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feat: support custom alphabet #421

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feat: support custom alphabet #421

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da0fc12
feat: support custom alphabet
seia-soto Feb 15, 2024
b493c34
chore: remove export of convertBaseShim
seia-soto Feb 15, 2024
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8 changes: 7 additions & 1 deletion readme.md
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Original file line number Diff line number Diff line change
Expand Up @@ -12,12 +12,18 @@

```ts
// Install it with `npm i baseroo`
import { convertBase } from 'baseroo'
import { convertBase, customAlphabet } from 'baseroo'

const base16Value = '8f.3333333333'

// Works for floating point numbers to a precision of 10 places.
const base10Value = convertBase(base16Value, 16, 10) // '143.1999999999'

// Supports base conversion using custom alphabet
const convertBaseWithUserAlphabet = customAlphabet(
'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/'
)
const base32Value = convertBase(base16Value, 16, 32) // '4f.6cpj6cpj'
```

### Background
Expand Down
15 changes: 9 additions & 6 deletions src/baseroo.ts
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Expand Up @@ -23,9 +23,6 @@ function bigIntPow(x: bigint, y: bigint): bigint {
return x * p2 * p2
}

export const defaultAlphabet = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/'
const defaultAlphabetRange = defaultAlphabet.split('')

function convertToBase10Integer(integerValue: string, fromAlphabet: string[]): bigint {
const fromBase = BigInt(fromAlphabet.length)

Expand Down Expand Up @@ -76,9 +73,7 @@ function convertFromBase10Fractional(base10Fractional: number, toAlphabet: strin
return value
}

export function convertBase(value: string, fromBase: number, toBase: number): string {
const range = defaultAlphabetRange

function convertBaseShim(range: string[], value: string, fromBase: number, toBase: number): string {
if (fromBase < 2 || fromBase > range.length) {
throw new InvalidBaseError('fromBase', fromBase, range.length)
}
Expand All @@ -104,3 +99,11 @@ export function convertBase(value: string, fromBase: number, toBase: number): st

return toBaseSign + toBaseInteger
}

export function customAlphabet(alphabet: string) {
return convertBaseShim.bind(null, alphabet.split(''))
}

export const defaultAlphabet = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/'

export const convertBase = customAlphabet(defaultAlphabet)