eslint-plugin-complete/dist/rules/require-break.js

An ESLint plugin that contains useful rules.

// This rule is mostly copied from the `no-fallthrough` ESLint core rule:
// https://github.com/eslint/eslint/blob/main/lib/rules/no-fallthrough.js
import { createRule } from "../utils.js";
export const requireBreak = createRule({
    name: "require-break",
    meta: {
        type: "layout",
        docs: {
            description: "Requires that each case of a switch statement has a `break` statement",
            recommended: true,
            requiresTypeChecking: false,
        },
        schema: [],
        messages: {
            noBreak: "Expected a 'break' statement.",
        },
    },
    defaultOptions: [],
    create(context) {
        const codePathSegments = [];
        let currentCodePathSegments = new Set();
        return {
            onCodePathStart() {
                codePathSegments.push(currentCodePathSegments);
                currentCodePathSegments = new Set();
            },
            onCodePathEnd() {
                const codePathSegmentsSet = codePathSegments.pop();
                if (codePathSegmentsSet !== undefined) {
                    currentCodePathSegments = codePathSegmentsSet;
                }
            },
            onUnreachableCodePathSegmentStart(segment) {
                currentCodePathSegments.add(segment);
            },
            onUnreachableCodePathSegmentEnd(segment) {
                currentCodePathSegments.delete(segment);
            },
            onCodePathSegmentStart(segment) {
                currentCodePathSegments.add(segment);
            },
            onCodePathSegmentEnd(segment) {
                currentCodePathSegments.delete(segment);
            },
            "SwitchCase:exit"(node) {
                /*
                 * `reachable` means fallthrough because statements preceded by
                 * `break`, `return`, or `throw` are unreachable.
                 * And allows empty cases and the last case.
                 */
                const thisNodeIsReachable = isAnySegmentReachable(currentCodePathSegments);
                const thisNodeIsFinalCase = node === node.parent.cases.at(-1);
                if (thisNodeIsReachable && thisNodeIsFinalCase) {
                    context.report({
                        messageId: "noBreak",
                        node,
                    });
                }
            },
        };
    },
});
/**
 * Checks all segments in a set and returns true if any are reachable.
 *
 * @param segments The segments to check.
 * @returns True if any segment is reachable; false otherwise.
 */
function isAnySegmentReachable(segments) {
    for (const segment of segments) {
        if (segment.reachable) {
            return true;
        }
    }
    return false;
}