mirror of
https://github.com/joelwmale/webhook-action.git
synced 2024-12-05 05:34:29 +01:00
335 lines
12 KiB
JavaScript
335 lines
12 KiB
JavaScript
|
/**
|
||
|
* @fileoverview Rule to check for the usage of var.
|
||
|
* @author Jamund Ferguson
|
||
|
*/
|
||
|
|
||
|
"use strict";
|
||
|
|
||
|
//------------------------------------------------------------------------------
|
||
|
// Requirements
|
||
|
//------------------------------------------------------------------------------
|
||
|
|
||
|
const astUtils = require("./utils/ast-utils");
|
||
|
|
||
|
//------------------------------------------------------------------------------
|
||
|
// Helpers
|
||
|
//------------------------------------------------------------------------------
|
||
|
|
||
|
/**
|
||
|
* Check whether a given variable is a global variable or not.
|
||
|
* @param {eslint-scope.Variable} variable The variable to check.
|
||
|
* @returns {boolean} `true` if the variable is a global variable.
|
||
|
*/
|
||
|
function isGlobal(variable) {
|
||
|
return Boolean(variable.scope) && variable.scope.type === "global";
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Finds the nearest function scope or global scope walking up the scope
|
||
|
* hierarchy.
|
||
|
* @param {eslint-scope.Scope} scope The scope to traverse.
|
||
|
* @returns {eslint-scope.Scope} a function scope or global scope containing the given
|
||
|
* scope.
|
||
|
*/
|
||
|
function getEnclosingFunctionScope(scope) {
|
||
|
let currentScope = scope;
|
||
|
|
||
|
while (currentScope.type !== "function" && currentScope.type !== "global") {
|
||
|
currentScope = currentScope.upper;
|
||
|
}
|
||
|
return currentScope;
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether the given variable has any references from a more specific
|
||
|
* function expression (i.e. a closure).
|
||
|
* @param {eslint-scope.Variable} variable A variable to check.
|
||
|
* @returns {boolean} `true` if the variable is used from a closure.
|
||
|
*/
|
||
|
function isReferencedInClosure(variable) {
|
||
|
const enclosingFunctionScope = getEnclosingFunctionScope(variable.scope);
|
||
|
|
||
|
return variable.references.some(reference =>
|
||
|
getEnclosingFunctionScope(reference.from) !== enclosingFunctionScope);
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether the given node is the assignee of a loop.
|
||
|
* @param {ASTNode} node A VariableDeclaration node to check.
|
||
|
* @returns {boolean} `true` if the declaration is assigned as part of loop
|
||
|
* iteration.
|
||
|
*/
|
||
|
function isLoopAssignee(node) {
|
||
|
return (node.parent.type === "ForOfStatement" || node.parent.type === "ForInStatement") &&
|
||
|
node === node.parent.left;
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether the given variable declaration is immediately initialized.
|
||
|
* @param {ASTNode} node A VariableDeclaration node to check.
|
||
|
* @returns {boolean} `true` if the declaration has an initializer.
|
||
|
*/
|
||
|
function isDeclarationInitialized(node) {
|
||
|
return node.declarations.every(declarator => declarator.init !== null);
|
||
|
}
|
||
|
|
||
|
const SCOPE_NODE_TYPE = /^(?:Program|BlockStatement|SwitchStatement|ForStatement|ForInStatement|ForOfStatement)$/u;
|
||
|
|
||
|
/**
|
||
|
* Gets the scope node which directly contains a given node.
|
||
|
* @param {ASTNode} node A node to get. This is a `VariableDeclaration` or
|
||
|
* an `Identifier`.
|
||
|
* @returns {ASTNode} A scope node. This is one of `Program`, `BlockStatement`,
|
||
|
* `SwitchStatement`, `ForStatement`, `ForInStatement`, and
|
||
|
* `ForOfStatement`.
|
||
|
*/
|
||
|
function getScopeNode(node) {
|
||
|
for (let currentNode = node; currentNode; currentNode = currentNode.parent) {
|
||
|
if (SCOPE_NODE_TYPE.test(currentNode.type)) {
|
||
|
return currentNode;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
/* istanbul ignore next : unreachable */
|
||
|
return null;
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether a given variable is redeclared or not.
|
||
|
* @param {eslint-scope.Variable} variable A variable to check.
|
||
|
* @returns {boolean} `true` if the variable is redeclared.
|
||
|
*/
|
||
|
function isRedeclared(variable) {
|
||
|
return variable.defs.length >= 2;
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether a given variable is used from outside of the specified scope.
|
||
|
* @param {ASTNode} scopeNode A scope node to check.
|
||
|
* @returns {Function} The predicate function which checks whether a given
|
||
|
* variable is used from outside of the specified scope.
|
||
|
*/
|
||
|
function isUsedFromOutsideOf(scopeNode) {
|
||
|
|
||
|
/**
|
||
|
* Checks whether a given reference is inside of the specified scope or not.
|
||
|
* @param {eslint-scope.Reference} reference A reference to check.
|
||
|
* @returns {boolean} `true` if the reference is inside of the specified
|
||
|
* scope.
|
||
|
*/
|
||
|
function isOutsideOfScope(reference) {
|
||
|
const scope = scopeNode.range;
|
||
|
const id = reference.identifier.range;
|
||
|
|
||
|
return id[0] < scope[0] || id[1] > scope[1];
|
||
|
}
|
||
|
|
||
|
return function(variable) {
|
||
|
return variable.references.some(isOutsideOfScope);
|
||
|
};
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Creates the predicate function which checks whether a variable has their references in TDZ.
|
||
|
*
|
||
|
* The predicate function would return `true`:
|
||
|
*
|
||
|
* - if a reference is before the declarator. E.g. (var a = b, b = 1;)(var {a = b, b} = {};)
|
||
|
* - if a reference is in the expression of their default value. E.g. (var {a = a} = {};)
|
||
|
* - if a reference is in the expression of their initializer. E.g. (var a = a;)
|
||
|
* @param {ASTNode} node The initializer node of VariableDeclarator.
|
||
|
* @returns {Function} The predicate function.
|
||
|
* @private
|
||
|
*/
|
||
|
function hasReferenceInTDZ(node) {
|
||
|
const initStart = node.range[0];
|
||
|
const initEnd = node.range[1];
|
||
|
|
||
|
return variable => {
|
||
|
const id = variable.defs[0].name;
|
||
|
const idStart = id.range[0];
|
||
|
const defaultValue = (id.parent.type === "AssignmentPattern" ? id.parent.right : null);
|
||
|
const defaultStart = defaultValue && defaultValue.range[0];
|
||
|
const defaultEnd = defaultValue && defaultValue.range[1];
|
||
|
|
||
|
return variable.references.some(reference => {
|
||
|
const start = reference.identifier.range[0];
|
||
|
const end = reference.identifier.range[1];
|
||
|
|
||
|
return !reference.init && (
|
||
|
start < idStart ||
|
||
|
(defaultValue !== null && start >= defaultStart && end <= defaultEnd) ||
|
||
|
(start >= initStart && end <= initEnd)
|
||
|
);
|
||
|
});
|
||
|
};
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether a given variable has name that is allowed for 'var' declarations,
|
||
|
* but disallowed for `let` declarations.
|
||
|
* @param {eslint-scope.Variable} variable The variable to check.
|
||
|
* @returns {boolean} `true` if the variable has a disallowed name.
|
||
|
*/
|
||
|
function hasNameDisallowedForLetDeclarations(variable) {
|
||
|
return variable.name === "let";
|
||
|
}
|
||
|
|
||
|
//------------------------------------------------------------------------------
|
||
|
// Rule Definition
|
||
|
//------------------------------------------------------------------------------
|
||
|
|
||
|
module.exports = {
|
||
|
meta: {
|
||
|
type: "suggestion",
|
||
|
|
||
|
docs: {
|
||
|
description: "require `let` or `const` instead of `var`",
|
||
|
category: "ECMAScript 6",
|
||
|
recommended: false,
|
||
|
url: "https://eslint.org/docs/rules/no-var"
|
||
|
},
|
||
|
|
||
|
schema: [],
|
||
|
fixable: "code",
|
||
|
|
||
|
messages: {
|
||
|
unexpectedVar: "Unexpected var, use let or const instead."
|
||
|
}
|
||
|
},
|
||
|
|
||
|
create(context) {
|
||
|
const sourceCode = context.getSourceCode();
|
||
|
|
||
|
/**
|
||
|
* Checks whether the variables which are defined by the given declarator node have their references in TDZ.
|
||
|
* @param {ASTNode} declarator The VariableDeclarator node to check.
|
||
|
* @returns {boolean} `true` if one of the variables which are defined by the given declarator node have their references in TDZ.
|
||
|
*/
|
||
|
function hasSelfReferenceInTDZ(declarator) {
|
||
|
if (!declarator.init) {
|
||
|
return false;
|
||
|
}
|
||
|
const variables = context.getDeclaredVariables(declarator);
|
||
|
|
||
|
return variables.some(hasReferenceInTDZ(declarator.init));
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Checks whether it can fix a given variable declaration or not.
|
||
|
* It cannot fix if the following cases:
|
||
|
*
|
||
|
* - A variable is a global variable.
|
||
|
* - A variable is declared on a SwitchCase node.
|
||
|
* - A variable is redeclared.
|
||
|
* - A variable is used from outside the scope.
|
||
|
* - A variable is used from a closure within a loop.
|
||
|
* - A variable might be used before it is assigned within a loop.
|
||
|
* - A variable might be used in TDZ.
|
||
|
* - A variable is declared in statement position (e.g. a single-line `IfStatement`)
|
||
|
* - A variable has name that is disallowed for `let` declarations.
|
||
|
*
|
||
|
* ## A variable is declared on a SwitchCase node.
|
||
|
*
|
||
|
* If this rule modifies 'var' declarations on a SwitchCase node, it
|
||
|
* would generate the warnings of 'no-case-declarations' rule. And the
|
||
|
* 'eslint:recommended' preset includes 'no-case-declarations' rule, so
|
||
|
* this rule doesn't modify those declarations.
|
||
|
*
|
||
|
* ## A variable is redeclared.
|
||
|
*
|
||
|
* The language spec disallows redeclarations of `let` declarations.
|
||
|
* Those variables would cause syntax errors.
|
||
|
*
|
||
|
* ## A variable is used from outside the scope.
|
||
|
*
|
||
|
* The language spec disallows accesses from outside of the scope for
|
||
|
* `let` declarations. Those variables would cause reference errors.
|
||
|
*
|
||
|
* ## A variable is used from a closure within a loop.
|
||
|
*
|
||
|
* A `var` declaration within a loop shares the same variable instance
|
||
|
* across all loop iterations, while a `let` declaration creates a new
|
||
|
* instance for each iteration. This means if a variable in a loop is
|
||
|
* referenced by any closure, changing it from `var` to `let` would
|
||
|
* change the behavior in a way that is generally unsafe.
|
||
|
*
|
||
|
* ## A variable might be used before it is assigned within a loop.
|
||
|
*
|
||
|
* Within a loop, a `let` declaration without an initializer will be
|
||
|
* initialized to null, while a `var` declaration will retain its value
|
||
|
* from the previous iteration, so it is only safe to change `var` to
|
||
|
* `let` if we can statically determine that the variable is always
|
||
|
* assigned a value before its first access in the loop body. To keep
|
||
|
* the implementation simple, we only convert `var` to `let` within
|
||
|
* loops when the variable is a loop assignee or the declaration has an
|
||
|
* initializer.
|
||
|
* @param {ASTNode} node A variable declaration node to check.
|
||
|
* @returns {boolean} `true` if it can fix the node.
|
||
|
*/
|
||
|
function canFix(node) {
|
||
|
const variables = context.getDeclaredVariables(node);
|
||
|
const scopeNode = getScopeNode(node);
|
||
|
|
||
|
if (node.parent.type === "SwitchCase" ||
|
||
|
node.declarations.some(hasSelfReferenceInTDZ) ||
|
||
|
variables.some(isGlobal) ||
|
||
|
variables.some(isRedeclared) ||
|
||
|
variables.some(isUsedFromOutsideOf(scopeNode)) ||
|
||
|
variables.some(hasNameDisallowedForLetDeclarations)
|
||
|
) {
|
||
|
return false;
|
||
|
}
|
||
|
|
||
|
if (astUtils.isInLoop(node)) {
|
||
|
if (variables.some(isReferencedInClosure)) {
|
||
|
return false;
|
||
|
}
|
||
|
if (!isLoopAssignee(node) && !isDeclarationInitialized(node)) {
|
||
|
return false;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
if (
|
||
|
!isLoopAssignee(node) &&
|
||
|
!(node.parent.type === "ForStatement" && node.parent.init === node) &&
|
||
|
!astUtils.STATEMENT_LIST_PARENTS.has(node.parent.type)
|
||
|
) {
|
||
|
|
||
|
// If the declaration is not in a block, e.g. `if (foo) var bar = 1;`, then it can't be fixed.
|
||
|
return false;
|
||
|
}
|
||
|
|
||
|
return true;
|
||
|
}
|
||
|
|
||
|
/**
|
||
|
* Reports a given variable declaration node.
|
||
|
* @param {ASTNode} node A variable declaration node to report.
|
||
|
* @returns {void}
|
||
|
*/
|
||
|
function report(node) {
|
||
|
context.report({
|
||
|
node,
|
||
|
messageId: "unexpectedVar",
|
||
|
|
||
|
fix(fixer) {
|
||
|
const varToken = sourceCode.getFirstToken(node, { filter: t => t.value === "var" });
|
||
|
|
||
|
return canFix(node)
|
||
|
? fixer.replaceText(varToken, "let")
|
||
|
: null;
|
||
|
}
|
||
|
});
|
||
|
}
|
||
|
|
||
|
return {
|
||
|
"VariableDeclaration:exit"(node) {
|
||
|
if (node.kind === "var") {
|
||
|
report(node);
|
||
|
}
|
||
|
}
|
||
|
};
|
||
|
}
|
||
|
};
|