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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 | 1x 1x 1x 1x 5x 5x 5x 5x 18x | import { pipe } from "@benneq/function";
import { map, takeWhile } from "@benneq/iterable";
import { numberSequence } from "@benneq/number";
import { CharCodeRange } from "./_types";
import { charCodeOf } from "./charCodeOf";
/**
* Iterates over a range of characters.
*
* Only the first character of the `initialCharacter` will be used.
*
* If `initialCharacter` is empty, the sequence will start with `rangeStart` if
* `stepSize` is positive, or `rangeEnd` if `stepSize` is negative.
*
* If `stepSize` is `0` the sequence is empty.
*
* @example
* Iterate over `uppercaseAsciiLetterRange`
* ```ts
* for (const c of characterSequence(uppercaseAsciiLetterRange)) {
* console.log(c); // 'A','B',...,'Z'
* }
* ```
*
* @example
* Start at letter 'D' and iterate backwards
* ```ts
* for (const c of characterSequence(uppercaseAsciiLetterRange, 'D', -1)) {
* console.log(c); // 'D','C','B','A'
* }
* ```
*
* @example
* Create a character Array
* ```ts
* const a = [...characterSequence(uppercaseAsciiLetterRange, 'V', 2)];
* console.log(a); // ['V', 'X', 'Z']
* ```
*
* @returns an Iterable that iterates through the characters
*/
export const characterSequence = (
[rangeStart, rangeEnd]: CharCodeRange,
initialCharacter = "",
stepSize = 1,
// internal variables:
charCode = initialCharacter
? charCodeOf(initialCharacter)
: stepSize < 0
? rangeEnd
: rangeStart
): Iterable<string> => {
if (process.env.NODE_ENV !== "production") {
console.assert(stepSize >= 1);
}
return pipe(
takeWhile<number>((value) => value >= rangeStart && value <= rangeEnd),
map(String.fromCharCode)
)(numberSequence(charCode, stepSize));
};
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