1 // go-linemap.h -- interface to location tracking -*- C++ -*-
2
3 // Copyright 2011 The Go Authors. All rights reserved.
4 // Use of this source code is governed by a BSD-style
5 // license that can be found in the LICENSE file.
6
7 #ifndef GO_LINEMAP_H
8 #define GO_LINEMAP_H
9
10 #include "go-system.h"
11
12 // The backend must define a type named Location which holds
13 // information about a location in a source file. The only thing the
14 // frontend does with instances of Location is pass them back to the
15 // backend interface. The Location type must be assignable, and it
16 // must be comparable: i.e., it must support operator= and operator<.
17 // The type is normally passed by value rather than by reference, and
18 // it should support that efficiently. The type should be defined in
19 // "go-location.h".
20 #include "go-location.h"
21
22 // The Linemap class is a pure abstract interface, plus some static
23 // convenience functions. The backend must implement the interface.
24
25 class Linemap
26 {
27 public:
28 Linemap()
29 {
30 // Only one instance of Linemap is allowed to exist.
31 go_assert(Linemap::instance_ == NULL);
32 Linemap::instance_ = this;
33 }
34
35 virtual
36 ~Linemap() { Linemap::instance_ = NULL; }
37
38 // Subsequent Location values will come from the file named
39 // FILE_NAME, starting at LINE_BEGIN. Normally LINE_BEGIN will be
40 // 0, but it will be non-zero if the Go source has a //line comment.
41 virtual void
42 start_file(const char* file_name, unsigned int line_begin) = 0;
43
44 // Subsequent Location values will come from the line LINE_NUMBER,
45 // in the current file. LINE_SIZE is the size of the line in bytes.
46 // This will normally be called for every line in a source file.
47 virtual void
48 start_line(unsigned int line_number, unsigned int line_size) = 0;
49
50 // Get a Location representing column position COLUMN on the current
51 // line in the current file.
52 virtual Location
53 get_location(unsigned int column) = 0;
54
55 // Stop generating Location values. This will be called after all
56 // input files have been read, in case any cleanup is required.
57 virtual void
58 stop() = 0;
59
60 // Produce a human-readable description of a Location, e.g.
61 // "foo.go:10". Returns an empty string for predeclared, builtin or
62 // unknown locations.
63 virtual std::string
64 to_string(Location) = 0;
65
66 // Return the file name for a given location.
67 virtual std::string
68 location_file(Location) = 0;
69
70 // Return the line number for a given location.
71 virtual int
72 location_line(Location) = 0;
73
74 protected:
75 // Return a special Location used for predeclared identifiers. This
76 // Location should be different from that for any actual source
77 // file. This location will be used for various different types,
78 // functions, and objects created by the frontend.
79 virtual Location
80 get_predeclared_location() = 0;
81
82 // Return a special Location which indicates that no actual location
83 // is known. This is used for undefined objects and for errors.
84 virtual Location
85 get_unknown_location() = 0;
86
87 // Return whether the argument is the Location returned by
88 // get_predeclared_location.
89 virtual bool
90 is_predeclared(Location) = 0;
91
92 // Return whether the argument is the Location returned by
93 // get_unknown_location.
94 virtual bool
95 is_unknown(Location) = 0;
96
97 // The single existing instance of Linemap.
98 static Linemap *instance_;
99
100 public:
101 // Following are convenience static functions, which allow us to
102 // access some virtual functions without explicitly passing around
103 // an instance of Linemap.
104
105 // Return the special Location used for predeclared identifiers.
106 static Location
107 predeclared_location()
108 {
109 go_assert(Linemap::instance_ != NULL);
110 return Linemap::instance_->get_predeclared_location();
111 }
112
113 // Return the special Location used when no location is known.
114 static Location
115 unknown_location()
116 {
117 go_assert(Linemap::instance_ != NULL);
118 return Linemap::instance_->get_unknown_location();
119 }
120
121 // Return whether the argument is the special location used for
122 // predeclared identifiers.
123 static bool
124 is_predeclared_location(Location loc)
125 {
126 go_assert(Linemap::instance_ != NULL);
127 return Linemap::instance_->is_predeclared(loc);
128 }
129
130 // Return whether the argument is the special location used when no
131 // location is known.
132 static bool
133 is_unknown_location(Location loc)
134 {
135 go_assert(Linemap::instance_ != NULL);
136 return Linemap::instance_->is_unknown(loc);
137 }
138
139 // Produce a human-readable description of a Location.
140 static std::string
141 location_to_string(Location loc)
142 {
143 go_assert(Linemap::instance_ != NULL);
144 return Linemap::instance_->to_string(loc);
145 }
146
147 // Return the file name of a location.
148 static std::string
149 location_to_file(Location loc)
150 {
151 go_assert(Linemap::instance_ != NULL);
152 return Linemap::instance_->location_file(loc);
153 }
154
155 // Return line number of a location.
156 static int
157 location_to_line(Location loc)
158 {
159 go_assert(Linemap::instance_ != NULL);
160 return Linemap::instance_->location_line(loc);
161 }
162 };
163
164 #endif // !defined(GO_LINEMAP_H)