@typescript-eslint/eslint-plugin
Version:
TypeScript plugin for ESLint
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JavaScript
;
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};
})();
Object.defineProperty(exports, "__esModule", { value: true });
const utils_1 = require("@typescript-eslint/utils");
const tsutils = __importStar(require("ts-api-utils"));
const ts = __importStar(require("typescript"));
const util_1 = require("../util");
const assertionFunctionUtils_1 = require("../util/assertionFunctionUtils");
exports.default = (0, util_1.createRule)({
name: 'strict-boolean-expressions',
meta: {
type: 'suggestion',
docs: {
description: 'Disallow certain types in boolean expressions',
requiresTypeChecking: true,
},
hasSuggestions: true,
messages: {
conditionErrorAny: 'Unexpected any value in {{context}}. ' +
'An explicit comparison or type conversion is required.',
conditionErrorNullableBoolean: 'Unexpected nullable boolean value in {{context}}. ' +
'Please handle the nullish case explicitly.',
conditionErrorNullableEnum: 'Unexpected nullable enum value in {{context}}. ' +
'Please handle the nullish/zero/NaN cases explicitly.',
conditionErrorNullableNumber: 'Unexpected nullable number value in {{context}}. ' +
'Please handle the nullish/zero/NaN cases explicitly.',
conditionErrorNullableObject: 'Unexpected nullable object value in {{context}}. ' +
'An explicit null check is required.',
conditionErrorNullableString: 'Unexpected nullable string value in {{context}}. ' +
'Please handle the nullish/empty cases explicitly.',
conditionErrorNullish: 'Unexpected nullish value in conditional. ' +
'The condition is always false.',
conditionErrorNumber: 'Unexpected number value in {{context}}. ' +
'An explicit zero/NaN check is required.',
conditionErrorObject: 'Unexpected object value in {{context}}. ' +
'The condition is always true.',
conditionErrorOther: 'Unexpected value in conditional. ' +
'A boolean expression is required.',
conditionErrorString: 'Unexpected string value in {{context}}. ' +
'An explicit empty string check is required.',
conditionFixCastBoolean: 'Explicitly convert value to a boolean (`Boolean(value)`)',
conditionFixCompareArrayLengthNonzero: "Change condition to check array's length (`value.length > 0`)",
conditionFixCompareArrayLengthZero: "Change condition to check array's length (`value.length === 0`)",
conditionFixCompareEmptyString: 'Change condition to check for empty string (`value !== ""`)',
conditionFixCompareFalse: 'Change condition to check if false (`value === false`)',
conditionFixCompareNaN: 'Change condition to check for NaN (`!Number.isNaN(value)`)',
conditionFixCompareNullish: 'Change condition to check for null/undefined (`value != null`)',
conditionFixCompareStringLength: "Change condition to check string's length (`value.length !== 0`)",
conditionFixCompareTrue: 'Change condition to check if true (`value === true`)',
conditionFixCompareZero: 'Change condition to check for 0 (`value !== 0`)',
conditionFixDefaultEmptyString: 'Explicitly treat nullish value the same as an empty string (`value ?? ""`)',
conditionFixDefaultFalse: 'Explicitly treat nullish value the same as false (`value ?? false`)',
conditionFixDefaultZero: 'Explicitly treat nullish value the same as 0 (`value ?? 0`)',
explicitBooleanReturnType: 'Add an explicit `boolean` return type annotation.',
noStrictNullCheck: 'This rule requires the `strictNullChecks` compiler option to be turned on to function correctly.',
predicateCannotBeAsync: "Predicate function should not be 'async'; expected a boolean return type.",
},
schema: [
{
type: 'object',
additionalProperties: false,
properties: {
allowAny: {
type: 'boolean',
description: 'Whether to allow `any`s in a boolean context.',
},
allowNullableBoolean: {
type: 'boolean',
description: 'Whether to allow nullable `boolean`s in a boolean context.',
},
allowNullableEnum: {
type: 'boolean',
description: 'Whether to allow nullable `enum`s in a boolean context.',
},
allowNullableNumber: {
type: 'boolean',
description: 'Whether to allow nullable `number`s in a boolean context.',
},
allowNullableObject: {
type: 'boolean',
description: 'Whether to allow nullable `object`s, `symbol`s, and functions in a boolean context.',
},
allowNullableString: {
type: 'boolean',
description: 'Whether to allow nullable `string`s in a boolean context.',
},
allowNumber: {
type: 'boolean',
description: 'Whether to allow `number`s in a boolean context.',
},
allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing: {
type: 'boolean',
description: 'Unless this is set to `true`, the rule will error on every file whose `tsconfig.json` does _not_ have the `strictNullChecks` compiler option (or `strict`) set to `true`.',
},
allowString: {
type: 'boolean',
description: 'Whether to allow `string`s in a boolean context.',
},
},
},
],
},
defaultOptions: [
{
allowAny: false,
allowNullableBoolean: false,
allowNullableEnum: false,
allowNullableNumber: false,
allowNullableObject: true,
allowNullableString: false,
allowNumber: true,
allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing: false,
allowString: true,
},
],
create(context, [options]) {
const services = (0, util_1.getParserServices)(context);
const checker = services.program.getTypeChecker();
const compilerOptions = services.program.getCompilerOptions();
const isStrictNullChecks = tsutils.isStrictCompilerOptionEnabled(compilerOptions, 'strictNullChecks');
if (!isStrictNullChecks &&
options.allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing !== true) {
context.report({
loc: {
start: { column: 0, line: 0 },
end: { column: 0, line: 0 },
},
messageId: 'noStrictNullCheck',
});
}
const traversedNodes = new Set();
return {
CallExpression: traverseCallExpression,
ConditionalExpression: traverseTestExpression,
DoWhileStatement: traverseTestExpression,
ForStatement: traverseTestExpression,
IfStatement: traverseTestExpression,
'LogicalExpression[operator!="??"]': traverseLogicalExpression,
'UnaryExpression[operator="!"]': traverseUnaryLogicalExpression,
WhileStatement: traverseTestExpression,
};
/**
* Inspects condition of a test expression. (`if`, `while`, `for`, etc.)
*/
function traverseTestExpression(node) {
if (node.test == null) {
return;
}
traverseNode(node.test, true);
}
/**
* Inspects the argument of a unary logical expression (`!`).
*/
function traverseUnaryLogicalExpression(node) {
traverseNode(node.argument, true);
}
/**
* Inspects the arguments of a logical expression (`&&`, `||`).
*
* If the logical expression is a descendant of a test expression,
* the `isCondition` flag should be set to true.
* Otherwise, if the logical expression is there on it's own,
* it's used for control flow and is not a condition itself.
*/
function traverseLogicalExpression(node, isCondition = false) {
// left argument is always treated as a condition
traverseNode(node.left, true);
// if the logical expression is used for control flow,
// then its right argument is used for its side effects only
traverseNode(node.right, isCondition);
}
function traverseCallExpression(node) {
const assertedArgument = (0, assertionFunctionUtils_1.findTruthinessAssertedArgument)(services, node);
if (assertedArgument != null) {
traverseNode(assertedArgument, true);
}
if ((0, util_1.isArrayMethodCallWithPredicate)(context, services, node)) {
const predicate = node.arguments.at(0);
if (predicate) {
checkArrayMethodCallPredicate(predicate);
}
}
}
/**
* Dedicated function to check array method predicate calls. Reports predicate
* arguments that don't return a boolean value.
*/
function checkArrayMethodCallPredicate(predicateNode) {
const isFunctionExpression = utils_1.ASTUtils.isFunction(predicateNode);
// custom message for accidental `async` function expressions
if (isFunctionExpression && predicateNode.async) {
return context.report({
node: predicateNode,
messageId: 'predicateCannotBeAsync',
});
}
const returnTypes = services
.getTypeAtLocation(predicateNode)
.getCallSignatures()
.map(signature => {
const type = signature.getReturnType();
if (tsutils.isTypeParameter(type)) {
return checker.getBaseConstraintOfType(type) ?? type;
}
return type;
});
const flattenTypes = [
...new Set(returnTypes.flatMap(type => tsutils.unionConstituents(type))),
];
const types = inspectVariantTypes(flattenTypes);
const reportType = determineReportType(types);
if (reportType == null) {
return;
}
const suggestions = [];
if (isFunctionExpression &&
predicateNode.body.type !== utils_1.AST_NODE_TYPES.BlockStatement) {
suggestions.push(...getSuggestionsForConditionError(predicateNode.body, reportType));
}
if (isFunctionExpression && !predicateNode.returnType) {
suggestions.push({
messageId: 'explicitBooleanReturnType',
fix: fixer => {
if (predicateNode.type === utils_1.AST_NODE_TYPES.ArrowFunctionExpression &&
(0, util_1.isParenlessArrowFunction)(predicateNode, context.sourceCode)) {
return [
fixer.insertTextBefore(predicateNode.params[0], '('),
fixer.insertTextAfter(predicateNode.params[0], '): boolean'),
];
}
if (predicateNode.params.length === 0) {
const closingBracket = (0, util_1.nullThrows)(context.sourceCode.getFirstToken(predicateNode, token => token.value === ')'), 'function expression has to have a closing parenthesis.');
return fixer.insertTextAfter(closingBracket, ': boolean');
}
const lastClosingParenthesis = (0, util_1.nullThrows)(context.sourceCode.getTokenAfter(predicateNode.params[predicateNode.params.length - 1], token => token.value === ')'), 'function expression has to have a closing parenthesis.');
return fixer.insertTextAfter(lastClosingParenthesis, ': boolean');
},
});
}
return context.report({
node: predicateNode,
messageId: reportType,
data: {
context: 'array predicate return type',
},
suggest: suggestions,
});
}
/**
* Inspects any node.
*
* If it's a logical expression then it recursively traverses its arguments.
* If it's any other kind of node then it's type is finally checked against the rule,
* unless `isCondition` flag is set to false, in which case
* it's assumed to be used for side effects only and is skipped.
*/
function traverseNode(node, isCondition) {
// prevent checking the same node multiple times
if (traversedNodes.has(node)) {
return;
}
traversedNodes.add(node);
// for logical operator, we check its operands
if (node.type === utils_1.AST_NODE_TYPES.LogicalExpression &&
node.operator !== '??') {
traverseLogicalExpression(node, isCondition);
return;
}
// skip if node is not a condition
if (!isCondition) {
return;
}
checkNode(node);
}
function determineReportType(types) {
const is = (...wantedTypes) => types.size === wantedTypes.length &&
wantedTypes.every(type => types.has(type));
// boolean
if (is('boolean') || is('truthy boolean')) {
// boolean is always ok
return undefined;
}
// never
if (is('never')) {
// never is always okay
return undefined;
}
// nullish
if (is('nullish')) {
// condition is always false
return 'conditionErrorNullish';
}
// Known edge case: boolean `true` and nullish values are always valid boolean expressions
if (is('nullish', 'truthy boolean')) {
return;
}
// nullable boolean
if (is('nullish', 'boolean')) {
return !options.allowNullableBoolean
? 'conditionErrorNullableBoolean'
: undefined;
}
// Known edge case: truthy primitives and nullish values are always valid boolean expressions
if ((options.allowNumber && is('nullish', 'truthy number')) ||
(options.allowString && is('nullish', 'truthy string'))) {
return;
}
// string
if (is('string') || is('truthy string')) {
return !options.allowString ? 'conditionErrorString' : undefined;
}
// nullable string
if (is('nullish', 'string')) {
return !options.allowNullableString
? 'conditionErrorNullableString'
: undefined;
}
// number
if (is('number') || is('truthy number')) {
return !options.allowNumber ? 'conditionErrorNumber' : undefined;
}
// nullable number
if (is('nullish', 'number')) {
return !options.allowNullableNumber
? 'conditionErrorNullableNumber'
: undefined;
}
// object
if (is('object')) {
return 'conditionErrorObject';
}
// nullable object
if (is('nullish', 'object')) {
return !options.allowNullableObject
? 'conditionErrorNullableObject'
: undefined;
}
// nullable enum
if (is('nullish', 'number', 'enum') ||
is('nullish', 'string', 'enum') ||
is('nullish', 'truthy number', 'enum') ||
is('nullish', 'truthy string', 'enum') ||
// mixed enums
is('nullish', 'truthy number', 'truthy string', 'enum') ||
is('nullish', 'truthy number', 'string', 'enum') ||
is('nullish', 'truthy string', 'number', 'enum') ||
is('nullish', 'number', 'string', 'enum')) {
return !options.allowNullableEnum
? 'conditionErrorNullableEnum'
: undefined;
}
// any
if (is('any')) {
return !options.allowAny ? 'conditionErrorAny' : undefined;
}
return 'conditionErrorOther';
}
function getSuggestionsForConditionError(node, conditionError) {
switch (conditionError) {
case 'conditionErrorAny':
return [
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `Boolean(${code})`,
}),
},
];
case 'conditionErrorNullableBoolean':
if (isLogicalNegationExpression(node.parent)) {
// if (!nullableBoolean)
return [
{
messageId: 'conditionFixDefaultFalse',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} ?? false`,
}),
},
{
messageId: 'conditionFixCompareFalse',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} === false`,
}),
},
];
}
// if (nullableBoolean)
return [
{
messageId: 'conditionFixDefaultFalse',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} ?? false`,
}),
},
{
messageId: 'conditionFixCompareTrue',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} === true`,
}),
},
];
case 'conditionErrorNullableEnum':
if (isLogicalNegationExpression(node.parent)) {
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} == null`,
}),
},
];
}
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} != null`,
}),
},
];
case 'conditionErrorNullableNumber':
if (isLogicalNegationExpression(node.parent)) {
// if (!nullableNumber)
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} == null`,
}),
},
{
messageId: 'conditionFixDefaultZero',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} ?? 0`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `!Boolean(${code})`,
}),
},
];
}
// if (nullableNumber)
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} != null`,
}),
},
{
messageId: 'conditionFixDefaultZero',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} ?? 0`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `Boolean(${code})`,
}),
},
];
case 'conditionErrorNullableObject':
if (isLogicalNegationExpression(node.parent)) {
// if (!nullableObject)
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} == null`,
}),
},
];
}
// if (nullableObject)
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} != null`,
}),
},
];
case 'conditionErrorNullableString':
if (isLogicalNegationExpression(node.parent)) {
// if (!nullableString)
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} == null`,
}),
},
{
messageId: 'conditionFixDefaultEmptyString',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} ?? ""`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `!Boolean(${code})`,
}),
},
];
}
// if (nullableString)
return [
{
messageId: 'conditionFixCompareNullish',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} != null`,
}),
},
{
messageId: 'conditionFixDefaultEmptyString',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} ?? ""`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `Boolean(${code})`,
}),
},
];
case 'conditionErrorNumber':
if (isArrayLengthExpression(node, checker, services)) {
if (isLogicalNegationExpression(node.parent)) {
// if (!array.length)
return [
{
messageId: 'conditionFixCompareArrayLengthZero',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} === 0`,
}),
},
];
}
// if (array.length)
return [
{
messageId: 'conditionFixCompareArrayLengthNonzero',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} > 0`,
}),
},
];
}
if (isLogicalNegationExpression(node.parent)) {
// if (!number)
return [
{
messageId: 'conditionFixCompareZero',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
// TODO: we have to compare to 0n if the type is bigint
wrap: code => `${code} === 0`,
}),
},
{
// TODO: don't suggest this for bigint because it can't be NaN
messageId: 'conditionFixCompareNaN',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `Number.isNaN(${code})`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `!Boolean(${code})`,
}),
},
];
}
// if (number)
return [
{
messageId: 'conditionFixCompareZero',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} !== 0`,
}),
},
{
messageId: 'conditionFixCompareNaN',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `!Number.isNaN(${code})`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `Boolean(${code})`,
}),
},
];
case 'conditionErrorString':
if (isLogicalNegationExpression(node.parent)) {
// if (!string)
return [
{
messageId: 'conditionFixCompareStringLength',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code}.length === 0`,
}),
},
{
messageId: 'conditionFixCompareEmptyString',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `${code} === ""`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node: node.parent,
innerNode: node,
sourceCode: context.sourceCode,
wrap: code => `!Boolean(${code})`,
}),
},
];
}
// if (string)
return [
{
messageId: 'conditionFixCompareStringLength',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code}.length > 0`,
}),
},
{
messageId: 'conditionFixCompareEmptyString',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `${code} !== ""`,
}),
},
{
messageId: 'conditionFixCastBoolean',
fix: (0, util_1.getWrappingFixer)({
node,
sourceCode: context.sourceCode,
wrap: code => `Boolean(${code})`,
}),
},
];
case 'conditionErrorObject':
case 'conditionErrorNullish':
case 'conditionErrorOther':
return [];
default:
conditionError;
throw new Error('Unreachable');
}
}
/**
* This function does the actual type check on a node.
* It analyzes the type of a node and checks if it is allowed in a boolean context.
*/
function checkNode(node) {
const type = (0, util_1.getConstrainedTypeAtLocation)(services, node);
const types = inspectVariantTypes(tsutils.unionConstituents(type));
const reportType = determineReportType(types);
if (reportType != null) {
context.report({
node,
messageId: reportType,
data: {
context: 'conditional',
},
suggest: getSuggestionsForConditionError(node, reportType),
});
}
}
/**
* Check union variants for the types we care about
*/
function inspectVariantTypes(types) {
const variantTypes = new Set();
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.Null | ts.TypeFlags.Undefined | ts.TypeFlags.VoidLike))) {
variantTypes.add('nullish');
}
const booleans = types.filter(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.BooleanLike));
// If incoming type is either "true" or "false", there will be one type
// object with intrinsicName set accordingly
// If incoming type is boolean, there will be two type objects with
// intrinsicName set "true" and "false" each because of ts-api-utils.unionConstituents()
if (booleans.length === 1) {
variantTypes.add(tsutils.isTrueLiteralType(booleans[0]) ? 'truthy boolean' : 'boolean');
}
else if (booleans.length === 2) {
variantTypes.add('boolean');
}
const strings = types.filter(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.StringLike));
if (strings.length) {
if (strings.every(type => type.isStringLiteral() && type.value !== '')) {
variantTypes.add('truthy string');
}
else {
variantTypes.add('string');
}
}
const numbers = types.filter(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.NumberLike | ts.TypeFlags.BigIntLike));
if (numbers.length) {
if (numbers.every(type => type.isNumberLiteral() && type.value !== 0)) {
variantTypes.add('truthy number');
}
else {
variantTypes.add('number');
}
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.EnumLike))) {
variantTypes.add('enum');
}
if (types.some(type => !tsutils.isTypeFlagSet(type, ts.TypeFlags.Null |
ts.TypeFlags.Undefined |
ts.TypeFlags.VoidLike |
ts.TypeFlags.BooleanLike |
ts.TypeFlags.StringLike |
ts.TypeFlags.NumberLike |
ts.TypeFlags.BigIntLike |
ts.TypeFlags.TypeParameter |
ts.TypeFlags.Any |
ts.TypeFlags.Unknown |
ts.TypeFlags.Never))) {
variantTypes.add(types.some(isBrandedBoolean) ? 'boolean' : 'object');
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.TypeParameter |
ts.TypeFlags.Any |
ts.TypeFlags.Unknown))) {
variantTypes.add('any');
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.Never))) {
variantTypes.add('never');
}
return variantTypes;
}
},
});
function isLogicalNegationExpression(node) {
return node.type === utils_1.AST_NODE_TYPES.UnaryExpression && node.operator === '!';
}
function isArrayLengthExpression(node, typeChecker, services) {
if (node.type !== utils_1.AST_NODE_TYPES.MemberExpression) {
return false;
}
if (node.computed) {
return false;
}
if (node.property.name !== 'length') {
return false;
}
const objectType = (0, util_1.getConstrainedTypeAtLocation)(services, node.object);
return (0, util_1.isTypeArrayTypeOrUnionOfArrayTypes)(objectType, typeChecker);
}
/**
* Verify is the type is a branded boolean (e.g. `type Foo = boolean & { __brand: 'Foo' }`)
*
* @param type The type checked
*/
function isBrandedBoolean(type) {
return (type.isIntersection() &&
type.types.some(childType => isBooleanType(childType)));
}
function isBooleanType(expressionType) {
return tsutils.isTypeFlagSet(expressionType, ts.TypeFlags.Boolean | ts.TypeFlags.BooleanLiteral);
}