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//===--- MultipleIncludeOpt.h - Header Multiple-Include Optzn ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Defines the MultipleIncludeOpt interface.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_MULTIPLEINCLUDEOPT_H
#define LLVM_CLANG_MULTIPLEINCLUDEOPT_H
namespace clang {
class IdentifierInfo;
/// \brief Implements the simple state machine that the Lexer class uses to
/// detect files subject to the 'multiple-include' optimization.
///
/// The public methods in this class are triggered by various
/// events that occur when a file is lexed, and after the entire file is lexed,
/// information about which macro (if any) controls the header is returned.
class MultipleIncludeOpt {
/// ReadAnyTokens - This is set to false when a file is first opened and true
/// any time a token is returned to the client or a (non-multiple-include)
/// directive is parsed. When the final \#endif is parsed this is reset back
/// to false, that way any tokens before the first \#ifdef or after the last
/// \#endif can be easily detected.
bool ReadAnyTokens;
/// ReadAnyTokens - This is set to false when a file is first opened and true
/// any time a token is returned to the client or a (non-multiple-include)
/// directive is parsed. When the final #endif is parsed this is reset back
/// to false, that way any tokens before the first #ifdef or after the last
/// #endif can be easily detected.
bool DidMacroExpansion;
/// TheMacro - The controlling macro for a file, if valid.
///
const IdentifierInfo *TheMacro;
public:
MultipleIncludeOpt() {
ReadAnyTokens = false;
DidMacroExpansion = false;
TheMacro = 0;
}
/// Invalidate - Permanently mark this file as not being suitable for the
/// include-file optimization.
void Invalidate() {
// If we have read tokens but have no controlling macro, the state-machine
// below can never "accept".
ReadAnyTokens = true;
TheMacro = 0;
}
/// getHasReadAnyTokensVal - This is used for the \#ifndef hande-shake at the
/// top of the file when reading preprocessor directives. Otherwise, reading
/// the "ifndef x" would count as reading tokens.
bool getHasReadAnyTokensVal() const { return ReadAnyTokens; }
// If a token is read, remember that we have seen a side-effect in this file.
void ReadToken() { ReadAnyTokens = true; }
/// ExpandedMacro - When a macro is expanded with this lexer as the current
/// buffer, this method is called to disable the MIOpt if needed.
void ExpandedMacro() { DidMacroExpansion = true; }
/// \brief Called when entering a top-level \#ifndef directive (or the
/// "\#if !defined" equivalent) without any preceding tokens.
///
/// Note, we don't care about the input value of 'ReadAnyTokens'. The caller
/// ensures that this is only called if there are no tokens read before the
/// \#ifndef. The caller is required to do this, because reading the \#if
/// line obviously reads in in tokens.
void EnterTopLevelIFNDEF(const IdentifierInfo *M) {
// If the macro is already set, this is after the top-level #endif.
if (TheMacro)
return Invalidate();
// If we have already expanded a macro by the end of the #ifndef line, then
// there is a macro expansion *in* the #ifndef line. This means that the
// condition could evaluate differently when subsequently #included. Reject
// this.
if (DidMacroExpansion)
return Invalidate();
// Remember that we're in the #if and that we have the macro.
ReadAnyTokens = true;
TheMacro = M;
}
/// \brief Invoked when a top level conditional (except \#ifndef) is found.
void EnterTopLevelConditional() {
// If a conditional directive (except #ifndef) is found at the top level,
// there is a chunk of the file not guarded by the controlling macro.
Invalidate();
}
/// \brief Called when the lexer exits the top-level conditional.
void ExitTopLevelConditional() {
// If we have a macro, that means the top of the file was ok. Set our state
// back to "not having read any tokens" so we can detect anything after the
// #endif.
if (!TheMacro) return Invalidate();
// At this point, we haven't "read any tokens" but we do have a controlling
// macro.
ReadAnyTokens = false;
}
/// \brief Once the entire file has been lexed, if there is a controlling
/// macro, return it.
const IdentifierInfo *GetControllingMacroAtEndOfFile() const {
// If we haven't read any tokens after the #endif, return the controlling
// macro if it's valid (if it isn't, it will be null).
if (!ReadAnyTokens)
return TheMacro;
return 0;
}
};
} // end namespace clang
#endif
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