lines-around-directive.js

/**
 * @fileoverview Require or disallow newlines around directives.
 * @author Kai Cataldo
 * @deprecated in ESLint v4.0.0
 */

"use strict";

const astUtils = require("./utils/ast-utils");

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../shared/types').Rule} */
module.exports = {
    meta: {
        type: "layout",

        docs: {
            description: "Require or disallow newlines around directives",
            recommended: false,
            url: "https://eslint.org/docs/latest/rules/lines-around-directive"
        },

        schema: [{
            oneOf: [
                {
                    enum: ["always", "never"]
                },
                {
                    type: "object",
                    properties: {
                        before: {
                            enum: ["always", "never"]
                        },
                        after: {
                            enum: ["always", "never"]
                        }
                    },
                    additionalProperties: false,
                    minProperties: 2
                }
            ]
        }],

        fixable: "whitespace",
        messages: {
            expected: "Expected newline {{location}} \"{{value}}\" directive.",
            unexpected: "Unexpected newline {{location}} \"{{value}}\" directive."
        },
        deprecated: true,
        replacedBy: ["padding-line-between-statements"]
    },

    create(context) {
        const sourceCode = context.sourceCode;
        const config = context.options[0] || "always";
        const expectLineBefore = typeof config === "string" ? config : config.before;
        const expectLineAfter = typeof config === "string" ? config : config.after;

        //--------------------------------------------------------------------------
        // Helpers
        //--------------------------------------------------------------------------

        /**
         * Check if node is preceded by a blank newline.
         * @param {ASTNode} node Node to check.
         * @returns {boolean} Whether or not the passed in node is preceded by a blank newline.
         */
        function hasNewlineBefore(node) {
            const tokenBefore = sourceCode.getTokenBefore(node, { includeComments: true });
            const tokenLineBefore = tokenBefore ? tokenBefore.loc.end.line : 0;

            return node.loc.start.line - tokenLineBefore >= 2;
        }

        /**
         * Gets the last token of a node that is on the same line as the rest of the node.
         * This will usually be the last token of the node, but it will be the second-to-last token if the node has a trailing
         * semicolon on a different line.
         * @param {ASTNode} node A directive node
         * @returns {Token} The last token of the node on the line
         */
        function getLastTokenOnLine(node) {
            const lastToken = sourceCode.getLastToken(node);
            const secondToLastToken = sourceCode.getTokenBefore(lastToken);

            return astUtils.isSemicolonToken(lastToken) && lastToken.loc.start.line > secondToLastToken.loc.end.line
                ? secondToLastToken
                : lastToken;
        }

        /**
         * Check if node is followed by a blank newline.
         * @param {ASTNode} node Node to check.
         * @returns {boolean} Whether or not the passed in node is followed by a blank newline.
         */
        function hasNewlineAfter(node) {
            const lastToken = getLastTokenOnLine(node);
            const tokenAfter = sourceCode.getTokenAfter(lastToken, { includeComments: true });

            return tokenAfter.loc.start.line - lastToken.loc.end.line >= 2;
        }

        /**
         * Report errors for newlines around directives.
         * @param {ASTNode} node Node to check.
         * @param {string} location Whether the error was found before or after the directive.
         * @param {boolean} expected Whether or not a newline was expected or unexpected.
         * @returns {void}
         */
        function reportError(node, location, expected) {
            context.report({
                node,
                messageId: expected ? "expected" : "unexpected",
                data: {
                    value: node.expression.value,
                    location
                },
                fix(fixer) {
                    const lastToken = getLastTokenOnLine(node);

                    if (expected) {
                        return location === "before" ? fixer.insertTextBefore(node, "\n") : fixer.insertTextAfter(lastToken, "\n");
                    }
                    return fixer.removeRange(location === "before" ? [node.range[0] - 1, node.range[0]] : [lastToken.range[1], lastToken.range[1] + 1]);
                }
            });
        }

        /**
         * Check lines around directives in node
         * @param {ASTNode} node node to check
         * @returns {void}
         */
        function checkDirectives(node) {
            const directives = astUtils.getDirectivePrologue(node);

            if (!directives.length) {
                return;
            }

            const firstDirective = directives[0];
            const leadingComments = sourceCode.getCommentsBefore(firstDirective);

            /*
             * Only check before the first directive if it is preceded by a comment or if it is at the top of
             * the file and expectLineBefore is set to "never". This is to not force a newline at the top of
             * the file if there are no comments as well as for compatibility with padded-blocks.
             */
            if (leadingComments.length) {
                if (expectLineBefore === "always" && !hasNewlineBefore(firstDirective)) {
                    reportError(firstDirective, "before", true);
                }

                if (expectLineBefore === "never" && hasNewlineBefore(firstDirective)) {
                    reportError(firstDirective, "before", false);
                }
            } else if (
                node.type === "Program" &&
                expectLineBefore === "never" &&
                !leadingComments.length &&
                hasNewlineBefore(firstDirective)
            ) {
                reportError(firstDirective, "before", false);
            }

            const lastDirective = directives[directives.length - 1];
            const statements = node.type === "Program" ? node.body : node.body.body;

            /*
             * Do not check after the last directive if the body only
             * contains a directive prologue and isn't followed by a comment to ensure
             * this rule behaves well with padded-blocks.
             */
            if (lastDirective === statements[statements.length - 1] && !lastDirective.trailingComments) {
                return;
            }

            if (expectLineAfter === "always" && !hasNewlineAfter(lastDirective)) {
                reportError(lastDirective, "after", true);
            }

            if (expectLineAfter === "never" && hasNewlineAfter(lastDirective)) {
                reportError(lastDirective, "after", false);
            }
        }

        //--------------------------------------------------------------------------
        // Public
        //--------------------------------------------------------------------------

        return {
            Program: checkDirectives,
            FunctionDeclaration: checkDirectives,
            FunctionExpression: checkDirectives,
            ArrowFunctionExpression: checkDirectives
        };
    }
};