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   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 }