gcc/rust/rust-linemap.h

   1 // rust-linemap.h -- interface to location tracking   -*- C++ -*-
   2
   3 // Copyright 2011 The Go Authors. All rights reserved.
   4 // Copyright (C) 2020-2024 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   Linemap () : in_file_ (false)
  37   {
  38     // Only one instance of Linemap is allowed to exist.
  39     rust_assert (Linemap::instance_ == NULL);
  40     Linemap::instance_ = this;
  41   }
  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)