Open-ILS/src/eg2/src/app/share/string/string.service.ts

   1 import {Injectable} from '@angular/core';
   2
   3 interface StringAssignment {
   4     key: string;     // keyboard command
   5     resolver: (ctx: any) => Promise<string>;
   6 }
   7
   8 interface PendingInterpolation {
   9     key: string;
  10     ctx: any;
  11     resolve: (string) => any;
  12     reject: (string) => any;
  13 }
  14
  15 @Injectable()
  16 export class StringService {
  17
  18     strings: {[key: string]: StringAssignment} = {};
  19
  20     // This service can only interpolate one string at a time, since it
  21     // maintains only one string component instance.  Avoid clobbering
  22     // in-process interpolation requests by maintaining a request queue.
  23     private pending: PendingInterpolation[];
  24
  25     constructor() {
  26         this.pending = [];
  27     }
  28
  29     register(assn: StringAssignment) {
  30         this.strings[assn.key] = assn;
  31     }
  32
  33     interpolate(key: string, ctx?: any): Promise<string> {
  34
  35         if (!this.strings[key]) {
  36             return Promise.reject(`String key not found: "${key}"`);
  37         }
  38
  39         return new Promise( (resolve, reject) => {
  40             const pend: PendingInterpolation = {
  41                 key: key,
  42                 ctx: ctx,
  43                 resolve: resolve,
  44                 reject: reject
  45             };
  46
  47             this.pending.push(pend);
  48
  49             // Avoid launching the pending string processer with >1
  50             // pending, because the processor will have already started.
  51             if (this.pending.length === 1) {
  52                 this.processPending();
  53             }
  54         });
  55     }
  56
  57     processPending() {
  58         const pstring = this.pending[0];
  59         this.strings[pstring.key].resolver(pstring.ctx).then(
  60             txt => {
  61                 pstring.resolve(txt);
  62                 this.pending.shift();
  63                 if (this.pending.length) {
  64                     this.processPending();
  65                 }
  66             },
  67             err => {
  68                 pstring.reject(err);
  69                 this.pending.shift();
  70                 if (this.pending.length) {
  71                     this.processPending();
  72                 }
  73             }
  74         );
  75     }
  76 }
  77
  78