30 lines
917 B
JavaScript
30 lines
917 B
JavaScript
export default function(P = Promise) {
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return function(source, listeners) {
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let current;
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if (typeof source.getCurrentEvent === 'function') {
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current = source.getCurrentEvent();
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}
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if (current != null) {
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// immediately resolve if we have previous cached data
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return P.resolve(current.data).then(function(cached) {
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source.open();
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return cached;
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});
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}
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// if we have no previously cached data, listen for the first response
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return new P(function(resolve, reject) {
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// close, cleanup and reject if we get an error
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listeners.add(source, 'error', function(e) {
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listeners.remove();
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e.target.close();
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reject(e.error);
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});
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// ...or cleanup and respond with the first lot of data
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listeners.add(source, 'message', function(e) {
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listeners.remove();
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resolve(e.data);
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});
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});
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};
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}
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