[PATCH 08/27] lib/parse-sexp: stem unquoted atoms

[David Bremner <david@tethera.net>]

This is somewhat less DWIM than the Xapian query parser, but it has
the advantage of simplicity.
---
 doc/man7/notmuch-sexp-queries.rst | 10 ++++++++--
 lib/parse-sexp.cc                 | 10 +++++++---
 test/T081-sexpr-search.sh         |  7 +++++--
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/doc/man7/notmuch-sexp-queries.rst b/doc/man7/notmuch-sexp-queries.rst
index e530912c..8a3bcd8b 100644
--- a/doc/man7/notmuch-sexp-queries.rst
+++ b/doc/man7/notmuch-sexp-queries.rst
@@ -41,8 +41,10 @@ subqueries.
     The empty list matches all messages
 
 *term*
-    Match all messages containing *term*, possibly after stemming
-    or phase splitting.
+    Match all messages containing *term*, possibly after
+    stemming or phase splitting. For discussion of stemming in
+    notmuch see :any:`notmuch-search-terms(7)`. Stemming only applies
+    to unquoted terms (basic values) in s-expression queries.
 
 ``(`` *field* |q1| |q2| ... |qn| ``)``
     Restrict the queries |q1| to |qn| to *field*, and combine with *and*
@@ -76,6 +78,10 @@ EXAMPLES
 ``Wizard``
     Match all messages containing the word "wizard", ignoring case.
 
+``added``
+    Match all messages containing "added", but also those containing "add", "additional",
+    "Additional", "adds", etc... via stemming.
+
 .. |q1| replace:: :math:`q_1`
 .. |q2| replace:: :math:`q_2`
 .. |qn| replace:: :math:`q_n`
diff --git a/lib/parse-sexp.cc b/lib/parse-sexp.cc
index 1ce3c9d4..1be5e209 100644
--- a/lib/parse-sexp.cc
+++ b/lib/parse-sexp.cc
@@ -1,5 +1,4 @@
-#include <xapian.h>
-#include "notmuch-private.h"
+#include "database-private.h"
 #include "sexp.h"
 
 #if HAVE_SFSEXP
@@ -17,7 +16,12 @@ _sexp_to_xapian_query (notmuch_database_t *notmuch, const sexp_t *sx,
 {
 
     if (sx->ty == SEXP_VALUE) {
-	output = Xapian::Query (Xapian::Unicode::tolower (sx->val));
+	std::string term = Xapian::Unicode::tolower (sx->val);
+	Xapian::Stem stem = *(notmuch->stemmer);
+	if (sx->aty == SEXP_BASIC)
+	    term = "Z" + stem (term);
+
+	output = Xapian::Query (term);
 	return NOTMUCH_STATUS_SUCCESS;
     }
 
diff --git a/test/T081-sexpr-search.sh b/test/T081-sexpr-search.sh
index 3ee9f71d..c5c3cf6b 100755
--- a/test/T081-sexpr-search.sh
+++ b/test/T081-sexpr-search.sh
@@ -22,18 +22,21 @@ EOF
 test_expect_equal_file EXPECTED OUTPUT
 
 test_begin_subtest "single term in body (case insensitive)"
-notmuch search --query-syntax=sexp 'Wizard' | notmuch_search_sanitize>OUTPUT
+notmuch search --query-syntax=sexp '"Wizard"' | notmuch_search_sanitize>OUTPUT
 cat <<EOF > EXPECTED
 thread:XXX   2009-11-18 [1/3] Carl Worth| Jan Janak; [notmuch] What a great idea! (inbox unread)
 EOF
 test_expect_equal_file EXPECTED OUTPUT
 
 test_begin_subtest "single term in body, stemmed version"
-test_subtest_known_broken
 notmuch search arriv > EXPECTED
 notmuch search --query-syntax=sexp arriv > OUTPUT
 test_expect_equal_file EXPECTED OUTPUT
 
+test_begin_subtest "single term in body, unstemmed version"
+notmuch search --query-syntax=sexp '"arriv"' > OUTPUT
+test_expect_equal_file /dev/null OUTPUT
+
 test_begin_subtest "Unbalanced parens"
 # A code 1 indicates the error was handled (a crash will return e.g. 139).
 test_expect_code 1 "notmuch search --query-syntax=sexp '('"
-- 
2.30.2