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no-unsafe-member-access.ts
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no-unsafe-member-access.ts
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import {
TSESTree,
AST_NODE_TYPES,
} from '@typescript-eslint/experimental-utils';
import * as util from '../util';
const enum State {
Unsafe = 1,
Safe = 2,
}
export default util.createRule({
name: 'no-unsafe-member-access',
meta: {
type: 'problem',
docs: {
description: 'Disallows member access on any typed variables',
category: 'Possible Errors',
recommended: 'error',
requiresTypeChecking: true,
},
messages: {
unsafeMemberExpression:
'Unsafe member access {{property}} on an any value.',
unsafeComputedMemberAccess:
'Computed name {{property}} resolves to an any value.',
},
schema: [],
},
defaultOptions: [],
create(context) {
const { program, esTreeNodeToTSNodeMap } = util.getParserServices(context);
const checker = program.getTypeChecker();
const sourceCode = context.getSourceCode();
const stateCache = new Map<TSESTree.Node, State>();
function checkMemberExpression(node: TSESTree.MemberExpression): State {
const cachedState = stateCache.get(node);
if (cachedState) {
return cachedState;
}
if (node.object.type === AST_NODE_TYPES.MemberExpression) {
const objectState = checkMemberExpression(node.object);
if (objectState === State.Unsafe) {
// if the object is unsafe, we know this will be unsafe as well
// we don't need to report, as we have already reported on the inner member expr
stateCache.set(node, objectState);
return objectState;
}
}
const tsNode = esTreeNodeToTSNodeMap.get(node.object);
const type = checker.getTypeAtLocation(tsNode);
const state = util.isTypeAnyType(type) ? State.Unsafe : State.Safe;
stateCache.set(node, state);
if (state === State.Unsafe) {
const propertyName = sourceCode.getText(node.property);
context.report({
node,
messageId: 'unsafeMemberExpression',
data: {
property: node.computed ? `[${propertyName}]` : `.${propertyName}`,
},
});
}
return state;
}
return {
// ignore MemberExpression if it's parent is TSClassImplements or TSInterfaceHeritage
':not(TSClassImplements, TSInterfaceHeritage) > MemberExpression': checkMemberExpression,
'MemberExpression[computed = true] > *.property'(
node: TSESTree.Expression,
): void {
if (
// x[1]
node.type === AST_NODE_TYPES.Literal ||
// x[1++] x[++x] etc
// FUN FACT - **all** update expressions return type number, regardless of the argument's type,
// because JS engines return NaN if there the argument is not a number.
node.type === AST_NODE_TYPES.UpdateExpression
) {
// perf optimizations - literals can obviously never be `any`
return;
}
const tsNode = esTreeNodeToTSNodeMap.get(node);
const type = checker.getTypeAtLocation(tsNode);
if (util.isTypeAnyType(type)) {
const propertyName = sourceCode.getText(node);
context.report({
node,
messageId: 'unsafeComputedMemberAccess',
data: {
property: `[${propertyName}]`,
},
});
}
},
};
},
});