grep: -W: don't extend context to trailing empty lines

Empty lines between functions are shown by grep -W, as it considers them
to be part of the function preceding them.  They are not interesting in
most languages.  The previous patches stopped showing them for diff -W.

Stop showing empty lines trailing a function with grep -W.  Grep scans
the lines of a buffer from top to bottom and prints matching lines
immediately.  Thus we need to peek ahead in order to determine if an
empty line is part of a function body and worth showing or not.

Remember how far ahead we peeked in order to avoid having to do so
repeatedly when handling multiple consecutive empty lines.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/grep.c b/grep.c
index 528b652f713d2b6db5f48e3829448212cc3837bf..fafb8b58e08282e70f97676784bcb7e23e776490 100644 (file)
--- a/grep.c
+++ b/grep.c
@@ -1396,9 +1396,17 @@ static int fill_textconv_grep(struct userdiff_driver *driver,
        return 0;
 }
 
+static int is_empty_line(const char *bol, const char *eol)
+{
+       while (bol < eol && isspace(*bol))
+               bol++;
+       return bol == eol;
+}
+
 static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int collect_hits)
 {
        char *bol;
+       char *peek_bol = NULL;
        unsigned long left;
        unsigned lno = 1;
        unsigned last_hit = 0;
@@ -1543,8 +1551,24 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
                                show_function = 1;
                        goto next_line;
                }
-               if (show_function && match_funcname(opt, gs, bol, eol))
-                       show_function = 0;
+               if (show_function && (!peek_bol || peek_bol < bol)) {
+                       unsigned long peek_left = left;
+                       char *peek_eol = eol;
+
+                       /*
+                        * Trailing empty lines are not interesting.
+                        * Peek past them to see if they belong to the
+                        * body of the current function.
+                        */
+                       peek_bol = bol;
+                       while (is_empty_line(peek_bol, peek_eol)) {
+                               peek_bol = peek_eol + 1;
+                               peek_eol = end_of_line(peek_bol, &peek_left);
+                       }
+
+                       if (match_funcname(opt, gs, peek_bol, peek_eol))
+                               show_function = 0;
+               }
                if (show_function ||
                    (last_hit && lno <= last_hit + opt->post_context)) {
                        /* If the last hit is within the post context,

diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index c42b82ae52761358b95f3d78ad0091877d0d83bc..befbde44f41f5bf3d3eec3351dd49da5f6dc5514 100755 (executable)
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -748,7 +748,7 @@ hello.c-#include <assert.h>
 hello.c:#include <stdio.h>
 EOF
 
-test_expect_failure 'grep -W shows no trailing empty lines' '
+test_expect_success 'grep -W shows no trailing empty lines' '
        git grep -W stdio >actual &&
        test_cmp expected actual
 '