doc/protocol.rst: clarify filter expressions with multiple tag values

Clarification for https://github.com/MusicPlayerDaemon/MPD/issues/505
This commit is contained in:
Max Kellermann 2019-03-16 13:21:22 +01:00
parent 3bf521d5ca
commit a4b8a0d801
1 changed files with 7 additions and 2 deletions

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@ -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.