Created
July 27, 2017 13:17
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task.run, unified approach
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| const co = require('bluebird').coroutine; | |
| let taskId = 0; | |
| class Task { | |
| constructor(values = {}) { | |
| const { id = `task${taskId++}`, files = [], globs = [], value } = values; | |
| this.id = id; | |
| this.files = files; | |
| this.globs = globs; | |
| this.value = value; | |
| this.result = Promise.resolve(this.state); | |
| this._index = 0; | |
| } | |
| get _() { return { files: this.files, globs: this.globs }; } | |
| get state() { return { id: this.id, files: this.files, globs: this.globs, value: this.value }; } | |
| run(fn, ...options) { | |
| const id = `${this.id}_${fn.name}${this._index++}`; | |
| // To avoid race issues with promise chain: | |
| // - `next` task/promise that is returned | |
| // - `context` task/promise that is passed to chain | |
| const next = new Task({ id }); | |
| const context = new Task({ id: `${id}c` }); | |
| next.result = this.result.then(async () => { | |
| context.files = this.files.slice(); | |
| context.globs = this.globs.slice(); | |
| context.value = this.value; | |
| let result = await co(fn)(context, ...options); | |
| // When returning original context, explicitly override | |
| // (strange transient behavior can result otherwise) | |
| if (result && result.id === context.id) { | |
| result = context; | |
| } | |
| if (result && result.files && result.globs) { | |
| next.files = result.files; | |
| next.globs = result.globs; | |
| next.value = undefined; | |
| } else { | |
| next.files = context.files; | |
| next.globs = context.globs; | |
| next.value = result; | |
| } | |
| return next.state; | |
| }); | |
| return next; | |
| } | |
| then(f, r) { return this.result.then(f, r); } | |
| catch(r) { return this.result.catch(r); } | |
| static get [Symbol.species || '@@species']() { return Promise; } | |
| } | |
| const plugins = { | |
| // ... | |
| }; | |
| for (let key in plugins) { | |
| Task.prototype[key] = function(...options) { | |
| return this.run(plugins[key], ...options); | |
| } | |
| } |
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