// response. loadFunc() must retrieve results in "modified_at desc"
// order.
//
-// done is true if there are no more pages to load.
-//
-// loading is true if a network request is in progress.
+// state is:
+// * 'loading' if a network request is in progress;
+// * 'done' if there are no more items to load;
+// * 'ready' otherwise.
//
// items is a stream that resolves to an array of all items retrieved so far.
//
// loadMore() loads the next page, if any.
-window.models = window.models || {}
-window.models.MultipageLoader = function(config) {
+window.MultipageLoader = function(config) {
var loader = this
Object.assign(loader, config, {
- done: false,
- loading: false,
- items: m.stream(),
+ state: 'ready',
+ DONE: 'done',
+ LOADING: 'loading',
+ READY: 'ready',
+
+ items: m.stream([]),
thresholdItem: null,
loadMore: function() {
- if (loader.done || loader.loading)
+ if (loader.state == loader.DONE || loader.state == loader.LOADING)
return
var filters = loader.thresholdItem ? [
["modified_at", "<=", loader.thresholdItem.modified_at],
["uuid", "!=", loader.thresholdItem.uuid],
] : []
- loader.loading = true
+ loader.state = loader.LOADING
loader.loadFunc(filters).then(function(resp) {
- var items = loader.items() || []
+ var items = loader.items()
Array.prototype.push.apply(items, resp.items)
- if (resp.items.length == 0)
- loader.done = true
- else
+ if (resp.items.length == 0) {
+ loader.state = loader.DONE
+ } else {
loader.thresholdItem = resp.items[resp.items.length-1]
- loader.loading = false
+ loader.state = loader.READY
+ }
loader.items(items)
}).catch(function(err) {
loader.err = err
- loader.loading = false
+ loader.state = loader.READY
})
},
})
// new MergingLoader({children: [loader, loader, ...]})
//
// The children must retrieve results in "modified_at desc" order.
-window.models = window.models || {}
-window.models.MergingLoader = function(config) {
+window.MergingLoader = function(config) {
var loader = this
Object.assign(loader, config, {
// Sorted items ready to display, merged from all children.
- items: m.stream(),
- done: false,
- loading: false,
+ items: m.stream([]),
+ state: 'ready',
+ DONE: 'done',
+ LOADING: 'loading',
+ READY: 'ready',
loadable: function() {
// Return an array of children that we could call
- // loadMore() on. Update loader.done and loader.loading.
- loader.done = true
- loader.loading = false
+ // loadMore() on. Update loader.state.
+ loader.state = loader.DONE
return loader.children.filter(function(child) {
- if (child.done)
+ if (child.state == child.DONE)
+ return false
+ if (child.state == child.LOADING) {
+ loader.state = loader.LOADING
return false
- loader.done = false
- if (!child.loading)
- return true
- loader.loading = true
- return false
+ }
+ if (loader.state == loader.DONE)
+ loader.state = loader.READY
+ return true
})
},
loadMore: function() {
// lowWaterMark.
loader.loadable().map(function(child) {
if (child.items().length - child.itemsDisplayed < loader.lowWaterMark) {
- loader.loading = true
+ loader.state = loader.LOADING
child.loadMore()
}
})
},
mergeItems: function() {
- // cutoff is the topmost (recent) of {bottom (oldest) entry of
- // any child that still has more pages left to fetch}
+ // We want to avoid moving items around on the screen once
+ // they're displayed.
+ //
+ // To this end, here we find the last safely displayable
+ // item ("cutoff") by getting the last item from each
+ // unfinished child, and taking the topmost (most recent)
+ // one of those.
+ //
+ // (If we were to display an item below that cutoff, the
+ // next page of results from an unfinished child could
+ // include items that get inserted above the cutoff,
+ // causing the cutoff item to move down.)
var cutoff
+ var cutoffUnknown = false
loader.children.forEach(function(child) {
+ if (child.state == child.DONE)
+ return
var items = child.items()
- if (items.length == 0 || child.done)
+ if (items.length == 0) {
+ // No idea what's coming in the next page.
+ cutoffUnknown = true
return
+ }
var last = items[items.length-1].modified_at
if (!cutoff || cutoff < last)
cutoff = last
})
+ if (cutoffUnknown)
+ return
var combined = []
loader.children.forEach(function(child) {
child.itemsDisplayed = 0
child.items().every(function(item) {
if (cutoff && item.modified_at < cutoff)
- // Some other children haven't caught up to this
- // point, so don't display this item or anything
- // after it.
+ // Don't display this item or anything after
+ // it (see "cutoff" comment above).
return false
combined.push(item)
child.itemsDisplayed++
projects / arvados.git / blobdiff