data-cache.js

A Map sub-class backed by a persistant store
Version vom 14.07.2017. Aktuellste Version
Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/31448/206062/data-cachejs.js
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// ==UserScript==
// @name         data-cache.js
// @version      1.0.0
// @description  A Map sub-class backed by a persistant store
// ==/UserScript==

/* jshint asi: true, esnext: true */

DataCache = (() => {

  const NORMAL = 'font-weight: normal; text-decoration: none; color: black'
  const ERROR = 'font-weight: bold; color: #f4f'
  const LINK = 'color: #05f; text-decoration: underline'
  const BOLD = 'font-weight: bold'
  const BLUE = 'color: #05f'

  // --------------------------------------------------------------------

  function* entries(v) {
    if (typeof v !== 'object') {
      throw new TypeError(`Non-object argument passed to entries(v)`, v)
    }

    if (typeof v.entries === 'function') {
      yield* v.entries()
    } else {
      for (const k of Object.keys(v)) {
        const val = [ k, v[k] ]
        yield val
      }
    }
  }

  // --------------------------------------------------------------------------

  class DataCache extends Map {
    constructor({ getter, setter = null, key = null, debug = false }) {
      super()

      setter = setter || getter

      if (key) {
        this._getter = () => getter(key)
        this._setter = value => setter(key, value)
      } else {
        this._getter = getter
        this._setter = setter || getter
      }

      this._key = key
      this._debug = typeof setter === 'boolean' ? setter : debug

      this.load()
    }

    // ------------------------------------------

    _set(k, v) {
      if (v === super.get(k)) {
        return false
      }

      super.set(k, v)
      return true
    }

    // ------------------------------------------

    set(k, v) {
      if (this._set(k, v)) {
        this.save()
      }
    }

    // ------------------------------------------

    delete(k) {
      if (super.has(k)) {
        super.delete(k)
        this.save()
      }
    }

    // ------------------------------------------

    clear() {
      if (this.size > 0) {
        super.clear()
        this.save()
      }
    }

    // ------------------------------------------

    update(obj) {
      let changed = false

      for (const [ k, v ] of entries(obj)) {
        changed = this._set(k, v) || changed
      }

      if (changed) {
        this.save()
      }

      return changed
    }

    // ------------------------------------------

    replace(obj) {
      let changed = false

      if (this.size > 0) {
        super.clear()
        changed = true
      }

      for (const [ k, v ] of entries(obj)) {
        changed = this._set(k, v) || changed
      }

      if (changed) {
        this.save()
      }

      return changed
    }

    // ------------------------------------------

    toJSON() {
      return [...this.entries()]
        .reduce((obj, [ k, v ]) => Object.assign(obj, { [k]: v }), {})
    }

    // ------------------------------------------

    save() {
      try {
        const json = this.toJSON()
        const jstr = JSON.stringify(json, null, this._debug * 2)

        // GM_setValue(this._key, jstr)
        this._setter(json)

        this._log(`save(): ${this.size} items\n\n${jstr}`)
      } catch (ex) {
        this._log(`save(): error: ${ex}`)
      }
    }

    // ------------------------------------------

    load(json) {
      super.clear()

      try {
        // json = json || JSON.parse(GM_getValue(this._key))
        json = json || this._getter()

        for (const [ k, v ] of entries(json)) {
          super.set(k, v)
        }

        this._log(`load(): ${this.size} items\n\n${JSON.stringify(json, null, 2)}`)
      }
      catch (ex) {
        this._log(`load(): error: ${ex}`)
      }
    }

    // ------------------------------------------

    edit(text) {
      const res = window.prompt(text, JSON.stringify(this.toJSON(), null, 2))

      if (typeof res !== 'string') return

      try {
        const json = JSON.parse(res)

        if (this.replace(json)) {
          this._log(`edit(): ${this.size} items\n\n${JSON.stringify(json, null, 2)}`)
        }
      } catch (ex) {
        this._log(`edit(): error: ${ex}`)
      }
    }

    // ------------------------------------------

    _log(msg) {
      if (this._debug) {
        const ks = this._key ? `key: %c'${this._key}'%c` : '%c%c'
        console.info(`DataCache(${ks}): ${msg}`, LINK, NORMAL)
      }
    }

    // ------------------------------------------

    toString() {
      const ks = this._key ? `key: '${this._key}', ` : ''
      const kl = [...this.keys()].map(String).join(', ')

      return `DataCache(${ks}debug: ${this._debug}): [ ${kl} ]`
    }

    // ------------------------------------------

    dump() {
      // this._log(JSON.stringify(this.toJSON(), null, 2))
      const el = [...this.entries()]
        .map(([ key, value ]) => ({ key, value }))

      console.table(el)
    }
  }

  DataCache[Symbol.toStringTag] = 'DataCache'

  // --------------------------------------------------------------------------

  return DataCache

})()