This patch adds `Collection.count_search_results()` method which
counts results from a search.

It's much faster than count `get_all_search_results()`, as we avoid
to create Entry instances for every results.

On a collection with 264 items, doing a search for '+', counting
all results with

    len(list(collection.get_all_search_results()))

takes ~930 ms on my system, while

    collection.count_search_results()

takes ~1.5 ms


---
 lesana/collection.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lesana/collection.py b/lesana/collection.py
index a3c6e22..00be506 100644
--- a/lesana/collection.py
+++ b/lesana/collection.py
@@ -414,6 +414,20 @@ class Collection(object):
             for match in mset:
                 yield self._match_to_entry(match)
             offset += pagesize
+            
+    def count_search_results(self):
+        if not self._enquire:
+            return
+        count = 0
+        offset = 0
+        pagesize = 100
+        while True:
+            mset = self._enquire.get_mset(offset, pagesize)
+            if mset.size() == 0:
+                break
+            count += mset.size()
+            offset += pagesize
+        return count
 
     def get_all_documents(self):
         """
-- 
2.36.0