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