135 lines
4.4 KiB
JavaScript
135 lines
4.4 KiB
JavaScript
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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