Enum#firstValue

NathanPB · Jan 20, 2022 · cb062c4 · cb062c4
1 parent 0146235
commit cb062c4
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Showing 3 changed files with 54 additions and 5 deletions.
diff --git a/src/enum.ts b/src/enum.ts
@@ -85,15 +85,32 @@ export function valueIsSpecificKey<T>(enumerator: Enumerator<T>, key: keyof T, v
  * @param search The value to be searched within the enum's values.
  * @param comparator Function used to check the equality between `search` and the enum values. Default is a strict equality check (a === b).
  */
-export function firstKeyWithValueOf<T, V>(
-  enumerator: Enumerator<T, V>,
+export function firstKeyWithValueOf<K, V>(
+  enumerator: Enumerator<K, V>,
   search: V | any,
   comparator: (search: V, enumValue: V)=>boolean = (search, enumValue) => search === enumValue
-): keyof T {
+): keyof K {
   const [key] = firstOrNull(Object.entries(enumerator), ([_, v]) => comparator(search, v))
     ?? throwExpr(new ValueNotFoundError(search, enumerator))
 
-  return key as keyof T
+  return key as keyof K
+}
+
+/**
+ * Casts a given string value into a TS comprehensible type
+ *
+ * Usually a shorthand for Enum[findFirstKeyWithValue(Enum, 'foo')]
+ *
+ * @param enumerator The enum.
+ * @param search The value to be searched within the enum's values.
+ * @param comparator Function used to check the equality between `search` and the enum values. Default is a strict equality check (a === b).
+ */
+export function firstValue<K, V>(
+  enumerator: Enumerator<K, V>,
+  search: V | any,
+  comparator: (search: V, enumValue: V)=>boolean = (search, enumValue) => search === enumValue
+) : V {
+  return enumerator[firstKeyWithValueOf(enumerator, search, comparator)]
 }
 
 /**

diff --git a/test/benchmark/enum.bench.ts b/test/benchmark/enum.bench.ts
@@ -10,6 +10,8 @@
 
 import {benchmarkSuite} from "@nathanpb/jest-bench";
 import {
+  firstKeyWithValueOf,
+  firstValue,
   isKeyOf,
   isValueOf,
   keys,
@@ -54,5 +56,19 @@ benchmarkSuite('#valueIsSpecificKey', {
   ['best']: () => void valueIsSpecificKey(TestEnum, 'DEPOSIT', TestEnum.DEPOSIT),
   ['avg']: () => void valueIsSpecificKey(TestEnum, 'BAR', TestEnum.BAR),
   ['worst']: () => void valueIsSpecificKey(TestEnum, 'BOANOITE', TestEnum.BOANOITE),
-  ['case not found']: () => { try { valueIsSpecificKey(TestEnum, 'BOANOITE', 'not container here') } catch(_) {} }
+  ['case not found']: () => void valueIsSpecificKey(TestEnum, 'BOANOITE', 'not container here')
+})
+
+benchmarkSuite('#firstKeyWithValueOf', {
+  ['best']: () => void firstKeyWithValueOf(TestEnum, TestEnum.DEPOSIT),
+  ['avg']: () => void firstKeyWithValueOf(TestEnum, TestEnum.BAR),
+  ['worst']: () => void firstKeyWithValueOf(TestEnum, TestEnum.BOANOITE),
+  ['case not found']: () => { try { firstKeyWithValueOf(TestEnum, 'not container here') } catch(_) {} }
+})
+
+benchmarkSuite('#firstValue', {
+  ['best']: () => void firstValue(TestEnum, TestEnum.DEPOSIT),
+  ['avg']: () => void firstValue(TestEnum, TestEnum.BAR),
+  ['worst']: () => void firstValue(TestEnum, TestEnum.BOANOITE),
+  ['case not found']: () => { try { firstValue(TestEnum, 'not container here') } catch(_) {} }
 })
diff --git a/test/enum.test.ts b/test/enum.test.ts
@@ -10,6 +10,7 @@
 
 import {
   firstKeyWithValueOf,
+  firstValue,
   isKeyOf,
   isValueOf,
   keys,
@@ -101,6 +102,21 @@ describe('#firstKeyWithValueOf', () => {
   )
 })
 
+describe('#firstValue', () => {
+  it('Should be DEPOSIT', () =>
+    expect(firstValue(TestEnum, '00')).toEqual('00')
+  )
+
+  it('Should be WITHDRAW', () =>
+    expect(firstValue(TestEnum, '01')).toEqual('01')
+  )
+
+  it('Should throw because the value was not found', () =>
+    expect(() => firstValue(TestEnum, '02'))
+      .toThrowError(ValueNotFoundError)
+  )
+})
+
 describe('#regexKeyMatcher', () => {
   describe('strict', () => {
     const regex = regexKeyMatcher(TestEnum)