Merge branch 'jk/graph-padding-fix' into maint
[git] / xdiff / xemit.c
1 /*
2  *  LibXDiff by Davide Libenzi ( File Differential Library )
3  *  Copyright (C) 2003  Davide Libenzi
4  *
5  *  This library is free software; you can redistribute it and/or
6  *  modify it under the terms of the GNU Lesser General Public
7  *  License as published by the Free Software Foundation; either
8  *  version 2.1 of the License, or (at your option) any later version.
9  *
10  *  This library is distributed in the hope that it will be useful,
11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  *  Lesser General Public License for more details.
14  *
15  *  You should have received a copy of the GNU Lesser General Public
16  *  License along with this library; if not, write to the Free Software
17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  *
19  *  Davide Libenzi <davidel@xmailserver.org>
20  *
21  */
22
23 #include "xinclude.h"
24
25 static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec) {
26
27         *rec = xdf->recs[ri]->ptr;
28
29         return xdf->recs[ri]->size;
30 }
31
32
33 static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
34         long size, psize = strlen(pre);
35         char const *rec;
36
37         size = xdl_get_rec(xdf, ri, &rec);
38         if (xdl_emit_diffrec(rec, size, pre, psize, ecb) < 0) {
39
40                 return -1;
41         }
42
43         return 0;
44 }
45
46
47 /*
48  * Starting at the passed change atom, find the latest change atom to be included
49  * inside the differential hunk according to the specified configuration.
50  * Also advance xscr if the first changes must be discarded.
51  */
52 xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
53 {
54         xdchange_t *xch, *xchp, *lxch;
55         long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
56         long max_ignorable = xecfg->ctxlen;
57         unsigned long ignored = 0; /* number of ignored blank lines */
58
59         /* remove ignorable changes that are too far before other changes */
60         for (xchp = *xscr; xchp && xchp->ignore; xchp = xchp->next) {
61                 xch = xchp->next;
62
63                 if (xch == NULL ||
64                     xch->i1 - (xchp->i1 + xchp->chg1) >= max_ignorable)
65                         *xscr = xch;
66         }
67
68         if (*xscr == NULL)
69                 return NULL;
70
71         lxch = *xscr;
72
73         for (xchp = *xscr, xch = xchp->next; xch; xchp = xch, xch = xch->next) {
74                 long distance = xch->i1 - (xchp->i1 + xchp->chg1);
75                 if (distance > max_common)
76                         break;
77
78                 if (distance < max_ignorable && (!xch->ignore || lxch == xchp)) {
79                         lxch = xch;
80                         ignored = 0;
81                 } else if (distance < max_ignorable && xch->ignore) {
82                         ignored += xch->chg2;
83                 } else if (lxch != xchp &&
84                            xch->i1 + ignored - (lxch->i1 + lxch->chg1) > max_common) {
85                         break;
86                 } else if (!xch->ignore) {
87                         lxch = xch;
88                         ignored = 0;
89                 } else {
90                         ignored += xch->chg2;
91                 }
92         }
93
94         return lxch;
95 }
96
97
98 static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
99 {
100         if (len > 0 &&
101                         (isalpha((unsigned char)*rec) || /* identifier? */
102                          *rec == '_' || /* also identifier? */
103                          *rec == '$')) { /* identifiers from VMS and other esoterico */
104                 if (len > sz)
105                         len = sz;
106                 while (0 < len && isspace((unsigned char)rec[len - 1]))
107                         len--;
108                 memcpy(buf, rec, len);
109                 return len;
110         }
111         return -1;
112 }
113
114 static long match_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri,
115                            char *buf, long sz)
116 {
117         const char *rec;
118         long len = xdl_get_rec(xdf, ri, &rec);
119         if (!xecfg->find_func)
120                 return def_ff(rec, len, buf, sz, xecfg->find_func_priv);
121         return xecfg->find_func(rec, len, buf, sz, xecfg->find_func_priv);
122 }
123
124 struct func_line {
125         long len;
126         char buf[80];
127 };
128
129 static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
130                           struct func_line *func_line, long start, long limit)
131 {
132         long l, size, step = (start > limit) ? -1 : 1;
133         char *buf, dummy[1];
134
135         buf = func_line ? func_line->buf : dummy;
136         size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
137
138         for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
139                 long len = match_func_rec(&xe->xdf1, xecfg, l, buf, size);
140                 if (len >= 0) {
141                         if (func_line)
142                                 func_line->len = len;
143                         return l;
144                 }
145         }
146         return -1;
147 }
148
149 static int is_empty_rec(xdfile_t *xdf, long ri)
150 {
151         const char *rec;
152         long len = xdl_get_rec(xdf, ri, &rec);
153
154         while (len > 0 && XDL_ISSPACE(*rec)) {
155                 rec++;
156                 len--;
157         }
158         return !len;
159 }
160
161 int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
162                   xdemitconf_t const *xecfg) {
163         long s1, s2, e1, e2, lctx;
164         xdchange_t *xch, *xche;
165         long funclineprev = -1;
166         struct func_line func_line = { 0 };
167
168         for (xch = xscr; xch; xch = xche->next) {
169                 xche = xdl_get_hunk(&xch, xecfg);
170                 if (!xch)
171                         break;
172
173                 s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
174                 s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
175
176                 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
177                         long fs1, i1 = xch->i1;
178
179                         /* Appended chunk? */
180                         if (i1 >= xe->xdf1.nrec) {
181                                 char dummy[1];
182                                 long i2 = xch->i2;
183
184                                 /*
185                                  * We don't need additional context if
186                                  * a whole function was added, possibly
187                                  * starting with empty lines.
188                                  */
189                                 while (i2 < xe->xdf2.nrec &&
190                                        is_empty_rec(&xe->xdf2, i2))
191                                         i2++;
192                                 if (i2 < xe->xdf2.nrec &&
193                                     match_func_rec(&xe->xdf2, xecfg, i2,
194                                                    dummy, sizeof(dummy)) >= 0)
195                                         goto post_context_calculation;
196
197                                 /*
198                                  * Otherwise get more context from the
199                                  * pre-image.
200                                  */
201                                 i1 = xe->xdf1.nrec - 1;
202                         }
203
204                         fs1 = get_func_line(xe, xecfg, NULL, i1, -1);
205                         if (fs1 < 0)
206                                 fs1 = 0;
207                         if (fs1 < s1) {
208                                 s2 -= s1 - fs1;
209                                 s1 = fs1;
210                         }
211                 }
212
213  post_context_calculation:
214                 lctx = xecfg->ctxlen;
215                 lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
216                 lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
217
218                 e1 = xche->i1 + xche->chg1 + lctx;
219                 e2 = xche->i2 + xche->chg2 + lctx;
220
221                 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
222                         long fe1 = get_func_line(xe, xecfg, NULL,
223                                                  xche->i1 + xche->chg1,
224                                                  xe->xdf1.nrec);
225                         while (fe1 > 0 && is_empty_rec(&xe->xdf1, fe1 - 1))
226                                 fe1--;
227                         if (fe1 < 0)
228                                 fe1 = xe->xdf1.nrec;
229                         if (fe1 > e1) {
230                                 e2 += fe1 - e1;
231                                 e1 = fe1;
232                         }
233
234                         /*
235                          * Overlap with next change?  Then include it
236                          * in the current hunk and start over to find
237                          * its new end.
238                          */
239                         if (xche->next) {
240                                 long l = XDL_MIN(xche->next->i1,
241                                                  xe->xdf1.nrec - 1);
242                                 if (l - xecfg->ctxlen <= e1 ||
243                                     get_func_line(xe, xecfg, NULL, l, e1) < 0) {
244                                         xche = xche->next;
245                                         goto post_context_calculation;
246                                 }
247                         }
248                 }
249
250                 /*
251                  * Emit current hunk header.
252                  */
253
254                 if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
255                         get_func_line(xe, xecfg, &func_line,
256                                       s1 - 1, funclineprev);
257                         funclineprev = s1 - 1;
258                 }
259                 if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
260                                       func_line.buf, func_line.len, ecb) < 0)
261                         return -1;
262
263                 /*
264                  * Emit pre-context.
265                  */
266                 for (; s2 < xch->i2; s2++)
267                         if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
268                                 return -1;
269
270                 for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
271                         /*
272                          * Merge previous with current change atom.
273                          */
274                         for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
275                                 if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
276                                         return -1;
277
278                         /*
279                          * Removes lines from the first file.
280                          */
281                         for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
282                                 if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
283                                         return -1;
284
285                         /*
286                          * Adds lines from the second file.
287                          */
288                         for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
289                                 if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
290                                         return -1;
291
292                         if (xch == xche)
293                                 break;
294                         s1 = xch->i1 + xch->chg1;
295                         s2 = xch->i2 + xch->chg2;
296                 }
297
298                 /*
299                  * Emit post-context.
300                  */
301                 for (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
302                         if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
303                                 return -1;
304         }
305
306         return 0;
307 }