xdiff: -W: don't include common trailing empty lines in context

diff --git a/xdiff/xemit.c b/xdiff/xemit.c
index 4266ada23f3c37c1989c7fa4283b423d16c0891b..bfa53d3dcd2e472017309ad764543334780408cc 100644 (file)
--- a/xdiff/xemit.c
+++ b/xdiff/xemit.c
@@ -120,19 +120,14 @@ static long def_ff(const char *rec, long len, char *buf, long sz, void *priv)
        return -1;
 }
 
-static int xdl_emit_common(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
-                           xdemitconf_t const *xecfg) {
-       xdfile_t *xdf = &xe->xdf2;
-       const char *rchg = xdf->rchg;
-       long ix;
-
-       for (ix = 0; ix < xdf->nrec; ix++) {
-               if (rchg[ix])
-                       continue;
-               if (xdl_emit_record(xdf, ix, "", ecb))
-                       return -1;
-       }
-       return 0;
+static long match_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri,
+                          char *buf, long sz)
+{
+       const char *rec;
+       long len = xdl_get_rec(xdf, ri, &rec);
+       if (!xecfg->find_func)
+               return def_ff(rec, len, buf, sz, xecfg->find_func_priv);
+       return xecfg->find_func(rec, len, buf, sz, xecfg->find_func_priv);
 }
 
 struct func_line {
@@ -143,7 +138,6 @@ struct func_line {
 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];
 
@@ -151,9 +145,7 @@ static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
        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);
+               long len = match_func_rec(&xe->xdf1, xecfg, l, buf, size);
                if (len >= 0) {
                        if (func_line)
                                func_line->len = len;
@@ -163,6 +155,18 @@ static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
        return -1;
 }
 
+static int is_empty_rec(xdfile_t *xdf, long ri)
+{
+       const char *rec;
+       long len = xdl_get_rec(xdf, ri, &rec);
+
+       while (len > 0 && XDL_ISSPACE(*rec)) {
+               rec++;
+               len--;
+       }
+       return !len;
+}
+
 int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
                  xdemitconf_t const *xecfg) {
        long s1, s2, e1, e2, lctx;
@@ -170,9 +174,6 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
        long funclineprev = -1;
        struct func_line func_line = { 0 };
 
-       if (xecfg->flags & XDL_EMIT_COMMON)
-               return xdl_emit_common(xe, xscr, ecb, xecfg);
-
        for (xch = xscr; xch; xch = xche->next) {
                xche = xdl_get_hunk(&xch, xecfg);
                if (!xch)
@@ -182,7 +183,34 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
                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);
+                       long fs1, i1 = xch->i1;
+
+                       /* Appended chunk? */
+                       if (i1 >= xe->xdf1.nrec) {
+                               char dummy[1];
+                               long i2 = xch->i2;
+
+                               /*
+                                * We don't need additional context if
+                                * a whole function was added, possibly
+                                * starting with empty lines.
+                                */
+                               while (i2 < xe->xdf2.nrec &&
+                                      is_empty_rec(&xe->xdf2, i2))
+                                       i2++;
+                               if (i2 < xe->xdf2.nrec &&
+                                   match_func_rec(&xe->xdf2, xecfg, i2,
+                                                  dummy, sizeof(dummy)) >= 0)
+                                       goto post_context_calculation;
+
+                               /*
+                                * Otherwise get more context from the
+                                * pre-image.
+                                */
+                               i1 = xe->xdf1.nrec - 1;
+                       }
+
+                       fs1 = get_func_line(xe, xecfg, NULL, i1, -1);
                        if (fs1 < 0)
                                fs1 = 0;
                        if (fs1 < s1) {
@@ -191,7 +219,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
                        }
                }
 
- again:
+ post_context_calculation:
                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));
@@ -203,6 +231,8 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
                        long fe1 = get_func_line(xe, xecfg, NULL,
                                                 xche->i1 + xche->chg1,
                                                 xe->xdf1.nrec);
+                       while (fe1 > 0 && is_empty_rec(&xe->xdf1, fe1 - 1))
+                               fe1--;
                        if (fe1 < 0)
                                fe1 = xe->xdf1.nrec;
                        if (fe1 > e1) {
@@ -220,7 +250,7 @@ int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
                                if (l <= e1 ||
                                    get_func_line(xe, xecfg, NULL, l, e1) < 0) {
                                        xche = xche->next;
-                                       goto again;
+                                       goto post_context_calculation;
                                }
                        }
                }