ability to parse from string

.github/workflows/publish.yml

@@ -16,8 +16,7 @@ jobs:
           registry-url: "https://registry.npmjs.org"
 
       - run: yarn install --frozen-lockfile
-      - run: yarn test
-      - run: yarn build
+      - run: yarn ci
 
       - run: npm publish
         env:

.github/workflows/test.yml

@@ -22,6 +22,4 @@ jobs:
           cache: "yarn"
 
       - run: yarn install --frozen-lockfile
-      - run: yarn format-check
-      - run: yarn test-cov
-      - run: yarn build
+      - run: yarn ci

package.json

@@ -1,7 +1,7 @@
 {
   "type": "module",
   "name": "fractions-math",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "author": "Vlad Pronsky <v.pronsky@gmail.com>",
   "repository": "vladkens/fractions-math",
   "description": "Implementing fractions module from The Python Standard Library on TypeScript",
@@ -26,7 +26,8 @@
     "test-cov": "c8 --include=src yarn test",
     "test-watch": "watchexec -c -e ts 'clear && yarn test'",
     "format": "prettier --write 'src/**/*.ts'",
-    "format-check": "prettier --check 'src/**/*.ts'"
+    "format-check": "prettier --check 'src/**/*.ts'",
+    "ci": "yarn format-check && yarn test-cov && yarn build"
   },
   "dependencies": {},
   "devDependencies": {

readme.md

@@ -40,12 +40,17 @@ const f5 = f4.div(f1).toString() // -> "6" (3 / 0.5)
 
 ## API
 
-### `fraq(...args) / Fraction.make(...args)`
+### `Fraction.make(...args: [Fraq] | [number, number])`
 
 Helper function to create fraction from various inputs.
+Also alias available: `fraq`
 
 ```typescript
-fraq(1, 2).toPair() // -> [1, 2]
+type Fraq = Fraction | [number, number] | number | string
+
+Fraction.make(1, 2).toPair() // -> [1, 2]
+fraq(1, 2).toPair() // ALIAS
+
 fraq(2).toPair() // -> [2, 1]
 fraq([2, 1]).toPair() // -> [2, 1]
 fraq(0.5).toPair() // -> [1, 2]
@@ -86,46 +91,46 @@ fraq(Math.PI).limit(1000).toString() // -> "355/113"
 fraq(1.1).limit().toString() // -> "11/10"
 ```
 
-### `.add(b: Fraction | number | [number, number])`
+### `.add(b: Fraq)`
 
 ```typescript
 fraq(1, 2).add([-1, 2]).toString() // -> "0"
 fraq(1, 2).add(1).toString() // -> "3/2"
 ```
 
-### `.sub(b: Fraction | number | [number, number])`
+### `.sub(b: Fraq)`
 
 ```typescript
 fraq(1, 2).sub([1, 2]).toString() // -> "0"
 fraq(1, 2).sub(1).toString() // -> "-1/2"
 ```
 
-### `.mul(b: Fraction | number | [number, number])`
+### `.mul(b: Fraq)`
 
 ```typescript
 fraq(1, 2).mul([1, 2]).toString() // -> "1/4"
 fraq(1, 2).mul(1.5).toString() // -> "3/4"
 ```
 
-### `.div(b: Fraction | number | [number, number])`
+### `.div(b: Fraq)`
 
 ```typescript
 fraq(1, 2).div([1, 2]).toString() // -> "1"
 fraq(1, 2).div(1.5).toString() // -> "1/3"
 fraq(1, 2).div(0).toString() // throws Error
 ```
 
-### `.eq(b: Fraction | number | [number, number])`
+### `.eq(b: Fraq)`
 
 ```typescript
 fraq(1, 2).eq(0.5) // -> true
 fraq(1, 2).eq([1, 3]) // -> false
 ```
 
-### `.lt(b: Fraction | number | [number, number]) -> boolean`
+### `.lt(b: Fraq) -> boolean`
 
-### `.lte(b: Fraction | number | [number, number]) -> boolean`
+### `.lte(b: Fraq) -> boolean`
 
-### `.gt(b: Fraction | number | [number, number]) -> boolean`
+### `.gt(b: Fraq) -> boolean`
 
-### `.gte(b: Fraction | number | [number, number]) -> boolean`
+### `.gte(b: Fraq) -> boolean`

src/main.test.ts

@@ -184,4 +184,62 @@ test("other", () => {
   equal(new Fraction(0, -1).toParts(), { s: 1, c: 0, n: 0, d: 1 })
 })
 
+test("should parse from string", () => {
+  equal(fraq("0").toPair(), [0, 1])
+  equal(fraq("1").toPair(), [1, 1])
+  equal(fraq("2").toPair(), [2, 1])
+
+  equal(fraq("-0").toPair(), [0, 1])
+  equal(fraq("-1").toPair(), [-1, 1])
+  equal(fraq("-2").toPair(), [-2, 1])
+
+  equal(fraq("1/1").toPair(), [1, 1])
+  equal(fraq("1/2").toPair(), [1, 2])
+  equal(fraq("1/3").toPair(), [1, 3])
+  equal(fraq("3/2").toPair(), [3, 2])
+  equal(fraq("3/4").toPair(), [3, 4])
+  equal(fraq("-1/2").toPair(), [-1, 2])
+  equal(fraq("1/-2").toPair(), [-1, 2])
+  throws(() => fraq("1/0").toPair(), /ZeroDivisionError/i)
+
+  equal(fraq("1 1/2").toPair(), [3, 2])
+  equal(fraq("1 1/3").toPair(), [4, 3])
+  equal(fraq("2 1/2").toPair(), [5, 2])
+  equal(fraq("2 1/3").toPair(), [7, 3])
+  equal(fraq("-1 1/2").toPair(), [-3, 2])
+  equal(fraq("-1 -1/2").toPair(), [3, 2])
+  equal(fraq("-1 -1/-2").toPair(), [-3, 2])
+  throws(() => fraq("1 1/0").toPair(), /ZeroDivisionError/i)
+
+  equal(fraq("2 9/3").toPair(), [5, 1])
+  equal(fraq("3 27/9").toPair(), [6, 1])
+
+  equal(fraq("0.5").toPair(), [1, 2])
+  equal(fraq("1.5").toPair(), [3, 2])
+  equal(fraq("-0.5").toPair(), [-1, 2])
+  equal(fraq("-1.5").toPair(), [-3, 2])
+  equal(fraq(".5").toPair(), [1, 2])
+  equal(fraq("-.5").toPair(), [-1, 2])
+  equal(fraq(".0").toPair(), [0, 1])
+  equal(fraq("-.0").toPair(), [0, 1])
+
+  equal(fraq("1.33").toPair(), [133, 100])
+  equal(fraq("1.333").toPair(), [1333, 1000])
+  equal(fraq("1.3333").toPair(), [13333, 10000])
+
+  equal(fraq(" 1/2 ").toPair(), [1, 2])
+  equal(fraq(" 1 1/2 ").toPair(), [3, 2])
+  equal(fraq(" -1/2 ").toPair(), [-1, 2])
+  equal(fraq(" -1 -1/-2 ").toPair(), [-3, 2])
+
+  equal(fraq(" 1 / 2 ").toPair(), [1, 2])
+  equal(fraq(" 1 1 / 2 ").toPair(), [3, 2])
+  equal(fraq("  -1  1  /  -2  ").toPair(), [3, 2])
+
+  throws(() => fraq("1 abc").toPair(), /ValueError/i)
+  throws(() => fraq("1 1/a").toPair(), /ValueError/i)
+  throws(() => fraq("a/1").toPair(), /ValueError/i)
+  throws(() => fraq("1/a").toPair(), /ValueError/i)
+})
+
 test.run()

src/main.ts

@@ -4,7 +4,7 @@
  * https://github.com/python/cpython/blob/3.11/Lib/fractions.py
  */
 
-export type Fraq = Fraction | [number, number] | number
+export type Fraq = Fraction | [number, number] | number | string
 type Parts = { s: 1 | -1; c: Number; n: Number; d: Number }
 
 export const gcd = (a: number, b: number): number => {
@@ -46,7 +46,7 @@ export class Fraction {
     this.d = b / g
   }
 
-  static make(...args: [Fraq] | [number, number]) {
+  static make(...args: [Fraq] | [number, number]): Fraction {
     if (args.length === 2) return new Fraction(...args)
 
     const val = args[0]
@@ -61,6 +61,34 @@ export class Fraction {
       return new Fraction(n, d)
     }
 
+    if (typeof val === "string") {
+      const m1 = /^([-]?\d+)\s+([-]?\d+)\s*\/\s*([-]?\d+)$/.exec(val.trim())
+      if (m1) {
+        const [c, n, d] = m1.slice(1).map((x) => parseInt(x, 10))
+        const s = Math.sign(c) * Math.sign(n) * Math.sign(d)
+
+        const b = Math.abs(d)
+        const a = (Math.abs(c) * b + Math.abs(n)) * s
+        return new Fraction(a, b)
+      }
+
+      const m2 = /^([-]?\d+)\s*\/\s*([-]?\d+)$/.exec(val.trim())
+      if (m2) {
+        const [n, d] = m2.slice(1).map((x) => parseInt(x, 10))
+        return new Fraction(n, d)
+      }
+
+      if (/^([-]?\d+)$/.test(val)) {
+        return new Fraction(parseInt(val, 10), 1)
+      }
+
+      if (/^([-]?\d*)\.(\d+)$/.test(val)) {
+        return Fraction.make(parseFloat(val))
+      }
+
+      throw new Error("ValueError")
+    }
+
     return new Fraction(...val)
   }