79 lines
1.6 KiB
JavaScript
79 lines
1.6 KiB
JavaScript
/**
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* Split a string by graphemes, not just bytes
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* @param s - the string to split into 'characters'
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*/
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export function chars(s: string): string[] {
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return s.split(/(?:)/u);
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}
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/**
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* Get the 'character length' of a string, not its UTF16 byte count
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* @param s - the string to check
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*/
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export function strlen(s: string): number {
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return chars(s).length;
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}
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/**
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* Is the character part of ascii?
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*
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* @param char - a one character string to check
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*/
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export function is_ascii(char: string): boolean {
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return chars(char).every((char) => {
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const point = char.codePointAt(0);
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if (point === undefined) {
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return false;
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}
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return point < 0x80;
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});
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}
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/**
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* Is the one char in the string an ascii control character?
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*
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* @param char - a one character string to check
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*/
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export function is_control(char: string): boolean {
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const code = char.codePointAt(0);
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if (code === undefined) {
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return false;
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}
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return is_ascii(char) && (code === 0x7f || code < 0x20);
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}
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/**
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* Get the key code for a ctrl chord
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* @param char - a one character string
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*/
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export function ctrl_key(char: string): string {
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// This is the normal use case, of course
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if (is_ascii(char)) {
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const point = char.codePointAt(0);
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if (point === undefined) {
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return char;
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}
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return String.fromCodePoint(point & 0x1f);
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}
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// If it's not ascii, just return the input key code
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return char;
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}
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/**
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* Trim a string to a max number of characters
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* @param s
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* @param maxLen
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*/
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export function truncate(s: string, maxLen: number): string {
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const chin = chars(s);
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if (maxLen >= chin.length) {
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return s;
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}
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return chin.slice(0, maxLen).join('');
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}
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