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/**
* @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/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;
}
};