Small camelCase conversion adjustments (#1537)

* Small camelCase conversion adjustments

* Remove unused exports

* Extract formatRuns

packages/util/src/string/camelCase.spec.ts

@@ -53,6 +53,9 @@ describe('stringCamelCase', (): void => {
     expect(
       stringCamelCase('DEDUP_KEY_PREFIX')
     ).toEqual('dedupKeyPrefix');
+    expect(
+      stringCamelCase(String('DEDUP_KEY_PREFIX'))
+    ).toEqual('dedupKeyPrefix');
     expect(
       stringCamelCase('SOMETHING')
     ).toEqual('something');
@@ -109,5 +112,6 @@ describe('stringCamelCase', (): void => {
     ).toEqual('aBCDef');
   });
 
-  performance('stringCamelCase', 100_000, randomWords, stringCamelCase);
+  performance('stringCamelCase (random)', 100_000, randomWords, stringCamelCase);
+  performance('stringCamelCase (NFTOrder)', 100_000, [['NFTOrder']], stringCamelCase);
 });

packages/util/src/string/camelCase.ts

@@ -3,6 +3,18 @@
 
 import type { AnyString } from '../types';
 
+export const CC_TO_UP = new Array<string>(256);
+export const CC_TO_LO = new Array<string>(256);
+
+for (let i = 0; i < CC_TO_UP.length; i++) {
+  CC_TO_LO[i] = String.fromCharCode(i).toLowerCase();
+  CC_TO_UP[i] = String.fromCharCode(i).toUpperCase();
+}
+
+function formatRuns (w: string): string {
+  return w.slice(0, w.length - 1).toLowerCase() + CC_TO_UP[w.charCodeAt(w.length - 1)];
+}
+
 // Inspired from https://stackoverflow.com/a/2970667
 //
 // this is not as optimal as the original answer (we split into multiple),
@@ -10,24 +22,22 @@ import type { AnyString } from '../types';
 // a major improvement over the original camelcase npm package (at running)
 //
 // original: 20.88 μs/op
-//     this:  1.20 μs/op
+//     this:  1.09 μs/op
 //
 // Caveat of this: only Ascii, but acceptable for the intended usecase
 function converter (format: (w: string, i: number) => string): (value: AnyString) => string {
-  const formatRuns = (w: string) => w.slice(0, w.length - 1).toLowerCase() + w.slice(-1).toUpperCase();
-
   return (value: AnyString): string => {
     const parts = value
-      .toString()
       // replace all seperators (including consequtive) with spaces
       .replace(/[-_., ]+/g, ' ')
       // we don't want leading or trailing spaces
       .trim()
       // split into words
       .split(' ');
+    const count = parts.length;
     let result = '';
 
-    for (let i = 0; i < parts.length; i++) {
+    for (let i = 0; i < count; i++) {
       const w = parts[i];
 
       // apply the formatting
@@ -52,7 +62,7 @@ function converter (format: (w: string, i: number) => string): (value: AnyString
  */
 export const stringCamelCase = converter((w, i) =>
   // lowercase for first letter/first word, else uppercase first, rest unchanged
-  (i ? w[0].toUpperCase() : w[0].toLowerCase()) + w.slice(1)
+  (i ? CC_TO_UP[w.charCodeAt(0)] : CC_TO_LO[w.charCodeAt(0)]) + w.slice(1)
 );
 
 /**
@@ -61,5 +71,5 @@ export const stringCamelCase = converter((w, i) =>
  */
 export const stringPascalCase = converter((w) =>
   // uppercase the first character, leave the rest unchanged
-  w[0].toUpperCase() + w.slice(1)
+  CC_TO_UP[w.charCodeAt(0)] + w.slice(1)
 );

packages/util/src/string/lowerFirst.spec.ts

@@ -1,6 +1,7 @@
 // Copyright 2017-2022 @polkadot/util authors & contributors
 // SPDX-License-Identifier: Apache-2.0
 
+import { performance } from '../test/performance';
 import { stringLowerFirst } from '.';
 
 describe('stringLowerFirst', (): void => {
@@ -33,4 +34,6 @@ describe('stringLowerFirst', (): void => {
       stringLowerFirst(null)
     ).toBe('');
   });
+
+  performance('stringLowerFirst', 1_000_000, [['HelloWorldSomething']], stringLowerFirst);
 });

packages/util/src/string/lowerFirst.ts

@@ -3,10 +3,12 @@
 
 import type { AnyString } from '../types';
 
-function converter (fn: (value: string) => string): (value?: AnyString | null) => string {
+import { CC_TO_LO, CC_TO_UP } from './camelCase';
+
+function converter (map: string[]): (value?: AnyString | null) => string {
   return (value?: AnyString | null): string =>
     value
-      ? fn(value[0]) + value.slice(1)
+      ? map[value.charCodeAt(0)] + value.slice(1)
       : '';
 }
 
@@ -24,7 +26,7 @@ function converter (fn: (value: string) => string): (value?: AnyString | null) =
  * stringLowerFirst('ABC'); // => 'aBC'
  * ```
  */
-export const stringLowerFirst = converter((s) => s.toLowerCase());
+export const stringLowerFirst = converter(CC_TO_LO);
 
 /**
  * @name stringUpperFirst
@@ -40,4 +42,4 @@ export const stringLowerFirst = converter((s) => s.toLowerCase());
  * stringUpperFirst('abc'); // => 'Abc'
  * ```
  */
-export const stringUpperFirst = converter((s) => s.toUpperCase());
+export const stringUpperFirst = converter(CC_TO_UP);

packages/util/src/string/upperFirst.spec.ts

@@ -1,6 +1,7 @@
 // Copyright 2017-2022 @polkadot/util authors & contributors
 // SPDX-License-Identifier: Apache-2.0
 
+import { performance } from '../test/performance';
 import { stringUpperFirst } from '.';
 
 describe('stringUpperFirst', (): void => {
@@ -33,4 +34,6 @@ describe('stringUpperFirst', (): void => {
       stringUpperFirst(null)
     ).toBe('');
   });
+
+  performance('stringUpperFirst', 1_000_000, [['helloWorldSomething']], stringUpperFirst);
 });