1 files changed, 165 insertions, 0 deletions
diff --git a/tools/eslint/lib/rules/lines-around-directive.js b/tools/eslint/lib/rules/lines-around-directive.js
new file mode 100644
index 0000000000..15a7779d7c
--- /dev/null
+++ b/tools/eslint/lib/rules/lines-around-directive.js
@@ -0,0 +1,165 @@
+/**
+ * @fileoverview Require or disallow newlines around directives.
+ * @author Kai Cataldo
+ */
+
+"use strict";
+
+const astUtils = require("../ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "require or disallow newlines around directives",
+            category: "Stylistic Issues",
+            recommended: false
+        },
+        schema: [{
+            oneOf: [
+                {
+                    enum: ["always", "never"]
+                },
+                {
+                    type: "object",
+                    properties: {
+                        before: {
+                            enum: ["always", "never"]
+                        },
+                        after: {
+                            enum: ["always", "never"]
+                        },
+                    },
+                    additionalProperties: false,
+                    minProperties: 2
+                }
+            ]
+        }]
+    },
+
+    create(context) {
+        const sourceCode = context.getSourceCode();
+        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.getTokenOrCommentBefore(node);
+            const tokenLineBefore = tokenBefore ? tokenBefore.loc.end.line : 0;
+
+            return node.loc.start.line - tokenLineBefore >= 2;
+        }
+
+        /**
+         * 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 tokenAfter = sourceCode.getTokenOrCommentAfter(node);
+
+            return tokenAfter.loc.start.line - node.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,
+                message: "{{expected}} newline {{location}} \"{{value}}\" directive.",
+                data: {
+                    expected: expected ? "Expected" : "Unexpected",
+                    value: node.expression.value,
+                    location
+                }
+            });
+        }
+
+        /**
+         * 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 hasTokenOrCommentBefore = !!sourceCode.getTokenOrCommentBefore(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 (
+                firstDirective.leadingComments && firstDirective.leadingComments.length ||
+
+                // Shebangs are not added to leading comments but are accounted for by the following.
+                node.type === "Program" && hasTokenOrCommentBefore
+            ) {
+                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" &&
+                !hasTokenOrCommentBefore &&
+                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
+        };
+    }
+};