Query modes

[kirillt]

The app uses "tags selector" to specify tags, i.e. it outputs some set of tags.
But there are multiple ways to interpret a selection into subset of resources.
Of the following 1, 2 and 5 seem to be most natural and modes 3, 4 might be useful sometimes.

1. Normal mode (intersection)

   Every resource which is marked with all of specified tags is displayed.
   I.e. resources which contain extra tags are also displayed.

2. Focus mode

   This mode is stricter: only those resources which are marked with all
   of specified tags and none of non-specified tags are displayed.
   I.e. resources which contain extra tags are filtered-out.

3. Extra mode

   This mode is derived from 1 and 2: we apply Normal mode
   and filter-out all resources from Focus mode.
   I.e. resources which are marked with all of specified tags
   and at least one of non-specified tags are displayed.
   We can also, on the opposite, define Focus mode via Extra mode.

4. Inversion mode

   This mode is inverted Normal mode: we take the whole
   collection and filter resources which are marked with all of specified tags out.
   I.e. we display only those resources which are not marked with any of specified tags.

5. Union mode

   We display all resources marked with at least one of specified tags.

To illustrate these modes, let's take some collection of resources:

• Resource 1 is marked with tag a
• Resource 2 is marked with tag b
• Resource 3 is marked with tag c
• Resource 4 is marked with tags a, b
• Resource 5 is marked with tags b, c
• Resource 6 is marked with tags a, c
• Resource 7 is marked with tags a, b, c
• Resource 8 isn't marked with any tag

Examples of queries on this collection:

1. Empty query (beginning of user's interaction)

   Normal mode outputs 1, 2, 3, 4, 5, 6, 7, 8
   Focus mode outputs 8
   Extra mode outputs 1, 2, 3, 4, 5, 6, 7
   Inversion mode outputs nothing
   Union mode outputs nothing

2. Single tag query, e.g. {a}

   Normal mode outputs 1, 4, 6, 7
   Focus mode outputs 1
   Extra mode outputs 4, 6, 7
   Inversion mode outputs 2, 3, 5, 8
   Union mode outputs 1, 4, 6, 7

3. Two tags query, e.g. {a, b}

   Normal mode outputs 4, 7
   Focus mode outputs 4
   Extra mode outputs 7
   Inversion mode outputs 1, 2, 3, 5, 6, 8
   Union mode outputs 1, 2, 4, 5, 6, 7

4. Three tags query, e.g. {a, b, c}

   Normal mode outputs 7
   Focus mode outputs 7
   Extra mode outputs nothing
   Inversion mode outputs 1, 2, 3, 4, 5, 6, 8
   Union mode outputs 1, 2, 3, 4, 5, 6, 7

[kirillt]

Right now, Normal mode is implemented and used for non-empty queries.
For empty query, actually, Focus/Extra modes are used (switching by "tags on/off" button).

It's better to replace "tags on/off" button with "switch modes" button which would cycle available query modes.

[kirillt]

It is necessary to think through how query modes should handle inverted tags as well.