| /** | |
|  * @fileoverview Rule to enforce a particular function style | |
|  * @author Nicholas C. Zakas | |
|  */ | |
| "use strict"; | |
| 
 | |
| //------------------------------------------------------------------------------ | |
| // Rule Definition | |
| //------------------------------------------------------------------------------ | |
|  | |
| /** @type {import('../shared/types').Rule} */ | |
| module.exports = { | |
|     meta: { | |
|         type: "suggestion", | |
| 
 | |
|         docs: { | |
|             description: "Enforce the consistent use of either `function` declarations or expressions", | |
|             recommended: false, | |
|             url: "https://eslint.org/docs/latest/rules/func-style" | |
|         }, | |
| 
 | |
|         schema: [ | |
|             { | |
|                 enum: ["declaration", "expression"] | |
|             }, | |
|             { | |
|                 type: "object", | |
|                 properties: { | |
|                     allowArrowFunctions: { | |
|                         type: "boolean", | |
|                         default: false | |
|                     } | |
|                 }, | |
|                 additionalProperties: false | |
|             } | |
|         ], | |
| 
 | |
|         messages: { | |
|             expression: "Expected a function expression.", | |
|             declaration: "Expected a function declaration." | |
|         } | |
|     }, | |
| 
 | |
|     create(context) { | |
| 
 | |
|         const style = context.options[0], | |
|             allowArrowFunctions = context.options[1] && context.options[1].allowArrowFunctions, | |
|             enforceDeclarations = (style === "declaration"), | |
|             stack = []; | |
| 
 | |
|         const nodesToCheck = { | |
|             FunctionDeclaration(node) { | |
|                 stack.push(false); | |
| 
 | |
|                 if (!enforceDeclarations && node.parent.type !== "ExportDefaultDeclaration") { | |
|                     context.report({ node, messageId: "expression" }); | |
|                 } | |
|             }, | |
|             "FunctionDeclaration:exit"() { | |
|                 stack.pop(); | |
|             }, | |
| 
 | |
|             FunctionExpression(node) { | |
|                 stack.push(false); | |
| 
 | |
|                 if (enforceDeclarations && node.parent.type === "VariableDeclarator") { | |
|                     context.report({ node: node.parent, messageId: "declaration" }); | |
|                 } | |
|             }, | |
|             "FunctionExpression:exit"() { | |
|                 stack.pop(); | |
|             }, | |
| 
 | |
|             ThisExpression() { | |
|                 if (stack.length > 0) { | |
|                     stack[stack.length - 1] = true; | |
|                 } | |
|             } | |
|         }; | |
| 
 | |
|         if (!allowArrowFunctions) { | |
|             nodesToCheck.ArrowFunctionExpression = function() { | |
|                 stack.push(false); | |
|             }; | |
| 
 | |
|             nodesToCheck["ArrowFunctionExpression:exit"] = function(node) { | |
|                 const hasThisExpr = stack.pop(); | |
| 
 | |
|                 if (enforceDeclarations && !hasThisExpr && node.parent.type === "VariableDeclarator") { | |
|                     context.report({ node: node.parent, messageId: "declaration" }); | |
|                 } | |
|             }; | |
|         } | |
| 
 | |
|         return nodesToCheck; | |
| 
 | |
|     } | |
| };
 |