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