ifile.c revision 170257 
1/*
2 * Copyright (C) 1984-2007  Mark Nudelman
3 *
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
6 *
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
9 */
10
11
12/*
13 * An IFILE represents an input file.
14 *
15 * It is actually a pointer to an ifile structure,
16 * but is opaque outside this module.
17 * Ifile structures are kept in a linked list in the order they
18 * appear on the command line.
19 * Any new file which does not already appear in the list is
20 * inserted after the current file.
21 */
22
23#include "less.h"
24
25extern IFILE	curr_ifile;
26
27struct ifile {
28	struct ifile *h_next;		/* Links for command line list */
29	struct ifile *h_prev;
30	char *h_filename;		/* Name of the file */
31	void *h_filestate;		/* File state (used in ch.c) */
32	int h_index;			/* Index within command line list */
33	int h_hold;			/* Hold count */
34	char h_opened;			/* Has this ifile been opened? */
35	struct scrpos h_scrpos;		/* Saved position within the file */
36};
37
38/*
39 * Convert an IFILE (external representation)
40 * to a struct file (internal representation), and vice versa.
41 */
42#define int_ifile(h)	((struct ifile *)(h))
43#define ext_ifile(h)	((IFILE)(h))
44
45/*
46 * Anchor for linked list.
47 */
48static struct ifile anchor = { &anchor, &anchor, NULL, NULL, 0, 0, '\0',
49				{ NULL_POSITION, 0 } };
50static int ifiles = 0;
51
52	static void
53incr_index(p, incr)
54	register struct ifile *p;
55	int incr;
56{
57	for (;  p != &anchor;  p = p->h_next)
58		p->h_index += incr;
59}
60
61/*
62 * Link an ifile into the ifile list.
63 */
64	static void
65link_ifile(p, prev)
66	struct ifile *p;
67	struct ifile *prev;
68{
69	/*
70	 * Link into list.
71	 */
72	if (prev == NULL)
73		prev = &anchor;
74	p->h_next = prev->h_next;
75	p->h_prev = prev;
76	prev->h_next->h_prev = p;
77	prev->h_next = p;
78	/*
79	 * Calculate index for the new one,
80	 * and adjust the indexes for subsequent ifiles in the list.
81	 */
82	p->h_index = prev->h_index + 1;
83	incr_index(p->h_next, 1);
84	ifiles++;
85}
86
87/*
88 * Unlink an ifile from the ifile list.
89 */
90	static void
91unlink_ifile(p)
92	struct ifile *p;
93{
94	p->h_next->h_prev = p->h_prev;
95	p->h_prev->h_next = p->h_next;
96	incr_index(p->h_next, -1);
97	ifiles--;
98}
99
100/*
101 * Allocate a new ifile structure and stick a filename in it.
102 * It should go after "prev" in the list
103 * (or at the beginning of the list if "prev" is NULL).
104 * Return a pointer to the new ifile structure.
105 */
106	static struct ifile *
107new_ifile(filename, prev)
108	char *filename;
109	struct ifile *prev;
110{
111	register struct ifile *p;
112
113	/*
114	 * Allocate and initialize structure.
115	 */
116	p = (struct ifile *) ecalloc(1, sizeof(struct ifile));
117	p->h_filename = save(filename);
118	p->h_scrpos.pos = NULL_POSITION;
119	p->h_opened = 0;
120	p->h_hold = 0;
121	p->h_filestate = NULL;
122	link_ifile(p, prev);
123	return (p);
124}
125
126/*
127 * Delete an existing ifile structure.
128 */
129	public void
130del_ifile(h)
131	IFILE h;
132{
133	register struct ifile *p;
134
135	if (h == NULL_IFILE)
136		return;
137	/*
138	 * If the ifile we're deleting is the currently open ifile,
139	 * move off it.
140	 */
141	unmark(h);
142	if (h == curr_ifile)
143		curr_ifile = getoff_ifile(curr_ifile);
144	p = int_ifile(h);
145	unlink_ifile(p);
146	free(p->h_filename);
147	free(p);
148}
149
150/*
151 * Get the ifile after a given one in the list.
152 */
153	public IFILE
154next_ifile(h)
155	IFILE h;
156{
157	register struct ifile *p;
158
159	p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
160	if (p->h_next == &anchor)
161		return (NULL_IFILE);
162	return (ext_ifile(p->h_next));
163}
164
165/*
166 * Get the ifile before a given one in the list.
167 */
168	public IFILE
169prev_ifile(h)
170	IFILE h;
171{
172	register struct ifile *p;
173
174	p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
175	if (p->h_prev == &anchor)
176		return (NULL_IFILE);
177	return (ext_ifile(p->h_prev));
178}
179
180/*
181 * Return a different ifile from the given one.
182 */
183	public IFILE
184getoff_ifile(ifile)
185	IFILE ifile;
186{
187	IFILE newifile;
188
189	if ((newifile = prev_ifile(ifile)) != NULL_IFILE)
190		return (newifile);
191	if ((newifile = next_ifile(ifile)) != NULL_IFILE)
192		return (newifile);
193	return (NULL_IFILE);
194}
195
196/*
197 * Return the number of ifiles.
198 */
199	public int
200nifile()
201{
202	return (ifiles);
203}
204
205/*
206 * Find an ifile structure, given a filename.
207 */
208	static struct ifile *
209find_ifile(filename)
210	char *filename;
211{
212	register struct ifile *p;
213
214	for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
215		if (strcmp(filename, p->h_filename) == 0)
216			return (p);
217	return (NULL);
218}
219
220/*
221 * Get the ifile associated with a filename.
222 * If the filename has not been seen before,
223 * insert the new ifile after "prev" in the list.
224 */
225	public IFILE
226get_ifile(filename, prev)
227	char *filename;
228	IFILE prev;
229{
230	register struct ifile *p;
231
232	if ((p = find_ifile(filename)) == NULL)
233		p = new_ifile(filename, int_ifile(prev));
234	return (ext_ifile(p));
235}
236
237/*
238 * Get the filename associated with a ifile.
239 */
240	public char *
241get_filename(ifile)
242	IFILE ifile;
243{
244	if (ifile == NULL)
245		return (NULL);
246	return (int_ifile(ifile)->h_filename);
247}
248
249/*
250 * Get the index of the file associated with a ifile.
251 */
252	public int
253get_index(ifile)
254	IFILE ifile;
255{
256	return (int_ifile(ifile)->h_index);
257}
258
259/*
260 * Save the file position to be associated with a given file.
261 */
262	public void
263store_pos(ifile, scrpos)
264	IFILE ifile;
265	struct scrpos *scrpos;
266{
267	int_ifile(ifile)->h_scrpos = *scrpos;
268}
269
270/*
271 * Recall the file position associated with a file.
272 * If no position has been associated with the file, return NULL_POSITION.
273 */
274	public void
275get_pos(ifile, scrpos)
276	IFILE ifile;
277	struct scrpos *scrpos;
278{
279	*scrpos = int_ifile(ifile)->h_scrpos;
280}
281
282/*
283 * Mark the ifile as "opened".
284 */
285	public void
286set_open(ifile)
287	IFILE ifile;
288{
289	int_ifile(ifile)->h_opened = 1;
290}
291
292/*
293 * Return whether the ifile has been opened previously.
294 */
295	public int
296opened(ifile)
297	IFILE ifile;
298{
299	return (int_ifile(ifile)->h_opened);
300}
301
302	public void
303hold_ifile(ifile, incr)
304	IFILE ifile;
305	int incr;
306{
307	int_ifile(ifile)->h_hold += incr;
308}
309
310	public int
311held_ifile(ifile)
312	IFILE ifile;
313{
314	return (int_ifile(ifile)->h_hold);
315}
316
317	public void *
318get_filestate(ifile)
319	IFILE ifile;
320{
321	return (int_ifile(ifile)->h_filestate);
322}
323
324	public void
325set_filestate(ifile, filestate)
326	IFILE ifile;
327	void *filestate;
328{
329	int_ifile(ifile)->h_filestate = filestate;
330}
331
332#if 0
333	public void
334if_dump()
335{
336	register struct ifile *p;
337
338	for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
339	{
340		printf("%x: %d. <%s> pos %d,%x\n",
341			p, p->h_index, p->h_filename,
342			p->h_scrpos.ln, p->h_scrpos.pos);
343		ch_dump(p->h_filestate);
344	}
345}
346#endif
347