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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>
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sunshineco authored and gitster committed Aug 6, 2013
1 parent 5bd9b79 commit 815834e9aa6148b7815b9aea7db5d44640a4383a
Showing with 32 additions and 7 deletions.
  1. +1 −1 builtin/blame.c
  2. +1 −1 line-log.c
  3. +26 −4 line-range.c
  4. +4 −1 line-range.h
View
@@ -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))
View
@@ -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))
View
@@ -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);
}
}
@@ -210,19 +227,24 @@ 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)
return -1;
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);
View
@@ -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);

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