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Diffstat (limited to 'src/data/composite/things/track/withAlbum.js')
-rw-r--r-- | src/data/composite/things/track/withAlbum.js | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/data/composite/things/track/withAlbum.js b/src/data/composite/things/track/withAlbum.js new file mode 100644 index 00000000..cbd16dcd --- /dev/null +++ b/src/data/composite/things/track/withAlbum.js @@ -0,0 +1,108 @@ +// Gets the track's album. This will early exit if albumData is missing. +// By default, if there's no album whose list of tracks includes this track, +// the output dependency will be null; set {notFoundMode: 'exit'} to early +// exit instead. +// +// This step models with Flash.withFlashAct. + +import {input, templateCompositeFrom} from '#composite'; +import {is} from '#validators'; + +import {exitWithoutDependency, withResultOfAvailabilityCheck} + from '#composite/control-flow'; +import {withPropertyFromList} from '#composite/data'; + +export default templateCompositeFrom({ + annotation: `withAlbum`, + + inputs: { + notFoundMode: input({ + validate: is('exit', 'null'), + defaultValue: 'null', + }), + }, + + outputs: ['#album'], + + steps: () => [ + // null albumData is always an early exit. + + exitWithoutDependency({ + dependency: 'albumData', + mode: input.value('null'), + }), + + // empty albumData conditionally exits early or outputs null. + + withResultOfAvailabilityCheck({ + from: 'albumData', + mode: input.value('empty'), + }).outputs({ + '#availability': '#albumDataAvailability', + }), + + { + dependencies: [input('notFoundMode'), '#albumDataAvailability'], + compute(continuation, { + [input('notFoundMode')]: notFoundMode, + ['#albumDataAvailability']: albumDataIsAvailable, + }) { + if (albumDataIsAvailable) return continuation(); + switch (notFoundMode) { + case 'exit': return continuation.exit(null); + case 'null': return continuation.raiseOutput({'#album': null}); + } + }, + }, + + withPropertyFromList({ + list: 'albumData', + property: input.value('tracks'), + }), + + { + dependencies: [input.myself(), '#albumData.tracks'], + compute: (continuation, { + [input.myself()]: track, + ['#albumData.tracks']: trackLists, + }) => continuation({ + ['#albumIndex']: + trackLists.findIndex(tracks => tracks.includes(track)), + }), + }, + + // album not found conditionally exits or outputs null. + + withResultOfAvailabilityCheck({ + from: '#albumIndex', + mode: input.value('index'), + }).outputs({ + '#availability': '#albumAvailability', + }), + + { + dependencies: [input('notFoundMode'), '#albumAvailability'], + compute(continuation, { + [input('notFoundMode')]: notFoundMode, + ['#albumAvailability']: albumIsAvailable, + }) { + if (albumIsAvailable) return continuation(); + switch (notFoundMode) { + case 'exit': return continuation.exit(null); + case 'null': return continuation.raiseOutput({'#album': null}); + } + }, + }, + + { + dependencies: ['albumData', '#albumIndex'], + compute: (continuation, { + ['albumData']: albumData, + ['#albumIndex']: albumIndex, + }) => continuation.raiseOutput({ + ['#album']: + albumData[albumIndex], + }), + }, + ], +}); |