//===--- FileIndex.h - Index for files. ---------------------------- C++-*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// FileIndex implements SymbolIndex for symbols from a set of files. Symbols are
// maintained at source-file granuality (e.g. with ASTs), and files can be
// updated dynamically.
//
//===---------------------------------------------------------------------===//

#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_FILEINDEX_H
#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_FILEINDEX_H

#include "../ClangdUnit.h"
#include "Index.h"
#include "MemIndex.h"
#include "clang/Lex/Preprocessor.h"

namespace clang {
namespace clangd {

/// \brief A container of Symbols from several source files. It can be updated
/// at source-file granularity, replacing all symbols from one file with a new
/// set.
///
/// This implements a snapshot semantics for symbols in a file. Each update to a
/// file will create a new snapshot for all symbols in the file. Snapshots are
/// managed with shared pointers that are shared between this class and the
/// users. For each file, this class only stores a pointer pointing to the
/// newest snapshot, and an outdated snapshot is deleted by the last owner of
/// the snapshot, either this class or the symbol index.
///
/// The snapshot semantics keeps critical sections minimal since we only need
/// locking when we swap or obtain refereces to snapshots.
class FileSymbols {
public:
  /// \brief Updates all symbols in a file. If \p Slab is nullptr, symbols for
  /// \p Path will be removed.
  void update(PathRef Path, std::unique_ptr<SymbolSlab> Slab);

  // The shared_ptr keeps the symbols alive
  std::shared_ptr<std::vector<const Symbol *>> allSymbols();

private:
  mutable std::mutex Mutex;

  /// \brief Stores the latest snapshots for all active files.
  llvm::StringMap<std::shared_ptr<SymbolSlab>> FileToSlabs;
};

/// \brief This manages symbls from files and an in-memory index on all symbols.
class FileIndex : public SymbolIndex {
public:
  /// \brief Update symbols in \p Path with symbols in \p AST. If \p AST is
  /// nullptr, this removes all symbols in the file.
  /// If \p AST is not null, \p PP cannot be null and it should be the
  /// preprocessor that was used to build \p AST.
  void update(PathRef Path, ASTContext *AST, std::shared_ptr<Preprocessor> PP);

  bool
  fuzzyFind(const FuzzyFindRequest &Req,
            llvm::function_ref<void(const Symbol &)> Callback) const override;

  void lookup(const LookupRequest &Req,
              llvm::function_ref<void(const Symbol &)> Callback) const override;

private:
  FileSymbols FSymbols;
  MemIndex Index;
};

/// Retrieves namespace and class level symbols in \p AST.
/// Exposed to assist in unit tests.
SymbolSlab indexAST(ASTContext &AST, std::shared_ptr<Preprocessor> PP);

} // namespace clangd
} // namespace clang

#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_FILEINDEX_H