1 /* Input handling for G++.
2 Copyright (C) 1992, 1993 Free Software Foundation, Inc.
3 Written by Ken Raeburn (raeburn@cygnus.com) while at Watchmaker Computing.
4
5 This file is part of GNU CC.
6
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
10 any later version.
11
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
20
21 /* G++ needs to do enough saving and re-parsing of text that it is
22 necessary to abandon the simple FILE* model and use a mechanism where
23 we can pre-empt one input stream with another derived from saved text;
24 we may need to do this arbitrarily often, and cannot depend on having
25 the GNU library available, so FILE objects just don't cut it.
26
27 This file is written as a separate module, but can be included by
28 cp-lex.c for very minor efficiency gains (primarily in function
29 inlining). */
30
31 #include <stdio.h>
32 #include "obstack.h"
33
34 extern FILE *finput;
35
36 struct pending_input *save_pending_input ();
37 void restore_pending_input ();
38
39 struct input_source {
40 /* saved string */
41 char *str;
42 int length;
43 /* current position, when reading as input */
44 int offset;
45 /* obstack to free this input string from when finished, if any */
46 struct obstack *obstack;
47 /* linked list maintenance */
48 struct input_source *next;
49 /* values to restore after reading all of current string */
50 char *filename;
51 int lineno;
52 struct pending_input *input;
53 int putback_char;
54 };
55
56 static struct input_source *input, *free_inputs;
57
58 extern char *input_filename;
59 extern int lineno;
60
61 #ifdef __GNUC__
62 #define inline __inline__
63 #else
64 #define inline
65 #endif
66
67 static inline struct input_source *
allocate_input()68 allocate_input ()
69 {
70 struct input_source *inp;
71 if (free_inputs)
72 {
73 inp = free_inputs;
74 free_inputs = inp->next;
75 inp->next = 0;
76 return inp;
77 }
78 inp = (struct input_source *) xmalloc (sizeof (struct input_source));
79 inp->next = 0;
80 inp->obstack = 0;
81 return inp;
82 }
83
84 static inline void
free_input(inp)85 free_input (inp)
86 struct input_source *inp;
87 {
88 if (inp->obstack)
89 obstack_free (inp->obstack, inp->str);
90 inp->obstack = 0;
91 inp->str = 0;
92 inp->length = 0;
93 inp->next = free_inputs;
94 free_inputs = inp;
95 }
96
97 static int putback_char = -1;
98
99 /* Some of these external functions are declared inline in case this file
100 is included in cp-lex.c. */
101
102 inline
103 void
feed_input(str,len,delete)104 feed_input (str, len, delete)
105 char *str;
106 int len;
107 struct obstack *delete;
108 {
109 struct input_source *inp = allocate_input ();
110
111 /* This shouldn't be necessary. */
112 while (len && !str[len-1])
113 len--;
114
115 inp->str = str;
116 inp->length = len;
117 inp->obstack = delete;
118 inp->offset = 0;
119 inp->next = input;
120 inp->filename = input_filename;
121 inp->lineno = lineno;
122 inp->input = save_pending_input ();
123 inp->putback_char = putback_char;
124 putback_char = -1;
125 input = inp;
126 }
127
128 struct pending_input *to_be_restored; /* XXX */
129 extern int end_of_file;
130
131 int
getch()132 getch ()
133 {
134 if (putback_char != -1)
135 {
136 int ch = putback_char;
137 putback_char = -1;
138 return ch;
139 }
140 if (input)
141 {
142 if (input->offset == input->length)
143 {
144 struct input_source *inp = input;
145 my_friendly_assert (putback_char == -1, 223);
146 to_be_restored = inp->input;
147 input->offset++;
148 return EOF;
149 }
150 else if (input->offset > input->length)
151 {
152 struct input_source *inp = input;
153
154 end_of_file = 0;
155 input = inp->next;
156 input_filename = inp->filename;
157 lineno = inp->lineno;
158 /* Get interface/implementation back in sync. */
159 extract_interface_info ();
160 putback_char = inp->putback_char;
161 free_input (inp);
162 return getch ();
163 }
164 if (input)
165 return input->str[input->offset++];
166 }
167 return getc (finput);
168 }
169
170 inline
171 void
put_back(ch)172 put_back (ch)
173 int ch;
174 {
175 my_friendly_assert (putback_char == -1, 224);
176 putback_char = ch;
177 }
178
179 inline
180 int
input_redirected()181 input_redirected ()
182 {
183 return input != 0;
184 }
185