imap: *SEARCH: use Parse::RecDescent

For properly parsing IMAP search requests, it's easier to use a
recursive descent parser generator to deal with subqueries and
the "OR" statement.

Parse::RecDescent was chosen since it's mature, well-known,
widely available and already used by our optional dependencies:
Inline::C and Mail::IMAPClient.  While it's possible to build
Xapian queries without using the Xapian string query parser;
this iteration of the IMAP parser still builds a string which is
passed to Xapian's query parser for ease-of-diagnostics.

Since this is a recursive descent parser dealing with untrusted
inputs, subqueries have a nesting limit of 10.  I expect that is
more than adequate for real-world use.

1 files changed, 2 insertions, 1 deletions

diff --git a/xt/mem-imapd-tls.t b/xt/mem-imapd-tls.t
index 648a0ad3..97e67d30 100644
--- a/xt/mem-imapd-tls.t
+++ b/xt/mem-imapd-tls.t
@@ -9,7 +9,8 @@ use Socket qw(SOCK_STREAM IPPROTO_TCP SOL_SOCKET);
 use PublicInbox::TestCommon;
 use PublicInbox::Syscall qw(:epoll);
 use PublicInbox::DS;
-require_mods(qw(DBD::SQLite Email::Address::XS||Mail::Address));
+require_mods(qw(DBD::SQLite Email::Address::XS||Mail::Address
+        Parse::RecDescent));
 my $inboxdir = $ENV{GIANT_INBOX_DIR};
 my $TEST_TLS;
 SKIP: {