Add new rule MD058/blanks-around-tables (fixes #132).

lib/md058.js

@@ -0,0 +1,48 @@
+// @ts-check
+
+"use strict";
+
+const { addErrorContextForLine, isBlankLine } = require("../helpers");
+const { filterByTypes } = require("../helpers/micromark.cjs");
+
+// eslint-disable-next-line jsdoc/valid-types
+/** @type import("./markdownlint").Rule */
+module.exports = {
+  "names": [ "MD058", "blanks-around-tables" ],
+  "description": "Tables should be surrounded by blank lines",
+  "tags": [ "table" ],
+  "parser": "micromark",
+  "function": function MD058(params, onError) {
+    // eslint-disable-next-line jsdoc/valid-types
+    /** @type import("../helpers/micromark.cjs").Token[] */
+    const micromarkTokens =
+      // @ts-ignore
+      params.parsers.micromark.tokens;
+    const { lines } = params;
+    // For every table...
+    const tables = filterByTypes(micromarkTokens, [ "table" ]);
+    for (const table of tables) {
+      // Look for a blank line above the table
+      const firstIndex = table.startLine - 1;
+      if (!isBlankLine(lines[firstIndex - 1])) {
+        addErrorContextForLine(
+          onError,
+          // @ts-ignore
+          lines,
+          firstIndex
+        );
+      }
+      // Look for a blank line below the table
+      const lastIndex = table.endLine - 1;
+      if (!isBlankLine(lines[lastIndex + 1])) {
+        addErrorContextForLine(
+          onError,
+          // @ts-ignore
+          lines,
+          lastIndex,
+          lastIndex + 2
+        );
+      }
+    }
+  }
+};