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New hooks API (replaces monkey-patching for currency) (#1683)
* added hook module to prebid core that allows extension of arbitrary functions * remove unused dependency tiny-queue * change PluginFunction to HookedFunction * more hook documentation fixes * allow context for hooked functions * added tests for context * remove withContext, just use bind * fix in hooks so asyncSeries keeps proper bound context
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,78 @@ | ||
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| /** | ||
| * @typedef {function} HookedFunction | ||
| * @property {function(function(), [number])} addHook A method that takes a new function to attach as a hook | ||
| * to the HookedFunction | ||
| * @property {function(function())} removeHook A method to remove attached hooks | ||
| */ | ||
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| /** | ||
| * A map of global hook methods to allow easy extension of hooked functions that are intended to be extended globally | ||
| * @type {{}} | ||
| */ | ||
| export const hooks = {}; | ||
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| /** | ||
| * A utility function for allowing a regular function to be extensible with additional hook functions | ||
| * @param {string} type The method for applying all attached hooks when this hooked function is called | ||
| * @param {function()} fn The function to make hookable | ||
| * @param {string} hookName If provided this allows you to register a name for a global hook to have easy access to | ||
| * the addHook and removeHook methods for that hook (which are usually accessed as methods on the function itself) | ||
| * @returns {HookedFunction} A new function that implements the HookedFunction interface | ||
| */ | ||
| export function createHook(type, fn, hookName) { | ||
| let _hooks = [{fn, priority: 0}]; | ||
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| let types = { | ||
| sync: function(...args) { | ||
| _hooks.forEach(hook => { | ||
| hook.fn.apply(this, args); | ||
| }); | ||
| }, | ||
| asyncSeries: function(...args) { | ||
| let curr = 0; | ||
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| const asyncSeriesNext = (...args) => { | ||
| let hook = _hooks[++curr]; | ||
| if (typeof hook === 'object' && typeof hook.fn === 'function') { | ||
| return hook.fn.apply(this, args.concat(asyncSeriesNext)) | ||
| } | ||
| }; | ||
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| return _hooks[curr].fn.apply(this, args.concat(asyncSeriesNext)); | ||
| } | ||
| }; | ||
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| if (!types[type]) { | ||
| throw 'invalid hook type'; | ||
| } | ||
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| let methods = { | ||
| addHook: function(fn, priority = 10) { | ||
| if (typeof fn === 'function') { | ||
| _hooks.push({ | ||
| fn, | ||
| priority: priority | ||
| }); | ||
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| _hooks.sort((a, b) => b.priority - a.priority); | ||
| } | ||
| }, | ||
| removeHook: function(removeFn) { | ||
| _hooks = _hooks.filter(hook => hook.fn === fn || hook.fn !== removeFn); | ||
| } | ||
| }; | ||
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| if (typeof hookName === 'string') { | ||
| hooks[hookName] = methods; | ||
| } | ||
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| function hookedFn(...args) { | ||
| if (_hooks.length === 0) { | ||
| return fn.apply(this, args); | ||
| } | ||
| return types[type].apply(this, args); | ||
| } | ||
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| return Object.assign(hookedFn, methods); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,151 @@ | ||
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| import { expect } from 'chai'; | ||
| import { createHook, hooks } from 'src/hook'; | ||
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| describe('the hook module', () => { | ||
| let sandbox; | ||
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| beforeEach(() => { | ||
| sandbox = sinon.sandbox.create(); | ||
| }); | ||
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| afterEach(() => { | ||
| sandbox.restore(); | ||
| }); | ||
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| it('should call all sync hooks attached to a function', () => { | ||
| let called = []; | ||
| let calledWith; | ||
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| let testFn = () => { | ||
| called.push(testFn); | ||
| }; | ||
| let testHook = (...args) => { | ||
| called.push(testHook); | ||
| calledWith = args; | ||
| }; | ||
| let testHook2 = () => { | ||
| called.push(testHook2); | ||
| }; | ||
| let testHook3 = () => { | ||
| called.push(testHook3); | ||
| }; | ||
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| let hookedTestFn = createHook('sync', testFn, 'testHook'); | ||
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| hookedTestFn.addHook(testHook, 50); | ||
| hookedTestFn.addHook(testHook2, 100); | ||
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| // make sure global test hooks work as well (with default priority) | ||
| hooks['testHook'].addHook(testHook3); | ||
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| hookedTestFn(1, 2, 3); | ||
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| expect(called).to.deep.equal([ | ||
| testHook2, | ||
| testHook, | ||
| testHook3, | ||
| testFn | ||
| ]); | ||
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| expect(calledWith).to.deep.equal([1, 2, 3]); | ||
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| called = []; | ||
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| hookedTestFn.removeHook(testHook); | ||
| hooks['testHook'].removeHook(testHook3); | ||
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| hookedTestFn(1, 2, 3); | ||
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| expect(called).to.deep.equal([ | ||
| testHook2, | ||
| testFn | ||
| ]); | ||
| }); | ||
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| it('should allow context to be passed to hooks, but keep bound contexts', () => { | ||
| let context; | ||
| let fn = function() { | ||
| context = this; | ||
| }; | ||
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| let boundContext = {}; | ||
| let calledBoundContext; | ||
| let hook = function() { | ||
| calledBoundContext = this; | ||
| }.bind(boundContext); | ||
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| let hookFn = createHook('sync', fn); | ||
| hookFn.addHook(hook); | ||
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| let newContext = {}; | ||
| hookFn.bind(newContext)(); | ||
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| expect(context).to.equal(newContext); | ||
| expect(calledBoundContext).to.equal(boundContext); | ||
| }); | ||
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| describe('asyncSeries', () => { | ||
| it('should call function as normal if no hooks attached', () => { | ||
| let fn = sandbox.spy(); | ||
| let hookFn = createHook('asyncSeries', fn); | ||
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| hookFn(1); | ||
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| expect(fn.calledOnce).to.equal(true); | ||
| expect(fn.firstCall.args[0]).to.equal(1); | ||
| }); | ||
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| it('should call hooks correctly applied in asyncSeries', () => { | ||
| let called = []; | ||
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| let testFn = (called) => { | ||
| called.push(testFn); | ||
| }; | ||
| let testHook = (called, next) => { | ||
| called.push(testHook); | ||
| next(called); | ||
| }; | ||
| let testHook2 = (called, next) => { | ||
| called.push(testHook2); | ||
| next(called); | ||
| }; | ||
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| let hookedTestFn = createHook('asyncSeries', testFn); | ||
| hookedTestFn.addHook(testHook); | ||
| hookedTestFn.addHook(testHook2); | ||
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| hookedTestFn(called); | ||
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| expect(called).to.deep.equal([ | ||
| testHook, | ||
| testHook2, | ||
| testFn | ||
| ]); | ||
| }); | ||
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| it('should allow context to be passed to hooks, but keep bound contexts', () => { | ||
| let context; | ||
| let fn = function() { | ||
| context = this; | ||
| }; | ||
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| let boundContext1 = {}; | ||
| let calledBoundContext1; | ||
| let hook1 = function(next) { | ||
| calledBoundContext1 = this; | ||
| next() | ||
| }.bind(boundContext1); | ||
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| let hookFn = createHook('asyncSeries', fn); | ||
| hookFn.addHook(hook1); | ||
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| let newContext = {}; | ||
| hookFn = hookFn.bind(newContext); | ||
| hookFn(); | ||
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| expect(context).to.equal(newContext); | ||
| expect(calledBoundContext1).to.equal(boundContext1); | ||
| }); | ||
| }); | ||
| }); |
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