0.2.0 - Mid migration

web/node_modules/redux/src/combineReducers.js

@@ -0,0 +1,175 @@
+import ActionTypes from './utils/actionTypes'
+import warning from './utils/warning'
+import isPlainObject from './utils/isPlainObject'
+import { kindOf } from './utils/kindOf'
+
+function getUnexpectedStateShapeWarningMessage(
+  inputState,
+  reducers,
+  action,
+  unexpectedKeyCache
+) {
+  const reducerKeys = Object.keys(reducers)
+  const argumentName =
+    action && action.type === ActionTypes.INIT
+      ? 'preloadedState argument passed to createStore'
+      : 'previous state received by the reducer'
+
+  if (reducerKeys.length === 0) {
+    return (
+      'Store does not have a valid reducer. Make sure the argument passed ' +
+      'to combineReducers is an object whose values are reducers.'
+    )
+  }
+
+  if (!isPlainObject(inputState)) {
+    return (
+      `The ${argumentName} has unexpected type of "${kindOf(
+        inputState
+      )}". Expected argument to be an object with the following ` +
+      `keys: "${reducerKeys.join('", "')}"`
+    )
+  }
+
+  const unexpectedKeys = Object.keys(inputState).filter(
+    (key) => !reducers.hasOwnProperty(key) && !unexpectedKeyCache[key]
+  )
+
+  unexpectedKeys.forEach((key) => {
+    unexpectedKeyCache[key] = true
+  })
+
+  if (action && action.type === ActionTypes.REPLACE) return
+
+  if (unexpectedKeys.length > 0) {
+    return (
+      `Unexpected ${unexpectedKeys.length > 1 ? 'keys' : 'key'} ` +
+      `"${unexpectedKeys.join('", "')}" found in ${argumentName}. ` +
+      `Expected to find one of the known reducer keys instead: ` +
+      `"${reducerKeys.join('", "')}". Unexpected keys will be ignored.`
+    )
+  }
+}
+
+function assertReducerShape(reducers) {
+  Object.keys(reducers).forEach((key) => {
+    const reducer = reducers[key]
+    const initialState = reducer(undefined, { type: ActionTypes.INIT })
+
+    if (typeof initialState === 'undefined') {
+      throw new Error(
+        `The slice reducer for key "${key}" returned undefined during initialization. ` +
+          `If the state passed to the reducer is undefined, you must ` +
+          `explicitly return the initial state. The initial state may ` +
+          `not be undefined. If you don't want to set a value for this reducer, ` +
+          `you can use null instead of undefined.`
+      )
+    }
+
+    if (
+      typeof reducer(undefined, {
+        type: ActionTypes.PROBE_UNKNOWN_ACTION(),
+      }) === 'undefined'
+    ) {
+      throw new Error(
+        `The slice reducer for key "${key}" returned undefined when probed with a random type. ` +
+          `Don't try to handle '${ActionTypes.INIT}' or other actions in "redux/*" ` +
+          `namespace. They are considered private. Instead, you must return the ` +
+          `current state for any unknown actions, unless it is undefined, ` +
+          `in which case you must return the initial state, regardless of the ` +
+          `action type. The initial state may not be undefined, but can be null.`
+      )
+    }
+  })
+}
+
+/**
+ * Turns an object whose values are different reducer functions, into a single
+ * reducer function. It will call every child reducer, and gather their results
+ * into a single state object, whose keys correspond to the keys of the passed
+ * reducer functions.
+ *
+ * @param {Object} reducers An object whose values correspond to different
+ * reducer functions that need to be combined into one. One handy way to obtain
+ * it is to use ES6 `import * as reducers` syntax. The reducers may never return
+ * undefined for any action. Instead, they should return their initial state
+ * if the state passed to them was undefined, and the current state for any
+ * unrecognized action.
+ *
+ * @returns {Function} A reducer function that invokes every reducer inside the
+ * passed object, and builds a state object with the same shape.
+ */
+export default function combineReducers(reducers) {
+  const reducerKeys = Object.keys(reducers)
+  const finalReducers = {}
+  for (let i = 0; i < reducerKeys.length; i++) {
+    const key = reducerKeys[i]
+
+    if (process.env.NODE_ENV !== 'production') {
+      if (typeof reducers[key] === 'undefined') {
+        warning(`No reducer provided for key "${key}"`)
+      }
+    }
+
+    if (typeof reducers[key] === 'function') {
+      finalReducers[key] = reducers[key]
+    }
+  }
+  const finalReducerKeys = Object.keys(finalReducers)
+
+  // This is used to make sure we don't warn about the same
+  // keys multiple times.
+  let unexpectedKeyCache
+  if (process.env.NODE_ENV !== 'production') {
+    unexpectedKeyCache = {}
+  }
+
+  let shapeAssertionError
+  try {
+    assertReducerShape(finalReducers)
+  } catch (e) {
+    shapeAssertionError = e
+  }
+
+  return function combination(state = {}, action) {
+    if (shapeAssertionError) {
+      throw shapeAssertionError
+    }
+
+    if (process.env.NODE_ENV !== 'production') {
+      const warningMessage = getUnexpectedStateShapeWarningMessage(
+        state,
+        finalReducers,
+        action,
+        unexpectedKeyCache
+      )
+      if (warningMessage) {
+        warning(warningMessage)
+      }
+    }
+
+    let hasChanged = false
+    const nextState = {}
+    for (let i = 0; i < finalReducerKeys.length; i++) {
+      const key = finalReducerKeys[i]
+      const reducer = finalReducers[key]
+      const previousStateForKey = state[key]
+      const nextStateForKey = reducer(previousStateForKey, action)
+      if (typeof nextStateForKey === 'undefined') {
+        const actionType = action && action.type
+        throw new Error(
+          `When called with an action of type ${
+            actionType ? `"${String(actionType)}"` : '(unknown type)'
+          }, the slice reducer for key "${key}" returned undefined. ` +
+            `To ignore an action, you must explicitly return the previous state. ` +
+            `If you want this reducer to hold no value, you can return null instead of undefined.`
+        )
+      }
+      nextState[key] = nextStateForKey
+      hasChanged = hasChanged || nextStateForKey !== previousStateForKey
+    }
+    hasChanged =
+      hasChanged || finalReducerKeys.length !== Object.keys(state).length
+    return hasChanged ? nextState : state
+  }
+}