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
  26
  27
  28 static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec);
  29 static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb);
  30
  31
  32
  33
  34 static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec) {
  35
  36         *rec = xdf->recs[ri]->ptr;
  37
  38         return xdf->recs[ri]->size;
  39 }
  40
  41
  42 static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
  43         long size, psize = strlen(pre);
  44         char const *rec;
  45
  46         size = xdl_get_rec(xdf, ri, &rec);
  47         if (xdl_emit_diffrec(rec, size, pre, psize, ecb) < 0) {
  48
  49                 return -1;
  50         }
  51
  52         return 0;
  53 }
  54
  55
  56 /*
  57  * Starting at the passed change atom, find the latest change atom to be included
  58  * inside the differential hunk according to the specified configuration.
  59  * Also advance xscr if the first changes must be discarded.
  60  */
  61 xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
  62 {
  63         xdchange_t *xch, *xchp, *lxch;
  64         long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
  65         long max_ignorable = xecfg->ctxlen;
  66         unsigned long ignored = 0; /* number of ignored blank lines */
  67
  68         /* remove ignorable changes that are too far before other changes */
  69         for (xchp = *xscr; xchp && xchp->ignore; xchp = xchp->next) {
  70                 xch = xchp->next;
  71
  72                 if (xch == NULL ||
  73                     xch->i1 - (xchp->i1 + xchp->chg1) >= max_ignorable)
  74                         *xscr = xch;
  75         }
  76
  77         if (*xscr == NULL)
  78                 return NULL;
  79
  80         lxch = *xscr;
  81
  82         for (xchp = *xscr, xch = xchp->next; xch; xchp = xch, xch = xch->next) {
  83                 long distance = xch->i1 - (xchp->i1 + xchp->chg1);
  84                 if (distance > max_common)
  85                         break;
  86
  87                 if (distance < max_ignorable && (!xch->ignore || lxch == xchp)) {
  88                         lxch = xch;
  89                         ignored = 0;
  90                 } else if (distance < max_ignorable && xch->ignore) {
  91                         ignored += xch->chg2;
  92                 } else if (lxch != xchp &&
  93                            xch->i1 + ignored - (lxch->i1 + lxch->chg1) > max_common) {
  94                         break;
  95                 } else if (!xch->ignore) {
  96                         lxch = xch;
  97                         ignored = 0;
  98                 } else {
  99                         ignored += xch->chg2;
 100                 }
 101         }
 102
 103         return lxch;
 104 }
 105
 106
 107 static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
 108 {
 109         if (len > 0 &&
 110                         (isalpha((unsigned char)*rec) || /* identifier? */
 111                          *rec == '_' || /* also identifier? */
 112                          *rec == '$')) { /* identifiers from VMS and other esoterico */
 113                 if (len > sz)
 114                         len = sz;
 115                 while (0 < len && isspace((unsigned char)rec[len - 1]))
 116                         len--;
 117                 memcpy(buf, rec, len);
 118                 return len;
 119         }
 120         return -1;
 121 }
 122
 123 struct func_line {
 124         long len;
 125         char buf[80];
 126 };
 127
 128 static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
 129                           struct func_line *func_line, long start, long limit)
 130 {
 131         find_func_t ff = xecfg->find_func ? xecfg->find_func : def_ff;
 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                 const char *rec;
 140                 long reclen = xdl_get_rec(&xe->xdf1, l, &rec);
 141                 long len = ff(rec, reclen, buf, size, xecfg->find_func_priv);
 142                 if (len >= 0) {
 143                         if (func_line)
 144                                 func_line->len = len;
 145                         return l;
 146                 }
 147         }
 148         return -1;
 149 }
 150
 151 int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
 152                   xdemitconf_t const *xecfg) {
 153         long s1, s2, e1, e2, lctx;
 154         xdchange_t *xch, *xche;
 155         long funclineprev = -1;
 156         struct func_line func_line = { 0 };
 157
 158         for (xch = xscr; xch; xch = xche->next) {
 159                 xche = xdl_get_hunk(&xch, xecfg);
 160                 if (!xch)
 161                         break;
 162
 163                 s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
 164                 s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
 165
 166                 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
 167                         long fs1 = get_func_line(xe, xecfg, NULL, xch->i1, -1);
 168                         if (fs1 < 0)
 169                                 fs1 = 0;
 170                         if (fs1 < s1) {
 171                                 s2 -= s1 - fs1;
 172                                 s1 = fs1;
 173                         }
 174                 }
 175
 176  again:
 177                 lctx = xecfg->ctxlen;
 178                 lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
 179                 lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
 180
 181                 e1 = xche->i1 + xche->chg1 + lctx;
 182                 e2 = xche->i2 + xche->chg2 + lctx;
 183
 184                 if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
 185                         long fe1 = get_func_line(xe, xecfg, NULL,
 186                                                  xche->i1 + xche->chg1,
 187                                                  xe->xdf1.nrec);
 188                         if (fe1 < 0)
 189                                 fe1 = xe->xdf1.nrec;
 190                         if (fe1 > e1) {
 191                                 e2 += fe1 - e1;
 192                                 e1 = fe1;
 193                         }
 194
 195                         /*
 196                          * Overlap with next change?  Then include it
 197                          * in the current hunk and start over to find
 198                          * its new end.
 199                          */
 200                         if (xche->next) {
 201                                 long l = xche->next->i1;
 202                                 if (l <= e1 ||
 203                                     get_func_line(xe, xecfg, NULL, l, e1) < 0) {
 204                                         xche = xche->next;
 205                                         goto again;
 206                                 }
 207                         }
 208                 }
 209
 210                 /*
 211                  * Emit current hunk header.
 212                  */
 213
 214                 if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
 215                         get_func_line(xe, xecfg, &func_line,
 216                                       s1 - 1, funclineprev);
 217                         funclineprev = s1 - 1;
 218                 }
 219                 if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
 220                                       func_line.buf, func_line.len, ecb) < 0)
 221                         return -1;
 222
 223                 /*
 224                  * Emit pre-context.
 225                  */
 226                 for (; s2 < xch->i2; s2++)
 227                         if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
 228                                 return -1;
 229
 230                 for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
 231                         /*
 232                          * Merge previous with current change atom.
 233                          */
 234                         for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
 235                                 if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
 236                                         return -1;
 237
 238                         /*
 239                          * Removes lines from the first file.
 240                          */
 241                         for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
 242                                 if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
 243                                         return -1;
 244
 245                         /*
 246                          * Adds lines from the second file.
 247                          */
 248                         for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
 249                                 if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
 250                                         return -1;
 251
 252                         if (xch == xche)
 253                                 break;
 254                         s1 = xch->i1 + xch->chg1;
 255                         s2 = xch->i2 + xch->chg2;
 256                 }
 257
 258                 /*
 259                  * Emit post-context.
 260                  */
 261                 for (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
 262                         if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
 263                                 return -1;
 264         }
 265
 266         return 0;
 267 }