blob: 3f2454c2a6c84f4a4f02b836e2e9bd9a6db5e8bc [file] [log] [blame]
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
const experimental_utils_1 = require("@typescript-eslint/experimental-utils");
const ts = __importStar(require("typescript"));
const tsutils = __importStar(require("tsutils"));
const util = __importStar(require("../util"));
exports.default = util.createRule({
name: 'strict-boolean-expressions',
meta: {
type: 'suggestion',
docs: {
description: 'Restricts the types allowed in boolean expressions',
category: 'Best Practices',
recommended: false,
requiresTypeChecking: true,
},
schema: [
{
type: 'object',
properties: {
allowString: { type: 'boolean' },
allowNumber: { type: 'boolean' },
allowNullableObject: { type: 'boolean' },
allowNullableBoolean: { type: 'boolean' },
allowNullableString: { type: 'boolean' },
allowNullableNumber: { type: 'boolean' },
allowAny: { type: 'boolean' },
allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing: {
type: 'boolean',
},
},
additionalProperties: false,
},
],
messages: {
conditionErrorOther: 'Unexpected value in conditional. ' +
'A boolean expression is required.',
conditionErrorAny: 'Unexpected any value in conditional. ' +
'An explicit comparison or type cast is required.',
conditionErrorNullish: 'Unexpected nullish value in conditional. ' +
'The condition is always false.',
conditionErrorNullableBoolean: 'Unexpected nullable boolean value in conditional. ' +
'Please handle the nullish case explicitly.',
conditionErrorString: 'Unexpected string value in conditional. ' +
'An explicit empty string check is required.',
conditionErrorNullableString: 'Unexpected nullable string value in conditional. ' +
'Please handle the nullish/empty cases explicitly.',
conditionErrorNumber: 'Unexpected number value in conditional. ' +
'An explicit zero/NaN check is required.',
conditionErrorNullableNumber: 'Unexpected nullable number value in conditional. ' +
'Please handle the nullish/zero/NaN cases explicitly.',
conditionErrorObject: 'Unexpected object value in conditional. ' +
'The condition is always true.',
conditionErrorNullableObject: 'Unexpected nullable object value in conditional. ' +
'An explicit null check is required.',
noStrictNullCheck: 'This rule requires the `strictNullChecks` compiler option to be turned on to function correctly.',
},
},
defaultOptions: [
{
allowString: true,
allowNumber: true,
allowNullableObject: true,
allowNullableBoolean: false,
allowNullableString: false,
allowNullableNumber: false,
allowAny: false,
allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing: false,
},
],
create(context, [options]) {
const service = util.getParserServices(context);
const checker = service.program.getTypeChecker();
const compilerOptions = service.program.getCompilerOptions();
const isStrictNullChecks = tsutils.isStrictCompilerOptionEnabled(compilerOptions, 'strictNullChecks');
if (!isStrictNullChecks &&
options.allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing !== true) {
context.report({
loc: {
start: { line: 0, column: 0 },
end: { line: 0, column: 0 },
},
messageId: 'noStrictNullCheck',
});
}
const checkedNodes = new Set();
return {
ConditionalExpression: checkTestExpression,
DoWhileStatement: checkTestExpression,
ForStatement: checkTestExpression,
IfStatement: checkTestExpression,
WhileStatement: checkTestExpression,
'LogicalExpression[operator!="??"]': checkNode,
'UnaryExpression[operator="!"]': checkUnaryLogicalExpression,
};
function checkTestExpression(node) {
if (node.test == null) {
return;
}
checkNode(node.test, true);
}
function checkUnaryLogicalExpression(node) {
checkNode(node.argument, true);
}
/**
* This function analyzes the type of a node and checks if it is allowed in a boolean context.
* It can recurse when checking nested logical operators, so that only the outermost operands are reported.
* The right operand of a logical expression is ignored unless it's a part of a test expression (if/while/ternary/etc).
* @param node The AST node to check.
* @param isTestExpr Whether the node is a descendant of a test expression.
*/
function checkNode(node, isTestExpr = false) {
// prevent checking the same node multiple times
if (checkedNodes.has(node)) {
return;
}
checkedNodes.add(node);
// for logical operator, we check its operands
if (node.type === experimental_utils_1.AST_NODE_TYPES.LogicalExpression &&
node.operator !== '??') {
checkNode(node.left, isTestExpr);
// we ignore the right operand when not in a context of a test expression
if (isTestExpr) {
checkNode(node.right, isTestExpr);
}
return;
}
const tsNode = service.esTreeNodeToTSNodeMap.get(node);
const type = util.getConstrainedTypeAtLocation(checker, tsNode);
const types = inspectVariantTypes(tsutils.unionTypeParts(type));
const is = (...wantedTypes) => types.size === wantedTypes.length &&
wantedTypes.every(type => types.has(type));
// boolean
if (is('boolean')) {
// boolean is always okay
return;
}
// never
if (is('never')) {
// never is always okay
return;
}
// nullish
if (is('nullish')) {
// condition is always false
context.report({ node, messageId: 'conditionErrorNullish' });
return;
}
// nullable boolean
if (is('nullish', 'boolean')) {
if (!options.allowNullableBoolean) {
context.report({ node, messageId: 'conditionErrorNullableBoolean' });
}
return;
}
// string
if (is('string')) {
if (!options.allowString) {
context.report({ node, messageId: 'conditionErrorString' });
}
return;
}
// nullable string
if (is('nullish', 'string')) {
if (!options.allowNullableString) {
context.report({ node, messageId: 'conditionErrorNullableString' });
}
return;
}
// number
if (is('number')) {
if (!options.allowNumber) {
context.report({ node, messageId: 'conditionErrorNumber' });
}
return;
}
// nullable number
if (is('nullish', 'number')) {
if (!options.allowNullableNumber) {
context.report({ node, messageId: 'conditionErrorNullableNumber' });
}
return;
}
// object
if (is('object')) {
// condition is always true
context.report({ node, messageId: 'conditionErrorObject' });
return;
}
// nullable object
if (is('nullish', 'object')) {
if (!options.allowNullableObject) {
context.report({ node, messageId: 'conditionErrorNullableObject' });
}
return;
}
// any
if (is('any')) {
if (!options.allowAny) {
context.report({ node, messageId: 'conditionErrorAny' });
}
return;
}
// other
context.report({ node, messageId: 'conditionErrorOther' });
}
/**
* 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');
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.BooleanLike))) {
variantTypes.add('boolean');
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.StringLike))) {
variantTypes.add('string');
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.NumberLike | ts.TypeFlags.BigIntLike))) {
variantTypes.add('number');
}
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.Any |
ts.TypeFlags.Unknown |
ts.TypeFlags.Never))) {
variantTypes.add('object');
}
if (types.some(type => util.isTypeAnyType(type) || util.isTypeUnknownType(type))) {
variantTypes.add('any');
}
if (types.some(type => tsutils.isTypeFlagSet(type, ts.TypeFlags.Never))) {
variantTypes.add('never');
}
return variantTypes;
}
},
});
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