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186 lines
6.4 KiB
186 lines
6.4 KiB
/** |
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* @fileoverview Enforce return after a callback. |
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* @author Jamund Ferguson |
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*/ |
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"use strict"; |
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//------------------------------------------------------------------------------ |
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// Rule Definition |
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//------------------------------------------------------------------------------ |
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module.exports = { |
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meta: { |
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deprecated: true, |
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replacedBy: [], |
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type: "suggestion", |
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docs: { |
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description: "require `return` statements after callbacks", |
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category: "Node.js and CommonJS", |
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recommended: false, |
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url: "https://eslint.org/docs/rules/callback-return" |
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}, |
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schema: [{ |
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type: "array", |
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items: { type: "string" } |
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}], |
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messages: { |
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missingReturn: "Expected return with your callback function." |
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} |
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}, |
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create(context) { |
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const callbacks = context.options[0] || ["callback", "cb", "next"], |
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sourceCode = context.getSourceCode(); |
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//-------------------------------------------------------------------------- |
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// Helpers |
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//-------------------------------------------------------------------------- |
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/** |
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* Find the closest parent matching a list of types. |
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* @param {ASTNode} node The node whose parents we are searching |
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* @param {Array} types The node types to match |
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* @returns {ASTNode} The matched node or undefined. |
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*/ |
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function findClosestParentOfType(node, types) { |
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if (!node.parent) { |
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return null; |
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} |
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if (types.indexOf(node.parent.type) === -1) { |
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return findClosestParentOfType(node.parent, types); |
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} |
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return node.parent; |
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} |
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/** |
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* Check to see if a node contains only identifiers |
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* @param {ASTNode} node The node to check |
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* @returns {boolean} Whether or not the node contains only identifiers |
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*/ |
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function containsOnlyIdentifiers(node) { |
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if (node.type === "Identifier") { |
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return true; |
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} |
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if (node.type === "MemberExpression") { |
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if (node.object.type === "Identifier") { |
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return true; |
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} |
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if (node.object.type === "MemberExpression") { |
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return containsOnlyIdentifiers(node.object); |
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} |
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} |
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return false; |
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} |
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/** |
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* Check to see if a CallExpression is in our callback list. |
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* @param {ASTNode} node The node to check against our callback names list. |
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* @returns {boolean} Whether or not this function matches our callback name. |
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*/ |
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function isCallback(node) { |
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return containsOnlyIdentifiers(node.callee) && callbacks.indexOf(sourceCode.getText(node.callee)) > -1; |
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} |
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/** |
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* Determines whether or not the callback is part of a callback expression. |
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* @param {ASTNode} node The callback node |
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* @param {ASTNode} parentNode The expression node |
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* @returns {boolean} Whether or not this is part of a callback expression |
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*/ |
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function isCallbackExpression(node, parentNode) { |
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// ensure the parent node exists and is an expression |
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if (!parentNode || parentNode.type !== "ExpressionStatement") { |
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return false; |
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} |
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// cb() |
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if (parentNode.expression === node) { |
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return true; |
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} |
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// special case for cb && cb() and similar |
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if (parentNode.expression.type === "BinaryExpression" || parentNode.expression.type === "LogicalExpression") { |
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if (parentNode.expression.right === node) { |
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return true; |
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} |
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} |
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return false; |
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} |
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//-------------------------------------------------------------------------- |
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// Public |
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//-------------------------------------------------------------------------- |
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return { |
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CallExpression(node) { |
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// if we're not a callback we can return |
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if (!isCallback(node)) { |
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return; |
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} |
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// find the closest block, return or loop |
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const closestBlock = findClosestParentOfType(node, ["BlockStatement", "ReturnStatement", "ArrowFunctionExpression"]) || {}; |
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// if our parent is a return we know we're ok |
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if (closestBlock.type === "ReturnStatement") { |
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return; |
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} |
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// arrow functions don't always have blocks and implicitly return |
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if (closestBlock.type === "ArrowFunctionExpression") { |
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return; |
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} |
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// block statements are part of functions and most if statements |
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if (closestBlock.type === "BlockStatement") { |
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// find the last item in the block |
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const lastItem = closestBlock.body[closestBlock.body.length - 1]; |
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// if the callback is the last thing in a block that might be ok |
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if (isCallbackExpression(node, lastItem)) { |
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const parentType = closestBlock.parent.type; |
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// but only if the block is part of a function |
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if (parentType === "FunctionExpression" || |
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parentType === "FunctionDeclaration" || |
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parentType === "ArrowFunctionExpression" |
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) { |
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return; |
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} |
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} |
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// ending a block with a return is also ok |
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if (lastItem.type === "ReturnStatement") { |
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// but only if the callback is immediately before |
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if (isCallbackExpression(node, closestBlock.body[closestBlock.body.length - 2])) { |
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return; |
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} |
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} |
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} |
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// as long as you're the child of a function at this point you should be asked to return |
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if (findClosestParentOfType(node, ["FunctionDeclaration", "FunctionExpression", "ArrowFunctionExpression"])) { |
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context.report({ node, messageId: "missingReturn" }); |
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} |
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} |
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}; |
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} |
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};
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