Intlayer

import { splitTextByLines } from './splitTextByLine'; type TrunkOptions = { lineStart?: number; lineLength?: number; charStart?: number; charLength?: number; }; export const getChunk = (text: string, options: TrunkOptions = {}): string => { const { lineStart, lineLength, charStart, charLength } = options; // Fast-path: if no filters were provided, return the whole text if ( lineStart === undefined && lineLength === undefined && charStart === undefined && charLength === undefined ) { return text; } // --------------------------------------------------------------------------- // Utility helpers to convert between line numbers and absolute char indices // --------------------------------------------------------------------------- const lines = splitTextByLines(text); const getCharIndexOfLineStart = (lineNumber: number): number => { if (lineNumber <= 0) return 0; // Sum the length of every previous line let idx = 0; for (let i = 0; i < Math.min(lineNumber, lines.length); i++) { idx += lines[i].length; } return idx; }; const getCharIndexOfLineEnd = (lineNumber: number): number => { // If the requested line number exceeds the number of lines, clamp to the last character if (lineNumber >= lines.length) { return text.length; } const line = lines[lineNumber]; const lineEnd = getCharIndexOfLineStart(lineNumber) + line.length; return lineEnd; }; // --------------------------------------------------------------------------- // Compute the effective (inclusive) charStart/charEnd for the requested slice // --------------------------------------------------------------------------- let effectiveStart = 0; // inclusive let effectiveEnd = text.length; // exclusive // Apply line boundaries if provided if (lineStart !== undefined) { effectiveStart = Math.max( effectiveStart, getCharIndexOfLineStart(lineStart) ); } // Apply character boundaries if provided if (charStart !== undefined) { effectiveStart = Math.max(effectiveStart, charStart); } // Apply line length boundary from lineStart (or 0) if (lineLength !== undefined) { const endLine = (lineStart ?? 0) + lineLength - 1; effectiveEnd = Math.min(effectiveEnd, getCharIndexOfLineEnd(endLine)); } // Apply character length boundary from effectiveStart if (charLength !== undefined) { effectiveEnd = Math.min( effectiveEnd, (charStart ?? effectiveStart) + charLength ); } // If bounds do not overlap, return empty string if (effectiveStart >= effectiveEnd) { return ''; } return text.slice(effectiveStart, effectiveEnd); };