X-Git-Url: http://nitlanguage.org

diff --git a/lib/vsm/vsm.nit b/lib/vsm/vsm.nit
index d589e89..e7ebc2e 100644
--- a/lib/vsm/vsm.nit
+++ b/lib/vsm/vsm.nit
@@ -77,6 +77,17 @@ class Vector
 		return super
 	end
 
+	# Increment value for `obj` term
+	#
+	# If the term isn't already in the vector, the new value is 1.0.
+	fun inc(obj: nullable Object) do
+		if has_key(obj) then
+			self[obj] += 1.0
+		else
+			self[obj] = 1.0
+		end
+	end
+
 	# The norm of the vector.
 	#
 	# `||x|| = (x1 ** 2 ... + xn ** 2).sqrt`
@@ -120,6 +131,11 @@ class VSMIndex
 	# Documents index
 	var documents = new HashSet[DOC]
 
+	# Inversed index
+	#
+	# Link documents to existing terms.
+	var inversed_index = new HashMap[nullable Object, Array[DOC]]
+
 	# Count for all terms in all indexed documents
 	#
 	# Used to compute the `inverse_doc_frequency`.
@@ -141,6 +157,12 @@ class VSMIndex
 	# Returns an `IndexMatch` for each indexed document.
 	# Results are ordered by descending similarity.
 	fun match_vector(query: Vector): Array[IndexMatch[DOC]] do
+		var documents = new HashSet[DOC]
+		for term, count in query do
+			if inversed_index.has_key(term) then
+				documents.add_all inversed_index[term]
+			end
+		end
 		var matches = new Array[IndexMatch[DOC]]
 		for doc in documents do
 			var sim = query.cosine_similarity(doc.tfidf)
@@ -161,11 +183,11 @@ class VSMIndex
 	# the auto update of the index.
 	fun index_document(doc: DOC, auto_update: nullable Bool) do
 		for term, count in doc.terms_count do
-			if not terms_doc_count.has_key(term) then
-				terms_doc_count[term] = 1.0
-			else
-				terms_doc_count[term] += 1.0
+			terms_doc_count.inc(term)
+			if not inversed_index.has_key(term) then
+				inversed_index[term] = new Array[DOC]
 			end
+			inversed_index[term].add doc
 		end
 		documents.add doc
 		if auto_update == null or auto_update then update_index
@@ -224,12 +246,7 @@ class StringIndex
 		loop
 			var token = reader.read_word
 			if token == "" then break
-
-			if not vector.has_key(token) then
-				vector[token] = 1.0
-			else
-				vector[token] += 1.0
-			end
+			vector.inc(token)
 		end
 		return vector
 	end