Current File : /home/vacivi36/.trash/vacivitta/node_modules/eslint/lib/rules/class-methods-use-this.js
/**
* @fileoverview Rule to enforce that all class methods use 'this'.
* @author Patrick Williams
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../types').Rule.RuleModule} */
module.exports = {
meta: {
dialects: ["javascript", "typescript"],
language: "javascript",
type: "suggestion",
defaultOptions: [
{
enforceForClassFields: true,
exceptMethods: [],
ignoreOverrideMethods: false,
},
],
docs: {
description: "Enforce that class methods utilize `this`",
recommended: false,
url: "https://eslint.org/docs/latest/rules/class-methods-use-this",
},
schema: [
{
type: "object",
properties: {
exceptMethods: {
type: "array",
items: {
type: "string",
},
},
enforceForClassFields: {
type: "boolean",
},
ignoreOverrideMethods: {
type: "boolean",
},
ignoreClassesWithImplements: {
enum: ["all", "public-fields"],
},
},
additionalProperties: false,
},
],
messages: {
missingThis: "Expected 'this' to be used by class {{name}}.",
},
},
create(context) {
const [options] = context.options;
const {
enforceForClassFields,
ignoreOverrideMethods,
ignoreClassesWithImplements,
} = options;
const exceptMethods = new Set(options.exceptMethods);
const stack = [];
/**
* Push `this` used flag initialized with `false` onto the stack.
* @returns {void}
*/
function pushContext() {
stack.push(false);
}
/**
* Pop `this` used flag from the stack.
* @returns {boolean | undefined} `this` used flag
*/
function popContext() {
return stack.pop();
}
/**
* Initializes the current context to false and pushes it onto the stack.
* These booleans represent whether 'this' has been used in the context.
* @returns {void}
* @private
*/
function enterFunction() {
pushContext();
}
/**
* Check if the node is an instance method
* @param {ASTNode} node node to check
* @returns {boolean} True if its an instance method
* @private
*/
function isInstanceMethod(node) {
switch (node.type) {
case "MethodDefinition":
return !node.static && node.kind !== "constructor";
case "PropertyDefinition":
return !node.static && enforceForClassFields;
default:
return false;
}
}
/**
* Check if the node's parent class implements any interfaces
* @param {ASTNode} node node to check
* @returns {boolean} True if parent class implements interfaces
* @private
*/
function hasImplements(node) {
const classNode = node.parent.parent;
return (
classNode?.type === "ClassDeclaration" &&
classNode.implements?.length > 0
);
}
/**
* Check if the node is an instance method not excluded by config
* @param {ASTNode} node node to check
* @returns {boolean} True if it is an instance method, and not excluded by config
* @private
*/
function isIncludedInstanceMethod(node) {
if (isInstanceMethod(node)) {
if (node.computed) {
return true;
}
if (ignoreOverrideMethods && node.override) {
return false;
}
if (ignoreClassesWithImplements) {
const implementsInterfaces = hasImplements(node);
if (implementsInterfaces) {
if (
ignoreClassesWithImplements === "all" ||
(ignoreClassesWithImplements === "public-fields" &&
node.key.type !== "PrivateIdentifier" &&
(!node.accessibility ||
node.accessibility === "public"))
) {
return false;
}
}
}
const hashIfNeeded =
node.key.type === "PrivateIdentifier" ? "#" : "";
const name =
node.key.type === "Literal"
? astUtils.getStaticStringValue(node.key)
: node.key.name || "";
return !exceptMethods.has(hashIfNeeded + name);
}
return false;
}
/**
* Checks if we are leaving a function that is a method, and reports if 'this' has not been used.
* Static methods and the constructor are exempt.
* Then pops the context off the stack.
* @param {ASTNode} node A function node that was entered.
* @returns {void}
* @private
*/
function exitFunction(node) {
const methodUsesThis = popContext();
if (isIncludedInstanceMethod(node.parent) && !methodUsesThis) {
context.report({
node,
loc: astUtils.getFunctionHeadLoc(node, context.sourceCode),
messageId: "missingThis",
data: {
name: astUtils.getFunctionNameWithKind(node),
},
});
}
}
/**
* Mark the current context as having used 'this'.
* @returns {void}
* @private
*/
function markThisUsed() {
if (stack.length) {
stack[stack.length - 1] = true;
}
}
return {
FunctionDeclaration: enterFunction,
"FunctionDeclaration:exit": exitFunction,
FunctionExpression: enterFunction,
"FunctionExpression:exit": exitFunction,
/*
* Class field value are implicit functions.
*/
"PropertyDefinition > *.key:exit": pushContext,
"PropertyDefinition:exit": popContext,
/*
* Class static blocks are implicit functions. They aren't required to use `this`,
* but we have to push context so that it captures any use of `this` in the static block
* separately from enclosing contexts, because static blocks have their own `this` and it
* shouldn't count as used `this` in enclosing contexts.
*/
StaticBlock: pushContext,
"StaticBlock:exit": popContext,
ThisExpression: markThisUsed,
Super: markThisUsed,
...(enforceForClassFields && {
"PropertyDefinition > ArrowFunctionExpression.value":
enterFunction,
"PropertyDefinition > ArrowFunctionExpression.value:exit":
exitFunction,
}),
};
},
};
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