Move each rule implementation into its own file (fixes #83).

lib/md009.js

@@ -0,0 +1,37 @@
+// @ts-check
+
+"use strict";
+
+var shared = require("./shared");
+
+var trailingSpaceRe = /\s+$/;
+
+module.exports = {
+  "names": [ "MD009", "no-trailing-spaces" ],
+  "description": "Trailing spaces",
+  "tags": [ "whitespace" ],
+  "function": function MD009(params, onError) {
+    var brSpaces = params.config.br_spaces || 0;
+    var listItemEmptyLines = params.config.list_item_empty_lines;
+    var allowListItemEmptyLines =
+      (listItemEmptyLines === undefined) ? false : !!listItemEmptyLines;
+    var listItemLineNumbers = [];
+    if (allowListItemEmptyLines) {
+      shared.filterTokens(params, "list_item_open", function forToken(token) {
+        for (var i = token.map[0]; i < token.map[1]; i++) {
+          listItemLineNumbers.push(i + 1);
+        }
+      });
+    }
+    shared.forEachLine(params, function forLine(line, lineIndex) {
+      var lineNumber = lineIndex + 1;
+      if (trailingSpaceRe.test(line) &&
+        (listItemLineNumbers.indexOf(lineNumber) === -1)) {
+        var expected = (brSpaces < 2) ? 0 : brSpaces;
+        shared.addErrorDetailIf(onError, lineNumber,
+          expected, line.length - shared.trimRight(line).length, null,
+          shared.rangeFromRegExp(line, trailingSpaceRe));
+      }
+    });
+  }
+};