1 | /*
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2 | MIT License http://www.opensource.org/licenses/mit-license.php
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3 | */
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4 |
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5 | ;
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6 |
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7 | const memoize = require("../util/memoize");
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8 |
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9 | const LAZY_TARGET = Symbol("lazy serialization target");
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10 | const LAZY_SERIALIZED_VALUE = Symbol("lazy serialization data");
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11 |
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12 | /**
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13 | * @template DeserializedType
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14 | * @template SerializedType
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15 | */
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16 | class SerializerMiddleware {
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17 | /* istanbul ignore next */
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18 | /**
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19 | * @abstract
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20 | * @param {DeserializedType} data data
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21 | * @param {Object} context context object
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22 | * @returns {SerializedType|Promise<SerializedType>} serialized data
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23 | */
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24 | serialize(data, context) {
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25 | const AbstractMethodError = require("../AbstractMethodError");
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26 | throw new AbstractMethodError();
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27 | }
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28 |
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29 | /* istanbul ignore next */
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30 | /**
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31 | * @abstract
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32 | * @param {SerializedType} data data
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33 | * @param {Object} context context object
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34 | * @returns {DeserializedType|Promise<DeserializedType>} deserialized data
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35 | */
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36 | deserialize(data, context) {
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37 | const AbstractMethodError = require("../AbstractMethodError");
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38 | throw new AbstractMethodError();
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39 | }
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40 |
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41 | /**
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42 | * @param {any | function(): Promise<any> | any} value contained value or function to value
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43 | * @param {SerializerMiddleware<any, any>} target target middleware
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44 | * @param {object=} options lazy options
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45 | * @param {any=} serializedValue serialized value
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46 | * @returns {function(): Promise<any> | any} lazy function
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47 | */
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48 | static createLazy(value, target, options = {}, serializedValue) {
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49 | if (SerializerMiddleware.isLazy(value, target)) return value;
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50 | const fn = typeof value === "function" ? value : () => value;
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51 | fn[LAZY_TARGET] = target;
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52 | /** @type {any} */ (fn).options = options;
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53 | fn[LAZY_SERIALIZED_VALUE] = serializedValue;
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54 | return fn;
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55 | }
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56 |
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57 | /**
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58 | * @param {function(): Promise<any> | any} fn lazy function
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59 | * @param {SerializerMiddleware<any, any>=} target target middleware
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60 | * @returns {boolean} true, when fn is a lazy function (optionally of that target)
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61 | */
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62 | static isLazy(fn, target) {
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63 | if (typeof fn !== "function") return false;
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64 | const t = fn[LAZY_TARGET];
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65 | return target ? t === target : !!t;
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66 | }
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67 |
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68 | /**
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69 | * @param {function(): Promise<any> | any} fn lazy function
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70 | * @returns {object} options
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71 | */
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72 | static getLazyOptions(fn) {
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73 | if (typeof fn !== "function") return undefined;
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74 | return /** @type {any} */ (fn).options;
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75 | }
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76 |
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77 | /**
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78 | * @param {function(): Promise<any> | any} fn lazy function
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79 | * @returns {any} serialized value
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80 | */
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81 | static getLazySerializedValue(fn) {
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82 | if (typeof fn !== "function") return undefined;
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83 | return fn[LAZY_SERIALIZED_VALUE];
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84 | }
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85 |
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86 | /**
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87 | * @param {function(): Promise<any> | any} fn lazy function
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88 | * @param {any} value serialized value
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89 | * @returns {void}
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90 | */
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91 | static setLazySerializedValue(fn, value) {
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92 | fn[LAZY_SERIALIZED_VALUE] = value;
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93 | }
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94 |
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95 | /**
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96 | * @param {function(): Promise<any> | any} lazy lazy function
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97 | * @param {function(any): Promise<any> | any} serialize serialize function
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98 | * @returns {function(): Promise<any> | any} new lazy
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99 | */
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100 | static serializeLazy(lazy, serialize) {
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101 | const fn = memoize(() => {
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102 | const r = lazy();
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103 | if (r instanceof Promise) return r.then(data => data && serialize(data));
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104 | if (r) return serialize(r);
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105 | return null;
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106 | });
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107 | fn[LAZY_TARGET] = lazy[LAZY_TARGET];
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108 | /** @type {any} */ (fn).options = /** @type {any} */ (lazy).options;
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109 | lazy[LAZY_SERIALIZED_VALUE] = fn;
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110 | return fn;
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111 | }
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112 |
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113 | /**
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114 | * @param {function(): Promise<any> | any} lazy lazy function
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115 | * @param {function(any): Promise<any> | any} deserialize deserialize function
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116 | * @returns {function(): Promise<any> | any} new lazy
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117 | */
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118 | static deserializeLazy(lazy, deserialize) {
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119 | const fn = memoize(() => {
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120 | const r = lazy();
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121 | if (r instanceof Promise) return r.then(data => deserialize(data));
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122 | return deserialize(r);
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123 | });
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124 | fn[LAZY_TARGET] = lazy[LAZY_TARGET];
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125 | /** @type {any} */ (fn).options = /** @type {any} */ (lazy).options;
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126 | fn[LAZY_SERIALIZED_VALUE] = lazy;
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127 | return fn;
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128 | }
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129 | }
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130 |
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131 | module.exports = SerializerMiddleware;
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