Python's operator.mul in TypeScript

How to use

Install via yarn add locutus and import: import { mul } from 'locutus/python/operator/mul'.

Or with CommonJS: const { mul } = require('locutus/python/operator/mul')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	mul(6, 7)	42
2	mul('ha', 3)	'hahaha'

Notes

• Multiplies numbers and repeats strings or arrays like Python’s operator.mul.

Dependencies

This function uses the following Locutus functions:

• _operator (python/_helpers)

Here's what our current TypeScript equivalent to Python's operator.mul looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

Copy code

import { pythonMul } from '../_helpers/_operator.ts'

export function mul(a: unknown, b: unknown): number | string | unknown[] {
  //      discuss at: https://locutus.io/python/operator/mul/
  // parity verified: Python 3.12
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Multiplies numbers and repeats strings or arrays like Python's operator.mul.
  //       example 1: mul(6, 7)
  //       returns 1: 42
  //       example 2: mul('ha', 3)
  //       returns 2: 'hahaha'

  return pythonMul(a, b, 'mul')
}

import { pythonMul } from '../_helpers/_operator.ts'

export function mul(a, b) {
  //      discuss at: https://locutus.io/python/operator/mul/
  // parity verified: Python 3.12
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Multiplies numbers and repeats strings or arrays like Python's operator.mul.
  //       example 1: mul(6, 7)
  //       returns 1: 42
  //       example 2: mul('ha', 3)
  //       returns 2: 'hahaha'

  return pythonMul(a, b, 'mul')
}

// python/_helpers/_operator (Locutus helper dependency)
function toPythonNumber(value: unknown, functionName: string): number {
  if (typeof value === 'number') {
    return value
  }

  if (typeof value === 'boolean') {
    return value ? 1 : 0
  }

  if (typeof value === 'bigint') {
    const numericValue = Number(value)
    if (!Number.isSafeInteger(numericValue)) {
      throw new RangeError(`${functionName}() bigint values must fit within JS safe integer precision`)
    }

    return numericValue
  }

  throw new TypeError(`${functionName}() expected a numeric value`)
}

function toPythonInteger(value: unknown, functionName: string): bigint {
  if (typeof value === 'boolean') {
    return value ? 1n : 0n
  }

  if (typeof value === 'bigint') {
    return value
  }

  if (typeof value === 'number' && Number.isFinite(value) && Number.isSafeInteger(value)) {
    return BigInt(value)
  }

  throw new TypeError(`${functionName}() expected an integer value`)
}

function fromPythonInteger(value: bigint, functionName: string): number {
  const numericValue = Number(value)
  if (!Number.isSafeInteger(numericValue)) {
    throw new RangeError(`${functionName}() result does not fit within JS safe integer precision`)
  }

  return numericValue
}

function pythonMul(left: unknown, right: unknown, functionName: string): number | string | unknown[] {
  if (typeof left === 'string') {
    return repeatString(left, right, functionName)
  }

  if (typeof right === 'string') {
    return repeatString(right, left, functionName)
  }

  if (Array.isArray(left)) {
    return repeatArray(left, right, functionName)
  }

  if (Array.isArray(right)) {
    return repeatArray(right, left, functionName)
  }

  return toPythonNumber(left, functionName) * toPythonNumber(right, functionName)
}

function repeatString(value: string, count: unknown, functionName: string): string {
  const normalized = normalizeRepeatCount(count, functionName)
  return value.repeat(normalized)
}

function repeatArray(value: unknown[], count: unknown, functionName: string): unknown[] {
  const normalized = normalizeRepeatCount(count, functionName)
  const out: unknown[] = []
  for (let index = 0; index < normalized; index += 1) {
    out.push(...value)
  }
  return out
}

function normalizeRepeatCount(count: unknown, functionName: string): number {
  const bigintCount = toPythonInteger(count, functionName)
  if (bigintCount <= 0n) {
    return 0
  }

  return fromPythonInteger(bigintCount, functionName)
}

// python/operator/mul (target function module)
function mul(a: unknown, b: unknown): number | string | unknown[] {
  //      discuss at: https://locutus.io/python/operator/mul/
  // parity verified: Python 3.12
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Multiplies numbers and repeats strings or arrays like Python's operator.mul.
  //       example 1: mul(6, 7)
  //       returns 1: 42
  //       example 2: mul('ha', 3)
  //       returns 2: 'hahaha'

  return pythonMul(a, b, 'mul')
}

// python/_helpers/_operator (Locutus helper dependency)
function toPythonNumber(value, functionName) {
  if (typeof value === 'number') {
    return value
  }

  if (typeof value === 'boolean') {
    return value ? 1 : 0
  }

  if (typeof value === 'bigint') {
    const numericValue = Number(value)
    if (!Number.isSafeInteger(numericValue)) {
      throw new RangeError(`${functionName}() bigint values must fit within JS safe integer precision`)
    }

    return numericValue
  }

  throw new TypeError(`${functionName}() expected a numeric value`)
}

function toPythonInteger(value, functionName) {
  if (typeof value === 'boolean') {
    return value ? 1n : 0n
  }

  if (typeof value === 'bigint') {
    return value
  }

  if (typeof value === 'number' && Number.isFinite(value) && Number.isSafeInteger(value)) {
    return BigInt(value)
  }

  throw new TypeError(`${functionName}() expected an integer value`)
}

function fromPythonInteger(value, functionName) {
  const numericValue = Number(value)
  if (!Number.isSafeInteger(numericValue)) {
    throw new RangeError(`${functionName}() result does not fit within JS safe integer precision`)
  }

  return numericValue
}

function pythonMul(left, right, functionName) {
  if (typeof left === 'string') {
    return repeatString(left, right, functionName)
  }

  if (typeof right === 'string') {
    return repeatString(right, left, functionName)
  }

  if (Array.isArray(left)) {
    return repeatArray(left, right, functionName)
  }

  if (Array.isArray(right)) {
    return repeatArray(right, left, functionName)
  }

  return toPythonNumber(left, functionName) * toPythonNumber(right, functionName)
}

function repeatString(value, count, functionName) {
  const normalized = normalizeRepeatCount(count, functionName)
  return value.repeat(normalized)
}

function repeatArray(value, count, functionName) {
  const normalized = normalizeRepeatCount(count, functionName)
  const out = []
  for (let index = 0; index < normalized; index += 1) {
    out.push(...value)
  }
  return out
}

function normalizeRepeatCount(count, functionName) {
  const bigintCount = toPythonInteger(count, functionName)
  if (bigintCount <= 0n) {
    return 0
  }

  return fromPythonInteger(bigintCount, functionName)
}

// python/operator/mul (target function module)
function mul(a, b) {
  //      discuss at: https://locutus.io/python/operator/mul/
  // parity verified: Python 3.12
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Multiplies numbers and repeats strings or arrays like Python's operator.mul.
  //       example 1: mul(6, 7)
  //       returns 1: 42
  //       example 2: mul('ha', 3)
  //       returns 2: 'hahaha'

  return pythonMul(a, b, 'mul')
}

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