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//===- PreprocessorLexer.h - C Language Family Lexer ------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// Defines the PreprocessorLexer interface.
#include "clang/Lex/MultipleIncludeOpt.h"
#include "clang/Lex/Token.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include <cassert>
namespace clang {
class FileEntry;
class Preprocessor;
class PreprocessorLexer {
virtual void anchor();
friend class Preprocessor;
// Preprocessor object controlling lexing.
Preprocessor *PP = nullptr;
/// The SourceManager FileID corresponding to the file being lexed.
const FileID FID;
/// Number of SLocEntries before lexing the file.
unsigned InitialNumSLocEntries = 0;
// Context-specific lexing flags set by the preprocessor.
/// True when parsing \#XXX; turns '\\n' into a tok::eod token.
bool ParsingPreprocessorDirective = false;
/// True after \#include; turns \<xx> or "xxx" into a tok::header_name token.
bool ParsingFilename = false;
/// True if in raw mode.
/// Raw mode disables interpretation of tokens and is a far faster mode to
/// lex in than non-raw-mode. This flag:
/// 1. If EOF of the current lexer is found, the include stack isn't popped.
/// 2. Identifier information is not looked up for identifier tokens. As an
/// effect of this, implicit macro expansion is naturally disabled.
/// 3. "#" tokens at the start of a line are treated as normal tokens, not
/// implicitly transformed by the lexer.
/// 4. All diagnostic messages are disabled.
/// 5. No callbacks are made into the preprocessor.
/// Note that in raw mode that the PP pointer may be null.
bool LexingRawMode = false;
/// A state machine that detects the \#ifndef-wrapping a file
/// idiom for the multiple-include optimization.
MultipleIncludeOpt MIOpt;
/// Information about the set of \#if/\#ifdef/\#ifndef blocks
/// we are currently in.
SmallVector<PPConditionalInfo, 4> ConditionalStack;
PreprocessorLexer() : FID() {}
PreprocessorLexer(Preprocessor *pp, FileID fid);
virtual ~PreprocessorLexer() = default;
virtual void IndirectLex(Token& Result) = 0;
/// Return the source location for the next observable location.
virtual SourceLocation getSourceLocation() = 0;
// #if directive handling.
/// pushConditionalLevel - When we enter a \#if directive, this keeps track of
/// what we are currently in for diagnostic emission (e.g. \#if with missing
/// \#endif).
void pushConditionalLevel(SourceLocation DirectiveStart, bool WasSkipping,
bool FoundNonSkip, bool FoundElse) {
PPConditionalInfo CI;
CI.IfLoc = DirectiveStart;
CI.WasSkipping = WasSkipping;
CI.FoundNonSkip = FoundNonSkip;
CI.FoundElse = FoundElse;
void pushConditionalLevel(const PPConditionalInfo &CI) {
/// popConditionalLevel - Remove an entry off the top of the conditional
/// stack, returning information about it. If the conditional stack is empty,
/// this returns true and does not fill in the arguments.
bool popConditionalLevel(PPConditionalInfo &CI) {
if (ConditionalStack.empty())
return true;
CI = ConditionalStack.pop_back_val();
return false;
/// Return the top of the conditional stack.
/// \pre This requires that there be a conditional active.
PPConditionalInfo &peekConditionalLevel() {
assert(!ConditionalStack.empty() && "No conditionals active!");
return ConditionalStack.back();
unsigned getConditionalStackDepth() const { return ConditionalStack.size(); }
PreprocessorLexer(const PreprocessorLexer &) = delete;
PreprocessorLexer &operator=(const PreprocessorLexer &) = delete;
// Misc. lexing methods.
/// Lex a token, producing a header-name token if possible.
void LexIncludeFilename(Token &FilenameTok);
/// Inform the lexer whether or not we are currently lexing a
/// preprocessor directive.
void setParsingPreprocessorDirective(bool f) {
ParsingPreprocessorDirective = f;
/// Return true if this lexer is in raw mode or not.
bool isLexingRawMode() const { return LexingRawMode; }
/// Return the preprocessor object for this lexer.
Preprocessor *getPP() const { return PP; }
FileID getFileID() const {
assert(PP &&
"PreprocessorLexer::getFileID() should only be used with a Preprocessor");
return FID;
/// Number of SLocEntries before lexing the file.
unsigned getInitialNumSLocEntries() const {
return InitialNumSLocEntries;
/// getFileEntry - Return the FileEntry corresponding to this FileID. Like
/// getFileID(), this only works for lexers with attached preprocessors.
const FileEntry *getFileEntry() const;
/// Iterator that traverses the current stack of preprocessor
/// conditional directives (\#if/\#ifdef/\#ifndef).
using conditional_iterator =
conditional_iterator conditional_begin() const {
return ConditionalStack.begin();
conditional_iterator conditional_end() const {
return ConditionalStack.end();
void setConditionalLevels(ArrayRef<PPConditionalInfo> CL) {
ConditionalStack.append(CL.begin(), CL.end());
} // namespace clang