Add libxdiff library

xdiff/xemit.c

+/*
+ *  LibXDiff by Davide Libenzi ( File Differential Library )
+ *  Copyright (C) 2003  Davide Libenzi
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *  Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+
+#include "xinclude.h"
+
+
+
+
+static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec);
+static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb);
+
+
+
+
+static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec) {
+
+        *rec = xdf->recs[ri]->ptr;
+
+        return xdf->recs[ri]->size;
+}
+
+
+static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
+        long size, psize = strlen(pre);
+        char const *rec;
+
+        size = xdl_get_rec(xdf, ri, &rec);
+        if (xdl_emit_diffrec(rec, size, pre, psize, ecb) < 0) {
+
+                return -1;
+        }
+
+        return 0;
+}
+
+
+/*
+ * Starting at the passed change atom, find the latest change atom to be included
+ * inside the differential hunk according to the specified configuration.
+ * Also advance xscr if the first changes must be discarded.
+ */
+xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
+{
+        xdchange_t *xch, *xchp, *lxch;
+        long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
+        long max_ignorable = xecfg->ctxlen;
+        unsigned long ignored = 0; /* number of ignored blank lines */
+
+        /* remove ignorable changes that are too far before other changes */
+        for (xchp = *xscr; xchp && xchp->ignore; xchp = xchp->next) {
+                xch = xchp->next;
+
+                if (xch == NULL ||
+                    xch->i1 - (xchp->i1 + xchp->chg1) >= max_ignorable)
+                        *xscr = xch;
+        }
+
+        if (*xscr == NULL)
+                return NULL;
+
+        lxch = *xscr;
+
+        for (xchp = *xscr, xch = xchp->next; xch; xchp = xch, xch = xch->next) {
+                long distance = xch->i1 - (xchp->i1 + xchp->chg1);
+                if (distance > max_common)
+                        break;
+
+                if (distance < max_ignorable && (!xch->ignore || lxch == xchp)) {
+                        lxch = xch;
+                        ignored = 0;
+                } else if (distance < max_ignorable && xch->ignore) {
+                        ignored += xch->chg2;
+                } else if (lxch != xchp &&
+                           xch->i1 + ignored - (lxch->i1 + lxch->chg1) > max_common) {
+                        break;
+                } else if (!xch->ignore) {
+                        lxch = xch;
+                        ignored = 0;
+                } else {
+                        ignored += xch->chg2;
+                }
+        }
+
+        return lxch;
+}
+
+
+static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
+{
+        if (len > 0 &&
+                        (isalpha((unsigned char)*rec) || /* identifier? */
+                         *rec == '_' || /* also identifier? */
+                         *rec == '$')) { /* identifiers from VMS and other esoterico */
+                if (len > sz)
+                        len = sz;
+                while (0 < len && isspace((unsigned char)rec[len - 1]))
+                        len--;
+                memcpy(buf, rec, len);
+                return len;
+        }
+        return -1;
+}
+
+struct func_line {
+        long len;
+        char buf[80];
+};
+
+static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
+                          struct func_line *func_line, long start, long limit)
+{
+        find_func_t ff = xecfg->find_func ? xecfg->find_func : def_ff;
+        long l, size, step = (start > limit) ? -1 : 1;
+        char *buf, dummy[1];
+
+        buf = func_line ? func_line->buf : dummy;
+        size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
+
+        for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
+                const char *rec;
+                long reclen = xdl_get_rec(&xe->xdf1, l, &rec);
+                long len = ff(rec, reclen, buf, size, xecfg->find_func_priv);
+                if (len >= 0) {
+                        if (func_line)
+                                func_line->len = len;
+                        return l;
+                }
+        }
+        return -1;
+}
+
+int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
+                  xdemitconf_t const *xecfg) {
+        long s1, s2, e1, e2, lctx;
+        xdchange_t *xch, *xche;
+        long funclineprev = -1;
+        struct func_line func_line = { 0 };
+
+        for (xch = xscr; xch; xch = xche->next) {
+                xche = xdl_get_hunk(&xch, xecfg);
+                if (!xch)
+                        break;
+
+                s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
+                s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
+
+                if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
+                        long fs1 = get_func_line(xe, xecfg, NULL, xch->i1, -1);
+                        if (fs1 < 0)
+                                fs1 = 0;
+                        if (fs1 < s1) {
+                                s2 -= s1 - fs1;
+                                s1 = fs1;
+                        }
+                }
+
+ again:
+                lctx = xecfg->ctxlen;
+                lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
+                lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
+
+                e1 = xche->i1 + xche->chg1 + lctx;
+                e2 = xche->i2 + xche->chg2 + lctx;
+
+                if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
+                        long fe1 = get_func_line(xe, xecfg, NULL,
+                                                 xche->i1 + xche->chg1,
+                                                 xe->xdf1.nrec);
+                        if (fe1 < 0)
+                                fe1 = xe->xdf1.nrec;
+                        if (fe1 > e1) {
+                                e2 += fe1 - e1;
+                                e1 = fe1;
+                        }
+
+                        /*
+                         * Overlap with next change?  Then include it
+                         * in the current hunk and start over to find
+                         * its new end.
+                         */
+                        if (xche->next) {
+                                long l = xche->next->i1;
+                                if (l <= e1 ||
+                                    get_func_line(xe, xecfg, NULL, l, e1) < 0) {
+                                        xche = xche->next;
+                                        goto again;
+                                }
+                        }
+                }
+
+                /*
+                 * Emit current hunk header.
+                 */
+
+                if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
+                        get_func_line(xe, xecfg, &func_line,
+                                      s1 - 1, funclineprev);
+                        funclineprev = s1 - 1;
+                }
+                if (xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
+                                      func_line.buf, func_line.len, ecb) < 0)
+                        return -1;
+
+                /*
+                 * Emit pre-context.
+                 */
+                for (; s2 < xch->i2; s2++)
+                        if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
+                                return -1;
+
+                for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
+                        /*
+                         * Merge previous with current change atom.
+                         */
+                        for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
+                                if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
+                                        return -1;
+
+                        /*
+                         * Removes lines from the first file.
+                         */
+                        for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
+                                if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
+                                        return -1;
+
+                        /*
+                         * Adds lines from the second file.
+                         */
+                        for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
+                                if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
+                                        return -1;
+
+                        if (xch == xche)
+                                break;
+                        s1 = xch->i1 + xch->chg1;
+                        s2 = xch->i2 + xch->chg2;
+                }
+
+                /*
+                 * Emit post-context.
+                 */
+                for (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
+                        if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
+                                return -1;
+        }
+
+        return 0;
+}