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Diffstat (limited to 'src/data/composite/wiki-data/withReverseContributionList.js')
-rw-r--r-- | src/data/composite/wiki-data/withReverseContributionList.js | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/src/data/composite/wiki-data/withReverseContributionList.js b/src/data/composite/wiki-data/withReverseContributionList.js new file mode 100644 index 0000000..eccb58b --- /dev/null +++ b/src/data/composite/wiki-data/withReverseContributionList.js @@ -0,0 +1,83 @@ +// Analogous implementation for withReverseReferenceList, for contributions. +// This is all duplicate code and both should be ported to the same underlying +// data form later on. +// +// This implementation uses a global cache (via WeakMap) to attempt to speed +// up subsequent similar accesses. +// +// This has absolutely not been rigorously tested with altering properties of +// data objects in a wiki data array which is reused. If a new wiki data array +// is used, a fresh cache will always be created. + +import {input, templateCompositeFrom} from '#composite'; + +import {exitWithoutDependency} from '#composite/control-flow'; + +import inputWikiData from './inputWikiData.js'; + +// Mapping of reference list property to WeakMap. +// Each WeakMap maps a wiki data array to another weak map, +// which in turn maps each referenced thing to an array of +// things referencing it. +const caches = new Map(); + +export default templateCompositeFrom({ + annotation: `withReverseContributionList`, + + inputs: { + data: inputWikiData({allowMixedTypes: false}), + list: input({type: 'string'}), + }, + + outputs: ['#reverseContributionList'], + + steps: () => [ + exitWithoutDependency({ + dependency: input('data'), + value: input.value([]), + mode: input.value('empty'), + }), + + { + dependencies: [input.myself(), input('data'), input('list')], + + compute: (continuation, { + [input.myself()]: myself, + [input('data')]: data, + [input('list')]: list, + }) => { + if (!caches.has(list)) { + caches.set(list, new WeakMap()); + } + + const cache = caches.get(list); + + if (!cache.has(data)) { + const cacheRecord = new WeakMap(); + + for (const referencingThing of data) { + const referenceList = referencingThing[list]; + + // Destructuring {who} is the only unique part of the + // withReverseContributionList implementation, compared to + // withReverseReferneceList. + for (const {who: referencedThing} of referenceList) { + if (cacheRecord.has(referencedThing)) { + cacheRecord.get(referencedThing).push(referencingThing); + } else { + cacheRecord.set(referencedThing, [referencingThing]); + } + } + } + + cache.set(data, cacheRecord); + } + + return continuation({ + ['#reverseContributionList']: + cache.get(data).get(myself) ?? [], + }); + }, + }, + ], +}); |