Commit b70e39416e0ec7a808742b9841a6cd32d45b3354
Add new backlinks filter obs function. This is a helper function to watch for links back to a message and add them to an observable list if they pass a given filter.
Gordon Martin committed on 11/26/2017, 8:17:54 PMParent: ba518865234ed63cae50900c6ee8404aa6686cfa
Files changed
| backlinks/obs_filter.js | added |
| backlinks/obs_filter.js | ||
|---|---|---|
| @@ -1,0 +1,80 @@ | ||
| 1 … | +var nest = require('depnest') | |
| 2 … | +var pull = require('pull-stream') | |
| 3 … | +var MutantPullReduce = require('mutant-pull-reduce') | |
| 4 … | +var Value = require('mutant/value') | |
| 5 … | + | |
| 6 … | +exports.needs = nest({ | |
| 7 … | + 'sbot.pull.backlinks': 'first' | |
| 8 … | +}) | |
| 9 … | + | |
| 10 … | +exports.gives = nest("backlinks.filter.obs", true) | |
| 11 … | + | |
| 12 … | +/** | |
| 13 … | + * sbot.filter.obs returns an observable list of messages that link | |
| 14 … | + * back to the message with the given message ID (@id). Only messages that | |
| 15 … | + * pass the filter function are added to the list. | |
| 16 … | + * | |
| 17 … | + * When a message arrives, if passing it to the filter function (@filterFn) | |
| 18 … | + * does not result in it returning 'true' the message is not added to the | |
| 19 … | + * observable list. | |
| 20 … | + * | |
| 21 … | + * A 'sync' observable property is also added to the returned observable | |
| 22 … | + * which is 'true' when all previously seen messages are caught up with. | |
| 23 … | + * | |
| 24 … | + * Note: Unlike backlinks.obs.for this does not cache the observable for | |
| 25 … | + * callers that supply the same arguments. | |
| 26 … | + */ | |
| 27 … | +exports.create = function(api) { | |
| 28 … | + function pullFilterReduceObs(id, filterFn) { | |
| 29 … | + if (!id || typeof(id) !== "string") { | |
| 30 … | + throw new Error("id must be a string.") | |
| 31 … | + } | |
| 32 … | + | |
| 33 … | + if (!filterFn || typeof(filterFn) !== "function") { | |
| 34 … | + throw new Error("filterFn must be a function.") | |
| 35 … | + } | |
| 36 … | + | |
| 37 … | + var sync = Value(false) | |
| 38 … | + | |
| 39 … | + var msgBacklinks = api.sbot.pull.backlinks({ | |
| 40 … | + query: [{ | |
| 41 … | + $filter: { | |
| 42 … | + dest: id | |
| 43 … | + } | |
| 44 … | + }], | |
| 45 … | + live: true | |
| 46 … | + }) | |
| 47 … | + | |
| 48 … | + var filteredBacklinks = pull( | |
| 49 … | + msgBacklinks, | |
| 50 … | + pull( | |
| 51 … | + pull.map(setSyncIfSyncMsg.bind(null, sync), | |
| 52 … | + pull.filter(filterFn) | |
| 53 … | + )) | |
| 54 … | + ) | |
| 55 … | + | |
| 56 … | + var backlinksObs = MutantPullReduce(filteredBacklinks, (state, msg) => { | |
| 57 … | + state.push(msg) | |
| 58 … | + return state; | |
| 59 … | + }, { | |
| 60 … | + startValue: [], | |
| 61 … | + nextTick: true | |
| 62 … | + }) | |
| 63 … | + | |
| 64 … | + backlinksObs.sync = sync | |
| 65 … | + | |
| 66 … | + return backlinksObs; | |
| 67 … | + } | |
| 68 … | + | |
| 69 … | + return nest({ | |
| 70 … | + "backlinks.filter.obs": (id, filterFn) => pullFilterReduceObs(id, filterFn) | |
| 71 … | + }) | |
| 72 … | +} | |
| 73 … | + | |
| 74 … | +function setSyncIfSyncMsg(syncObs, msg) { | |
| 75 … | + if (msg.sync) { | |
| 76 … | + syncObs.set(true) | |
| 77 … | + } | |
| 78 … | + | |
| 79 … | + return msg | |
| 80 … | +} | |
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