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/**
* @fileoverview Rule to flag use of an lexical declarations inside a case clause
* @author Erik Arvidsson
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "Disallow lexical declarations in case clauses",
recommended: true,
url: "https://eslint.org/docs/latest/rules/no-case-declarations"
},
schema: [],
messages: {
unexpected: "Unexpected lexical declaration in case block."
}
},
create(context) {
/**
* Checks whether or not a node is a lexical declaration.
* @param {ASTNode} node A direct child statement of a switch case.
* @returns {boolean} Whether or not the node is a lexical declaration.
*/
function isLexicalDeclaration(node) {
switch (node.type) {
case "FunctionDeclaration":
case "ClassDeclaration":
return true;
case "VariableDeclaration":
return node.kind !== "var";
default:
return false;
}
}
return {
SwitchCase(node) {
for (let i = 0; i < node.consequent.length; i++) {
const statement = node.consequent[i];
if (isLexicalDeclaration(statement)) {
context.report({
node: statement,
messageId: "unexpected"
});
}
}
}
};
}
};