Website Structure

Frontend-Learner/node_modules/koa-convert/index.js

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+'use strict'
+
+/**
+ * Module dependencies.
+ */
+
+const co = require('co')
+const compose = require('koa-compose')
+
+/**
+ * Expose `convert()`.
+ */
+
+module.exports = convert
+
+/**
+ * Convert Koa legacy generator-based middleware
+ * to modern promise-based middleware.
+ *
+ *
+ * @api public
+ * */
+
+function convert (mw) {
+  if (typeof mw !== 'function') {
+    throw new TypeError('middleware must be a function')
+  }
+
+  // assume it's Promise-based middleware
+  if (
+    mw.constructor.name !== 'GeneratorFunction' &&
+    mw.constructor.name !== 'AsyncGeneratorFunction'
+  ) {
+    return mw
+  }
+
+  const converted = function (ctx, next) {
+    return co.call(
+      ctx,
+      mw.call(
+        ctx,
+        (function * (next) { return yield next() })(next)
+      ))
+  }
+
+  converted._name = mw._name || mw.name
+  return converted
+}
+
+/**
+ * Convert and compose multiple middleware
+ * (could mix legacy and modern ones)
+ * and return modern promise middleware.
+ *
+ *
+ * @api public
+ * */
+
+// convert.compose(mw, mw, mw)
+// convert.compose([mw, mw, mw])
+convert.compose = function (arr) {
+  if (!Array.isArray(arr)) {
+    arr = Array.from(arguments)
+  }
+
+  return compose(arr.map(convert))
+}
+
+/**
+ * Convert Koa modern promise-based middleware
+ * to legacy generator-based middleware.
+ *
+ *
+ * @api public
+ * */
+
+convert.back = function (mw) {
+  if (typeof mw !== 'function') {
+    throw new TypeError('middleware must be a function')
+  }
+
+  // assume it's generator middleware
+  if (mw.constructor.name === 'GeneratorFunction' || mw.constructor.name === 'AsyncGeneratorFunction') {
+    return mw
+  }
+
+  const converted = function * (next) {
+    const ctx = this
+    let called = false
+
+    yield mw(ctx, function () {
+      if (called) {
+        // guard against multiple next() calls
+        // https://github.com/koajs/compose/blob/4e3e96baf58b817d71bd44a8c0d78bb42623aa95/index.js#L36
+        throw new Error('next() called multiple times')
+      }
+
+      called = true
+      return co.call(ctx, next)
+    })
+  }
+
+  converted._name = mw._name || mw.name
+  return converted
+}