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       1              : // rust-linemap.h -- interface to location tracking   -*- C++ -*-
       2              : 
       3              : // Copyright 2011 The Go Authors. All rights reserved.
       4              : // Copyright (C) 2020-2026 Free Software Foundation, Inc.
       5              : 
       6              : // Use of this source code is governed by a BSD-style
       7              : // license that can be found in the '../go/gofrontend/LICENSE' file.
       8              : 
       9              : #ifndef RUST_LINEMAP_H
      10              : #define RUST_LINEMAP_H
      11              : 
      12              : #include "rust-system.h"
      13              : 
      14              : // The backend must define a type named Location which holds
      15              : // information about a location in a source file.  The only thing the
      16              : // frontend does with instances of Location is pass them back to the
      17              : // backend interface.  The Location type must be assignable, and it
      18              : // must be comparable: i.e., it must support operator= and operator<.
      19              : // The type is normally passed by value rather than by reference, and
      20              : // it should support that efficiently.  The type should be defined in
      21              : // "rust-location.h".
      22              : #include "rust-location.h"
      23              : 
      24              : // The Linemap class is a pure abstract interface, plus some static
      25              : // convenience functions.  The backend must implement the interface.
      26              : 
      27              : /* TODO: probably better to replace linemap implementation as pure abstract
      28              :  * interface with some sort of compile-time switch (macros or maybe templates if
      29              :  * doable without too much extra annoyance) as to the definition of the methods
      30              :  * or whatever. This is to improve performance, as virtual function calls would
      31              :  * otherwise have to be made in tight loops like in the lexer. */
      32              : 
      33              : class Linemap
      34              : {
      35              : public:
      36         4635 :   Linemap () : in_file_ (false)
      37              :   {
      38              :     // Only one instance of Linemap is allowed to exist.
      39         4635 :     rust_assert (Linemap::instance_ == NULL);
      40         4635 :     Linemap::instance_ = this;
      41         4635 :   }
      42              : 
      43              :   ~Linemap () { Linemap::instance_ = NULL; }
      44              : 
      45              :   // Subsequent Location values will come from the file named
      46              :   // FILE_NAME, starting at LINE_BEGIN.  Normally LINE_BEGIN will be
      47              :   // 0, but it will be non-zero if the Rust source has a //line comment.
      48              :   void start_file (const char *file_name, unsigned int line_begin);
      49              : 
      50              :   // Stop generating Location values.  This will be called after all
      51              :   // input files have been read, in case any cleanup is required.
      52              :   void stop ();
      53              : 
      54              : protected:
      55              :   // The single existing instance of Linemap.
      56              :   static Linemap *instance_;
      57              : 
      58              : public:
      59              :   // Following are convenience static functions, which allow us to
      60              :   // access some virtual functions without explicitly passing around
      61              :   // an instance of Linemap.
      62              : 
      63              :   // Produce a human-readable description of a Location, e.g.
      64              :   // "foo.rust:10". Returns an empty string for predeclared, builtin or
      65              :   // unknown locations.
      66              :   static std::string location_to_string (location_t loc);
      67              : 
      68              : private:
      69              :   // Whether we are currently reading a file.
      70              :   bool in_file_;
      71              : };
      72              : 
      73              : #endif // !defined(RUST_LINEMAP_H)