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no-mixed-enums.ts
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no-mixed-enums.ts
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import type { TSESTree } from '@typescript-eslint/utils';
import * as tsutils from 'tsutils';
import * as ts from 'typescript';
import * as util from '../util';
type AllowedType = ts.TypeFlags.Number | ts.TypeFlags.String;
export default util.createRule({
name: 'no-mixed-enums',
meta: {
docs: {
description: 'Disallow enums from having both number and string members',
recommended: 'strict',
requiresTypeChecking: true,
},
messages: {
mixed: `Mixing number and string enums can be confusing.`,
},
schema: [],
type: 'problem',
},
defaultOptions: [],
create(context) {
const parserServices = util.getParserServices(context);
const typeChecker = parserServices.program.getTypeChecker();
function getAllowedType(node: ts.Node): AllowedType {
return tsutils.isTypeFlagSet(
typeChecker.getTypeAtLocation(node),
ts.TypeFlags.StringLike,
)
? ts.TypeFlags.String
: ts.TypeFlags.Number;
}
function getAllowedTypeOfEnum(
node: TSESTree.TSEnumDeclaration,
): AllowedType | undefined {
const tsNode = parserServices.esTreeNodeToTSNodeMap.get(node.id);
const declarations = typeChecker
.getSymbolAtLocation(tsNode)!
.getDeclarations()!;
for (const declaration of declarations) {
for (const member of (declaration as ts.EnumDeclaration).members) {
return member.initializer
? getAllowedType(member.initializer)
: ts.TypeFlags.Number;
}
}
return undefined;
}
function getAllowedTypeOfInitializer(
initializer: TSESTree.Expression | undefined,
): ts.TypeFlags.Number | ts.TypeFlags.String {
return initializer
? getAllowedType(parserServices.esTreeNodeToTSNodeMap.get(initializer))
: ts.TypeFlags.Number;
}
return {
TSEnumDeclaration(node: TSESTree.TSEnumDeclaration): void {
const allowedType = getAllowedTypeOfEnum(node);
if (allowedType === undefined) {
return;
}
for (const member of node.members) {
if (getAllowedTypeOfInitializer(member.initializer) !== allowedType) {
context.report({
messageId: 'mixed',
node: member.initializer ?? member,
});
return;
}
}
},
};
},
});