359 lines
11 KiB
JavaScript
359 lines
11 KiB
JavaScript
/**
|
|
* @fileoverview Rule to flag on declaring variables already declared in the outer scope
|
|
* @author Ilya Volodin
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require('./utils/ast-utils');
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
const FUNC_EXPR_NODE_TYPES = new Set([
|
|
'ArrowFunctionExpression',
|
|
'FunctionExpression',
|
|
]);
|
|
const CALL_EXPR_NODE_TYPE = new Set(['CallExpression']);
|
|
const FOR_IN_OF_TYPE = /^For(?:In|Of)Statement$/u;
|
|
const SENTINEL_TYPE =
|
|
/^(?:(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression|CatchClause|ImportDeclaration|ExportNamedDeclaration)$/u;
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
/** @type {import('../types').Rule.RuleModule} */
|
|
module.exports = {
|
|
meta: {
|
|
type: 'suggestion',
|
|
|
|
defaultOptions: [
|
|
{
|
|
allow: [],
|
|
builtinGlobals: false,
|
|
hoist: 'functions',
|
|
ignoreOnInitialization: false,
|
|
},
|
|
],
|
|
|
|
docs: {
|
|
description:
|
|
'Disallow variable declarations from shadowing variables declared in the outer scope',
|
|
recommended: false,
|
|
url: 'https://eslint.org/docs/latest/rules/no-shadow',
|
|
},
|
|
|
|
schema: [
|
|
{
|
|
type: 'object',
|
|
properties: {
|
|
builtinGlobals: { type: 'boolean' },
|
|
hoist: { enum: ['all', 'functions', 'never'] },
|
|
allow: {
|
|
type: 'array',
|
|
items: {
|
|
type: 'string',
|
|
},
|
|
},
|
|
ignoreOnInitialization: { type: 'boolean' },
|
|
},
|
|
additionalProperties: false,
|
|
},
|
|
],
|
|
|
|
messages: {
|
|
noShadow:
|
|
"'{{name}}' is already declared in the upper scope on line {{shadowedLine}} column {{shadowedColumn}}.",
|
|
noShadowGlobal: "'{{name}}' is already a global variable.",
|
|
},
|
|
},
|
|
|
|
create(context) {
|
|
const [{ builtinGlobals, hoist, allow, ignoreOnInitialization }] =
|
|
context.options;
|
|
const sourceCode = context.sourceCode;
|
|
|
|
/**
|
|
* Checks whether or not a given location is inside of the range of a given node.
|
|
* @param {ASTNode} node An node to check.
|
|
* @param {number} location A location to check.
|
|
* @returns {boolean} `true` if the location is inside of the range of the node.
|
|
*/
|
|
function isInRange(node, location) {
|
|
return node && node.range[0] <= location && location <= node.range[1];
|
|
}
|
|
|
|
/**
|
|
* Searches from the current node through its ancestry to find a matching node.
|
|
* @param {ASTNode} node a node to get.
|
|
* @param {(node: ASTNode) => boolean} match a callback that checks whether or not the node verifies its condition or not.
|
|
* @returns {ASTNode|null} the matching node.
|
|
*/
|
|
function findSelfOrAncestor(node, match) {
|
|
let currentNode = node;
|
|
|
|
while (currentNode && !match(currentNode)) {
|
|
currentNode = currentNode.parent;
|
|
}
|
|
return currentNode;
|
|
}
|
|
|
|
/**
|
|
* Finds function's outer scope.
|
|
* @param {Scope} scope Function's own scope.
|
|
* @returns {Scope} Function's outer scope.
|
|
*/
|
|
function getOuterScope(scope) {
|
|
const upper = scope.upper;
|
|
|
|
if (upper.type === 'function-expression-name') {
|
|
return upper.upper;
|
|
}
|
|
return upper;
|
|
}
|
|
|
|
/**
|
|
* Checks if a variable and a shadowedVariable have the same init pattern ancestor.
|
|
* @param {Object} variable a variable to check.
|
|
* @param {Object} shadowedVariable a shadowedVariable to check.
|
|
* @returns {boolean} Whether or not the variable and the shadowedVariable have the same init pattern ancestor.
|
|
*/
|
|
function isInitPatternNode(variable, shadowedVariable) {
|
|
const outerDef = shadowedVariable.defs[0];
|
|
|
|
if (!outerDef) {
|
|
return false;
|
|
}
|
|
|
|
const { variableScope } = variable.scope;
|
|
|
|
if (
|
|
!(
|
|
FUNC_EXPR_NODE_TYPES.has(variableScope.block.type) &&
|
|
getOuterScope(variableScope) === shadowedVariable.scope
|
|
)
|
|
) {
|
|
return false;
|
|
}
|
|
|
|
const fun = variableScope.block;
|
|
const { parent } = fun;
|
|
|
|
const callExpression = findSelfOrAncestor(parent, (node) =>
|
|
CALL_EXPR_NODE_TYPE.has(node.type)
|
|
);
|
|
|
|
if (!callExpression) {
|
|
return false;
|
|
}
|
|
|
|
let node = outerDef.name;
|
|
const location = callExpression.range[1];
|
|
|
|
while (node) {
|
|
if (node.type === 'VariableDeclarator') {
|
|
if (isInRange(node.init, location)) {
|
|
return true;
|
|
}
|
|
if (
|
|
FOR_IN_OF_TYPE.test(node.parent.parent.type) &&
|
|
isInRange(node.parent.parent.right, location)
|
|
) {
|
|
return true;
|
|
}
|
|
break;
|
|
} else if (node.type === 'AssignmentPattern') {
|
|
if (isInRange(node.right, location)) {
|
|
return true;
|
|
}
|
|
} else if (SENTINEL_TYPE.test(node.type)) {
|
|
break;
|
|
}
|
|
|
|
node = node.parent;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Check if variable name is allowed.
|
|
* @param {ASTNode} variable The variable to check.
|
|
* @returns {boolean} Whether or not the variable name is allowed.
|
|
*/
|
|
function isAllowed(variable) {
|
|
return allow.includes(variable.name);
|
|
}
|
|
|
|
/**
|
|
* 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 {Object} variable The variable to check.
|
|
* @returns {boolean} 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 === 'ClassDeclaration' &&
|
|
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 {Object} variable The variable to check.
|
|
* @param {Object} scopeVar The scope variable to look for.
|
|
* @returns {boolean} Whether or not the variable is inside initializer of scopeVar.
|
|
*/
|
|
function isOnInitializer(variable, scopeVar) {
|
|
const outerScope = scopeVar.scope;
|
|
const outerDef = scopeVar.defs[0];
|
|
const outer = outerDef && outerDef.parent && outerDef.parent.range;
|
|
const innerScope = variable.scope;
|
|
const innerDef = variable.defs[0];
|
|
const inner = innerDef && innerDef.name.range;
|
|
|
|
return (
|
|
outer &&
|
|
inner &&
|
|
outer[0] < inner[0] &&
|
|
inner[1] < outer[1] &&
|
|
((innerDef.type === 'FunctionName' &&
|
|
innerDef.node.type === 'FunctionExpression') ||
|
|
innerDef.node.type === 'ClassExpression') &&
|
|
outerScope === innerScope.upper
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Get a range of a variable's identifier node.
|
|
* @param {Object} variable The variable to get.
|
|
* @returns {Array|undefined} The range of the variable's identifier node.
|
|
*/
|
|
function getNameRange(variable) {
|
|
const def = variable.defs[0];
|
|
|
|
return def && def.name.range;
|
|
}
|
|
|
|
/**
|
|
* Get declared line and column of a variable.
|
|
* @param {eslint-scope.Variable} variable The variable to get.
|
|
* @returns {Object} The declared line and column of the variable.
|
|
*/
|
|
function getDeclaredLocation(variable) {
|
|
const identifier = variable.identifiers[0];
|
|
let obj;
|
|
|
|
if (identifier) {
|
|
obj = {
|
|
global: false,
|
|
line: identifier.loc.start.line,
|
|
column: identifier.loc.start.column + 1,
|
|
};
|
|
} else {
|
|
obj = {
|
|
global: true,
|
|
};
|
|
}
|
|
return obj;
|
|
}
|
|
|
|
/**
|
|
* Checks if a variable is in TDZ of scopeVar.
|
|
* @param {Object} variable The variable to check.
|
|
* @param {Object} scopeVar The variable of TDZ.
|
|
* @returns {boolean} 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"}.
|
|
(hoist !== 'functions' ||
|
|
!outerDef ||
|
|
outerDef.node.type !== 'FunctionDeclaration')
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Checks the current context for shadowed variables.
|
|
* @param {Scope} scope Fixme
|
|
* @returns {void}
|
|
*/
|
|
function checkForShadows(scope) {
|
|
const variables = scope.variables;
|
|
|
|
for (let i = 0; i < variables.length; ++i) {
|
|
const variable = variables[i];
|
|
|
|
// Skips "arguments" or variables of a class name in the class scope of ClassDeclaration.
|
|
if (
|
|
variable.identifiers.length === 0 ||
|
|
isDuplicatedClassNameVariable(variable) ||
|
|
isAllowed(variable)
|
|
) {
|
|
continue;
|
|
}
|
|
|
|
// Gets shadowed variable.
|
|
const shadowed = astUtils.getVariableByName(scope.upper, variable.name);
|
|
|
|
if (
|
|
shadowed &&
|
|
(shadowed.identifiers.length > 0 ||
|
|
(builtinGlobals && 'writeable' in shadowed)) &&
|
|
!isOnInitializer(variable, shadowed) &&
|
|
!(ignoreOnInitialization && isInitPatternNode(variable, shadowed)) &&
|
|
!(hoist !== 'all' && isInTdz(variable, shadowed))
|
|
) {
|
|
const location = getDeclaredLocation(shadowed);
|
|
const messageId = location.global ? 'noShadowGlobal' : 'noShadow';
|
|
const data = { name: variable.name };
|
|
|
|
if (!location.global) {
|
|
data.shadowedLine = location.line;
|
|
data.shadowedColumn = location.column;
|
|
}
|
|
context.report({
|
|
node: variable.identifiers[0],
|
|
messageId,
|
|
data,
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
return {
|
|
'Program:exit'(node) {
|
|
const globalScope = sourceCode.getScope(node);
|
|
const stack = globalScope.childScopes.slice();
|
|
|
|
while (stack.length) {
|
|
const scope = stack.pop();
|
|
|
|
stack.push(...scope.childScopes);
|
|
checkForShadows(scope);
|
|
}
|
|
},
|
|
};
|
|
},
|
|
};
|