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/**
* @fileoverview A rule to set the maximum number of line of code in a function.
* @author Pete Ward <peteward44@gmail.com>
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
const { upperCaseFirst } = require("../shared/string-utils");
//------------------------------------------------------------------------------
// Constants
//------------------------------------------------------------------------------
const OPTIONS_SCHEMA = {
type: "object",
properties: {
max: {
type: "integer",
minimum: 0
},
skipComments: {
type: "boolean"
},
skipBlankLines: {
type: "boolean"
},
IIFEs: {
type: "boolean"
}
},
additionalProperties: false
};
const OPTIONS_OR_INTEGER_SCHEMA = {
oneOf: [
OPTIONS_SCHEMA,
{
type: "integer",
minimum: 1
}
]
};
/**
* Given a list of comment nodes, return a map with numeric keys (source code line numbers) and comment token values.
* @param {Array} comments An array of comment nodes.
* @returns {Map<string, Node>} A map with numeric keys (source code line numbers) and comment token values.
*/
function getCommentLineNumbers(comments) {
const map = new Map();
comments.forEach(comment => {
for (let i = comment.loc.start.line; i <= comment.loc.end.line; i++) {
map.set(i, comment);
}
});
return map;
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "enforce a maximum number of lines of code in a function",
recommended: false,
url: "https://eslint.org/docs/rules/max-lines-per-function"
},
schema: [
OPTIONS_OR_INTEGER_SCHEMA
],
messages: {
exceed: "{{name}} has too many lines ({{lineCount}}). Maximum allowed is {{maxLines}}."
}
},
create(context) {
const sourceCode = context.getSourceCode();
const lines = sourceCode.lines;
const option = context.options[0];
let maxLines = 50;
let skipComments = false;
let skipBlankLines = false;
let IIFEs = false;
if (typeof option === "object") {
maxLines = typeof option.max === "number" ? option.max : 50;
skipComments = !!option.skipComments;
skipBlankLines = !!option.skipBlankLines;
IIFEs = !!option.IIFEs;
} else if (typeof option === "number") {
maxLines = option;
}
const commentLineNumbers = getCommentLineNumbers(sourceCode.getAllComments());
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Tells if a comment encompasses the entire line.
* @param {string} line The source line with a trailing comment
* @param {number} lineNumber The one-indexed line number this is on
* @param {ASTNode} comment The comment to remove
* @returns {boolean} If the comment covers the entire line
*/
function isFullLineComment(line, lineNumber, comment) {
const start = comment.loc.start,
end = comment.loc.end,
isFirstTokenOnLine = start.line === lineNumber && !line.slice(0, start.column).trim(),
isLastTokenOnLine = end.line === lineNumber && !line.slice(end.column).trim();
return comment &&
(start.line < lineNumber || isFirstTokenOnLine) &&
(end.line > lineNumber || isLastTokenOnLine);
}
/**
* Identifies is a node is a FunctionExpression which is part of an IIFE
* @param {ASTNode} node Node to test
* @returns {boolean} True if it's an IIFE
*/
function isIIFE(node) {
return (node.type === "FunctionExpression" || node.type === "ArrowFunctionExpression") && node.parent && node.parent.type === "CallExpression" && node.parent.callee === node;
}
/**
* Identifies is a node is a FunctionExpression which is embedded within a MethodDefinition or Property
* @param {ASTNode} node Node to test
* @returns {boolean} True if it's a FunctionExpression embedded within a MethodDefinition or Property
*/
function isEmbedded(node) {
if (!node.parent) {
return false;
}
if (node !== node.parent.value) {
return false;
}
if (node.parent.type === "MethodDefinition") {
return true;
}
if (node.parent.type === "Property") {
return node.parent.method === true || node.parent.kind === "get" || node.parent.kind === "set";
}
return false;
}
/**
* Count the lines in the function
* @param {ASTNode} funcNode Function AST node
* @returns {void}
* @private
*/
function processFunction(funcNode) {
const node = isEmbedded(funcNode) ? funcNode.parent : funcNode;
if (!IIFEs && isIIFE(node)) {
return;
}
let lineCount = 0;
for (let i = node.loc.start.line - 1; i < node.loc.end.line; ++i) {
const line = lines[i];
if (skipComments) {
if (commentLineNumbers.has(i + 1) && isFullLineComment(line, i + 1, commentLineNumbers.get(i + 1))) {
continue;
}
}
if (skipBlankLines) {
if (line.match(/^\s*$/u)) {
continue;
}
}
lineCount++;
}
if (lineCount > maxLines) {
const name = upperCaseFirst(astUtils.getFunctionNameWithKind(funcNode));
context.report({
node,
messageId: "exceed",
data: { name, lineCount, maxLines }
});
}
}
//--------------------------------------------------------------------------
// Public API
//--------------------------------------------------------------------------
return {
FunctionDeclaration: processFunction,
FunctionExpression: processFunction,
ArrowFunctionExpression: processFunction
};
}
};
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