X-Git-Url: https://git.phdru.name/?a=blobdiff_plain;f=parser%2Fgrammar;h=7c34096e3bdb10aaee6557185dcca6c60fb6d893;hb=fc9a4ef6e9dcde7e48ca54609ba7c9e80a1f20a7;hp=17d3098324c6117c5c509a4c27ece95030766876;hpb=2167fc0e09f4343c0fe67c8c754e29a41769e684;p=phdru.name%2Fcgi-bin%2Fblog-ru%2Fsearch-tags.git

diff --git a/parser/grammar b/parser/grammar
index 17d3098..7c34096 100644
--- a/parser/grammar
+++ b/parser/grammar
@@ -3,12 +3,15 @@
 # The grammar defines expressions in the following forms:
 #  TAG - search blog posts that contain the tag;
 #  !TAG - search blog posts that don't contain the tag;
-#  TAG && TAG, TAG & TAG - search blog posts that contain both tags;
+#  TAG & TAG - search blog posts that contain both tags;
 #  TAG | TAG - search blog posts that contain any of the tags;
-# Parentheses are allowed to group expressions:
+# Parentheses are allowed to group expressions; for example:
 #  TAG & (TAG | TAG)
 #  !(TAG | TAG)
-# and so on. This  is a simple version of the grammar and it allows
+# Allowed operators: conjunction - & &&
+#                    disjunction - | ||
+#                    negation    - !
+# This  is a simple version of the grammar and it allows
 # rather stupid expressions, like !!TAG or ((TAG)); in the future
 # it will be fixed by making the grammar more complex and stricter.
 
@@ -23,8 +26,13 @@ NOT_OP : '!'
 SP1 : '[ \t]+'
 
 expression : NAME
-           | expression AND_OP AND_OP expression
-           | expression AND_OP expression
-           | expression OR_OP expression
-           | NOT_OP expression
-           | '(' expression ')'
+           | expression SP0 AND_OP AND_OP SP0 expression
+           | expression SP0 AND_OP SP0 expression
+           | NOT_OP SP0 expression
+           | expression SP0 OR_OP OR_OP SP0 expression
+           | expression SP0 OR_OP SP0 expression
+           | '(' SP0 expression SP0 ')'
+
+SP0 : SP1 | empty
+
+empty :