vpatch: highlight spaces when they might be important.

If a wiggle is needed due to white-space issues, it is good
to show them.
So in cases where that might be happening - unmatches space or
extraneous space - highlight spaces as inverse-video and tabs as
underlines.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/vpatch.c b/vpatch.c
index 0b99ac79a52d18d050d38954ce640784824d6cf2..0682c437aeaa0e3cd2dcf459ae0b5e0b6cccc1b5 100644 (file)
--- a/vpatch.c
+++ b/vpatch.c
@@ -842,6 +842,7 @@ static void draw_mside(int mode, int row, int offset, int start, int cols,
        int col = 0;
        char tag;
        unsigned int tag_attr;
+       int changed = 0;
 
        switch (pos.state) {
        default: /* keep compiler happy */
@@ -883,6 +884,9 @@ static void draw_mside(int mode, int row, int offset, int start, int cols,
        cols--;
        (void)attrset(A_NORMAL);
 
+       if (check_line(pos, fm, fb, fa, m, mode))
+               changed = 1;
+
        /* find previous visible newline, or start of file */
        do
                e = prev_melmnt(&pos.p, fm, fb, fa, m);
@@ -892,6 +896,8 @@ static void draw_mside(int mode, int row, int offset, int start, int cols,
 
        while (1) {
                unsigned char *c;
+               unsigned int attr;
+               int highlight_space;
                int l;
                e = next_melmnt(&pos.p, fm, fb, fa, m);
                if (e.start == NULL ||
@@ -939,15 +945,25 @@ static void draw_mside(int mode, int row, int offset, int start, int cols,
                        continue;
                if (e.start[0] == 0)
                        continue;
-               (void)attrset(visible(mode, m[pos.p.m].type, pos.p.s));
                c = (unsigned char *)e.start;
+               highlight_space = 0;
+               attr = visible(mode, m[pos.p.m].type, pos.p.s);
+               if ((attr == a_unmatched || attr == a_extra) &&
+                   changed &&
+                   (*c == ' ' || *c == '\t'))
+                       highlight_space = 1;
                for (l = 0; l < e.len; l++) {
                        int scol = col;
+                       (void)attrset(attr);
                        if (*c >= ' ' && *c != 0x7f) {
+                               if (highlight_space)
+                                       (void)attrset(attr|A_REVERSE);
                                if (col >= start && col < start+cols)
                                        mvaddch(row, col-start+offset, *c);
                                col++;
                        } else if (*c == '\t') {
+                               if (highlight_space)
+                                       (void)attrset(attr|A_UNDERLINE);
                                do {
                                        if (col >= start && col < start+cols) {
                                                mvaddch(row, col-start+offset, ' ');