//===- VariadicMacroSupport.h - state machines and scope guards -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines support types to help with preprocessing variadic macro
// (i.e. macros that use: ellipses __VA_ARGS__ ) definitions and
// expansions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LEX_VARIADICMACROSUPPORT_H
#define LLVM_CLANG_LEX_VARIADICMACROSUPPORT_H
#include "clang/Lex/Preprocessor.h"
#include "llvm/ADT/SmallVector.h"
namespace clang {
class Preprocessor;
/// An RAII class that tracks when the Preprocessor starts and stops lexing
/// the definition of a (ISO C/C++) variadic macro. As an example, this is
/// useful for unpoisoning and repoisoning certain identifiers (such as
/// __VA_ARGS__) that are only allowed in this context. Also, being a friend
/// of the Preprocessor class allows it to access PP's cached identifiers
/// directly (as opposed to performing a lookup each time).
class VariadicMacroScopeGuard {
const Preprocessor &PP;
IdentifierInfo *const Ident__VA_ARGS__;
IdentifierInfo *const Ident__VA_OPT__;
public:
VariadicMacroScopeGuard(const Preprocessor &P)
: PP(P), Ident__VA_ARGS__(PP.Ident__VA_ARGS__),
Ident__VA_OPT__(PP.Ident__VA_OPT__) {
assert(Ident__VA_ARGS__->isPoisoned() && "__VA_ARGS__ should be poisoned "
"outside an ISO C/C++ variadic "
"macro definition!");
assert(
!Ident__VA_OPT__ ||
(Ident__VA_OPT__->isPoisoned() && "__VA_OPT__ should be poisoned!"));
}
/// Client code should call this function just before the Preprocessor is
/// about to Lex tokens from the definition of a variadic (ISO C/C++) macro.
void enterScope() {
Ident__VA_ARGS__->setIsPoisoned(false);
if (Ident__VA_OPT__)
Ident__VA_OPT__->setIsPoisoned(false);
}
/// Client code should call this function as soon as the Preprocessor has
/// either completed lexing the macro's definition tokens, or an error
/// occurred and the context is being exited. This function is idempotent
/// (might be explicitly called, and then reinvoked via the destructor).
void exitScope() {
Ident__VA_ARGS__->setIsPoisoned(true);
if (Ident__VA_OPT__)
Ident__VA_OPT__->setIsPoisoned(true);
}
~VariadicMacroScopeGuard() { exitScope(); }
};
/// A class for tracking whether we're inside a VA_OPT during a
/// traversal of the tokens of a variadic macro definition.
class VAOptDefinitionContext {
/// Contains all the locations of so far unmatched lparens.
SmallVector<SourceLocation, 8> UnmatchedOpeningParens;
const IdentifierInfo *const Ident__VA_OPT__;
public:
VAOptDefinitionContext(Preprocessor &PP)
: Ident__VA_OPT__(PP.Ident__VA_OPT__) {}
bool isVAOptToken(const Token &T) const {
return Ident__VA_OPT__ && T.getIdentifierInfo() == Ident__VA_OPT__;
}
/// Returns true if we have seen the __VA_OPT__ and '(' but before having
/// seen the matching ')'.
bool isInVAOpt() const { return UnmatchedOpeningParens.size(); }
/// Call this function as soon as you see __VA_OPT__ and '('.
void sawVAOptFollowedByOpeningParens(const SourceLocation LParenLoc) {
assert(!isInVAOpt() && "Must NOT be within VAOPT context to call this");
UnmatchedOpeningParens.push_back(LParenLoc);
}
SourceLocation getUnmatchedOpeningParenLoc() const {
assert(isInVAOpt() && "Must be within VAOPT context to call this");
return UnmatchedOpeningParens.back();
}
/// Call this function each time an rparen is seen. It returns true only if
/// the rparen that was just seen was the eventual (non-nested) closing
/// paren for VAOPT, and ejects us out of the VAOPT context.
bool sawClosingParen() {
assert(isInVAOpt() && "Must be within VAOPT context to call this");
UnmatchedOpeningParens.pop_back();
return !UnmatchedOpeningParens.size();
}
/// Call this function each time an lparen is seen.
void sawOpeningParen(SourceLocation LParenLoc) {
assert(isInVAOpt() && "Must be within VAOPT context to call this");
UnmatchedOpeningParens.push_back(LParenLoc);
}
/// Are we at the top level within the __VA_OPT__?
bool isAtTopLevel() const { return UnmatchedOpeningParens.size() == 1; }
};
/// A class for tracking whether we're inside a VA_OPT during a
/// traversal of the tokens of a macro during macro expansion.
class VAOptExpansionContext : VAOptDefinitionContext {
Token SyntheticEOFToken;
// The (spelling) location of the current __VA_OPT__ in the replacement list
// of the function-like macro being expanded.
SourceLocation VAOptLoc;
// NumOfTokensPriorToVAOpt : when != -1, contains the index *of* the first
// token of the current VAOPT contents (so we know where to start eager
// token-pasting and stringification) *within* the substituted tokens of
// the function-like macro's new replacement list.
int NumOfTokensPriorToVAOpt = -1;
unsigned LeadingSpaceForStringifiedToken : 1;
unsigned StringifyBefore : 1;
unsigned CharifyBefore : 1;
unsigned BeginsWithPlaceholder : 1;
unsigned EndsWithPlaceholder : 1;
bool hasStringifyBefore() const {
assert(!isReset() &&
"Must only be called if the state has not been reset");
return StringifyBefore;
}
bool isReset() const {
return NumOfTokensPriorToVAOpt == -1 ||
VAOptLoc.isInvalid();
}
public:
VAOptExpansionContext(Preprocessor &PP)
: VAOptDefinitionContext(PP), LeadingSpaceForStringifiedToken(false),
StringifyBefore(false), CharifyBefore(false),
BeginsWithPlaceholder(false), EndsWithPlaceholder(false) {
SyntheticEOFToken.startToken();
SyntheticEOFToken.setKind(tok::eof);
}
void reset() {
VAOptLoc = SourceLocation();
NumOfTokensPriorToVAOpt = -1;
LeadingSpaceForStringifiedToken = false;
StringifyBefore = false;
CharifyBefore = false;
BeginsWithPlaceholder = false;
EndsWithPlaceholder = false;
}
const Token &getEOFTok() const { return SyntheticEOFToken; }
void sawHashOrHashAtBefore(const bool HasLeadingSpace,
const bool IsHashAt) {
StringifyBefore = !IsHashAt;
CharifyBefore = IsHashAt;
LeadingSpaceForStringifiedToken = HasLeadingSpace;
}
void hasPlaceholderAfterHashhashAtStart() { BeginsWithPlaceholder = true; }
void hasPlaceholderBeforeRParen() {
if (isAtTopLevel())
EndsWithPlaceholder = true;
}
bool beginsWithPlaceholder() const {
assert(!isReset() &&
"Must only be called if the state has not been reset");
return BeginsWithPlaceholder;
}
bool endsWithPlaceholder() const {
assert(!isReset() &&
"Must only be called if the state has not been reset");
return EndsWithPlaceholder;
}
bool hasCharifyBefore() const {
assert(!isReset() &&
"Must only be called if the state has not been reset");
return CharifyBefore;
}
bool hasStringifyOrCharifyBefore() const {
return hasStringifyBefore() || hasCharifyBefore();
}
unsigned int getNumberOfTokensPriorToVAOpt() const {
assert(!isReset() &&
"Must only be called if the state has not been reset");
return NumOfTokensPriorToVAOpt;
}
bool getLeadingSpaceForStringifiedToken() const {
assert(hasStringifyBefore() &&
"Must only be called if this has been marked for stringification");
return LeadingSpaceForStringifiedToken;
}
void sawVAOptFollowedByOpeningParens(const SourceLocation VAOptLoc,
const unsigned int NumPriorTokens) {
assert(VAOptLoc.isFileID() && "Must not come from a macro expansion");
assert(isReset() && "Must only be called if the state has been reset");
VAOptDefinitionContext::sawVAOptFollowedByOpeningParens(SourceLocation());
this->VAOptLoc = VAOptLoc;
NumOfTokensPriorToVAOpt = NumPriorTokens;
assert(NumOfTokensPriorToVAOpt > -1 &&
"Too many prior tokens");
}
SourceLocation getVAOptLoc() const {
assert(!isReset() &&
"Must only be called if the state has not been reset");
assert(VAOptLoc.isValid() && "__VA_OPT__ location must be valid");
return VAOptLoc;
}
using VAOptDefinitionContext::isVAOptToken;
using VAOptDefinitionContext::isInVAOpt;
using VAOptDefinitionContext::sawClosingParen;
using VAOptDefinitionContext::sawOpeningParen;
};
} // end namespace clang
#endif