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Adds the "eval" function to Promise (see http://www.bluejava.com/4PQ for details)
Promise.eval = function(ar)
{
// We accept either an array or items specified as individual arguments...
// ...but we convert the series into an array either way
if(!Array.isArray(ar))
ar = Array.prototype.slice.call(arguments)
var items = { } // map names to items
// This forEach is where it all happens - we evaluate each item within the eval array.
// If there are dependencies, those are first resolved.
// Its the mother of all promise workflows is just 10 lines!
ar.forEach(function(zex, i) {
items[zex.name || ("_p" + i)] =
Promise.all((zex.deps || []).map(function(arg) {
// even if items[arg] is undefined, using "arg in items" is true when the property exists
if(typeof arg === "string" && arg in items)
return items[arg]
else
return arg
}))
.then(function(dResults) {
var value = zex.value
if(typeof value === "function")
value = value.apply(null, dResults)
return value
})
})
// Now we just wait for each promise to complete - then assign the resolved value to its named property
var names = Object.keys(items),
itemVals = names.map(function(name) { return items[name] }) // Object.values()
return Promise.all(itemVals)
.then(function(paResults) {
var results = { }
names.forEach(function(name, i) {
results[name] = paResults[i]
})
return results
})
}
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