Add components

slider/node_modules/eslint/lib/rules/no-fallthrough.js

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+/**
+ * @fileoverview Rule to flag fall-through cases in switch statements.
+ * @author Matt DuVall <http://mattduvall.com/>
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const { directivesPattern } = require("../shared/directives");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const DEFAULT_FALLTHROUGH_COMMENT = /falls?\s?through/iu;
+
+/**
+ * Checks all segments in a set and returns true if any are reachable.
+ * @param {Set<CodePathSegment>} segments The segments to check.
+ * @returns {boolean} True if any segment is reachable; false otherwise.
+ */
+function isAnySegmentReachable(segments) {
+	for (const segment of segments) {
+		if (segment.reachable) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+/**
+ * Checks whether or not a given comment string is really a fallthrough comment and not an ESLint directive.
+ * @param {string} comment The comment string to check.
+ * @param {RegExp} fallthroughCommentPattern The regular expression used for checking for fallthrough comments.
+ * @returns {boolean} `true` if the comment string is truly a fallthrough comment.
+ */
+function isFallThroughComment(comment, fallthroughCommentPattern) {
+	return (
+		fallthroughCommentPattern.test(comment) &&
+		!directivesPattern.test(comment.trim())
+	);
+}
+
+/**
+ * Checks whether or not a given case has a fallthrough comment.
+ * @param {ASTNode} caseWhichFallsThrough SwitchCase node which falls through.
+ * @param {ASTNode} subsequentCase The case after caseWhichFallsThrough.
+ * @param {RuleContext} context A rule context which stores comments.
+ * @param {RegExp} fallthroughCommentPattern A pattern to match comment to.
+ * @returns {null | object} the comment if the case has a valid fallthrough comment, otherwise null
+ */
+function getFallthroughComment(
+	caseWhichFallsThrough,
+	subsequentCase,
+	context,
+	fallthroughCommentPattern,
+) {
+	const sourceCode = context.sourceCode;
+
+	if (
+		caseWhichFallsThrough.consequent.length === 1 &&
+		caseWhichFallsThrough.consequent[0].type === "BlockStatement"
+	) {
+		const trailingCloseBrace = sourceCode.getLastToken(
+			caseWhichFallsThrough.consequent[0],
+		);
+		const commentInBlock = sourceCode
+			.getCommentsBefore(trailingCloseBrace)
+			.pop();
+
+		if (
+			commentInBlock &&
+			isFallThroughComment(
+				commentInBlock.value,
+				fallthroughCommentPattern,
+			)
+		) {
+			return commentInBlock;
+		}
+	}
+
+	const comment = sourceCode.getCommentsBefore(subsequentCase).pop();
+
+	if (
+		comment &&
+		isFallThroughComment(comment.value, fallthroughCommentPattern)
+	) {
+		return comment;
+	}
+
+	return null;
+}
+
+/**
+ * Checks whether a node and a token are separated by blank lines
+ * @param {ASTNode} node The node to check
+ * @param {Token} token The token to compare against
+ * @returns {boolean} `true` if there are blank lines between node and token
+ */
+function hasBlankLinesBetween(node, token) {
+	return token.loc.start.line > node.loc.end.line + 1;
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../types').Rule.RuleModule} */
+module.exports = {
+	meta: {
+		type: "problem",
+
+		defaultOptions: [
+			{
+				allowEmptyCase: false,
+				reportUnusedFallthroughComment: false,
+			},
+		],
+
+		docs: {
+			description: "Disallow fallthrough of `case` statements",
+			recommended: true,
+			url: "https://eslint.org/docs/latest/rules/no-fallthrough",
+		},
+
+		schema: [
+			{
+				type: "object",
+				properties: {
+					commentPattern: {
+						type: "string",
+					},
+					allowEmptyCase: {
+						type: "boolean",
+					},
+					reportUnusedFallthroughComment: {
+						type: "boolean",
+					},
+				},
+				additionalProperties: false,
+			},
+		],
+		messages: {
+			unusedFallthroughComment:
+				"Found a comment that would permit fallthrough, but case cannot fall through.",
+			case: "Expected a 'break' statement before 'case'.",
+			default: "Expected a 'break' statement before 'default'.",
+		},
+	},
+
+	create(context) {
+		const codePathSegments = [];
+		let currentCodePathSegments = new Set();
+		const sourceCode = context.sourceCode;
+		const [
+			{ allowEmptyCase, commentPattern, reportUnusedFallthroughComment },
+		] = context.options;
+		const fallthroughCommentPattern = commentPattern
+			? new RegExp(commentPattern, "u")
+			: DEFAULT_FALLTHROUGH_COMMENT;
+
+		/*
+		 * We need to use leading comments of the next SwitchCase node because
+		 * trailing comments is wrong if semicolons are omitted.
+		 */
+		let previousCase = null;
+
+		return {
+			onCodePathStart() {
+				codePathSegments.push(currentCodePathSegments);
+				currentCodePathSegments = new Set();
+			},
+
+			onCodePathEnd() {
+				currentCodePathSegments = codePathSegments.pop();
+			},
+
+			onUnreachableCodePathSegmentStart(segment) {
+				currentCodePathSegments.add(segment);
+			},
+
+			onUnreachableCodePathSegmentEnd(segment) {
+				currentCodePathSegments.delete(segment);
+			},
+
+			onCodePathSegmentStart(segment) {
+				currentCodePathSegments.add(segment);
+			},
+
+			onCodePathSegmentEnd(segment) {
+				currentCodePathSegments.delete(segment);
+			},
+
+			SwitchCase(node) {
+				/*
+				 * Checks whether or not there is a fallthrough comment.
+				 * And reports the previous fallthrough node if that does not exist.
+				 */
+
+				if (previousCase && previousCase.node.parent === node.parent) {
+					const previousCaseFallthroughComment =
+						getFallthroughComment(
+							previousCase.node,
+							node,
+							context,
+							fallthroughCommentPattern,
+						);
+
+					if (
+						previousCase.isFallthrough &&
+						!previousCaseFallthroughComment
+					) {
+						context.report({
+							messageId: node.test ? "case" : "default",
+							node,
+						});
+					} else if (
+						reportUnusedFallthroughComment &&
+						!previousCase.isSwitchExitReachable &&
+						previousCaseFallthroughComment
+					) {
+						context.report({
+							messageId: "unusedFallthroughComment",
+							node: previousCaseFallthroughComment,
+						});
+					}
+				}
+				previousCase = null;
+			},
+
+			"SwitchCase:exit"(node) {
+				const nextToken = sourceCode.getTokenAfter(node);
+
+				/*
+				 * `reachable` meant fall through because statements preceded by
+				 * `break`, `return`, or `throw` are unreachable.
+				 * And allows empty cases and the last case.
+				 */
+				const isSwitchExitReachable = isAnySegmentReachable(
+					currentCodePathSegments,
+				);
+				const isFallthrough =
+					isSwitchExitReachable &&
+					(node.consequent.length > 0 ||
+						(!allowEmptyCase &&
+							hasBlankLinesBetween(node, nextToken))) &&
+					node.parent.cases.at(-1) !== node;
+
+				previousCase = {
+					node,
+					isSwitchExitReachable,
+					isFallthrough,
+				};
+			},
+		};
+	},
+};