, unless done through
/// operator->(). The one exception is allowing vector::at() for pseudoarrays.
bool ForLoopIndexUseVisitor::TraverseCXXMemberCallExpr(
CXXMemberCallExpr *MemberCall) {
MemberExpr *Member =
dyn_cast<MemberExpr>(MemberCall->getCallee()->IgnoreParenImpCasts());
if (!Member)
return VisitorBase::TraverseCXXMemberCallExpr(MemberCall);
// We specifically allow an accessor named "at" to let STL in, though
// this is restricted to pseudo-arrays by requiring a single, integer
// argument.
const IdentifierInfo *Ident = Member->getMemberDecl()->getIdentifier();
if (Ident && Ident->isStr("at") && MemberCall->getNumArgs() == 1) {
if (isIndexInSubscriptExpr(Context, MemberCall->getArg(0), IndexVar,
Member->getBase(), ContainerExpr,
ContainerNeedsDereference)) {
Usages.push_back(Usage(MemberCall));
return true;
}
}
if (containsExpr(Context, &DependentExprs, Member->getBase()))
ConfidenceLevel.lowerTo(TCK_Risky);
return VisitorBase::TraverseCXXMemberCallExpr(MemberCall);
}
//// \brief Apply the source transformations necessary to migrate the loop!
void LoopFixer::doConversion(ASTContext *Context,
const VarDecl *IndexVar,
const VarDecl *MaybeContainer,
StringRef ContainerString,
const UsageResult &Usages,
const DeclStmt *AliasDecl,
bool AliasUseRequired,
bool AliasFromForInit,
const ForStmt *TheLoop,
bool ContainerNeedsDereference,
bool DerefByValue,
bool DerefByConstRef) {
std::string VarName;
bool VarNameFromAlias = Usages.size() == 1 && AliasDecl;
bool AliasVarIsRef = false;
if (VarNameFromAlias) {
const VarDecl *AliasVar = cast<VarDecl>(AliasDecl->getSingleDecl());
VarName = AliasVar->getName().str();
AliasVarIsRef = AliasVar->getType()->isReferenceType();
// We keep along the entire DeclStmt to keep the correct range here.
const SourceRange &ReplaceRange = AliasDecl->getSourceRange();
std::string ReplacementText;
if (AliasUseRequired)
ReplacementText = VarName;
else if (AliasFromForInit)
// FIXME: Clang includes the location of the ';' but only for DeclStmt's
// in a for loop's init clause. Need to put this ';' back while removing
// the declaration of the alias variable. This is probably a bug.
ReplacementText = ";";
Owner.addReplacementForCurrentTU(Replacement(
Context->getSourceManager(),
CharSourceRange::getTokenRange(ReplaceRange), ReplacementText));
// No further replacements are made to the loop, since the iterator or index
// was used exactly once - in the initialization of AliasVar.
} else {
VariableNamer Namer(&TUInfo.getGeneratedDecls(),
&TUInfo.getParentFinder().getStmtToParentStmtMap(),
TheLoop, IndexVar, MaybeContainer, Context);
VarName = Namer.createIndexName();
// First, replace all usages of the array subscript expression with our new
// variable.
for (UsageResult::const_iterator I = Usages.begin(), E = Usages.end();
I != E; ++I) {
std::string ReplaceText = I->IsArrow ? VarName + "." : VarName;
TUInfo.getReplacedVars().insert(std::make_pair(TheLoop, IndexVar));
Owner.addReplacementForCurrentTU(
Replacement(Context->getSourceManager(),
CharSourceRange::getTokenRange(I->Range), ReplaceText));
}
}
// Now, we need to construct the new range expresion.
SourceRange ParenRange(TheLoop->getLParenLoc(), TheLoop->getRParenLoc());
QualType AutoRefType = Context->getAutoDeductType();
// If the new variable name is from the aliased variable, then the reference
// type for the new variable should only be used if the aliased variable was
// declared as a reference.
if (!VarNameFromAlias || AliasVarIsRef) {
// If an iterator's operator*() returns a 'T&' we can bind that to 'auto&'.
// If operator*() returns 'T' we can bind that to 'auto&&' which will deduce
// to 'T&&'.
if (DerefByValue)
AutoRefType = Context->getRValueReferenceType(AutoRefType);
else {
if (DerefByConstRef)
AutoRefType = Context->getConstType(AutoRefType);
AutoRefType = Context->getLValueReferenceType(AutoRefType);
}
}
std::string MaybeDereference = ContainerNeedsDereference ? "*" : "";
std::string TypeString = AutoRefType.getAsString();
std::string Range = ("(" + TypeString + " " + VarName + " : "
+ MaybeDereference + ContainerString + ")").str();
Owner.addReplacementForCurrentTU(
Replacement(Context->getSourceManager(),
CharSourceRange::getTokenRange(ParenRange), Range));
TUInfo.getGeneratedDecls().insert(make_pair(TheLoop, VarName));
}
