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      1 //===- clang/Lex/DependencyDirectivesSourceMinimizer.h -  ----------*- C++ -*-//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 ///
      9 /// \file
     10 /// This is the interface for minimizing header and source files to the
     11 /// minimum necessary preprocessor directives for evaluating includes. It
     12 /// reduces the source down to #define, #include, #import, @import, and any
     13 /// conditional preprocessor logic that contains one of those.
     14 ///
     15 //===----------------------------------------------------------------------===//
     16 
     17 #ifndef LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
     18 #define LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
     19 
     20 #include "clang/Basic/SourceLocation.h"
     21 #include "llvm/ADT/ArrayRef.h"
     22 #include "llvm/ADT/SmallVector.h"
     23 #include "llvm/ADT/StringRef.h"
     24 
     25 namespace clang {
     26 
     27 class DiagnosticsEngine;
     28 
     29 namespace minimize_source_to_dependency_directives {
     30 
     31 /// Represents the kind of preprocessor directive or a module declaration that
     32 /// is tracked by the source minimizer in its token output.
     33 enum TokenKind {
     34   pp_none,
     35   pp_include,
     36   pp___include_macros,
     37   pp_define,
     38   pp_undef,
     39   pp_import,
     40   pp_pragma_import,
     41   pp_pragma_once,
     42   pp_include_next,
     43   pp_if,
     44   pp_ifdef,
     45   pp_ifndef,
     46   pp_elif,
     47   pp_else,
     48   pp_endif,
     49   decl_at_import,
     50   cxx_export_decl,
     51   cxx_module_decl,
     52   cxx_import_decl,
     53   pp_eof,
     54 };
     55 
     56 /// Represents a simplified token that's lexed as part of the source
     57 /// minimization. It's used to track the location of various preprocessor
     58 /// directives that could potentially have an effect on the depedencies.
     59 struct Token {
     60   /// The kind of token.
     61   TokenKind K = pp_none;
     62 
     63   /// Offset into the output byte stream of where the directive begins.
     64   int Offset = -1;
     65 
     66   Token(TokenKind K, int Offset) : K(K), Offset(Offset) {}
     67 };
     68 
     69 /// Simplified token range to track the range of a potentially skippable PP
     70 /// directive.
     71 struct SkippedRange {
     72   /// Offset into the output byte stream of where the skipped directive begins.
     73   int Offset;
     74 
     75   /// The number of bytes that can be skipped before the preprocessing must
     76   /// resume.
     77   int Length;
     78 };
     79 
     80 /// Computes the potential source ranges that can be skipped by the preprocessor
     81 /// when skipping a directive like #if, #ifdef or #elsif.
     82 ///
     83 /// \returns false on success, true on error.
     84 bool computeSkippedRanges(ArrayRef<Token> Input,
     85                           llvm::SmallVectorImpl<SkippedRange> &Range);
     86 
     87 } // end namespace minimize_source_to_dependency_directives
     88 
     89 /// Minimize the input down to the preprocessor directives that might have
     90 /// an effect on the dependencies for a compilation unit.
     91 ///
     92 /// This function deletes all non-preprocessor code, and strips anything that
     93 /// can't affect what gets included. It canonicalizes whitespace where
     94 /// convenient to stabilize the output against formatting changes in the input.
     95 ///
     96 /// Clears the output vectors at the beginning of the call.
     97 ///
     98 /// \returns false on success, true on error. If the diagnostic engine is not
     99 /// null, an appropriate error is reported using the given input location
    100 /// with the offset that corresponds to the minimizer's current buffer offset.
    101 bool minimizeSourceToDependencyDirectives(
    102     llvm::StringRef Input, llvm::SmallVectorImpl<char> &Output,
    103     llvm::SmallVectorImpl<minimize_source_to_dependency_directives::Token>
    104         &Tokens,
    105     DiagnosticsEngine *Diags = nullptr,
    106     SourceLocation InputSourceLoc = SourceLocation());
    107 
    108 } // end namespace clang
    109 
    110 #endif // LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
    111