no-shadow.js
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"use strict";
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
Object.defineProperty(o, k2, { enumerable: true, get: function() { return m[k]; } });
}) : (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 (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
__setModuleDefault(result, mod);
return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
const experimental_utils_1 = require("@typescript-eslint/experimental-utils");
const scope_manager_1 = require("@typescript-eslint/scope-manager");
const util = __importStar(require("../util"));
exports.default = util.createRule({
name: 'no-shadow',
meta: {
type: 'suggestion',
docs: {
description: 'Disallow variable declarations from shadowing variables declared in the outer scope',
category: 'Variables',
recommended: false,
extendsBaseRule: true,
},
schema: [
{
type: 'object',
properties: {
builtinGlobals: {
type: 'boolean',
},
hoist: {
enum: ['all', 'functions', 'never'],
},
allow: {
type: 'array',
items: {
type: 'string',
},
},
ignoreTypeValueShadow: {
type: 'boolean',
},
ignoreFunctionTypeParameterNameValueShadow: {
type: 'boolean',
},
},
additionalProperties: false,
},
],
messages: {
noShadow: "'{{name}}' is already declared in the upper scope.",
},
},
defaultOptions: [
{
allow: [],
builtinGlobals: false,
hoist: 'functions',
ignoreTypeValueShadow: true,
ignoreFunctionTypeParameterNameValueShadow: true,
},
],
create(context, [options]) {
/**
* Check if a scope is a TypeScript module augmenting the global namespace.
*/
function isGlobalAugmentation(scope) {
return ((scope.type === scope_manager_1.ScopeType.tsModule && !!scope.block.global) ||
(!!scope.upper && isGlobalAugmentation(scope.upper)));
}
/**
* Check if variable is a `this` parameter.
*/
function isThisParam(variable) {
return variable.defs[0].type === 'Parameter' && variable.name === 'this';
}
function isTypeValueShadow(variable, shadowed) {
if (options.ignoreTypeValueShadow !== true) {
return false;
}
if (!('isValueVariable' in variable)) {
// this shouldn't happen...
return false;
}
const isShadowedValue = 'isValueVariable' in shadowed ? shadowed.isValueVariable : true;
return variable.isValueVariable !== isShadowedValue;
}
function isFunctionTypeParameterNameValueShadow(variable, shadowed) {
if (options.ignoreFunctionTypeParameterNameValueShadow !== true) {
return false;
}
if (!('isValueVariable' in variable)) {
// this shouldn't happen...
return false;
}
const isShadowedValue = 'isValueVariable' in shadowed ? shadowed.isValueVariable : true;
if (!isShadowedValue) {
return false;
}
const id = variable.identifiers[0];
return util.isFunctionType(id.parent);
}
/**
* Check if variable name is allowed.
* @param variable The variable to check.
* @returns Whether or not the variable name is allowed.
*/
function isAllowed(variable) {
return options.allow.indexOf(variable.name) !== -1;
}
/**
* Checks if a variable of the class name in the class scope of ClassDeclaration.
*
* ClassDeclaration creates two variables of its name into its outer scope and its class scope.
* So we should ignore the variable in the class scope.
* @param variable The variable to check.
* @returns Whether or not the variable of the class name in the class scope of ClassDeclaration.
*/
function isDuplicatedClassNameVariable(variable) {
const block = variable.scope.block;
return (block.type === experimental_utils_1.AST_NODE_TYPES.ClassDeclaration &&
block.id === variable.identifiers[0]);
}
/**
* Checks if a variable of the class name in the class scope of TSEnumDeclaration.
*
* TSEnumDeclaration creates two variables of its name into its outer scope and its class scope.
* So we should ignore the variable in the class scope.
* @param variable The variable to check.
* @returns Whether or not the variable of the class name in the class scope of TSEnumDeclaration.
*/
function isDuplicatedEnumNameVariable(variable) {
const block = variable.scope.block;
return (block.type === experimental_utils_1.AST_NODE_TYPES.TSEnumDeclaration &&
block.id === variable.identifiers[0]);
}
/**
* Checks if a variable is inside the initializer of scopeVar.
*
* To avoid reporting at declarations such as `var a = function a() {};`.
* But it should report `var a = function(a) {};` or `var a = function() { function a() {} };`.
* @param variable The variable to check.
* @param scopeVar The scope variable to look for.
* @returns Whether or not the variable is inside initializer of scopeVar.
*/
function isOnInitializer(variable, scopeVar) {
var _a;
const outerScope = scopeVar.scope;
const outerDef = scopeVar.defs[0];
const outer = (_a = outerDef === null || outerDef === void 0 ? void 0 : outerDef.parent) === null || _a === void 0 ? void 0 : _a.range;
const innerScope = variable.scope;
const innerDef = variable.defs[0];
const inner = innerDef === null || innerDef === void 0 ? void 0 : innerDef.name.range;
return !!(outer &&
inner &&
outer[0] < inner[0] &&
inner[1] < outer[1] &&
((innerDef.type === 'FunctionName' &&
innerDef.node.type === experimental_utils_1.AST_NODE_TYPES.FunctionExpression) ||
innerDef.node.type === experimental_utils_1.AST_NODE_TYPES.ClassExpression) &&
outerScope === innerScope.upper);
}
/**
* Get a range of a variable's identifier node.
* @param variable The variable to get.
* @returns The range of the variable's identifier node.
*/
function getNameRange(variable) {
const def = variable.defs[0];
return def === null || def === void 0 ? void 0 : def.name.range;
}
/**
* Checks if a variable is in TDZ of scopeVar.
* @param variable The variable to check.
* @param scopeVar The variable of TDZ.
* @returns Whether or not the variable is in TDZ of scopeVar.
*/
function isInTdz(variable, scopeVar) {
const outerDef = scopeVar.defs[0];
const inner = getNameRange(variable);
const outer = getNameRange(scopeVar);
return !!(inner &&
outer &&
inner[1] < outer[0] &&
// Excepts FunctionDeclaration if is {"hoist":"function"}.
(options.hoist !== 'functions' ||
!outerDef ||
outerDef.node.type !== experimental_utils_1.AST_NODE_TYPES.FunctionDeclaration));
}
/**
* Finds the variable by a given name in a given scope and its upper scopes.
* @param initScope A scope to start find.
* @param name A variable name to find.
* @returns A found variable or `null`.
*/
function getVariableByName(initScope, name) {
let scope = initScope;
while (scope) {
const variable = scope.set.get(name);
if (variable) {
return variable;
}
scope = scope.upper;
}
return null;
}
/**
* Checks the current context for shadowed variables.
* @param {Scope} scope Fixme
*/
function checkForShadows(scope) {
// ignore global augmentation
if (isGlobalAugmentation(scope)) {
return;
}
const variables = scope.variables;
for (const variable of variables) {
// ignore "arguments"
if (variable.identifiers.length === 0) {
continue;
}
// this params are pseudo-params that cannot be shadowed
if (isThisParam(variable)) {
continue;
}
// ignore variables of a class name in the class scope of ClassDeclaration
if (isDuplicatedClassNameVariable(variable)) {
continue;
}
// ignore variables of a class name in the class scope of ClassDeclaration
if (isDuplicatedEnumNameVariable(variable)) {
continue;
}
// ignore configured allowed names
if (isAllowed(variable)) {
continue;
}
// Gets shadowed variable.
const shadowed = getVariableByName(scope.upper, variable.name);
if (!shadowed) {
continue;
}
// ignore type value variable shadowing if configured
if (isTypeValueShadow(variable, shadowed)) {
continue;
}
// ignore function type parameter name shadowing if configured
if (isFunctionTypeParameterNameValueShadow(variable, shadowed)) {
continue;
}
const isESLintGlobal = 'writeable' in shadowed;
if ((shadowed.identifiers.length > 0 ||
(options.builtinGlobals && isESLintGlobal)) &&
!isOnInitializer(variable, shadowed) &&
!(options.hoist !== 'all' && isInTdz(variable, shadowed))) {
context.report({
node: variable.identifiers[0],
messageId: 'noShadow',
data: {
name: variable.name,
},
});
}
}
}
return {
'Program:exit'() {
const globalScope = context.getScope();
const stack = globalScope.childScopes.slice();
while (stack.length) {
const scope = stack.pop();
stack.push(...scope.childScopes);
checkForShadows(scope);
}
},
};
},
});
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