87 lines
2.4 KiB
JavaScript
87 lines
2.4 KiB
JavaScript
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/**
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* Adapted from: https://github.com/elastic/require-in-the-middle
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*/
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import Module from 'module'
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export default function Hook(find, onrequire) {
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if (!(this instanceof Hook)) return new Hook(find, onrequire)
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if (typeof Module._resolveFilename !== 'function') {
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throw new Error(
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`Error: Expected Module._resolveFilename to be a function (was: ${typeof Module._resolveFilename}) - aborting!`
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)
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}
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this.cache = {}
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this.deps = []
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this._unhooked = false
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this._origRequire = Module.prototype.require
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let self = this
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let patching = {}
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this._require = Module.prototype.require = function(request) {
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if (self._unhooked) {
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// if the patched require function could not be removed because
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// someone else patched it after it was patched here, we just
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// abort and pass the request onwards to the original require
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return self._origRequire.apply(this, arguments)
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}
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let filename = Module._resolveFilename(request, this)
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// return known patched modules immediately
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if (self.cache.hasOwnProperty(filename)) {
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return self.cache[filename]
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}
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// Check if this module has a patcher in-progress already.
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// Otherwise, mark this module as patching in-progress.
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let patched = patching[filename]
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if (!patched) {
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patching[filename] = true
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}
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let exports = self._origRequire.apply(this, arguments)
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if (filename !== find) {
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if (self._watching) {
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self.deps.push(filename)
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}
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return exports
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}
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// If it's already patched, just return it as-is.
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if (patched) return exports
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// The module has already been loaded,
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// so the patching mark can be cleaned up.
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delete patching[filename]
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// only call onrequire the first time a module is loaded
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if (!self.cache.hasOwnProperty(filename)) {
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// ensure that the cache entry is assigned a value before calling
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// onrequire, in case calling onrequire requires the same module.
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self.cache[filename] = exports
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self.cache[filename] = onrequire(exports)
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}
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return self.cache[filename]
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}
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}
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Hook.prototype.unhook = function() {
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this._unhooked = true
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if (this._require === Module.prototype.require) {
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Module.prototype.require = this._origRequire
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}
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}
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Hook.prototype.watch = function() {
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this._watching = true
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}
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Hook.prototype.unwatch = function() {
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this._watching = false
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}
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