42 lines
1.1 KiB
JavaScript
42 lines
1.1 KiB
JavaScript
const jsonDiffer = require('fast-json-patch')
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const clone = require('clone')
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module.exports = {
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generateHistoryEntry,
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replayHistory,
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snapshotFromTxMeta,
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migrateFromSnapshotsToDiffs,
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}
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function migrateFromSnapshotsToDiffs (longHistory) {
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return (
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longHistory
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// convert non-initial history entries into diffs
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.map((entry, index) => {
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if (index === 0) return entry
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return generateHistoryEntry(longHistory[index - 1], entry)
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})
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)
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}
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function generateHistoryEntry (previousState, newState, note) {
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const entry = jsonDiffer.compare(previousState, newState)
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// Add a note to the first op, since it breaks if we append it to the entry
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if (note && entry[0]) entry[0].note = note
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return entry
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}
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function replayHistory (_shortHistory) {
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const shortHistory = clone(_shortHistory)
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return shortHistory.reduce((val, entry) => jsonDiffer.applyPatch(val, entry).newDocument)
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}
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function snapshotFromTxMeta (txMeta) {
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// create txMeta snapshot for history
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const snapshot = clone(txMeta)
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// dont include previous history in this snapshot
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delete snapshot.history
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return snapshot
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}
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