[example] Import Relay example

From https://github.com/relayjs/relay-examples/tree/a5e1139906197ceeca70c30cd98cef48e952c04c/todo

Author: alloy

example/.babelrc

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+{
+  "passPerPreset": true,
+  "plugins": [
+    "relay",
+    "transform-runtime"
+  ],
+  "presets": [
+    "react",
+    "es2015",
+    "stage-0"
+  ]
+}

example/.eslintignore

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+__generated__/

example/.eslintrc

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+---
+
+extends:
+  - fbjs

example/.gitignore

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+.DS_Store
+__generated__/

example/.watchmanconfig

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+# Relay TodoMVC
+
+## Installation
+
+```
+npm install
+```
+
+## Running
+
+Set up generated files:
+
+```
+npm run update-schema
+npm run build
+```
+
+Start a local server:
+
+```
+npm start
+```
+
+## Developing
+
+Any changes you make to files in the `js/` directory will cause the server to
+automatically rebuild the app and refresh your browser.
+
+If at any time you make changes to `data/schema.js`, stop the server,
+regenerate `data/schema.graphql`, and restart the server:
+
+```
+npm run update-schema
+npm run build
+npm start
+```
+
+## License
+
+    This file provided by Facebook is for non-commercial testing and evaluation
+    purposes only.  Facebook reserves all rights not expressly granted.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+    ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

example/README.md

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+/**
+ * This file provided by Facebook is for non-commercial testing and evaluation
+ * purposes only.  Facebook reserves all rights not expressly granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+export class Todo {}
+export class User {}
+
+// Mock authenticated ID
+const VIEWER_ID = 'me';
+
+// Mock user data
+const viewer = new User();
+viewer.id = VIEWER_ID;
+const usersById = {
+  [VIEWER_ID]: viewer,
+};
+
+// Mock todo data
+const todosById = {};
+const todoIdsByUser = {
+  [VIEWER_ID]: [],
+};
+let nextTodoId = 0;
+addTodo('Taste JavaScript', true);
+addTodo('Buy a unicorn', false);
+
+export function addTodo(text, complete) {
+  const todo = new Todo();
+  todo.complete = !!complete;
+  todo.id = `${nextTodoId++}`;
+  todo.text = text;
+  todosById[todo.id] = todo;
+  todoIdsByUser[VIEWER_ID].push(todo.id);
+  return todo.id;
+}
+
+export function changeTodoStatus(id, complete) {
+  const todo = getTodo(id);
+  todo.complete = complete;
+}
+
+export function getTodo(id) {
+  return todosById[id];
+}
+
+export function getTodos(status = 'any') {
+  const todos = todoIdsByUser[VIEWER_ID].map(id => todosById[id]);
+  if (status === 'any') {
+    return todos;
+  }
+  return todos.filter(todo => todo.complete === (status === 'completed'));
+}
+
+export function getUser(id) {
+  return usersById[id];
+}
+
+export function getViewer() {
+  return getUser(VIEWER_ID);
+}
+
+export function markAllTodos(complete) {
+  const changedTodos = [];
+  getTodos().forEach(todo => {
+    if (todo.complete !== complete) {
+      todo.complete = complete;
+      changedTodos.push(todo);
+    }
+  });
+  return changedTodos.map(todo => todo.id);
+}
+
+export function removeTodo(id) {
+  const todoIndex = todoIdsByUser[VIEWER_ID].indexOf(id);
+  if (todoIndex !== -1) {
+    todoIdsByUser[VIEWER_ID].splice(todoIndex, 1);
+  }
+  delete todosById[id];
+}
+
+export function removeCompletedTodos() {
+  const todosToRemove = getTodos().filter(todo => todo.complete);
+  todosToRemove.forEach(todo => removeTodo(todo.id));
+  return todosToRemove.map(todo => todo.id);
+}
+
+export function renameTodo(id, text) {
+  const todo = getTodo(id);
+  todo.text = text;
+}

example/data/database.js

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+input AddTodoInput {
+  text: String!
+  clientMutationId: String
+}
+
+type AddTodoPayload {
+  todoEdge: TodoEdge
+  viewer: User
+  clientMutationId: String
+}
+
+input ChangeTodoStatusInput {
+  complete: Boolean!
+  id: ID!
+  clientMutationId: String
+}
+
+type ChangeTodoStatusPayload {
+  todo: Todo
+  viewer: User
+  clientMutationId: String
+}
+
+input MarkAllTodosInput {
+  complete: Boolean!
+  clientMutationId: String
+}
+
+type MarkAllTodosPayload {
+  changedTodos: [Todo]
+  viewer: User
+  clientMutationId: String
+}
+
+type Mutation {
+  addTodo(input: AddTodoInput!): AddTodoPayload
+  changeTodoStatus(input: ChangeTodoStatusInput!): ChangeTodoStatusPayload
+  markAllTodos(input: MarkAllTodosInput!): MarkAllTodosPayload
+  removeCompletedTodos(input: RemoveCompletedTodosInput!): RemoveCompletedTodosPayload
+  removeTodo(input: RemoveTodoInput!): RemoveTodoPayload
+  renameTodo(input: RenameTodoInput!): RenameTodoPayload
+}
+
+# An object with an ID
+interface Node {
+  # The id of the object.
+  id: ID!
+}
+
+# Information about pagination in a connection.
+type PageInfo {
+  # When paginating forwards, are there more items?
+  hasNextPage: Boolean!
+
+  # When paginating backwards, are there more items?
+  hasPreviousPage: Boolean!
+
+  # When paginating backwards, the cursor to continue.
+  startCursor: String
+
+  # When paginating forwards, the cursor to continue.
+  endCursor: String
+}
+
+type Query {
+  viewer: User
+
+  # Fetches an object given its ID
+  node(
+    # The ID of an object
+    id: ID!
+  ): Node
+}
+
+input RemoveCompletedTodosInput {
+  clientMutationId: String
+}
+
+type RemoveCompletedTodosPayload {
+  deletedTodoIds: [String]
+  viewer: User
+  clientMutationId: String
+}
+
+input RemoveTodoInput {
+  id: ID!
+  clientMutationId: String
+}
+
+type RemoveTodoPayload {
+  deletedTodoId: ID
+  viewer: User
+  clientMutationId: String
+}
+
+input RenameTodoInput {
+  id: ID!
+  text: String!
+  clientMutationId: String
+}
+
+type RenameTodoPayload {
+  todo: Todo
+  clientMutationId: String
+}
+
+type Todo implements Node {
+  # The ID of an object
+  id: ID!
+  text: String
+  complete: Boolean
+}
+
+# A connection to a list of items.
+type TodoConnection {
+  # Information to aid in pagination.
+  pageInfo: PageInfo!
+
+  # A list of edges.
+  edges: [TodoEdge]
+}
+
+# An edge in a connection.
+type TodoEdge {
+  # The item at the end of the edge
+  node: Todo
+
+  # A cursor for use in pagination
+  cursor: String!
+}
+
+type User implements Node {
+  # The ID of an object
+  id: ID!
+  todos(status: String = "any", after: String, first: Int, before: String, last: Int): TodoConnection
+  totalCount: Int
+  completedCount: Int
+}