refactor IDV parser to use map why not

lib/idv.ts

@@ -7,7 +7,7 @@ const LEADING_WHITESPACE = /^([ \t]+)/;
 const ENTRY = /^(.+?):\s*(.*)/;
 
 export class Idv {
-  collections: Record<string, undefined | [string, string[]][]> = {};
+  collections: Map<string, undefined | [string, string[]][]> = new Map();
 
   public static parse(input: string): Idv {
     const idv = new Idv();
@@ -53,14 +53,16 @@ export class Idv {
         if (matches) {
           const [, collection, distinguisher] = matches;
 
-          if (this.collections[collection] == undefined) {
-            this.collections[collection] = [];
+          if (!this.collections.has(collection)) {
+            this.collections.set(collection, []);
           }
 
           currentDocument = [];
           currentIndent = undefined;
           // TODO: implement backslash escaping in the distinguisher
-          this.collections[collection].push([distinguisher, currentDocument]);
+          this.collections
+            .get(collection)!
+            .push([distinguisher, currentDocument]);
         } else {
           throw new Error("Failed to parse a property");
         }
@@ -71,12 +73,12 @@ export class Idv {
   }
 
   public getProperty<T>(name: string, parse: UnionParser<T>): T | undefined {
-    const firstEntry = this.collections[name]?.[0];
+    const firstEntry = this.collections.get(name)?.[0];
     return firstEntry && parse(firstEntry[0], firstEntry[1]);
   }
 
   public getList<T>(name: string, parse: UnionParser<T>): T[] {
-    return (this.collections[name] ?? []).map(([distinguisher, document]) =>
+    return (this.collections.get(name) ?? []).map(([distinguisher, document]) =>
       parse(distinguisher, document)
     );
   }
@@ -86,7 +88,7 @@ export class Idv {
     parseDocument: DocumentParser<T>
   ): Record<string, T> {
     return Object.fromEntries(
-      (this.collections[name] ?? []).map(([distinguisher, document]) => [
+      (this.collections.get(name) ?? []).map(([distinguisher, document]) => [
         distinguisher,
         parseDocument(document),
       ])
@@ -99,7 +101,7 @@ export class Idv {
   ): Record<string, T> {
     const idvMap: Map<string, Idv> = new Map();
 
-    (this.collections[name] ?? []).forEach(([distinguisher, document]) => {
+    (this.collections.get(name) ?? []).forEach(([distinguisher, document]) => {
       let idv = idvMap.get(distinguisher);
       if (idv == undefined) {
         idvMap.set(distinguisher, (idv = new Idv()));

tsconfig.json

@@ -3,6 +3,7 @@
     "isolatedModules": true,
     "lib": ["ES2019", "DOM"],
     "strict": true,
+    "target": "ES2020",
     "noEmit": true
   }
 }