lib: regexp matching in 'subject' and 'from'

[notmuch] / lib / regexp-fields.cc

diff --git a/lib/regexp-fields.cc b/lib/regexp-fields.cc
new file mode 100644 (file)
index 0000000..9873af8
--- /dev/null
+++ b/lib/regexp-fields.cc
@@ -0,0 +1,149 @@
+/* regexp-fields.cc - field processor glue for regex supporting fields
+ *
+ * This file is part of notmuch.
+ *
+ * Copyright © 2015 Austin Clements
+ * Copyright © 2016 David Bremner
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/ .
+ *
+ * Author: Austin Clements <aclements@csail.mit.edu>
+ *                David Bremner <david@tethera.net>
+ */
+
+#include "regexp-fields.h"
+#include "notmuch-private.h"
+#include "database-private.h"
+
+#if HAVE_XAPIAN_FIELD_PROCESSOR
+static void
+compile_regex (regex_t &regexp, const char *str)
+{
+    int err = regcomp (&regexp, str, REG_EXTENDED | REG_NOSUB);
+
+    if (err != 0) {
+       size_t len = regerror (err, &regexp, NULL, 0);
+       char *buffer = new char[len];
+       std::string msg;
+       (void) regerror (err, &regexp, buffer, len);
+       msg.assign (buffer, len);
+       delete buffer;
+
+       throw Xapian::QueryParserError (msg);
+    }
+}
+
+RegexpPostingSource::RegexpPostingSource (Xapian::valueno slot, const std::string &regexp)
+    : slot_ (slot)
+{
+    compile_regex (regexp_, regexp.c_str ());
+}
+
+RegexpPostingSource::~RegexpPostingSource ()
+{
+    regfree (&regexp_);
+}
+
+void
+RegexpPostingSource::init (const Xapian::Database &db)
+{
+    db_ = db;
+    it_ = db_.valuestream_begin (slot_);
+    end_ = db.valuestream_end (slot_);
+    started_ = false;
+
+    /* make sure we start on a matching value */
+    while (!at_end() && regexec (&regexp_, (*it_).c_str (), 0, NULL, 0) != 0) {
+       ++it_;
+    }
+}
+
+Xapian::doccount
+RegexpPostingSource::get_termfreq_min () const
+{
+    return 0;
+}
+
+Xapian::doccount
+RegexpPostingSource::get_termfreq_est () const
+{
+    return get_termfreq_max () / 2;
+}
+
+Xapian::doccount
+RegexpPostingSource::get_termfreq_max () const
+{
+    return db_.get_value_freq (slot_);
+}
+
+Xapian::docid
+RegexpPostingSource::get_docid () const
+{
+    return it_.get_docid ();
+}
+
+bool
+RegexpPostingSource::at_end () const
+{
+    return it_ == end_;
+}
+
+void
+RegexpPostingSource::next (unused (double min_wt))
+{
+    if (started_ && ! at_end ())
+       ++it_;
+    started_ = true;
+
+    for (; ! at_end (); ++it_) {
+       std::string value = *it_;
+       if (regexec (&regexp_, value.c_str (), 0, NULL, 0) == 0)
+           break;
+    }
+}
+
+static inline Xapian::valueno _find_slot (std::string prefix)
+{
+    if (prefix == "from")
+       return NOTMUCH_VALUE_FROM;
+    else if (prefix == "subject")
+       return NOTMUCH_VALUE_SUBJECT;
+    else
+       throw Xapian::QueryParserError ("unsupported regexp field '" + prefix + "'");
+}
+
+RegexpFieldProcessor::RegexpFieldProcessor (std::string prefix, Xapian::QueryParser &parser_, notmuch_database_t *notmuch_)
+       : slot (_find_slot (prefix)), term_prefix (_find_prefix (prefix.c_str ())),
+         parser (parser_), notmuch (notmuch_)
+{
+};
+
+Xapian::Query
+RegexpFieldProcessor::operator() (const std::string & str)
+{
+    if (str.at (0) == '/') {
+       if (str.at (str.size () - 1) == '/'){
+           RegexpPostingSource *postings = new RegexpPostingSource (slot, str.substr(1,str.size () - 2));
+           return Xapian::Query (postings->release ());
+       } else {
+           throw Xapian::QueryParserError ("unmatched regex delimiter in '" + str + "'");
+       }
+    } else {
+       /* TODO replace this with a nicer API level triggering of
+        * phrase parsing, when possible */
+       std::string quoted='"' + str + '"';
+       return parser.parse_query (quoted, NOTMUCH_QUERY_PARSER_FLAGS, term_prefix);
+    }
+}
+#endif