//===- clang/Lex/DependencyDirectivesSourceMinimizer.h -  ----------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This is the interface for minimizing header and source files to the
/// minimum necessary preprocessor directives for evaluating includes. It
/// reduces the source down to #define, #include, #import, @import, and any
/// conditional preprocessor logic that contains one of those.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H
#define LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H

#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"

namespace clang {

class DiagnosticsEngine;

namespace minimize_source_to_dependency_directives {

/// Represents the kind of preprocessor directive or a module declaration that
/// is tracked by the source minimizer in its token output.
enum TokenKind {
  pp_none,
  pp_include,
  pp___include_macros,
  pp_define,
  pp_undef,
  pp_import,
  pp_pragma_import,
  pp_pragma_once,
  pp_include_next,
  pp_if,
  pp_ifdef,
  pp_ifndef,
  pp_elif,
  pp_else,
  pp_endif,
  decl_at_import,
  cxx_export_decl,
  cxx_module_decl,
  cxx_import_decl,
  pp_eof,
};

/// Represents a simplified token that's lexed as part of the source
/// minimization. It's used to track the location of various preprocessor
/// directives that could potentially have an effect on the depedencies.
struct Token {
  /// The kind of token.
  TokenKind K = pp_none;

  /// Offset into the output byte stream of where the directive begins.
  int Offset = -1;

  Token(TokenKind K, int Offset) : K(K), Offset(Offset) {}
};

/// Simplified token range to track the range of a potentially skippable PP
/// directive.
struct SkippedRange {
  /// Offset into the output byte stream of where the skipped directive begins.
  int Offset;

  /// The number of bytes that can be skipped before the preprocessing must
  /// resume.
  int Length;
};

/// Computes the potential source ranges that can be skipped by the preprocessor
/// when skipping a directive like #if, #ifdef or #elsif.
///
/// \returns false on success, true on error.
bool computeSkippedRanges(ArrayRef<Token> Input,
                          llvm::SmallVectorImpl<SkippedRange> &Range);

} // end namespace minimize_source_to_dependency_directives

/// Minimize the input down to the preprocessor directives that might have
/// an effect on the dependencies for a compilation unit.
///
/// This function deletes all non-preprocessor code, and strips anything that
/// can't affect what gets included. It canonicalizes whitespace where
/// convenient to stabilize the output against formatting changes in the input.
///
/// Clears the output vectors at the beginning of the call.
///
/// \returns false on success, true on error. If the diagnostic engine is not
/// null, an appropriate error is reported using the given input location
/// with the offset that corresponds to the minimizer's current buffer offset.
bool minimizeSourceToDependencyDirectives(
    llvm::StringRef Input, llvm::SmallVectorImpl<char> &Output,
    llvm::SmallVectorImpl<minimize_source_to_dependency_directives::Token>
        &Tokens,
    DiagnosticsEngine *Diags = nullptr,
    SourceLocation InputSourceLoc = SourceLocation());

} // end namespace clang

#endif // LLVM_CLANG_LEX_DEPENDENCY_DIRECTIVES_SOURCE_MINIMIZER_H