line-range: teach -L/RE/ to search relative to anchor point

Range specification -L/RE/ for blame/log unconditionally begins
searching at line one. Mailing list discussion [1] suggests that, in the
presence of multiple -L options, -L/RE/ should search relative to the
endpoint of the previous -L range, if any.

Teach the parsing machinery underlying blame's and log's -L options to
accept a start point for -L/RE/ searches. Follow-up patches will upgrade
blame and log to take advantage of this ability.

[1]: http://thread.gmane.org/gmane.comp.version-control.git/229755/focus=229966

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/blame.c b/builtin/blame.c
index 2f4d9e2d75d475057c4aef5781c8d4a41a45cd24..7b084d8445272e368ddfd96e5d9f74e8353b70bd 100644 (file)
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2479,7 +2479,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        for (range_i = 0; range_i < range_list.nr; ++range_i) {
                long bottom, top;
                if (parse_range_arg(range_list.items[range_i].string,
-                                   nth_line_cb, &sb, lno,
+                                   nth_line_cb, &sb, lno, 1,
                                    &bottom, &top, sb.path))
                        usage(blame_usage);
                if (lno < top || ((lno || bottom) && lno < bottom))

diff --git a/line-log.c b/line-log.c
index bdadf35a1eb1c20c883c62675af47ed033876465..38f827ba9a01b96316358bba43ffd74e5d3682fe 100644 (file)
--- a/line-log.c
+++ b/line-log.c
@@ -591,7 +591,7 @@ parse_lines(struct commit *commit, const char *prefix, struct string_list *args)
                cb_data.line_ends = ends;
 
                if (parse_range_arg(range_part, nth_line, &cb_data,
-                                   lines, &begin, &end,
+                                   lines, 1, &begin, &end,
                                    full_name))
                        die("malformed -L argument '%s'", range_part);
                if (lines < end || ((lines || begin) && lines < begin))

diff --git a/line-range.c b/line-range.c
index 69e8d6b6c02101b4243e1850aa52c377ccaa0a2b..bbf3c0f4481e9dd762d6a55e531cb983bbcbaff1 100644 (file)
--- a/line-range.c
+++ b/line-range.c
@@ -6,6 +6,18 @@
 
 /*
  * Parse one item in the -L option
+ *
+ * 'begin' is applicable only to relative range anchors. Absolute anchors
+ * ignore this value.
+ *
+ * When parsing "-L A,B", parse_loc() is called once for A and once for B.
+ *
+ * When parsing A, 'begin' must be a negative number, the absolute value of
+ * which is the line at which relative start-of-range anchors should be
+ * based. Beginning of file is represented by -1.
+ *
+ * When parsing B, 'begin' must be the positive line number immediately
+ * following the line computed for 'A'.
  */
 static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
                             void *data, long lines, long begin, long *ret)
@@ -46,6 +58,10 @@ static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
                        *ret = num;
                return term;
        }
+
+       if (begin < 0)
+               begin = -begin;
+
        if (spec[0] != '/')
                return spec;
 
@@ -85,7 +101,8 @@ static const char *parse_loc(const char *spec, nth_line_fn_t nth_line,
        else {
                char errbuf[1024];
                regerror(reg_error, &regexp, errbuf, 1024);
-               die("-L parameter '%s': %s", spec + 1, errbuf);
+               die("-L parameter '%s' starting at line %ld: %s",
+                   spec + 1, begin + 1, errbuf);
        }
 }
 
@@ -210,11 +227,16 @@ static const char *parse_range_funcname(const char *arg, nth_line_fn_t nth_line_
 }
 
 int parse_range_arg(const char *arg, nth_line_fn_t nth_line_cb,
-                   void *cb_data, long lines, long *begin, long *end,
-                   const char *path)
+                   void *cb_data, long lines, long anchor,
+                   long *begin, long *end, const char *path)
 {
        *begin = *end = 0;
 
+       if (anchor < 1)
+               anchor = 1;
+       if (anchor > lines)
+               anchor = lines + 1;
+
        if (*arg == ':') {
                arg = parse_range_funcname(arg, nth_line_cb, cb_data, lines, begin, end, path);
                if (!arg || *arg)
@@ -222,7 +244,7 @@ int parse_range_arg(const char *arg, nth_line_fn_t nth_line_cb,
                return 0;
        }
 
-       arg = parse_loc(arg, nth_line_cb, cb_data, lines, 1, begin);
+       arg = parse_loc(arg, nth_line_cb, cb_data, lines, -anchor, begin);
 
        if (*arg == ',')
                arg = parse_loc(arg + 1, nth_line_cb, cb_data, lines, *begin + 1, end);

diff --git a/line-range.h b/line-range.h
index ae3d0123b447c1c619695c2d0aaf619d1daaa991..83ba3c25e88a4601dc17ce01dc57dfbc33c05b2e 100644 (file)
--- a/line-range.h
+++ b/line-range.h
@@ -9,6 +9,9 @@
  * line 'lno' inside the 'cb_data'.  The caller is expected to already
  * have a suitable map at hand to make this a constant-time lookup.
  *
+ * 'anchor' is the 1-based line at which relative range specifications
+ * should be anchored. Absolute ranges are unaffected by this value.
+ *
  * Returns 0 in case of success and -1 if there was an error.  The
  * actual range is stored in *begin and *end.  The counting starts
  * at 1!  In case of error, the caller should show usage message.
@@ -18,7 +21,7 @@ typedef const char *(*nth_line_fn_t)(void *data, long lno);
 
 extern int parse_range_arg(const char *arg,
                           nth_line_fn_t nth_line_cb,
-                          void *cb_data, long lines,
+                          void *cb_data, long lines, long anchor,
                           long *begin, long *end,
                           const char *path);