/**
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* @fileoverview Rule to enforce declarations in program or function body root.
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* @author Brandon Mills
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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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type: "problem",
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docs: {
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description: "disallow variable or `function` declarations in nested blocks",
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category: "Possible Errors",
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recommended: true,
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url: "https://eslint.org/docs/rules/no-inner-declarations"
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},
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schema: [
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{
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enum: ["functions", "both"]
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}
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]
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},
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create(context) {
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/**
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* Find the nearest Program or Function ancestor node.
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* @returns {Object} Ancestor's type and distance from node.
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*/
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function nearestBody() {
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const ancestors = context.getAncestors();
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let ancestor = ancestors.pop(),
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generation = 1;
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while (ancestor && ["Program", "FunctionDeclaration",
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"FunctionExpression", "ArrowFunctionExpression"
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].indexOf(ancestor.type) < 0) {
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generation += 1;
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ancestor = ancestors.pop();
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}
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return {
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// Type of containing ancestor
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type: ancestor.type,
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// Separation between ancestor and node
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distance: generation
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};
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}
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/**
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* Ensure that a given node is at a program or function body's root.
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* @param {ASTNode} node Declaration node to check.
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* @returns {void}
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*/
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function check(node) {
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const body = nearestBody(),
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valid = ((body.type === "Program" && body.distance === 1) ||
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body.distance === 2);
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if (!valid) {
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context.report({
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node,
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message: "Move {{type}} declaration to {{body}} root.",
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data: {
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type: (node.type === "FunctionDeclaration" ? "function" : "variable"),
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body: (body.type === "Program" ? "program" : "function body")
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}
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});
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}
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}
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return {
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FunctionDeclaration: check,
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VariableDeclaration(node) {
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if (context.options[0] === "both" && node.kind === "var") {
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check(node);
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}
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}
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};
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}
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};
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