name : foldFlowLines.js 'use strict'; const FOLD_FLOW = 'flow'; const FOLD_BLOCK = 'block'; const FOLD_QUOTED = 'quoted'; /** * Tries to keep input at up to `lineWidth` characters, splitting only on spaces * not followed by newlines or spaces unless `mode` is `'quoted'`. Lines are * terminated with `\n` and started with `indent`. */ function foldFlowLines(text, indent, mode = 'flow', { indentAtStart, lineWidth = 80, minContentWidth = 20, onFold, onOverflow } = {}) { if (!lineWidth || lineWidth < 0) return text; const endStep = Math.max(1 + minContentWidth, 1 + lineWidth - indent.length); if (text.length <= endStep) return text; const folds = []; const escapedFolds = {}; let end = lineWidth - indent.length; if (typeof indentAtStart === 'number') { if (indentAtStart > lineWidth - Math.max(2, minContentWidth)) folds.push(0); else end = lineWidth - indentAtStart; } let split = undefined; let prev = undefined; let overflow = false; let i = -1; let escStart = -1; let escEnd = -1; if (mode === FOLD_BLOCK) { i = consumeMoreIndentedLines(text, i); if (i !== -1) end = i + endStep; } for (let ch; (ch = text[(i += 1)]);) { if (mode === FOLD_QUOTED && ch === '\\') { escStart = i; switch (text[i + 1]) { case 'x': i += 3; break; case 'u': i += 5; break; case 'U': i += 9; break; default: i += 1; } escEnd = i; } if (ch === '\n') { if (mode === FOLD_BLOCK) i = consumeMoreIndentedLines(text, i); end = i + endStep; split = undefined; } else { if (ch === ' ' && prev && prev !== ' ' && prev !== '\n' && prev !== '\t') { // space surrounded by non-space can be replaced with newline + indent const next = text[i + 1]; if (next && next !== ' ' && next !== '\n' && next !== '\t') split = i; } if (i >= end) { if (split) { folds.push(split); end = split + endStep; split = undefined; } else if (mode === FOLD_QUOTED) { // white-space collected at end may stretch past lineWidth while (prev === ' ' || prev === '\t') { prev = ch; ch = text[(i += 1)]; overflow = true; } // Account for newline escape, but don't break preceding escape const j = i > escEnd + 1 ? i - 2 : escStart - 1; // Bail out if lineWidth & minContentWidth are shorter than an escape string if (escapedFolds[j]) return text; folds.push(j); escapedFolds[j] = true; end = j + endStep; split = undefined; } else { overflow = true; } } } prev = ch; } if (overflow && onOverflow) onOverflow(); if (folds.length === 0) return text; if (onFold) onFold(); let res = text.slice(0, folds[0]); for (let i = 0; i < folds.length; ++i) { const fold = folds[i]; const end = folds[i + 1] || text.length; if (fold === 0) res = `\n${indent}${text.slice(0, end)}`; else { if (mode === FOLD_QUOTED && escapedFolds[fold]) res += `${text[fold]}\\`; res += `\n${indent}${text.slice(fold + 1, end)}`; } } return res; } /** * Presumes `i + 1` is at the start of a line * @returns index of last newline in more-indented block */ function consumeMoreIndentedLines(text, i) { let ch = text[i + 1]; while (ch === ' ' || ch === '\t') { do { ch = text[(i += 1)]; } while (ch && ch !== '\n'); ch = text[i + 1]; } return i; } exports.FOLD_BLOCK = FOLD_BLOCK; exports.FOLD_FLOW = FOLD_FLOW; exports.FOLD_QUOTED = FOLD_QUOTED; exports.foldFlowLines = foldFlowLines;