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6 |
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7 | import * as map from './map.js'
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8 | import * as set from './set.js'
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9 | import * as array from './array.js'
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10 |
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11 | /**
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12 | * Handles named events.
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13 | *
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14 | * @template N
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15 | */
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16 | export class Observable {
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17 | constructor () {
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18 | |
19 |
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20 |
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21 |
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22 | this._observers = map.create()
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23 | }
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24 |
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25 | |
26 |
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27 |
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28 |
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29 | on (name, f) {
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30 | map.setIfUndefined(this._observers, name, set.create).add(f)
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31 | }
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32 |
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33 | /**
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34 | * @param {N} name
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35 | * @param {function} f
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36 | */
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37 | once (name, f) {
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38 | |
39 |
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40 |
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41 | const _f = (...args) => {
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42 | this.off(name, _f)
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43 | f(...args)
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44 | }
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45 | this.on(name, _f)
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46 | }
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47 |
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48 | |
49 |
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50 |
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51 |
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52 | off (name, f) {
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53 | const observers = this._observers.get(name)
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54 | if (observers !== undefined) {
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55 | observers.delete(f)
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56 | if (observers.size === 0) {
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57 | this._observers.delete(name)
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58 | }
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59 | }
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60 | }
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61 |
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62 | |
63 |
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64 |
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65 |
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66 |
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67 |
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68 |
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69 |
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70 |
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71 | emit (name, args) {
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72 |
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73 | return array.from((this._observers.get(name) || map.create()).values()).forEach(f => f(...args))
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74 | }
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75 |
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76 | destroy () {
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77 | this._observers = map.create()
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78 | }
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79 | }
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