//===--- SymbolLocation.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
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLLOCATION_H
#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLLOCATION_H

#include "llvm/ADT/StringRef.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdint>

namespace clang {
namespace clangd {

struct SymbolLocation {
  // Specify a position (Line, Column) of symbol. Using Line/Column allows us to
  // build LSP responses without reading the file content.
  //
  // clangd uses the following definitions, which differ slightly from LSP:
  //  - Line is the number of newline characters (\n) before the point.
  //  - Column is (by default) the number of UTF-16 code between the last \n
  //    (or start of file) and the point.
  //    If the `offsetEncoding` protocol extension is used to negotiate UTF-8,
  //    then it is instead the number of *bytes* since the last \n.
  //
  // Position is encoded into 32 bits to save space.
  // If Line/Column overflow, the value will be their maximum value.
  struct Position {
    Position() : LineColumnPacked(0) {}
    void setLine(uint32_t Line);
    uint32_t line() const { return LineColumnPacked >> ColumnBits; }
    void setColumn(uint32_t Column);
    uint32_t column() const { return LineColumnPacked & MaxColumn; }
    uint32_t rep() const { return LineColumnPacked; }

    bool hasOverflow() const {
      return line() == MaxLine || column() == MaxColumn;
    }

    static constexpr unsigned ColumnBits = 12;
    static constexpr uint32_t MaxLine = (1 << (32 - ColumnBits)) - 1;
    static constexpr uint32_t MaxColumn = (1 << ColumnBits) - 1;

  private:
    uint32_t LineColumnPacked; // Top 20 bit line, bottom 12 bits column.
  };

  /// The symbol range, using half-open range [Start, End).
  Position Start;
  Position End;

  explicit operator bool() const { return !llvm::StringRef(FileURI).empty(); }

  // The URI of the source file where a symbol occurs.
  // The string must be null-terminated.
  //
  // We avoid using llvm::StringRef here to save memory.
  // WARNING: unless you know what you are doing, it is recommended to use it
  // via llvm::StringRef.
  const char *FileURI = "";
};

inline bool operator==(const SymbolLocation::Position &L,
                       const SymbolLocation::Position &R) {
  return std::make_tuple(L.line(), L.column()) ==
         std::make_tuple(R.line(), R.column());
}
inline bool operator<(const SymbolLocation::Position &L,
                      const SymbolLocation::Position &R) {
  return std::make_tuple(L.line(), L.column()) <
         std::make_tuple(R.line(), R.column());
}
inline bool operator==(const SymbolLocation &L, const SymbolLocation &R) {
  assert(L.FileURI && R.FileURI);
  return !std::strcmp(L.FileURI, R.FileURI) &&
         std::tie(L.Start, L.End) == std::tie(R.Start, R.End);
}
inline bool operator<(const SymbolLocation &L, const SymbolLocation &R) {
  assert(L.FileURI && R.FileURI);
  int Cmp = std::strcmp(L.FileURI, R.FileURI);
  if (Cmp != 0)
    return Cmp < 0;
  return std::tie(L.Start, L.End) < std::tie(R.Start, R.End);
}

llvm::raw_ostream &operator<<(llvm::raw_ostream &, const SymbolLocation &);

} // namespace clangd
} // namespace clang

#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLLOCATION_H