382 lines
12 KiB
JavaScript
382 lines
12 KiB
JavaScript
/**
|
|
* @fileoverview Enforce stateless components to be written as a pure function
|
|
* @author Yannick Croissant
|
|
* @author Alberto Rodríguez
|
|
* @copyright 2015 Alberto Rodríguez. All rights reserved.
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
const Components = require('../util/Components');
|
|
const versionUtil = require('../util/version');
|
|
const astUtil = require('../util/ast');
|
|
const docsUrl = require('../util/docsUrl');
|
|
|
|
// ------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
// ------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
docs: {
|
|
description: 'Enforce stateless components to be written as a pure function',
|
|
category: 'Stylistic Issues',
|
|
recommended: false,
|
|
url: docsUrl('prefer-stateless-function')
|
|
},
|
|
schema: [{
|
|
type: 'object',
|
|
properties: {
|
|
ignorePureComponents: {
|
|
default: false,
|
|
type: 'boolean'
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}]
|
|
},
|
|
|
|
create: Components.detect((context, components, utils) => {
|
|
const configuration = context.options[0] || {};
|
|
const ignorePureComponents = configuration.ignorePureComponents || false;
|
|
|
|
// --------------------------------------------------------------------------
|
|
// Public
|
|
// --------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Checks whether a given array of statements is a single call of `super`.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode[]} body - An array of statements to check.
|
|
* @returns {boolean} `true` if the body is a single call of `super`.
|
|
*/
|
|
function isSingleSuperCall(body) {
|
|
return (
|
|
body.length === 1 &&
|
|
body[0].type === 'ExpressionStatement' &&
|
|
body[0].expression.type === 'CallExpression' &&
|
|
body[0].expression.callee.type === 'Super'
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Checks whether a given node is a pattern which doesn't have any side effects.
|
|
* Default parameters and Destructuring parameters can have side effects.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode} node - A pattern node.
|
|
* @returns {boolean} `true` if the node doesn't have any side effects.
|
|
*/
|
|
function isSimple(node) {
|
|
return node.type === 'Identifier' || node.type === 'RestElement';
|
|
}
|
|
|
|
/**
|
|
* Checks whether a given array of expressions is `...arguments` or not.
|
|
* `super(...arguments)` passes all arguments through.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode[]} superArgs - An array of expressions to check.
|
|
* @returns {boolean} `true` if the superArgs is `...arguments`.
|
|
*/
|
|
function isSpreadArguments(superArgs) {
|
|
return (
|
|
superArgs.length === 1 &&
|
|
superArgs[0].type === 'SpreadElement' &&
|
|
superArgs[0].argument.type === 'Identifier' &&
|
|
superArgs[0].argument.name === 'arguments'
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Checks whether given 2 nodes are identifiers which have the same name or not.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode} ctorParam - A node to check.
|
|
* @param {ASTNode} superArg - A node to check.
|
|
* @returns {boolean} `true` if the nodes are identifiers which have the same
|
|
* name.
|
|
*/
|
|
function isValidIdentifierPair(ctorParam, superArg) {
|
|
return (
|
|
ctorParam.type === 'Identifier' &&
|
|
superArg.type === 'Identifier' &&
|
|
ctorParam.name === superArg.name
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Checks whether given 2 nodes are a rest/spread pair which has the same values.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode} ctorParam - A node to check.
|
|
* @param {ASTNode} superArg - A node to check.
|
|
* @returns {boolean} `true` if the nodes are a rest/spread pair which has the
|
|
* same values.
|
|
*/
|
|
function isValidRestSpreadPair(ctorParam, superArg) {
|
|
return (
|
|
ctorParam.type === 'RestElement' &&
|
|
superArg.type === 'SpreadElement' &&
|
|
isValidIdentifierPair(ctorParam.argument, superArg.argument)
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Checks whether given 2 nodes have the same value or not.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode} ctorParam - A node to check.
|
|
* @param {ASTNode} superArg - A node to check.
|
|
* @returns {boolean} `true` if the nodes have the same value or not.
|
|
*/
|
|
function isValidPair(ctorParam, superArg) {
|
|
return (
|
|
isValidIdentifierPair(ctorParam, superArg) ||
|
|
isValidRestSpreadPair(ctorParam, superArg)
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Checks whether the parameters of a constructor and the arguments of `super()`
|
|
* have the same values or not.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {ASTNode[]} ctorParams - The parameters of a constructor to check.
|
|
* @param {ASTNode} superArgs - The arguments of `super()` to check.
|
|
* @returns {boolean} `true` if those have the same values.
|
|
*/
|
|
function isPassingThrough(ctorParams, superArgs) {
|
|
if (ctorParams.length !== superArgs.length) {
|
|
return false;
|
|
}
|
|
|
|
for (let i = 0; i < ctorParams.length; ++i) {
|
|
if (!isValidPair(ctorParams[i], superArgs[i])) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Checks whether the constructor body is a redundant super call.
|
|
* @see ESLint no-useless-constructor rule
|
|
* @param {Array} body - constructor body content.
|
|
* @param {Array} ctorParams - The params to check against super call.
|
|
* @returns {boolean} true if the construtor body is redundant
|
|
*/
|
|
function isRedundantSuperCall(body, ctorParams) {
|
|
return (
|
|
isSingleSuperCall(body) &&
|
|
ctorParams.every(isSimple) &&
|
|
(
|
|
isSpreadArguments(body[0].expression.arguments) ||
|
|
isPassingThrough(ctorParams, body[0].expression.arguments)
|
|
)
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Check if a given AST node have any other properties the ones available in stateless components
|
|
* @param {ASTNode} node The AST node being checked.
|
|
* @returns {Boolean} True if the node has at least one other property, false if not.
|
|
*/
|
|
function hasOtherProperties(node) {
|
|
const properties = astUtil.getComponentProperties(node);
|
|
return properties.some((property) => {
|
|
const name = astUtil.getPropertyName(property);
|
|
const isDisplayName = name === 'displayName';
|
|
const isPropTypes = name === 'propTypes' || name === 'props' && property.typeAnnotation;
|
|
const contextTypes = name === 'contextTypes';
|
|
const defaultProps = name === 'defaultProps';
|
|
const isUselessConstructor = property.kind === 'constructor' &&
|
|
!!property.value.body &&
|
|
isRedundantSuperCall(property.value.body.body, property.value.params);
|
|
const isRender = name === 'render';
|
|
return !isDisplayName && !isPropTypes && !contextTypes && !defaultProps && !isUselessConstructor && !isRender;
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark component as pure as declared
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markSCUAsDeclared(node) {
|
|
components.set(node, {
|
|
hasSCU: true
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark childContextTypes as declared
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markChildContextTypesAsDeclared(node) {
|
|
components.set(node, {
|
|
hasChildContextTypes: true
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark a setState as used
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markThisAsUsed(node) {
|
|
components.set(node, {
|
|
useThis: true
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark a props or context as used
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markPropsOrContextAsUsed(node) {
|
|
components.set(node, {
|
|
usePropsOrContext: true
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark a ref as used
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markRefAsUsed(node) {
|
|
components.set(node, {
|
|
useRef: true
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark return as invalid
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markReturnAsInvalid(node) {
|
|
components.set(node, {
|
|
invalidReturn: true
|
|
});
|
|
}
|
|
|
|
/**
|
|
* Mark a ClassDeclaration as having used decorators
|
|
* @param {ASTNode} node The AST node being checked.
|
|
*/
|
|
function markDecoratorsAsUsed(node) {
|
|
components.set(node, {
|
|
useDecorators: true
|
|
});
|
|
}
|
|
|
|
function visitClass(node) {
|
|
if (ignorePureComponents && utils.isPureComponent(node)) {
|
|
markSCUAsDeclared(node);
|
|
}
|
|
|
|
if (node.decorators && node.decorators.length) {
|
|
markDecoratorsAsUsed(node);
|
|
}
|
|
}
|
|
|
|
return {
|
|
ClassDeclaration: visitClass,
|
|
ClassExpression: visitClass,
|
|
|
|
// Mark `this` destructuring as a usage of `this`
|
|
VariableDeclarator(node) {
|
|
// Ignore destructuring on other than `this`
|
|
if (!node.id || node.id.type !== 'ObjectPattern' || !node.init || node.init.type !== 'ThisExpression') {
|
|
return;
|
|
}
|
|
// Ignore `props` and `context`
|
|
const useThis = node.id.properties.some((property) => {
|
|
const name = astUtil.getPropertyName(property);
|
|
return name !== 'props' && name !== 'context';
|
|
});
|
|
if (!useThis) {
|
|
markPropsOrContextAsUsed(node);
|
|
return;
|
|
}
|
|
markThisAsUsed(node);
|
|
},
|
|
|
|
// Mark `this` usage
|
|
MemberExpression(node) {
|
|
if (node.object.type !== 'ThisExpression') {
|
|
if (node.property && node.property.name === 'childContextTypes') {
|
|
const component = utils.getRelatedComponent(node);
|
|
if (!component) {
|
|
return;
|
|
}
|
|
markChildContextTypesAsDeclared(component.node);
|
|
}
|
|
return;
|
|
// Ignore calls to `this.props` and `this.context`
|
|
}
|
|
if (
|
|
(node.property.name || node.property.value) === 'props' ||
|
|
(node.property.name || node.property.value) === 'context'
|
|
) {
|
|
markPropsOrContextAsUsed(node);
|
|
return;
|
|
}
|
|
markThisAsUsed(node);
|
|
},
|
|
|
|
// Mark `ref` usage
|
|
JSXAttribute(node) {
|
|
const name = context.getSourceCode().getText(node.name);
|
|
if (name !== 'ref') {
|
|
return;
|
|
}
|
|
markRefAsUsed(node);
|
|
},
|
|
|
|
// Mark `render` that do not return some JSX
|
|
ReturnStatement(node) {
|
|
let blockNode;
|
|
let scope = context.getScope();
|
|
while (scope) {
|
|
blockNode = scope.block && scope.block.parent;
|
|
if (blockNode && (blockNode.type === 'MethodDefinition' || blockNode.type === 'Property')) {
|
|
break;
|
|
}
|
|
scope = scope.upper;
|
|
}
|
|
const isRender = blockNode && blockNode.key && blockNode.key.name === 'render';
|
|
const allowNull = versionUtil.testReactVersion(context, '15.0.0'); // Stateless components can return null since React 15
|
|
const isReturningJSX = utils.isReturningJSX(node, !allowNull);
|
|
const isReturningNull = node.argument && (node.argument.value === null || node.argument.value === false);
|
|
if (
|
|
!isRender ||
|
|
(allowNull && (isReturningJSX || isReturningNull)) ||
|
|
(!allowNull && isReturningJSX)
|
|
) {
|
|
return;
|
|
}
|
|
markReturnAsInvalid(node);
|
|
},
|
|
|
|
'Program:exit'() {
|
|
const list = components.list();
|
|
Object.keys(list).forEach((component) => {
|
|
if (
|
|
hasOtherProperties(list[component].node) ||
|
|
list[component].useThis ||
|
|
list[component].useRef ||
|
|
list[component].invalidReturn ||
|
|
list[component].hasChildContextTypes ||
|
|
list[component].useDecorators ||
|
|
(!utils.isES5Component(list[component].node) && !utils.isES6Component(list[component].node))
|
|
) {
|
|
return;
|
|
}
|
|
|
|
if (list[component].hasSCU) {
|
|
return;
|
|
}
|
|
context.report({
|
|
node: list[component].node,
|
|
message: 'Component should be written as a pure function'
|
|
});
|
|
});
|
|
}
|
|
};
|
|
})
|
|
};
|