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

lib/md042.js

@@ -0,0 +1,40 @@
+// @ts-check
+
+"use strict";
+
+var shared = require("./shared");
+
+var emptyLinkRe = /\[[^\]]*](?:\((?:#?|(?:<>))\))/;
+
+module.exports = {
+  "names": [ "MD042", "no-empty-links" ],
+  "description": "No empty links",
+  "tags": [ "links" ],
+  "function": function MD042(params, onError) {
+    shared.filterTokens(params, "inline", function forToken(token) {
+      var inLink = false;
+      var linkText = "";
+      var emptyLink = false;
+      token.children.forEach(function forChild(child) {
+        if (child.type === "link_open") {
+          inLink = true;
+          linkText = "";
+          child.attrs.forEach(function forAttr(attr) {
+            if (attr[0] === "href" && (!attr[1] || (attr[1] === "#"))) {
+              emptyLink = true;
+            }
+          });
+        } else if (child.type === "link_close") {
+          inLink = false;
+          if (emptyLink) {
+            shared.addErrorContext(onError, child.lineNumber,
+              "[" + linkText + "]()", null, null,
+              shared.rangeFromRegExp(child.line, emptyLinkRe));
+          }
+        } else if (inLink) {
+          linkText += child.content;
+        }
+      });
+    });
+  }
+};