Fix: small performance improvement through caching

Author: Wanasit Tanakitrungruang

benchmark/benchmark.js

@@ -2,7 +2,7 @@ const chrono = require("..");
 const b = require("benny");
 
 b.suite(
-    "Example",
+    "Basic parsing benchmark",
 
     b.add("Parsing empty string", () => {
         chrono.parse("");

package.json

@@ -43,7 +43,7 @@
   },
   "scripts": {
     "build": "tsc -p tsconfig.build.json",
-    "benchmark": "node ./benchmark/benchmark.js",
+    "benchmark": "npm run build && node ./benchmark/benchmark.js",
     "document": "typedoc",
     "prepare": "npm run build",
     "eslint": "eslint src test",

src/locales/en/parsers/ENCasualDateParser.ts

@@ -5,9 +5,11 @@ import { AbstractParserWithWordBoundaryChecking } from "../../../common/parsers/
 import { assignSimilarDate } from "../../../utils/dayjs";
 import * as references from "../../../common/casualReferences";
 
+const PATTERN = /(now|today|tonight|tomorrow|tmr|yesterday|last\s*night)(?=\W|$)/i;
+
 export default class ENCasualDateParser extends AbstractParserWithWordBoundaryChecking {
     innerPattern(context: ParsingContext): RegExp {
-        return /(now|today|tonight|tomorrow|tmr|yesterday|last\s*night)(?=\W|$)/i;
+        return PATTERN;
     }
 
     innerExtract(context: ParsingContext, match: RegExpMatchArray): ParsingComponents | ParsingResult {

src/locales/en/parsers/ENCasualTimeParser.ts

@@ -4,9 +4,11 @@ import { AbstractParserWithWordBoundaryChecking } from "../../../common/parsers/
 import dayjs from "dayjs";
 import { assignTheNextDay } from "../../../utils/dayjs";
 
+const PATTERN = /(?:this)?\s*(morning|afternoon|evening|night|midnight|noon)(?=\W|$)/i;
+
 export default class ENCasualTimeParser extends AbstractParserWithWordBoundaryChecking {
     innerPattern() {
-        return /(?:this)?\s*(morning|afternoon|evening|night|midnight|noon)(?=\W|$)/i;
+        return PATTERN;
     }
 
     innerExtract(context: ParsingContext, match: RegExpMatchArray) {

src/locales/en/parsers/ENTimeUnitCasualRelativeFormatParser.ts

@@ -4,9 +4,11 @@ import { ParsingComponents } from "../../../results";
 import { AbstractParserWithWordBoundaryChecking } from "../../../common/parsers/AbstractParserWithWordBoundary";
 import { reverseTimeUnits } from "../../../utils/timeunits";
 
+const PATTERN = new RegExp(`(this|last|past|next|\\+|-)\\s*(${TIME_UNITS_PATTERN})(?=\\W|$)`, "i");
+
 export default class ENTimeUnitCasualRelativeFormatParser extends AbstractParserWithWordBoundaryChecking {
     innerPattern(): RegExp {
-        return new RegExp(`(this|last|past|next|\\+|-)\\s*(${TIME_UNITS_PATTERN})(?=\\W|$)`, "i");
+        return PATTERN;
     }
 
     innerExtract(context: ParsingContext, match: RegExpMatchArray): ParsingComponents {