1 | import type { Draft } from 'immer';
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2 | import type { AnyAction, Action, Reducer } from 'redux';
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3 | import type { ActionReducerMapBuilder } from './mapBuilders';
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4 | import type { NoInfer } from './tsHelpers';
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5 | /**
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6 | * Defines a mapping from action types to corresponding action object shapes.
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7 | *
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8 | * @deprecated This should not be used manually - it is only used for internal
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9 | * inference purposes and should not have any further value.
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10 | * It might be removed in the future.
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11 | * @public
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12 | */
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13 | export declare type Actions<T extends keyof any = string> = Record<T, Action>;
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14 | export interface ActionMatcher<A extends AnyAction> {
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15 | (action: AnyAction): action is A;
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16 | }
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17 | export declare type ActionMatcherDescription<S, A extends AnyAction> = {
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18 | matcher: ActionMatcher<A>;
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19 | reducer: CaseReducer<S, NoInfer<A>>;
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20 | };
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21 | export declare type ReadonlyActionMatcherDescriptionCollection<S> = ReadonlyArray<ActionMatcherDescription<S, any>>;
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22 | export declare type ActionMatcherDescriptionCollection<S> = Array<ActionMatcherDescription<S, any>>;
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23 | /**
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24 | * An *case reducer* is a reducer function for a specific action type. Case
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25 | * reducers can be composed to full reducers using `createReducer()`.
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26 | *
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27 | * Unlike a normal Redux reducer, a case reducer is never called with an
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28 | * `undefined` state to determine the initial state. Instead, the initial
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29 | * state is explicitly specified as an argument to `createReducer()`.
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30 | *
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31 | * In addition, a case reducer can choose to mutate the passed-in `state`
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32 | * value directly instead of returning a new state. This does not actually
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33 | * cause the store state to be mutated directly; instead, thanks to
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34 | * [immer](https://github.com/mweststrate/immer), the mutations are
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35 | * translated to copy operations that result in a new state.
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36 | *
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37 | * @public
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38 | */
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39 | export declare type CaseReducer<S = any, A extends Action = AnyAction> = (state: Draft<S>, action: A) => S | void | Draft<S>;
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40 | /**
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41 | * A mapping from action types to case reducers for `createReducer()`.
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42 | *
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43 | * @deprecated This should not be used manually - it is only used
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44 | * for internal inference purposes and using it manually
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45 | * would lead to type erasure.
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46 | * It might be removed in the future.
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47 | * @public
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48 | */
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49 | export declare type CaseReducers<S, AS extends Actions> = {
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50 | [T in keyof AS]: AS[T] extends Action ? CaseReducer<S, AS[T]> : void;
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51 | };
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52 | /**
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53 | * A utility function that allows defining a reducer as a mapping from action
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54 | * type to *case reducer* functions that handle these action types. The
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55 | * reducer's initial state is passed as the first argument.
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56 | *
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57 | * @remarks
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58 | * The body of every case reducer is implicitly wrapped with a call to
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59 | * `produce()` from the [immer](https://github.com/mweststrate/immer) library.
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60 | * This means that rather than returning a new state object, you can also
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61 | * mutate the passed-in state object directly; these mutations will then be
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62 | * automatically and efficiently translated into copies, giving you both
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63 | * convenience and immutability.
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64 | *
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65 | * @overloadSummary
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66 | * This overload accepts a callback function that receives a `builder` object as its argument.
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67 | * That builder provides `addCase`, `addMatcher` and `addDefaultCase` functions that may be
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68 | * called to define what actions this reducer will handle.
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69 | *
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70 | * @param initialState - The initial state that should be used when the reducer is called the first time.
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71 | * @param builderCallback - A callback that receives a *builder* object to define
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72 | * case reducers via calls to `builder.addCase(actionCreatorOrType, reducer)`.
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73 | * @example
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74 | ```ts
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75 | import {
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76 | createAction,
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77 | createReducer,
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78 | AnyAction,
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79 | PayloadAction,
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80 | } from "@reduxjs/toolkit";
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81 |
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82 | const increment = createAction<number>("increment");
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83 | const decrement = createAction<number>("decrement");
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84 |
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85 | function isActionWithNumberPayload(
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86 | action: AnyAction
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87 | ): action is PayloadAction<number> {
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88 | return typeof action.payload === "number";
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89 | }
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90 |
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91 | createReducer(
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92 | {
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93 | counter: 0,
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94 | sumOfNumberPayloads: 0,
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95 | unhandledActions: 0,
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96 | },
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97 | (builder) => {
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98 | builder
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99 | .addCase(increment, (state, action) => {
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100 | // action is inferred correctly here
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101 | state.counter += action.payload;
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102 | })
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103 | // You can chain calls, or have separate `builder.addCase()` lines each time
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104 | .addCase(decrement, (state, action) => {
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105 | state.counter -= action.payload;
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106 | })
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107 | // You can apply a "matcher function" to incoming actions
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108 | .addMatcher(isActionWithNumberPayload, (state, action) => {})
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109 | // and provide a default case if no other handlers matched
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110 | .addDefaultCase((state, action) => {});
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111 | }
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112 | );
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113 | ```
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114 | * @public
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115 | */
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116 | export declare function createReducer<S>(initialState: S, builderCallback: (builder: ActionReducerMapBuilder<S>) => void): Reducer<S>;
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117 | /**
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118 | * A utility function that allows defining a reducer as a mapping from action
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119 | * type to *case reducer* functions that handle these action types. The
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120 | * reducer's initial state is passed as the first argument.
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121 | *
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122 | * The body of every case reducer is implicitly wrapped with a call to
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123 | * `produce()` from the [immer](https://github.com/mweststrate/immer) library.
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124 | * This means that rather than returning a new state object, you can also
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125 | * mutate the passed-in state object directly; these mutations will then be
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126 | * automatically and efficiently translated into copies, giving you both
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127 | * convenience and immutability.
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128 | *
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129 | * @overloadSummary
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130 | * This overload accepts an object where the keys are string action types, and the values
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131 | * are case reducer functions to handle those action types.
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132 | *
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133 | * @param initialState - The initial state that should be used when the reducer is called the first time.
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134 | * @param actionsMap - An object mapping from action types to _case reducers_, each of which handles one specific action type.
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135 | * @param actionMatchers - An array of matcher definitions in the form `{matcher, reducer}`.
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136 | * All matching reducers will be executed in order, independently if a case reducer matched or not.
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137 | * @param defaultCaseReducer - A "default case" reducer that is executed if no case reducer and no matcher
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138 | * reducer was executed for this action.
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139 | *
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140 | * @example
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141 | ```js
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142 | const counterReducer = createReducer(0, {
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143 | increment: (state, action) => state + action.payload,
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144 | decrement: (state, action) => state - action.payload
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145 | })
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146 | ```
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147 |
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148 | * Action creators that were generated using [`createAction`](./createAction) may be used directly as the keys here, using computed property syntax:
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149 |
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150 | ```js
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151 | const increment = createAction('increment')
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152 | const decrement = createAction('decrement')
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153 |
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154 | const counterReducer = createReducer(0, {
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155 | [increment]: (state, action) => state + action.payload,
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156 | [decrement.type]: (state, action) => state - action.payload
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157 | })
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158 | ```
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159 | * @public
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160 | */
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161 | export declare function createReducer<S, CR extends CaseReducers<S, any> = CaseReducers<S, any>>(initialState: S, actionsMap: CR, actionMatchers?: ActionMatcherDescriptionCollection<S>, defaultCaseReducer?: CaseReducer<S>): Reducer<S>;
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