lib: add support for date:<expr>..! to mean date:<expr>..<expr>

It doesn't seem likely we can support simple date:<expr> expanding to
date:<expr>..<expr> any time soon. (This can be done with a future
version of Xapian, or with a custom query query parser.) In the mean
time, provide shorthand date:<expr>..! to mean the same. This is
useful, as the expansion takes place before interpetation, and we can
use, for example, date:yesterday..! to match from beginning of
yesterday to end of yesterday.

Idea from Mark Walters <markwalters1009@gmail.com>.

doc/man7/notmuch-search-terms.rst

@@ -278,6 +278,13 @@ In this case, <since> is taken as the earliest time it could describe
 could describe (the end of yesterday). Similarly, date:january..february
 matches from the beginning of January to the end of February.
 
+date:<expr>..! can be used as a shorthand for date:<expr>..<expr>. The
+expansion takes place before interpretation, and thus, for example,
+date:monday..! matches from the beginning of Monday until the end of
+Monday. (Note that entering date:<expr> without "..", for example
+date:yesterday, won't work, as it's not interpreted as a range
+expression at all. Again, use date:yesterday..!)
+
 Currently, we do not support spaces in range expressions. You can
 replace the spaces with '\_', or (in most cases) '-', or (in some cases)
 leave the spaces out altogether. Examples in this man page use spaces
@@ -288,11 +295,6 @@ to specify date:..<until> or date:<since>.. to not limit the start or
 end time, respectively. Pre-1.2.1 Xapian does not report an error on
 open ended ranges, but it does not work as expected either.
 
-Entering date:expr without ".." (for example date:yesterday) won't work,
-as it's not interpreted as a range expression at all. You can achieve
-the expected result by duplicating the expr both sides of ".." (for
-example date:yesterday..yesterday).
-
 Relative date and time
 ----------------------
 

lib/parse-time-vrp.cc

@@ -31,6 +31,7 @@ Xapian::valueno
 ParseTimeValueRangeProcessor::operator() (std::string &begin, std::string &end)
 {
     time_t t, now;
+    std::string b;
 
     /* Require date: prefix in start of the range... */
     if (STRNCMP_LITERAL (begin.c_str (), PREFIX))
@@ -38,6 +39,7 @@ ParseTimeValueRangeProcessor::operator() (std::string &begin, std::string &end)
 
     /* ...and remove it. */
     begin.erase (0, sizeof (PREFIX) - 1);
+    b = begin;
 
     /* Use the same 'now' for begin and end. */
     if (time (&now) == (time_t) -1)
@@ -51,6 +53,9 @@ ParseTimeValueRangeProcessor::operator() (std::string &begin, std::string &end)
     }
 
     if (!end.empty ()) {
+	if (end == "!" && ! b.empty ())
+	    end = b;
+
 	if (parse_time_string (end.c_str (), &t, &now, PARSE_TIME_ROUND_UP_INCLUSIVE))
 	    return Xapian::BAD_VALUENO;
 

test/T500-search-date.sh

@@ -8,6 +8,10 @@ test_begin_subtest "Absolute date range"
 output=$(notmuch search date:2010-12-16..12/16/2010 | notmuch_search_sanitize)
 test_expect_equal "$output" "thread:XXX   2010-12-16 [1/1] Olivier Berger; Essai accentué (inbox unread)"
 
+test_begin_subtest "Absolute date range with 'same' operator"
+output=$(notmuch search date:2010-12-16..! | notmuch_search_sanitize)
+test_expect_equal "$output" "thread:XXX   2010-12-16 [1/1] Olivier Berger; Essai accentué (inbox unread)"
+
 test_begin_subtest "Absolute time range with TZ"
 notmuch search date:18-Nov-2009_02:19:26-0800..2009-11-18_04:49:52-06:00 | notmuch_search_sanitize > OUTPUT
 cat <<EOF >EXPECTED