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comparison miscellany/less-177/ifile.c @ 0:bce86c4163a3

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Initial revision
author kono
date Mon, 18 Apr 2005 23:46:02 +0900
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-1:000000000000 0:bce86c4163a3
1 /*
2 * An IFILE represents an input file.
3 *
4 * It is actually a pointer to an ifile structure,
5 * but is opaque outside this module.
6 * Ifile structures are kept in a linked list in the order they
7 * appear on the command line.
8 * Any new file which does not already appear in the list is
9 * inserted after the current file.
10 */
11
12 #include "less.h"
13
14 struct ifile {
15 struct ifile *h_next; /* Links for command line list */
16 struct ifile *h_prev;
17 int h_index; /* Index within command line list */
18 char *h_filename; /* Name of the file */
19 struct scrpos h_scrpos; /* Saved position within the file */
20 };
21
22 /*
23 * Convert an IFILE (external representation)
24 * to a struct file (internal representation), and vice versa.
25 */
26 #define int_ifile(h) ((struct ifile *)(h))
27 #define ext_ifile(h) ((IFILE)(h))
28
29 /*
30 * Anchor for linked list.
31 */
32 static struct ifile anchor = { &anchor, &anchor, 0 };
33 static int ifiles = 0;
34
35 /*
36 * Allocate a new ifile structure and stick a filename in it.
37 * It should go after "prev" in the list
38 * (or at the beginning of the list if "prev" is NULL).
39 * Return a pointer to the new ifile structure.
40 */
41 static struct ifile *
42 new_ifile(filename, prev)
43 char *filename;
44 struct ifile *prev;
45 {
46 register struct ifile *p;
47 register struct ifile *np;
48
49 /*
50 * Allocate and initialize structure.
51 */
52 p = (struct ifile *) ecalloc(1, sizeof(struct ifile));
53 p->h_filename = filename;
54 p->h_scrpos.pos = NULL_POSITION;
55
56 /*
57 * Link into list.
58 */
59 if (prev == NULL)
60 prev = &anchor;
61 p->h_next = prev->h_next;
62 p->h_prev = prev;
63 prev->h_next->h_prev = p;
64 prev->h_next = p;
65
66 /*
67 * Calculate index for the new one,
68 * and adjust the indexes for subsequent ifiles in the list.
69 */
70 p->h_index = prev->h_index + 1;
71 for (np = p->h_next; np != &anchor; np = np->h_next)
72 np->h_index++;
73
74 ifiles++;
75 return (p);
76 }
77
78 /*
79 * Get the ifile after a given one in the list.
80 */
81 public IFILE
82 next_ifile(h)
83 IFILE h;
84 {
85 register struct ifile *p;
86
87 p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
88 if (p->h_next == &anchor)
89 return (NULL_IFILE);
90 return (ext_ifile(p->h_next));
91 }
92
93 /*
94 * Get the ifile before a given one in the list.
95 */
96 public IFILE
97 prev_ifile(h)
98 IFILE h;
99 {
100 register struct ifile *p;
101
102 p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
103 if (p->h_prev == &anchor)
104 return (NULL_IFILE);
105 return (ext_ifile(p->h_prev));
106 }
107
108 /*
109 * Return the number of ifiles.
110 */
111 public int
112 nifile()
113 {
114 return (ifiles);
115 }
116
117 /*
118 * Find an ifile structure, given a filename.
119 */
120 static struct ifile *
121 find_ifile(filename)
122 char *filename;
123 {
124 register struct ifile *p;
125
126 for (p = anchor.h_next; p != &anchor; p = p->h_next)
127 if (strcmp(filename, p->h_filename) == 0)
128 return (p);
129 return (NULL);
130 }
131
132 /*
133 * Get the ifile associated with a filename.
134 * If the filename has not been seen before,
135 * insert the new ifile after "prev" in the list.
136 */
137 public IFILE
138 get_ifile(filename, prev)
139 char *filename;
140 IFILE prev;
141 {
142 register struct ifile *p;
143
144 if ((p = find_ifile(filename)) == NULL)
145 p = new_ifile(save(filename), int_ifile(prev));
146 return (ext_ifile(p));
147 }
148
149 /*
150 * Get the filename associated with a ifile.
151 */
152 public char *
153 get_filename(ifile)
154 IFILE ifile;
155 {
156 if (ifile == NULL)
157 return (NULL);
158 return (int_ifile(ifile)->h_filename);
159 }
160
161 /*
162 * Get the index of the file associated with a ifile.
163 */
164 public int
165 get_index(ifile)
166 IFILE ifile;
167 {
168 return (int_ifile(ifile)->h_index);
169 }
170
171 /*
172 * Save the file position to be associated with a given file.
173 */
174 public void
175 store_pos(ifile, scrpos)
176 IFILE ifile;
177 struct scrpos *scrpos;
178 {
179 int_ifile(ifile)->h_scrpos = *scrpos;
180 }
181
182 /*
183 * Recall the file position associated with a file.
184 * If no position has been associated with the file, return NULL_POSITION.
185 */
186 public void
187 get_pos(ifile, scrpos)
188 IFILE ifile;
189 struct scrpos *scrpos;
190 {
191 *scrpos = int_ifile(ifile)->h_scrpos;
192 }