@typescript-eslint/eslint-plugin
Version:
TypeScript plugin for ESLint
320 lines (316 loc) • 14.4 kB
JavaScript
"use strict";
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
var desc = Object.getOwnPropertyDescriptor(m, k);
if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
desc = { enumerable: true, get: function() { return m[k]; } };
}
Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || (function () {
var ownKeys = function(o) {
ownKeys = Object.getOwnPropertyNames || function (o) {
var ar = [];
for (var k in o) if (Object.prototype.hasOwnProperty.call(o, k)) ar[ar.length] = k;
return ar;
};
return ownKeys(o);
};
return function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k = ownKeys(mod), i = 0; i < k.length; i++) if (k[i] !== "default") __createBinding(result, mod, k[i]);
__setModuleDefault(result, mod);
return result;
};
})();
Object.defineProperty(exports, "__esModule", { value: true });
exports.NullishComparisonType = exports.OperandValidity = void 0;
exports.gatherLogicalOperands = gatherLogicalOperands;
const utils_1 = require("@typescript-eslint/utils");
const ts_api_utils_1 = require("ts-api-utils");
const ts = __importStar(require("typescript"));
const util_1 = require("../../util");
var ComparisonValueType;
(function (ComparisonValueType) {
ComparisonValueType["Null"] = "Null";
ComparisonValueType["Undefined"] = "Undefined";
ComparisonValueType["UndefinedStringLiteral"] = "UndefinedStringLiteral";
})(ComparisonValueType || (ComparisonValueType = {}));
var OperandValidity;
(function (OperandValidity) {
OperandValidity["Valid"] = "Valid";
OperandValidity["Invalid"] = "Invalid";
})(OperandValidity || (exports.OperandValidity = OperandValidity = {}));
var NullishComparisonType;
(function (NullishComparisonType) {
/** `x != null`, `x != undefined` */
NullishComparisonType["NotEqualNullOrUndefined"] = "NotEqualNullOrUndefined";
/** `x == null`, `x == undefined` */
NullishComparisonType["EqualNullOrUndefined"] = "EqualNullOrUndefined";
/** `x !== null` */
NullishComparisonType["NotStrictEqualNull"] = "NotStrictEqualNull";
/** `x === null` */
NullishComparisonType["StrictEqualNull"] = "StrictEqualNull";
/** `x !== undefined`, `typeof x !== 'undefined'` */
NullishComparisonType["NotStrictEqualUndefined"] = "NotStrictEqualUndefined";
/** `x === undefined`, `typeof x === 'undefined'` */
NullishComparisonType["StrictEqualUndefined"] = "StrictEqualUndefined";
/** `!x` */
NullishComparisonType["NotBoolean"] = "NotBoolean";
/** `x` */
NullishComparisonType["Boolean"] = "Boolean";
})(NullishComparisonType || (exports.NullishComparisonType = NullishComparisonType = {}));
const NULLISH_FLAGS = ts.TypeFlags.Null | ts.TypeFlags.Undefined;
function isValidFalseBooleanCheckType(node, disallowFalseyLiteral, parserServices, options) {
const type = parserServices.getTypeAtLocation(node);
const types = (0, ts_api_utils_1.unionConstituents)(type);
if (disallowFalseyLiteral &&
/*
```
declare const x: false | {a: string};
x && x.a;
!x || x.a;
```
We don't want to consider these two cases because the boolean expression
narrows out the non-nullish falsy cases - so converting the chain to `x?.a`
would introduce a build error
*/ (types.some(t => (0, ts_api_utils_1.isBooleanLiteralType)(t) && t.intrinsicName === 'false') ||
types.some(t => (0, ts_api_utils_1.isStringLiteralType)(t) && t.value === '') ||
types.some(t => (0, ts_api_utils_1.isNumberLiteralType)(t) && t.value === 0) ||
types.some(t => (0, ts_api_utils_1.isBigIntLiteralType)(t) && t.value.base10Value === '0'))) {
return false;
}
let allowedFlags = NULLISH_FLAGS | ts.TypeFlags.Object;
if (options.checkAny === true) {
allowedFlags |= ts.TypeFlags.Any;
}
if (options.checkUnknown === true) {
allowedFlags |= ts.TypeFlags.Unknown;
}
if (options.checkString === true) {
allowedFlags |= ts.TypeFlags.StringLike;
}
if (options.checkNumber === true) {
allowedFlags |= ts.TypeFlags.NumberLike;
}
if (options.checkBoolean === true) {
allowedFlags |= ts.TypeFlags.BooleanLike;
}
if (options.checkBigInt === true) {
allowedFlags |= ts.TypeFlags.BigIntLike;
}
return types.every(t => (0, util_1.isTypeFlagSet)(t, allowedFlags));
}
function gatherLogicalOperands(node, parserServices, sourceCode, options) {
const result = [];
const { newlySeenLogicals, operands } = flattenLogicalOperands(node);
for (const operand of operands) {
const areMoreOperands = operand !== operands.at(-1);
switch (operand.type) {
case utils_1.AST_NODE_TYPES.BinaryExpression: {
// check for "yoda" style logical: null != x
const { comparedExpression, comparedValue, isYoda } = (() => {
// non-yoda checks are by far the most common, so check for them first
const comparedValueRight = getComparisonValueType(operand.right);
if (comparedValueRight) {
return {
comparedExpression: operand.left,
comparedValue: comparedValueRight,
isYoda: false,
};
}
return {
comparedExpression: operand.right,
comparedValue: getComparisonValueType(operand.left),
isYoda: true,
};
})();
if (comparedValue === ComparisonValueType.UndefinedStringLiteral) {
if (comparedExpression.type === utils_1.AST_NODE_TYPES.UnaryExpression &&
comparedExpression.operator === 'typeof') {
const argument = comparedExpression.argument;
if (argument.type === utils_1.AST_NODE_TYPES.Identifier &&
// typeof window === 'undefined'
(0, util_1.isReferenceToGlobalFunction)(argument.name, argument, sourceCode)) {
result.push({ type: OperandValidity.Invalid });
continue;
}
// typeof x.y === 'undefined'
result.push({
comparedName: comparedExpression.argument,
comparisonType: operand.operator.startsWith('!')
? NullishComparisonType.NotStrictEqualUndefined
: NullishComparisonType.StrictEqualUndefined,
isYoda,
node: operand,
type: OperandValidity.Valid,
});
continue;
}
// y === 'undefined'
result.push({ type: OperandValidity.Invalid });
continue;
}
switch (operand.operator) {
case '!=':
case '==':
if (comparedValue === ComparisonValueType.Null ||
comparedValue === ComparisonValueType.Undefined) {
// x == null, x == undefined
result.push({
comparedName: comparedExpression,
comparisonType: operand.operator.startsWith('!')
? NullishComparisonType.NotEqualNullOrUndefined
: NullishComparisonType.EqualNullOrUndefined,
isYoda,
node: operand,
type: OperandValidity.Valid,
});
continue;
}
// x == something :(
result.push({ type: OperandValidity.Invalid });
continue;
case '!==':
case '===': {
const comparedName = comparedExpression;
switch (comparedValue) {
case ComparisonValueType.Null:
result.push({
comparedName,
comparisonType: operand.operator.startsWith('!')
? NullishComparisonType.NotStrictEqualNull
: NullishComparisonType.StrictEqualNull,
isYoda,
node: operand,
type: OperandValidity.Valid,
});
continue;
case ComparisonValueType.Undefined:
result.push({
comparedName,
comparisonType: operand.operator.startsWith('!')
? NullishComparisonType.NotStrictEqualUndefined
: NullishComparisonType.StrictEqualUndefined,
isYoda,
node: operand,
type: OperandValidity.Valid,
});
continue;
default:
// x === something :(
result.push({ type: OperandValidity.Invalid });
continue;
}
}
}
result.push({ type: OperandValidity.Invalid });
continue;
}
case utils_1.AST_NODE_TYPES.UnaryExpression:
if (operand.operator === '!' &&
isValidFalseBooleanCheckType(operand.argument, areMoreOperands && node.operator === '||', parserServices, options)) {
result.push({
comparedName: operand.argument,
comparisonType: NullishComparisonType.NotBoolean,
isYoda: false,
node: operand,
type: OperandValidity.Valid,
});
continue;
}
result.push({ type: OperandValidity.Invalid });
continue;
case utils_1.AST_NODE_TYPES.LogicalExpression:
// explicitly ignore the mixed logical expression cases
result.push({ type: OperandValidity.Invalid });
continue;
default:
if (isValidFalseBooleanCheckType(operand, areMoreOperands && node.operator === '&&', parserServices, options)) {
result.push({
comparedName: operand,
comparisonType: NullishComparisonType.Boolean,
isYoda: false,
node: operand,
type: OperandValidity.Valid,
});
}
else {
result.push({ type: OperandValidity.Invalid });
}
continue;
}
}
return {
newlySeenLogicals,
operands: result,
};
/*
The AST is always constructed such the first element is always the deepest element.
I.e. for this code: `foo && foo.bar && foo.bar.baz && foo.bar.baz.buzz`
The AST will look like this:
{
left: {
left: {
left: foo
right: foo.bar
}
right: foo.bar.baz
}
right: foo.bar.baz.buzz
}
So given any logical expression, we can perform a depth-first traversal to get
the operands in order.
Note that this function purposely does not inspect mixed logical expressions
like `foo || foo.bar && foo.bar.baz` - separate selector
*/
function flattenLogicalOperands(node) {
const operands = [];
const newlySeenLogicals = new Set([node]);
const stack = [node.right, node.left];
let current;
while ((current = stack.pop())) {
if (current.type === utils_1.AST_NODE_TYPES.LogicalExpression &&
current.operator === node.operator) {
newlySeenLogicals.add(current);
stack.push(current.right);
stack.push(current.left);
}
else {
operands.push(current);
}
}
return {
newlySeenLogicals,
operands,
};
}
function getComparisonValueType(node) {
switch (node.type) {
case utils_1.AST_NODE_TYPES.Literal:
// eslint-disable-next-line eqeqeq, @typescript-eslint/internal/eqeq-nullish -- intentional exact comparison against null
if (node.value === null && node.raw === 'null') {
return ComparisonValueType.Null;
}
if (node.value === 'undefined') {
return ComparisonValueType.UndefinedStringLiteral;
}
return null;
case utils_1.AST_NODE_TYPES.Identifier:
if (node.name === 'undefined') {
return ComparisonValueType.Undefined;
}
return null;
}
return null;
}
}