From: Josef 'Jeff' Sipek <jeff.sipek@open-xchange.com>
Date: Mon, 4 Jan 2021 17:01:28 +0000 (-0500)
Subject: lib: event-filter - Make NOT operator right associative and higher precedence
X-Git-Tag: 2.3.14.rc1~92
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=abe9c7585d9f83622d9380596dde6ed0b5862388;p=thirdparty%2Fdovecot%2Fcore.git

lib: event-filter - Make NOT operator right associative and higher precedence

For example, consider the filter:

    event=* AND
    NOT event=foo AND
    NOT event=bar AND
    NOT event=baz

The "NOT" operator is supposed to be bound to the comparisons to the
immediate right.  That is, it supposed to be equivalent to:

    event=* AND
    (NOT event=foo) AND
    (NOT event=bar) AND
    (NOT event=baz)

Both of these should produce the following parse tree:

    AND
      AND
        AND
          EQ EVENT '*'
          NOT
            EQ EVENT 'foo'
        NOT
          EQ EVENT 'bar'
      NOT
        EQ EVENT 'baz'

Instead, before this commit, the NOTs were getting bound to the entire
sub-expression to the right.  Therefore, the original filter expression
was being parsed as if it were:

    event=* AND
    NOT (event=foo AND
         NOT (event=bar AND
              NOT event=baz))

Which produced the following parse tree:

    AND
      EQ EVENT '*'
      NOT
        AND
          EQ EVENT 'foo'
          NOT
            AND
              EQ EVENT 'bar'
              NOT
                EQ EVENT 'baz'
---

diff --git a/src/lib/event-filter-parser.y b/src/lib/event-filter-parser.y
index 3900b36395..a1e4347480 100644
--- a/src/lib/event-filter-parser.y
+++ b/src/lib/event-filter-parser.y
@@ -142,8 +142,8 @@ static struct event_filter_node *logic(struct event_filter_parser_state *state,
 %type <op> op
 %type <node> expr key_value
 
-%precedence NOT
 %left AND OR
+%right NOT
 
 %%
 filter : expr			{ state->output = $1; }