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authorMax Kellermann <max@musicpd.org>2019-03-16 13:21:22 +0100
committerMax Kellermann <max@musicpd.org>2019-03-16 13:23:44 +0100
commita4b8a0d801ab86a1798402942b566657ab2ccdeb (patch)
tree87e5dd0317ce6956956ac38a61858f715c22f1d8 /doc/protocol.rst
parent3bf521d5caadb395bd26e0df82d8d8d3de78b599 (diff)
doc/protocol.rst: clarify filter expressions with multiple tag values
Clarification for https://github.com/MusicPlayerDaemon/MPD/issues/505
Diffstat (limited to 'doc/protocol.rst')
-rw-r--r--doc/protocol.rst9
1 files changed, 7 insertions, 2 deletions
diff --git a/doc/protocol.rst b/doc/protocol.rst
index cc23c14aa..bbe1a655b 100644
--- a/doc/protocol.rst
+++ b/doc/protocol.rst
@@ -144,8 +144,10 @@ syntax::
``EXPRESSION`` is a string enclosed in parantheses which can be one
of:
-- ``(TAG == 'VALUE')``: match a tag value.
- ``(TAG != 'VALUE')``: mismatch a tag value.
+- ``(TAG == 'VALUE')``: match a tag value; if there are multiple
+ values of the given type, at least one must match.
+ ``(TAG != 'VALUE')``: mismatch a tag value; if there are multiple
+ values of the given type, none of them must match.
The special tag ``any`` checks all
tag types.
``AlbumArtist`` looks for
@@ -153,6 +155,9 @@ of:
and falls back to ``Artist`` tags if
``AlbumArtist`` does not exist.
``VALUE`` is what to find.
+ An empty value string means: match only if the given tag type does
+ not exist at all; this implies that negation with an empty value
+ checks for the existence of the given tag type.
- ``(TAG contains 'VALUE')`` checks if the given value is a substring
of the tag value.