feat: Introduce SchemaBuilder

lerna.json

@@ -1,5 +1,6 @@
 {
   "lerna": "2.0.0-rc.5",
+  "npmClient": "yarn",
   "packages": [
     "packages/*"
   ],

package.json

@@ -1,5 +1,15 @@
 {
   "devDependencies": {
-    "lerna": "^2.0.0-rc.5"
+    "babel-eslint": "^7.2.3",
+    "eslint": "^4.0.0",
+    "eslint-config-prettier": "^2.1.1",
+    "eslint-plugin-jest": "^20.0.3",
+    "eslint-plugin-prettier": "^2.1.2",
+    "jest": "^20.0.4",
+    "lerna": "^2.0.0-rc.5",
+    "prettier": "^1.4.4"
+  },
+  "jest": {
+    "testRegex": "__tests__/.*\\.test\\.js$"
   }
 }

packages/graphql-build/index.js

@@ -0,0 +1,82 @@
+const debug = require("debug")("graphql-builder");
+const INDENT = "  ";
+
+class SchemaBuilder {
+  constructor() {
+    // this.context will be replaced by the 'context' hooks, do not store
+    // copies of it!
+    this.context = {};
+
+    // Because hooks can nest, this keeps track of how deep we are.
+    this.depth = -1;
+
+    this.hooks = {
+      // The context object is passed to all hooks, hook the 'context' event to
+      // extend this object:
+      context: [],
+
+      // Add 'query', 'mutation' or 'subscription' types in this hook:
+      schema: [],
+
+      // When creating a GraphQLObjectType we'll execute, in order, the
+      // following hooks:
+      // - 'objectType' to add any root-level attributes, e.g. add a description
+      // - 'objectType:fields' to add fields to this object type
+      // - 'objectType:field' to enhance an individual field
+      objectType: [],
+      "objectType:fields": [],
+      "objectType:field": [],
+    };
+  }
+
+  /*
+   * Every hook `fn` takes three arguments:
+   * - obj - the object currently being inspected
+   * - context - the global context object (which contains a number of utilities)
+   * - scope - information specific to the current invocation of the hook
+   *
+   * The function must either return a replacement object for `obj` or `obj` itself
+   */
+  hook(hookName, fn) {
+    if (!this.hooks[hookName]) {
+      throw new Error(`Sorry, '${hookName}' is not a supported hook`);
+    }
+    this.hooks[hookName].push(fn);
+  }
+
+  applyHooks(hookName, oldObj, scope) {
+    const isContext = hookName === "context";
+    if (isContext) this.context = oldObj;
+
+    this.depth++;
+    debug(`${INDENT.repeat(this.depth)}[${hookName}]: Running...`);
+
+    const hooks = this.hooks[hookName];
+    if (!hooks) {
+      throw new Error(`Sorry, '${hookName}' is not a registered hook`);
+    }
+
+    let newObj = oldObj;
+    for (const hook of hooks) {
+      newObj = hook(newObj, this.context, scope);
+      if (!newObj) {
+        throw new Error(`Hook for '${hookName}' returned falsy value`);
+      }
+      if (isContext) {
+        this.context = newObj;
+      }
+    }
+
+    debug(`${INDENT.repeat(this.depth)}[${hookName}]: Complete`);
+    this.depth--;
+
+    return newObj;
+  }
+}
+
+const buildSchema = async (plugins, options) => {
+  const builder = new SchemaBuilder();
+  for (const plugin of plugins) {
+    await plugin(builder, options);
+  }
+};

packages/graphql-build/package.json

@@ -0,0 +1,34 @@
+{
+  "name": "graphql-build",
+  "version": "0.0.0",
+  "description": "Build a GraphQL schema from plugins",
+  "main": "index.js",
+  "scripts": {},
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/benjie/graphql-build.git"
+  },
+  "keywords": [
+    "graphql",
+    "apollo",
+    "graphqljs",
+    "plugin",
+    "build",
+    "extension"
+  ],
+  "author": "Benjie Gillam <benjie@jemjie.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/benjie/graphql-build/issues"
+  },
+  "homepage": "https://github.com/benjie/graphql-build#readme",
+  "dependencies": {
+    "dataloader": "^1.3.0",
+    "debug": ">=2",
+    "graphql": ">=0.9"
+  },
+  "engines": {
+    "node": ">=8",
+    "yarn": "^0.24.5"
+  }
+}

packages/graphql-build/yarn.lock

@@ -0,0 +1,27 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+dataloader@^1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/dataloader/-/dataloader-1.3.0.tgz#6fec5be4b30a712e4afd30b86b4334566b97673b"
+
+debug@>=2:
+  version "2.6.8"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-2.6.8.tgz#e731531ca2ede27d188222427da17821d68ff4fc"
+  dependencies:
+    ms "2.0.0"
+
+graphql@>=0.9:
+  version "0.10.3"
+  resolved "https://registry.yarnpkg.com/graphql/-/graphql-0.10.3.tgz#c313afd5518e673351bee18fb63e2a0e487407ab"
+  dependencies:
+    iterall "^1.1.0"
+
+iterall@^1.1.0:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/iterall/-/iterall-1.1.1.tgz#f7f0af11e9a04ec6426260f5019d9fcca4d50214"
+
+ms@2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/ms/-/ms-2.0.0.tgz#5608aeadfc00be6c2901df5f9861788de0d597c8"