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Copy pathstring.ts
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241 lines (216 loc) · 6.83 KB
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import { count_iterator } from './iterator.ts';
/**
* Truncates a string to a maximum length, adding a suffix if needed that defaults to `...`.
*/
export const truncate = (str: string, maxLength: number, suffix = '...'): string => {
if (maxLength < suffix.length) return '';
if (str.length > maxLength) {
return str.substring(0, maxLength - suffix.length) + suffix;
}
return str;
};
/**
* Removes characters inclusive of `stripped`.
*/
export const strip_start = (source: string, stripped: string): string => {
if (!stripped || !source.startsWith(stripped)) return source;
return source.substring(stripped.length);
};
/**
* Removes characters inclusive of `stripped`.
*/
export const strip_end = (source: string, stripped: string): string => {
if (!stripped || !source.endsWith(stripped)) return source;
return source.substring(0, source.length - stripped.length);
};
/**
* Removes characters inclusive of `stripped`.
*/
export const strip_after = (source: string, stripped: string): string => {
if (!stripped) return source;
const idx = source.indexOf(stripped);
if (idx === -1) return source;
return source.substring(0, idx);
};
/**
* Removes characters inclusive of `stripped`.
*/
export const strip_before = (source: string, stripped: string): string => {
if (!stripped) return source;
const idx = source.indexOf(stripped);
if (idx === -1) return source;
return source.substring(idx + stripped.length);
};
/**
* Adds the substring `ensured` to the start of the `source` string if it's not already present.
*/
export const ensure_start = (source: string, ensured: string): string => {
if (source.startsWith(ensured)) return source;
return ensured + source;
};
/**
* Adds the substring `ensured` to the end of the `source` string if it's not already present.
*/
export const ensure_end = (source: string, ensured: string): string => {
if (source.endsWith(ensured)) return source;
return source + ensured;
};
/**
* Removes leading and trailing spaces from each line of a string.
*/
export const deindent = (str: string): string =>
str
.split('\n')
.filter(Boolean)
.map((s) => s.trim())
.join('\n');
/**
* Returns a plural suffix based on a count.
*/
export const plural = (count: number | undefined | null, suffix = 's'): string =>
count === 1 ? '' : suffix;
/**
* Returns the count of graphemes in a string, the individually rendered characters.
*/
export const count_graphemes = (str: string): number =>
count_iterator(new Intl.Segmenter().segment(str));
/**
* Strips ANSI escape sequences from a string.
*/
export const strip_ansi = (str: string): string => str.replaceAll(/\x1B\[[0-9;]*[a-zA-Z]/g, ''); // eslint-disable-line no-control-regex
/**
* Stringifies a value like `JSON.stringify` but with some corner cases handled better.
*
* @source https://2ality.com/2025/04/stringification-javascript.html
*/
export const stringify = (value: unknown): string =>
typeof value === 'bigint' ? value + 'n' : (JSON.stringify(value) ?? String(value));
/**
* Calculate the display width of a string in terminal columns.
* - Strips ANSI escape codes (they have 0 width)
* - Emojis and other wide characters take 2 columns
* - Tab characters take 4 columns
* - Newlines and other control characters take 0 columns
* - Uses `Intl.Segmenter` to properly handle grapheme clusters (e.g., family emoji "👨👩👧👦")
*/
export const string_display_width = (str: string): number => {
// Strip ANSI codes first (they have 0 display width)
const clean = strip_ansi(str);
let width = 0;
const segmenter = new Intl.Segmenter();
for (const { segment } of segmenter.segment(clean)) {
const code = segment.codePointAt(0)!;
// Handle control characters
if (code === 0x09) {
// Tab = 4 columns
width += 4;
continue;
}
if (code < 0x20 || (code >= 0x7f && code < 0xa0)) {
// Other control characters (including newline) = 0 width
continue;
}
// Emoji and other wide characters (rough heuristic)
// - Most emoji are in range 0x1F300-0x1FAFF
// - Some are in 0x2600-0x27BF (misc symbols)
// - CJK characters 0x4E00-0x9FFF also double-width
// - Grapheme clusters with multiple code points (like ZWJ sequences) are typically emoji
if (
segment.length > 1 || // Multi-codepoint graphemes (ZWJ sequences, etc.)
(code >= 0x1f300 && code <= 0x1faff) ||
(code >= 0x2600 && code <= 0x27bf) ||
(code >= 0x1f600 && code <= 0x1f64f) ||
(code >= 0x1f680 && code <= 0x1f6ff) ||
(code >= 0x4e00 && code <= 0x9fff) // CJK
) {
width += 2;
} else {
width += 1;
}
}
return width;
};
/**
* Pad a string to a target display width (accounting for wide characters).
*/
export const pad_width = (
str: string,
target_width: number,
align: 'left' | 'right' = 'left'
): string => {
const current_width = string_display_width(str);
const padding = Math.max(0, target_width - current_width);
if (align === 'left') {
return str + ' '.repeat(padding);
} else {
return ' '.repeat(padding) + str;
}
};
/**
* Calculates the Levenshtein distance between two strings.
* Useful for typo detection and fuzzy matching.
*
* @returns the edit distance between the strings
*/
export const levenshtein_distance = (a: string, b: string): number => {
if (a.length === 0) return b.length;
if (b.length === 0) return a.length;
if (a === b) return 0;
// Use shorter string for rows to minimize space
const a_shorter = a.length <= b.length;
const short = a_shorter ? a : b;
const long = a_shorter ? b : a;
const short_len = short.length;
const long_len = long.length;
// Only need two rows: previous and current
let prev = new Uint16Array(short_len + 1);
let curr = new Uint16Array(short_len + 1);
// Initialize first row
for (let j = 0; j <= short_len; j++) {
prev[j] = j;
}
for (let i = 1; i <= long_len; i++) {
curr[0] = i;
const long_char = long.charCodeAt(i - 1);
for (let j = 1; j <= short_len; j++) {
if (long_char === short.charCodeAt(j - 1)) {
curr[j] = prev[j - 1]!;
} else {
curr[j] = 1 + Math.min(prev[j - 1]!, prev[j]!, curr[j - 1]!);
}
}
[prev, curr] = [curr, prev];
}
return prev[short_len]!;
};
/**
* Escapes a string for use inside a single-quoted JS string literal.
*
* Uses a single-pass regex replacement to escape backslashes, single quotes,
* newlines, carriage returns, and Unicode line/paragraph separators.
*/
export const escape_js_string = (value: string): string =>
value.replace(/[\\'\n\r\u2028\u2029]/g, (ch) => {
switch (ch) {
case '\\':
return '\\\\';
case "'":
return "\\'";
case '\n':
return '\\n';
case '\r':
return '\\r';
case '\u2028':
return '\\u2028';
case '\u2029':
return '\\u2029';
default:
return ch;
}
});
/**
* Check if content appears to be binary.
*
* Checks for null bytes in the first 8KB of content.
*/
export const string_is_binary = (content: string): boolean => content.slice(0, 8192).includes('\0');