wallet-core/node_modules/append-transform/index.js
2017-05-28 00:40:43 +02:00

89 lines
2.1 KiB
JavaScript

'use strict';
var js = require('default-require-extensions/js');
module.exports = appendTransform;
var count = 0;
function appendTransform(transform, ext, extensions) {
// Generate a unique key for this transform
var key = __dirname + count; // eslint-disable-line
count++;
ext = ext || '.js';
extensions = extensions || require.extensions;
var forwardGet;
var forwardSet;
var descriptor = Object.getOwnPropertyDescriptor(extensions, ext) || {value: js, configurable: true};
if (
((descriptor.get || descriptor.set) && !(descriptor.get && descriptor.set)) ||
!descriptor.configurable
) {
throw new Error('Somebody did bad things to require.extensions["' + ext + '"]');
}
if (descriptor.get) {
// wrap a previous append-transform install and pass through to the getter/setter pair it created
forwardGet = function () {
return descriptor.get();
};
forwardSet = function (val) {
descriptor.set(val);
return forwardGet();
};
} else {
forwardGet = function () {
return descriptor.value;
};
forwardSet = function (val) {
descriptor.value = val;
return val;
};
}
function wrapCustomHook(hook) {
return function (module, filename) {
// We wrap every added extension, but we only apply the transform to the one on top of the stack
if (!module[key]) {
module[key] = true;
var originalCompile = module._compile;
module._compile = function replacementCompile(code, filename) {
module._compile = originalCompile;
code = transform(code, filename);
module._compile(code, filename);
};
}
hook(module, filename);
};
}
// wrap the original
forwardSet(wrapCustomHook(forwardGet()));
var hooks = [forwardGet()];
function setCurrentHook(hook) {
var restoreIndex = hooks.indexOf(hook);
if (restoreIndex === -1) {
hooks.push(forwardSet(wrapCustomHook(hook)));
} else {
// we have already scene this hook, and it is being reverted (proxyquire, etc) - don't wrap again.
hooks.splice(restoreIndex + 1, hooks.length);
forwardSet(hook);
}
}
Object.defineProperty(extensions, ext, {
configurable: true,
enumerable: true,
get: forwardGet,
set: setCurrentHook
});
}