src/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, see
  17  *  <http://www.gnu.org/licenses/>.
  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 = (long)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) > (unsigned long)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         (void)priv;
 101
 102         if (len > 0 &&
 103                         (isalpha((unsigned char)*rec) || /* identifier? */
 104                          *rec == '_' || /* also identifier? */
 105                          *rec == '$')) { /* identifiers from VMS and other esoterico */
 106                 if (len > sz)
 107                         len = sz;
 108                 while (0 < len && isspace((unsigned char)rec[len - 1]))
 109                         len--;
 110                 memcpy(buf, rec, len);
 111                 return len;
 112         }
 113         return -1;
 114 }
 115
 116 static long match_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri,
 117                            char *buf, long sz)
 118 {
 119         const char *rec;
 120         long len = xdl_get_rec(xdf, ri, &rec);
 121         if (!xecfg->find_func)
 122                 return def_ff(rec, len, buf, sz, xecfg->find_func_priv);
 123         return xecfg->find_func(rec, len, buf, sz, xecfg->find_func_priv);
 124 }
 125
 126 static int is_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri)
 127 {
 128         char dummy[1];
 129         return match_func_rec(xdf, xecfg, ri, dummy, sizeof(dummy)) >= 0;
 130 }
 131
 132 struct func_line {
 133         long len;
 134         char buf[80];
 135 };
 136
 137 static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
 138                           struct func_line *func_line, long start, long limit)
 139 {
 140         long l, size, step = (start > limit) ? -1 : 1;
 141         char *buf, dummy[1];
 142
 143         buf = func_line ? func_line->buf : dummy;
 144         size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
 145
 146         for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
 147                 long len = match_func_rec(&xe->xdf1, xecfg, l, buf, size);
 148                 if (len >= 0) {
 149                         if (func_line)
 150                                 func_line->len = len;
 151                         return l;
 152                 }
 153         }
 154         return -1;
 155 }
 156
 157 static int is_empty_rec(xdfile_t *xdf, long ri)
 158 {
 159         const char *rec;
 160         long len = xdl_get_rec(xdf, ri, &rec);
 161
 162         while (len > 0 && XDL_ISSPACE(*rec)) {
 163                 rec++;
 164                 len--;
 165         }
 166         return !len;
 167 }
 168
 169 int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 170                   xdemitconf_t const *xecfg) {
 171         long s1, s2, e1, e2, lctx;
 172         xdchange_t *xch, *xche;
 173         long funclineprev = -1;
 174         struct func_line func_line = { 0 };
 175
 176         for (xch = xscr; xch; xch = xche->next) {
 177                 xche = xdl_get_hunk(&xch, xecfg);
 178                 if (!xch)
 179                         break;
 180
 181                 s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
 182                 s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
 183
 184                 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
 185                         long fs1, i1 = xch->i1;
 186
 187                         /* Appended chunk? */
 188                         if (i1 >= xe->xdf1.nrec) {
 189                                 long i2 = xch->i2;
 190
 191                                 /*
 192                                  * We don't need additional context if
 193                                  * a whole function was added.
 194                                  */
 195                                 while (i2 < xe->xdf2.nrec) {
 196                                         if (is_func_rec(&xe->xdf2, xecfg, i2))
 197                                                 goto post_context_calculation;
 198                                         i2++;
 199                                 }
 200
 201                                 /*
 202                                  * Otherwise get more context from the
 203                                  * pre-image.
 204                                  */
 205                                 i1 = xe->xdf1.nrec - 1;
 206                         }
 207
 208                         fs1 = get_func_line(xe, xecfg, NULL, i1, -1);
 209                         while (fs1 > 0 && !is_empty_rec(&xe->xdf1, fs1 - 1) &&
 210                                !is_func_rec(&xe->xdf1, xecfg, fs1 - 1))
 211                                 fs1--;
 212                         if (fs1 < 0)
 213                                 fs1 = 0;
 214                         if (fs1 < s1) {
 215                                 s2 -= s1 - fs1;
 216                                 s1 = fs1;
 217                         }
 218                 }
 219
 220  post_context_calculation:
 221                 lctx = xecfg->ctxlen;
 222                 lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
 223                 lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
 224
 225                 e1 = xche->i1 + xche->chg1 + lctx;
 226                 e2 = xche->i2 + xche->chg2 + lctx;
 227
 228                 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
 229                         long fe1 = get_func_line(xe, xecfg, NULL,
 230                                                  xche->i1 + xche->chg1,
 231                                                  xe->xdf1.nrec);
 232                         while (fe1 > 0 && is_empty_rec(&xe->xdf1, fe1 - 1))
 233                                 fe1--;
 234                         if (fe1 < 0)
 235                                 fe1 = xe->xdf1.nrec;
 236                         if (fe1 > e1) {
 237                                 e2 += fe1 - e1;
 238                                 e1 = fe1;
 239                         }
 240
 241                         /*
 242                          * Overlap with next change?  Then include it
 243                          * in the current hunk and start over to find
 244                          * its new end.
 245                          */
 246                         if (xche->next) {
 247                                 long l = XDL_MIN(xche->next->i1,
 248                                                  xe->xdf1.nrec - 1);
 249                                 if (l - xecfg->ctxlen <= e1 ||
 250                                     get_func_line(xe, xecfg, NULL, l, e1) < 0) {
 251                                         xche = xche->next;
 252                                         goto post_context_calculation;
 253                                 }
 254                         }
 255                 }
 256
 257                 /*
 258                  * Emit current hunk header.
 259                  */
 260
 261                 if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
 262                         get_func_line(xe, xecfg, &func_line,
 263                                       s1 - 1, funclineprev);
 264                         funclineprev = s1 - 1;
 265                 }
 266                 if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
 267                                       func_line.buf, func_line.len, ecb) < 0)
 268                         return -1;
 269
 270                 /*
 271                  * Emit pre-context.
 272                  */
 273                 for (; s2 < xch->i2; s2++)
 274                         if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
 275                                 return -1;
 276
 277                 for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
 278                         /*
 279                          * Merge previous with current change atom.
 280                          */
 281                         for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
 282                                 if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
 283                                         return -1;
 284
 285                         /*
 286                          * Removes lines from the first file.
 287                          */
 288                         for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
 289                                 if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
 290                                         return -1;
 291
 292                         /*
 293                          * Adds lines from the second file.
 294                          */
 295                         for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
 296                                 if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
 297                                         return -1;
 298
 299                         if (xch == xche)
 300                                 break;
 301                         s1 = xch->i1 + xch->chg1;
 302                         s2 = xch->i2 + xch->chg2;
 303                 }
 304
 305                 /*
 306                  * Emit post-context.
 307                  */
 308                 for (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
 309                         if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
 310                                 return -1;
 311         }
 312
 313         return 0;
 314 }