Module query

A query language over the catalog and over what the user wrote about it.

Options compose by AND and by nothing else. That is the ceiling no number of new flags ever raises: there is no --genre metal OR --genre jazz, no “everything except this label”, no “between 1990 and 1999”. A grammar has all three for free, and having one is what turns a saved query into a smart collection — which, since a selection is already what --csv, --m3u and M3’s queue consume, is playable the day it is written.

genre:metal year:1990..1999 rating:>=4 -label:earache
(artist:ozzy OR artist:dio) loved
album.rating:5 played:0
work:"War Pigs" instrument:guitar
guest:"Zakk Wylde" with:"Ozzy Osbourne"

It is an interface, not a storage engine. Defined on its own it works today over the vectors in memory and tomorrow over SQL. Defined as “whatever the database makes easy” it would arrive late and shaped by the wrong concerns.

Everything evaluates against a track, because a track is the finest grain and every coarser answer is a fold of it: the albums matching a query are the albums of the tracks matching it. One evaluator, not five.

Modules

browse

Versioned dynamic browsing collections; audio and catalog identities remain unchanged.

Structs

Context

Everything needed to answer, gathered once rather than per track.

QueryError

Why a query could not be read.

Sort

How a result is ordered.

Term

One condition: a field, and what it is being asked.

Enums

Compare

How two numbers are compared.

Field

Which value of a track a term reads.

Query

A parsed query, ready to be run against any catalog.

Scope

Which entity an opinion was written on.

SortKey

What a result can be ordered on.

Test

What a term asks of a value.

Functions

asks_about_the_track_itself

true when the expression asks about something the user wrote, at the track’s own scope — the case where rescoped has anything to offer.

field_names

The field names, for a help message or a completion.

matches

Whether one track satisfies a query.

parse

Reads a query, rejecting incomplete operators and invalid numeric bounds.

rescoped

The same question, asked of the album or the artist instead of the track.

run

The tracks a query matches, in catalog order.

sort

Puts a result in order.

sort_key_names

The sort keys, for a help message.

unknown_values

Values a query names that the library has never heard of.