mirror of
https://github.com/Microsoft/vscode
synced 2024-08-27 13:00:58 +00:00
![Matt Bierner](/assets/img/avatar_default.png)
Resubmission of #157532 with the following changes: - Use `eslint-plugin-local` instead of `yarn` link to run our plugins - Move our plugins to a top level `.eslintplugin` dir (as required by `eslint-plugin-local`) - Update all names to `local/`
152 lines
5 KiB
TypeScript
152 lines
5 KiB
TypeScript
/*---------------------------------------------------------------------------------------------
|
|
* Copyright (c) Microsoft Corporation. All rights reserved.
|
|
* Licensed under the MIT License. See License.txt in the project root for license information.
|
|
*--------------------------------------------------------------------------------------------*/
|
|
|
|
// FORKED FROM https://github.com/eslint/eslint/blob/b23ad0d789a909baf8d7c41a35bc53df932eaf30/lib/rules/no-unused-expressions.js
|
|
// and added support for `OptionalCallExpression`, see https://github.com/facebook/create-react-app/issues/8107 and https://github.com/eslint/eslint/issues/12642
|
|
|
|
/**
|
|
* @fileoverview Flag expressions in statement position that do not side effect
|
|
* @author Michael Ficarra
|
|
*/
|
|
|
|
import * as eslint from 'eslint';
|
|
import { TSESTree } from '@typescript-eslint/experimental-utils';
|
|
import * as ESTree from 'estree';
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
type: 'suggestion',
|
|
|
|
docs: {
|
|
description: 'disallow unused expressions',
|
|
category: 'Best Practices',
|
|
recommended: false,
|
|
url: 'https://eslint.org/docs/rules/no-unused-expressions'
|
|
},
|
|
|
|
schema: [
|
|
{
|
|
type: 'object',
|
|
properties: {
|
|
allowShortCircuit: {
|
|
type: 'boolean',
|
|
default: false
|
|
},
|
|
allowTernary: {
|
|
type: 'boolean',
|
|
default: false
|
|
},
|
|
allowTaggedTemplates: {
|
|
type: 'boolean',
|
|
default: false
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
]
|
|
},
|
|
|
|
create(context: eslint.Rule.RuleContext) {
|
|
const config = context.options[0] || {},
|
|
allowShortCircuit = config.allowShortCircuit || false,
|
|
allowTernary = config.allowTernary || false,
|
|
allowTaggedTemplates = config.allowTaggedTemplates || false;
|
|
|
|
// eslint-disable-next-line jsdoc/require-description
|
|
/**
|
|
* @param node any node
|
|
* @returns whether the given node structurally represents a directive
|
|
*/
|
|
function looksLikeDirective(node: TSESTree.Node): boolean {
|
|
return node.type === 'ExpressionStatement' &&
|
|
node.expression.type === 'Literal' && typeof node.expression.value === 'string';
|
|
}
|
|
|
|
// eslint-disable-next-line jsdoc/require-description
|
|
/**
|
|
* @param predicate ([a] -> Boolean) the function used to make the determination
|
|
* @param list the input list
|
|
* @returns the leading sequence of members in the given list that pass the given predicate
|
|
*/
|
|
function takeWhile<T>(predicate: (item: T) => boolean, list: T[]): T[] {
|
|
for (let i = 0; i < list.length; ++i) {
|
|
if (!predicate(list[i])) {
|
|
return list.slice(0, i);
|
|
}
|
|
}
|
|
return list.slice();
|
|
}
|
|
|
|
// eslint-disable-next-line jsdoc/require-description
|
|
/**
|
|
* @param node a Program or BlockStatement node
|
|
* @returns the leading sequence of directive nodes in the given node's body
|
|
*/
|
|
function directives(node: TSESTree.Program | TSESTree.BlockStatement): TSESTree.Node[] {
|
|
return takeWhile(looksLikeDirective, node.body);
|
|
}
|
|
|
|
// eslint-disable-next-line jsdoc/require-description
|
|
/**
|
|
* @param node any node
|
|
* @param ancestors the given node's ancestors
|
|
* @returns whether the given node is considered a directive in its current position
|
|
*/
|
|
function isDirective(node: TSESTree.Node, ancestors: TSESTree.Node[]): boolean {
|
|
const parent = ancestors[ancestors.length - 1],
|
|
grandparent = ancestors[ancestors.length - 2];
|
|
|
|
return (parent.type === 'Program' || parent.type === 'BlockStatement' &&
|
|
(/Function/u.test(grandparent.type))) &&
|
|
directives(parent).indexOf(node) >= 0;
|
|
}
|
|
|
|
/**
|
|
* Determines whether or not a given node is a valid expression. Recurses on short circuit eval and ternary nodes if enabled by flags.
|
|
* @param node any node
|
|
* @returns whether the given node is a valid expression
|
|
*/
|
|
function isValidExpression(node: TSESTree.Node): boolean {
|
|
if (allowTernary) {
|
|
|
|
// Recursive check for ternary and logical expressions
|
|
if (node.type === 'ConditionalExpression') {
|
|
return isValidExpression(node.consequent) && isValidExpression(node.alternate);
|
|
}
|
|
}
|
|
|
|
if (allowShortCircuit) {
|
|
if (node.type === 'LogicalExpression') {
|
|
return isValidExpression(node.right);
|
|
}
|
|
}
|
|
|
|
if (allowTaggedTemplates && node.type === 'TaggedTemplateExpression') {
|
|
return true;
|
|
}
|
|
|
|
if (node.type === 'ExpressionStatement') {
|
|
return isValidExpression(node.expression);
|
|
}
|
|
|
|
return /^(?:Assignment|OptionalCall|Call|New|Update|Yield|Await|Chain)Expression$/u.test(node.type) ||
|
|
(node.type === 'UnaryExpression' && ['delete', 'void'].indexOf(node.operator) >= 0);
|
|
}
|
|
|
|
return {
|
|
ExpressionStatement(node: TSESTree.ExpressionStatement) {
|
|
if (!isValidExpression(node.expression) && !isDirective(node, <TSESTree.Node[]>context.getAncestors())) {
|
|
context.report({ node: <ESTree.Node>node, message: `Expected an assignment or function call and instead saw an expression. ${node.expression}` });
|
|
}
|
|
}
|
|
};
|
|
|
|
}
|
|
};
|