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TypeScript
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104import { stripVTControlCharacters } from "node:util"import stringWidth from "string-width"import type { Rows } from "./row-index.js"
export type Point = { row: number; column: number }export type Selection = { anchor: Point; head: Point }
type Grapheme = { text: string; start: number; end: number }type PlainRow = { width: number; graphemes: Grapheme[] }
const segmenter = new Intl.Segmenter(undefined, { granularity: "grapheme" })const inverse = "\u001b[7m"const reset = "\u001b[0m"
function coordinate(value: number): number { return Number.isFinite(value) ? Math.trunc(value) : value === Infinity ? Number.MAX_SAFE_INTEGER : 0}
function clamp(value: number, maximum: number): number { return Math.min(maximum, Math.max(0, coordinate(value)))}
function plainRow(line: string): PlainRow { const text = stripVTControlCharacters(line) const graphemes: Grapheme[] = [] let column = 0 for (const { segment } of segmenter.segment(text)) { const start = column column += stringWidth(segment) graphemes.push({ text: segment, start, end: column }) } return { width: column, graphemes }}
function ordered(a: Point, b: Point): [Point, Point] { return a.row < b.row || (a.row === b.row && a.column <= b.column) ? [a, b] : [b, a]}
function selected(row: PlainRow, from: number, to: number): string { return row.graphemes .filter(({ start, end }) => end > from && start < to) .map(({ text }) => text) .join("")}
/** Copies a terminal-cell range without ANSI styling or flattening the row source. */export function selectedText(rows: Rows, selection: Selection): string { if (selection.anchor.row === selection.head.row && selection.anchor.column === selection.head.column) return "" if (rows.length === 0) return ""
const lastRow = rows.length - 1 const anchorRow = clamp(selection.anchor.row, lastRow) const headRow = clamp(selection.head.row, lastRow) const firstRow = Math.min(anchorRow, headRow) const finalRow = Math.max(anchorRow, headRow) const source = rows.slice(firstRow, finalRow + 1).map(plainRow) if (source.length === 0) return ""
const point = (candidate: Point, row: number): Point => { const local = source[row - firstRow] return { row, column: clamp(candidate.column, local?.width ?? 0) } } const [start, end] = ordered( point(selection.anchor, anchorRow), point(selection.head, headRow), ) if (start.row === end.row && start.column === end.column) return ""
return source.map((row, offset) => { const rowNumber = firstRow + offset const from = rowNumber === start.row ? start.column : 0 const to = rowNumber === end.row ? end.column : row.width return selected(row, from, to) }).join("\n")}
/** Adds inverse video to the selected cells of a visible row window. */export function highlightSelection(lines: string[], startRow: number, selection: Selection): string[] { const [start, end] = ordered(selection.anchor, selection.head) if (start.row === end.row && start.column === end.column) return lines
return lines.map((line, offset) => { const rowNumber = startRow + offset if (rowNumber < start.row || rowNumber > end.row) return line
const row = plainRow(line) const from = clamp(rowNumber === start.row ? start.column : 0, row.width) const to = clamp(rowNumber === end.row ? end.column : row.width, row.width) const chosen = row.graphemes.map(({ start, end }) => end > from && start < to) if (!chosen.some(Boolean)) return line
let result = "" let highlighted = false row.graphemes.forEach(({ text }, index) => { if (chosen[index] !== highlighted) { result += chosen[index] ? inverse : reset highlighted = chosen[index]! } result += text }) return result + (highlighted ? reset : "") })}