export function getFoldingRanges()

in src/services/htmlFolding.ts [83:171]
81 lines of code
26 McCabe index (conditional complexity)

export function getFoldingRanges(document: TextDocument, context: { rangeLimit?: number }): FoldingRange[] {
	const scanner = createScanner(document.getText());
	let token = scanner.scan();
	const ranges: FoldingRange[] = [];
	const stack: { startLine: number, tagName: string }[] = [];
	let lastTagName = null;
	let prevStart = -1;

	function addRange(range: FoldingRange) {
		ranges.push(range);
		prevStart = range.startLine;
	}

	while (token !== TokenType.EOS) {
		switch (token) {
			case TokenType.StartTag: {
				const tagName = scanner.getTokenText();
				const startLine = document.positionAt(scanner.getTokenOffset()).line;
				stack.push({ startLine, tagName });
				lastTagName = tagName;
				break;
			}
			case TokenType.EndTag: {
				lastTagName = scanner.getTokenText();
				break;
			}
			case TokenType.StartTagClose:
				if (!lastTagName || !isVoidElement(lastTagName)) {
					break;
				}
			// fallthrough
			case TokenType.EndTagClose:
			case TokenType.StartTagSelfClose: {
				let i = stack.length - 1;
				while (i >= 0 && stack[i].tagName !== lastTagName) {
					i--;
				}
				if (i >= 0) {
					const stackElement = stack[i];
					stack.length = i;
					const line = document.positionAt(scanner.getTokenOffset()).line;
					const startLine = stackElement.startLine;
					const endLine = line - 1;
					if (endLine > startLine && prevStart !== startLine) {
						addRange({ startLine, endLine });
					}
				}
				break;
			}
			case TokenType.Comment: {
				let startLine = document.positionAt(scanner.getTokenOffset()).line;
				const text = scanner.getTokenText();
				const m = text.match(/^\s*#(region\b)|(endregion\b)/);
				if (m) {
					if (m[1]) { // start pattern match
						stack.push({ startLine, tagName: '' }); // empty tagName marks region
					} else {
						let i = stack.length - 1;
						while (i >= 0 && stack[i].tagName.length) {
							i--;
						}
						if (i >= 0) {
							const stackElement = stack[i];
							stack.length = i;
							const endLine = startLine;
							startLine = stackElement.startLine;
							if (endLine > startLine && prevStart !== startLine) {
								addRange({ startLine, endLine, kind: FoldingRangeKind.Region });
							}
						}
					}
				} else {
					const endLine = document.positionAt(scanner.getTokenOffset() + scanner.getTokenLength()).line;
					if (startLine < endLine) {
						addRange({ startLine, endLine, kind: FoldingRangeKind.Comment });
					}
				}
				break;
			}
		}
		token = scanner.scan();
	}

	const rangeLimit = context && context.rangeLimit || Number.MAX_VALUE;
	if (ranges.length > rangeLimit) {
		return limitRanges(ranges, rangeLimit);
	}
	return ranges;
}