Add MD052/reference-links-images and MD053/link-image-reference-definitions for reporting issues with link and image references (fixes #144, fixes #390, fixes #425, fixes #456).

lib/cache.js

@@ -34,9 +34,18 @@ module.exports.lineMetadata = (value) => {
   return lineMetadata;
 };
 
+let referenceLinkImageData = null;
+module.exports.referenceLinkImageData = (value) => {
+  if (value) {
+    referenceLinkImageData = value;
+  }
+  return referenceLinkImageData;
+};
+
 module.exports.clear = () => {
   codeBlockAndSpanRanges = null;
   flattenedLists = null;
   htmlElementRanges = null;
   lineMetadata = null;
+  referenceLinkImageData = null;
 };

lib/markdownlint.js

@@ -499,14 +499,17 @@ function lintContent(
     frontMatterLines
   });
   const lineMetadata = helpers.getLineMetadata(paramsBase);
-  cache.lineMetadata(lineMetadata);
   cache.codeBlockAndSpanRanges(
     helpers.codeBlockAndSpanRanges(paramsBase, lineMetadata)
   );
+  cache.flattenedLists(helpers.flattenLists(paramsBase.tokens));
   cache.htmlElementRanges(
     helpers.htmlElementRanges(paramsBase, lineMetadata)
   );
-  cache.flattenedLists(helpers.flattenLists(paramsBase.tokens));
+  cache.lineMetadata(lineMetadata);
+  cache.referenceLinkImageData(
+    helpers.getReferenceLinkImageData(paramsBase, lineMetadata)
+  );
   // Function to run for each rule
   let results = [];
   // eslint-disable-next-line jsdoc/require-jsdoc

lib/md013.js

@@ -3,13 +3,12 @@
 "use strict";
 
 const { addErrorDetailIf, filterTokens, forEachHeading, forEachLine,
-  includesSorted } = require("../helpers");
+  includesSorted, linkReferenceDefinitionRe } = require("../helpers");
 const { lineMetadata } = require("./cache");
 
 const longLineRePrefix = "^.{";
 const longLineRePostfixRelaxed = "}.*\\s.*$";
 const longLineRePostfixStrict = "}.+$";
-const labelRe = /^\s*\[.*[^\\]]:/;
 const linkOrImageOnlyLineRe = /^[es]*(lT?L|I)[ES]*$/;
 const sternModeRe = /^([#>\s]*\s)?\S*$/;
 const tokenTypeMap = {
@@ -83,7 +82,7 @@ module.exports = {
           (strict ||
            (!(stern && sternModeRe.test(line)) &&
             !includesSorted(linkOnlyLineNumbers, lineNumber) &&
-            !labelRe.test(line))) &&
+            !linkReferenceDefinitionRe.test(line))) &&
           lengthRe.test(line)) {
         addErrorDetailIf(
           onError,

lib/md044.js

@@ -3,7 +3,8 @@
 "use strict";
 
 const { addErrorDetailIf, bareUrlRe, escapeForRegExp, forEachLine,
-  forEachLink, overlapsAnyRange, linkReferenceRe } = require("../helpers");
+  forEachLink, overlapsAnyRange, linkReferenceDefinitionRe } =
+  require("../helpers");
 const { codeBlockAndSpanRanges, htmlElementRanges, lineMetadata } =
   require("./cache");
 
@@ -23,7 +24,7 @@ module.exports = {
       (htmlElements === undefined) ? true : !!htmlElements;
     const exclusions = [];
     forEachLine(lineMetadata(), (line, lineIndex) => {
-      if (linkReferenceRe.test(line)) {
+      if (linkReferenceDefinitionRe.test(line)) {
         exclusions.push([ lineIndex, 0, line.length ]);
       } else {
         let match = null;

lib/md052.js

@@ -0,0 +1,35 @@
+// @ts-check
+
+"use strict";
+
+const { addError } = require("../helpers");
+const { referenceLinkImageData } = require("./cache");
+
+module.exports = {
+  "names": [ "MD052", "reference-links-images" ],
+  "description":
+    "Reference links and images should use a label that is defined",
+  "tags": [ "images", "links" ],
+  "function": function MD052(params, onError) {
+    const { lines } = params;
+    const { references, definitions } = referenceLinkImageData();
+    // Look for links/images that use an undefined link reference
+    for (const reference of references.entries()) {
+      const [ label, datas ] = reference;
+      if (!definitions.has(label)) {
+        for (const data of datas) {
+          const [ lineIndex, index, length ] = data;
+          // Context will be incomplete if reporting for a multi-line link
+          const context = lines[lineIndex].slice(index, index + length);
+          addError(
+            onError,
+            lineIndex + 1,
+            `Missing link or image reference definition: "${label}"`,
+            context,
+            [ index + 1, context.length ]
+          );
+        }
+      }
+    }
+  }
+};

lib/md053.js

@@ -0,0 +1,52 @@
+// @ts-check
+
+"use strict";
+
+const { addError, ellipsify, linkReferenceDefinitionRe } =
+  require("../helpers");
+const { referenceLinkImageData } = require("./cache");
+
+module.exports = {
+  "names": [ "MD053", "link-image-reference-definitions" ],
+  "description": "Link and image reference definitions should be needed",
+  "tags": [ "images", "links" ],
+  "function": function MD053(params, onError) {
+    const { lines } = params;
+    const { references, shortcuts, definitions, duplicateDefinitions } =
+      referenceLinkImageData();
+    const singleLineDefinition = (line) => (
+      line.replace(linkReferenceDefinitionRe, "").trim().length > 0
+    );
+    const deleteFixInfo = {
+      "deleteCount": -1
+    };
+    // Look for unused link references (unreferenced by any link/image)
+    for (const definition of definitions.entries()) {
+      const [ label, lineIndex ] = definition;
+      if (!references.has(label) && !shortcuts.has(label)) {
+        const line = lines[lineIndex];
+        addError(
+          onError,
+          lineIndex + 1,
+          `Unused link or image reference definition: "${label}"`,
+          ellipsify(line),
+          [ 1, line.length ],
+          singleLineDefinition(line) ? deleteFixInfo : 0
+        );
+      }
+    }
+    // Look for duplicate link references (defined more than once)
+    for (const duplicateDefinition of duplicateDefinitions) {
+      const [ label, lineIndex ] = duplicateDefinition;
+      const line = lines[lineIndex];
+      addError(
+        onError,
+        lineIndex + 1,
+        `Duplicate link or image reference definition: "${label}"`,
+        ellipsify(line),
+        [ 1, line.length ],
+        singleLineDefinition(line) ? deleteFixInfo : 0
+      );
+    }
+  }
+};

lib/rules.js

@@ -50,7 +50,9 @@ const rules = [
   require("./md047"),
   require("./md048"),
   ...require("./md049-md050"),
-  require("./md051")
+  require("./md051"),
+  require("./md052"),
+  require("./md053")
 ];
 rules.forEach((rule) => {
   const name = rule.names[0].toLowerCase();