--- /dev/null
+/**
+ * @fileoverview Specify the maximum number of statements allowed per line.
+ * @author Kenneth Williams
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "layout",
+
+ docs: {
+ description: "enforce a maximum number of statements allowed per line",
+ category: "Stylistic Issues",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/max-statements-per-line"
+ },
+
+ schema: [
+ {
+ type: "object",
+ properties: {
+ max: {
+ type: "integer",
+ minimum: 1,
+ default: 1
+ }
+ },
+ additionalProperties: false
+ }
+ ],
+ messages: {
+ exceed: "This line has {{numberOfStatementsOnThisLine}} {{statements}}. Maximum allowed is {{maxStatementsPerLine}}."
+ }
+ },
+
+ create(context) {
+
+ const sourceCode = context.getSourceCode(),
+ options = context.options[0] || {},
+ maxStatementsPerLine = typeof options.max !== "undefined" ? options.max : 1;
+
+ let lastStatementLine = 0,
+ numberOfStatementsOnThisLine = 0,
+ firstExtraStatement;
+
+ //--------------------------------------------------------------------------
+ // Helpers
+ //--------------------------------------------------------------------------
+
+ const SINGLE_CHILD_ALLOWED = /^(?:(?:DoWhile|For|ForIn|ForOf|If|Labeled|While)Statement|Export(?:Default|Named)Declaration)$/u;
+
+ /**
+ * Reports with the first extra statement, and clears it.
+ * @returns {void}
+ */
+ function reportFirstExtraStatementAndClear() {
+ if (firstExtraStatement) {
+ context.report({
+ node: firstExtraStatement,
+ messageId: "exceed",
+ data: {
+ numberOfStatementsOnThisLine,
+ maxStatementsPerLine,
+ statements: numberOfStatementsOnThisLine === 1 ? "statement" : "statements"
+ }
+ });
+ }
+ firstExtraStatement = null;
+ }
+
+ /**
+ * Gets the actual last token of a given node.
+ * @param {ASTNode} node A node to get. This is a node except EmptyStatement.
+ * @returns {Token} The actual last token.
+ */
+ function getActualLastToken(node) {
+ return sourceCode.getLastToken(node, astUtils.isNotSemicolonToken);
+ }
+
+ /**
+ * Addresses a given node.
+ * It updates the state of this rule, then reports the node if the node violated this rule.
+ * @param {ASTNode} node A node to check.
+ * @returns {void}
+ */
+ function enterStatement(node) {
+ const line = node.loc.start.line;
+
+ /*
+ * Skip to allow non-block statements if this is direct child of control statements.
+ * `if (a) foo();` is counted as 1.
+ * But `if (a) foo(); else foo();` should be counted as 2.
+ */
+ if (SINGLE_CHILD_ALLOWED.test(node.parent.type) &&
+ node.parent.alternate !== node
+ ) {
+ return;
+ }
+
+ // Update state.
+ if (line === lastStatementLine) {
+ numberOfStatementsOnThisLine += 1;
+ } else {
+ reportFirstExtraStatementAndClear();
+ numberOfStatementsOnThisLine = 1;
+ lastStatementLine = line;
+ }
+
+ // Reports if the node violated this rule.
+ if (numberOfStatementsOnThisLine === maxStatementsPerLine + 1) {
+ firstExtraStatement = firstExtraStatement || node;
+ }
+ }
+
+ /**
+ * Updates the state of this rule with the end line of leaving node to check with the next statement.
+ * @param {ASTNode} node A node to check.
+ * @returns {void}
+ */
+ function leaveStatement(node) {
+ const line = getActualLastToken(node).loc.end.line;
+
+ // Update state.
+ if (line !== lastStatementLine) {
+ reportFirstExtraStatementAndClear();
+ numberOfStatementsOnThisLine = 1;
+ lastStatementLine = line;
+ }
+ }
+
+ //--------------------------------------------------------------------------
+ // Public API
+ //--------------------------------------------------------------------------
+
+ return {
+ BreakStatement: enterStatement,
+ ClassDeclaration: enterStatement,
+ ContinueStatement: enterStatement,
+ DebuggerStatement: enterStatement,
+ DoWhileStatement: enterStatement,
+ ExpressionStatement: enterStatement,
+ ForInStatement: enterStatement,
+ ForOfStatement: enterStatement,
+ ForStatement: enterStatement,
+ FunctionDeclaration: enterStatement,
+ IfStatement: enterStatement,
+ ImportDeclaration: enterStatement,
+ LabeledStatement: enterStatement,
+ ReturnStatement: enterStatement,
+ SwitchStatement: enterStatement,
+ ThrowStatement: enterStatement,
+ TryStatement: enterStatement,
+ VariableDeclaration: enterStatement,
+ WhileStatement: enterStatement,
+ WithStatement: enterStatement,
+ ExportNamedDeclaration: enterStatement,
+ ExportDefaultDeclaration: enterStatement,
+ ExportAllDeclaration: enterStatement,
+
+ "BreakStatement:exit": leaveStatement,
+ "ClassDeclaration:exit": leaveStatement,
+ "ContinueStatement:exit": leaveStatement,
+ "DebuggerStatement:exit": leaveStatement,
+ "DoWhileStatement:exit": leaveStatement,
+ "ExpressionStatement:exit": leaveStatement,
+ "ForInStatement:exit": leaveStatement,
+ "ForOfStatement:exit": leaveStatement,
+ "ForStatement:exit": leaveStatement,
+ "FunctionDeclaration:exit": leaveStatement,
+ "IfStatement:exit": leaveStatement,
+ "ImportDeclaration:exit": leaveStatement,
+ "LabeledStatement:exit": leaveStatement,
+ "ReturnStatement:exit": leaveStatement,
+ "SwitchStatement:exit": leaveStatement,
+ "ThrowStatement:exit": leaveStatement,
+ "TryStatement:exit": leaveStatement,
+ "VariableDeclaration:exit": leaveStatement,
+ "WhileStatement:exit": leaveStatement,
+ "WithStatement:exit": leaveStatement,
+ "ExportNamedDeclaration:exit": leaveStatement,
+ "ExportDefaultDeclaration:exit": leaveStatement,
+ "ExportAllDeclaration:exit": leaveStatement,
+ "Program:exit": reportFirstExtraStatementAndClear
+ };
+ }
+};
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