Replace helpers.linkRe with helpers.forEachLink to fix "Polynomial regular expression used on uncontrolled data" and to better support link syntax.

demo/markdownlint-browser.js

@@ -49,9 +49,6 @@ module.exports.listItemMarkerRe = /^([\s>]*)(?:[*+-]|\d+[.)])\s+/;
 module.exports.orderedListItemMarkerRe = /^[\s>]*0*(\d+)[.)]/;
 // Regular expression for all instances of emphasis markers
 var emphasisMarkersRe = /[_*]/g;
-// Regular expression for inline links and shortcut reference links
-var linkRe = /(\[(?:[^[\]]?(?:\[[^[\]]*\])?)*\])(\([^)]*\)|\[[^\]]*\])?/g;
-module.exports.linkRe = linkRe;
 // Regular expression for link reference definition lines
 module.exports.linkReferenceRe = /^ {0,3}\[[^\]]+]:\s.*$/;
 // All punctuation characters (normal and full-width)
@@ -630,6 +627,89 @@ module.exports.frontMatterHasTitle =
         return !ignoreFrontMatter &&
             frontMatterLines.some(function (line) { return frontMatterTitleRe.test(line); });
     };
+/**
+ * Calls the provided function for each link.
+ *
+ * @param {string} line Line of Markdown input.
+ * @param {Function} handler Function taking (index, link, text, destination).
+ * @returns {void}
+ */
+function forEachLink(line, handler) {
+    // Helper to find matching close symbol for link text/destination
+    var findClosingSymbol = function (index) {
+        var begin = line[index];
+        var end = (begin === "[") ? "]" : ")";
+        var nesting = 0;
+        var escaping = false;
+        var pointy = false;
+        for (var i = index + 1; i < line.length; i++) {
+            var current = line[i];
+            if (current === "\\") {
+                escaping = !escaping;
+            }
+            else if (!escaping && (current === begin)) {
+                nesting++;
+            }
+            else if (!escaping && (current === end)) {
+                if (nesting > 0) {
+                    nesting--;
+                }
+                else if (!pointy) {
+                    // Return index after matching close symbol
+                    return i + 1;
+                }
+            }
+            else if ((i === index + 1) && (begin === "(") && (current === "<")) {
+                pointy = true;
+            }
+            else if (!escaping && pointy && current === ">") {
+                pointy = false;
+                nesting = 0;
+            }
+            else {
+                escaping = false;
+            }
+        }
+        // No match found
+        return -1;
+    };
+    // Scan line for unescaped "[" character
+    var escaping = false;
+    for (var i = 0; i < line.length; i++) {
+        var current = line[i];
+        if (current === "\\") {
+            escaping = !escaping;
+        }
+        else if (!escaping && (current === "[")) {
+            // Scan for matching close "]" of link text
+            var textEnd = findClosingSymbol(i);
+            if (textEnd !== -1) {
+                if ((line[textEnd] === "(") || (line[textEnd] === "[")) {
+                    // Scan for matching close ")" or "]" of link destination
+                    var destEnd = findClosingSymbol(textEnd);
+                    if (destEnd !== -1) {
+                        // Call handler with link text and destination
+                        var link = line.slice(i, destEnd);
+                        var text = line.slice(i, textEnd);
+                        var dest = line.slice(textEnd, destEnd);
+                        handler(i, link, text, dest);
+                        i = destEnd;
+                    }
+                }
+                if (i < textEnd) {
+                    // Call handler with link text only
+                    var text = line.slice(i, textEnd);
+                    handler(i, text, text);
+                    i = textEnd;
+                }
+            }
+        }
+        else {
+            escaping = false;
+        }
+    }
+}
+module.exports.forEachLink = forEachLink;
 /**
  * Returns a list of emphasis markers in code spans and links.
  *
@@ -642,13 +722,12 @@ function emphasisMarkersInContent(params) {
     // Search links
     lines.forEach(function (tokenLine, tokenLineIndex) {
         var inLine = [];
-        var linkMatch = null;
+        forEachLink(tokenLine, function (index, match) {
-        while ((linkMatch = linkRe.exec(tokenLine))) {
             var markerMatch = null;
-            while ((markerMatch = emphasisMarkersRe.exec(linkMatch[0]))) {
+            while ((markerMatch = emphasisMarkersRe.exec(match))) {
-                inLine.push(linkMatch.index + markerMatch.index);
+                inLine.push(index + markerMatch.index);
             }
-        }
+        });
         byLine[tokenLineIndex] = inLine;
     });
     // Search code spans
@@ -4035,7 +4114,7 @@ module.exports = {
 "use strict";
 // @ts-check
 
-var _a = __webpack_require__(/*! ../helpers */ "../helpers/helpers.js"), addErrorDetailIf = _a.addErrorDetailIf, bareUrlRe = _a.bareUrlRe, escapeForRegExp = _a.escapeForRegExp, forEachLine = _a.forEachLine, overlapsAnyRange = _a.overlapsAnyRange, linkRe = _a.linkRe, linkReferenceRe = _a.linkReferenceRe;
+var _a = __webpack_require__(/*! ../helpers */ "../helpers/helpers.js"), addErrorDetailIf = _a.addErrorDetailIf, bareUrlRe = _a.bareUrlRe, escapeForRegExp = _a.escapeForRegExp, forEachLine = _a.forEachLine, forEachLink = _a.forEachLink, overlapsAnyRange = _a.overlapsAnyRange, linkReferenceRe = _a.linkReferenceRe;
 var _b = __webpack_require__(/*! ./cache */ "../lib/cache.js"), codeBlockAndSpanRanges = _b.codeBlockAndSpanRanges, lineMetadata = _b.lineMetadata;
 module.exports = {
     "names": ["MD044", "proper-names"],
@@ -4057,12 +4136,11 @@ module.exports = {
                 while ((match = bareUrlRe.exec(line)) !== null) {
                     exclusions.push([lineIndex, match.index, match[0].length]);
                 }
-                while ((match = linkRe.exec(line)) !== null) {
+                forEachLink(line, function (index, _, text, destination) {
-                    var text = match[1], destination = match[2];
                     if (destination) {
-                        exclusions.push([lineIndex, match.index + text.length, destination.length]);
+                        exclusions.push([lineIndex, index + text.length, destination.length]);
                     }
-                }
+                });
             }
         });
         if (!includeCodeBlocks) {

helpers/helpers.js

@@ -26,11 +26,6 @@ module.exports.orderedListItemMarkerRe = /^[\s>]*0*(\d+)[.)]/;
 // Regular expression for all instances of emphasis markers
 const emphasisMarkersRe = /[_*]/g;
 
-// Regular expression for inline links and shortcut reference links
-const linkRe =
-  /(\[(?:[^[\]]?(?:\[[^[\]]*\])?)*\])(\([^)]*\)|\[[^\]]*\])?/g;
-module.exports.linkRe = linkRe;
-
 // Regular expression for link reference definition lines
 module.exports.linkReferenceRe = /^ {0,3}\[[^\]]+]:\s.*$/;
 
@@ -648,6 +643,82 @@ module.exports.frontMatterHasTitle =
       frontMatterLines.some((line) => frontMatterTitleRe.test(line));
   };
 
+/**
+ * Calls the provided function for each link.
+ *
+ * @param {string} line Line of Markdown input.
+ * @param {Function} handler Function taking (index, link, text, destination).
+ * @returns {void}
+ */
+function forEachLink(line, handler) {
+  // Helper to find matching close symbol for link text/destination
+  const findClosingSymbol = (index) => {
+    const begin = line[index];
+    const end = (begin === "[") ? "]" : ")";
+    let nesting = 0;
+    let escaping = false;
+    let pointy = false;
+    for (let i = index + 1; i < line.length; i++) {
+      const current = line[i];
+      if (current === "\\") {
+        escaping = !escaping;
+      } else if (!escaping && (current === begin)) {
+        nesting++;
+      } else if (!escaping && (current === end)) {
+        if (nesting > 0) {
+          nesting--;
+        } else if (!pointy) {
+          // Return index after matching close symbol
+          return i + 1;
+        }
+      } else if ((i === index + 1) && (begin === "(") && (current === "<")) {
+        pointy = true;
+      } else if (!escaping && pointy && current === ">") {
+        pointy = false;
+        nesting = 0;
+      } else {
+        escaping = false;
+      }
+    }
+    // No match found
+    return -1;
+  };
+  // Scan line for unescaped "[" character
+  let escaping = false;
+  for (let i = 0; i < line.length; i++) {
+    const current = line[i];
+    if (current === "\\") {
+      escaping = !escaping;
+    } else if (!escaping && (current === "[")) {
+      // Scan for matching close "]" of link text
+      const textEnd = findClosingSymbol(i);
+      if (textEnd !== -1) {
+        if ((line[textEnd] === "(") || (line[textEnd] === "[")) {
+          // Scan for matching close ")" or "]" of link destination
+          const destEnd = findClosingSymbol(textEnd);
+          if (destEnd !== -1) {
+            // Call handler with link text and destination
+            const link = line.slice(i, destEnd);
+            const text = line.slice(i, textEnd);
+            const dest = line.slice(textEnd, destEnd);
+            handler(i, link, text, dest);
+            i = destEnd;
+          }
+        }
+        if (i < textEnd) {
+          // Call handler with link text only
+          const text = line.slice(i, textEnd);
+          handler(i, text, text);
+          i = textEnd;
+        }
+      }
+    } else {
+      escaping = false;
+    }
+  }
+}
+module.exports.forEachLink = forEachLink;
+
 /**
  * Returns a list of emphasis markers in code spans and links.
  *
@@ -660,13 +731,12 @@ function emphasisMarkersInContent(params) {
   // Search links
   lines.forEach((tokenLine, tokenLineIndex) => {
     const inLine = [];
-    let linkMatch = null;
+    forEachLink(tokenLine, (index, match) => {
-    while ((linkMatch = linkRe.exec(tokenLine))) {
       let markerMatch = null;
-      while ((markerMatch = emphasisMarkersRe.exec(linkMatch[0]))) {
+      while ((markerMatch = emphasisMarkersRe.exec(match))) {
-        inLine.push(linkMatch.index + markerMatch.index);
+        inLine.push(index + markerMatch.index);
       }
-    }
+    });
     byLine[tokenLineIndex] = inLine;
   });
   // Search code spans

lib/md044.js

@@ -3,7 +3,7 @@
 "use strict";
 
 const { addErrorDetailIf, bareUrlRe, escapeForRegExp, forEachLine,
-  overlapsAnyRange, linkRe, linkReferenceRe } = require("../helpers");
+  forEachLink, overlapsAnyRange, linkReferenceRe } = require("../helpers");
 const { codeBlockAndSpanRanges, lineMetadata } = require("./cache");
 
 module.exports = {
@@ -25,14 +25,13 @@ module.exports = {
         while ((match = bareUrlRe.exec(line)) !== null) {
           exclusions.push([ lineIndex, match.index, match[0].length ]);
         }
-        while ((match = linkRe.exec(line)) !== null) {
+        forEachLink(line, (index, _, text, destination) => {
-          const [ , text, destination ] = match;
           if (destination) {
             exclusions.push(
-              [ lineIndex, match.index + text.length, destination.length ]
+              [ lineIndex, index + text.length, destination.length ]
             );
           }
-        }
+        });
       }
     });
     if (!includeCodeBlocks) {

test/markdownlint-test-helpers.js

@@ -1000,3 +1000,286 @@ test("deepFreeze", (t) => {
     t.throws(scenario, null, "Assigned to frozen object.");
   });
 });
+
+test("forEachLink", (t) => {
+  t.plan(291);
+  const testCases = [
+    [
+      "",
+      []
+    ],
+    [
+      "Text",
+      []
+    ],
+    [
+      "Text [text] (text) text",
+      [ [ 5, "[text]", "[text]", undefined ] ]
+    ],
+    [
+      "Text [text] text (text) text",
+      [ [ 5, "[text]", "[text]", undefined ] ]
+    ],
+    [
+      "Text [text] [text] text",
+      [
+        [ 5, "[text]", "[text]", undefined ],
+        [ 12, "[text]", "[text]", undefined ]
+      ]
+    ],
+    [
+      "Text [text] text [text] text",
+      [
+        [ 5, "[text]", "[text]", undefined ],
+        [ 17, "[text]", "[text]", undefined ]
+      ]
+    ],
+    [
+      "Text [link](destination) text",
+      [ [ 5, "[link](destination)", "[link]", "(destination)" ] ]
+    ],
+    [
+      "Text [link0](destination0) text [link1](destination1) text",
+      [
+        [ 5, "[link0](destination0)", "[link0]", "(destination0)" ],
+        [ 32, "[link1](destination1)", "[link1]", "(destination1)" ]
+      ]
+    ],
+    [
+      "Text [link0] text [link1](destination1) text [link2] text",
+      [
+        [ 5, "[link0]", "[link0]", undefined ],
+        [ 18, "[link1](destination1)", "[link1]", "(destination1)" ],
+        [ 45, "[link2]", "[link2]", undefined ]
+      ]
+    ],
+    [
+      "Text [link0](destination0) text [link1] text [link2](destination2) text",
+      [
+        [ 5, "[link0](destination0)", "[link0]", "(destination0)" ],
+        [ 32, "[link1]", "[link1]", undefined ],
+        [ 45, "[link2](destination2)", "[link2]", "(destination2)" ]
+      ]
+    ],
+    [
+      "Text [link0][destination0] text [link1] text [link2](destination2) text",
+      [
+        [ 5, "[link0][destination0]", "[link0]", "[destination0]" ],
+        [ 32, "[link1]", "[link1]", undefined ],
+        [ 45, "[link2](destination2)", "[link2]", "(destination2)" ]
+      ]
+    ],
+    [
+      "Text [link0](destination0) text [link1] text [link2][destination2] text",
+      [
+        [ 5, "[link0](destination0)", "[link0]", "(destination0)" ],
+        [ 32, "[link1]", "[link1]", undefined ],
+        [ 45, "[link2][destination2]", "[link2]", "[destination2]" ]
+      ]
+    ],
+    [
+      "Text [link](destination \"title\") text",
+      [
+        [
+          5,
+          "[link](destination \"title\")",
+          "[link]",
+          "(destination \"title\")"
+        ]
+      ]
+    ],
+    [
+      "Text [link](<destination> \"title\") text",
+      [
+        [
+          5,
+          "[link](<destination> \"title\")",
+          "[link]",
+          "(<destination> \"title\")"
+        ]
+      ]
+    ],
+    [
+      "Text [link](destination \"ti\\\"tle\") text",
+      [
+        [
+          5,
+          "[link](destination \"ti\\\"tle\")",
+          "[link]",
+          "(destination \"ti\\\"tle\")"
+        ]
+      ]
+    ],
+    [
+      "Text [link](destination 'title') text",
+      [
+        [
+          5,
+          "[link](destination 'title')",
+          "[link]",
+          "(destination 'title')"
+        ]
+      ]
+    ],
+    [
+      "Text [link](destination (title)) text",
+      [
+        [
+          5,
+          "[link](destination (title))",
+          "[link]",
+          "(destination (title))"
+        ]
+      ]
+    ],
+    [
+      "Text [link](\"title\") text",
+      [ [ 5, "[link](\"title\")", "[link]", "(\"title\")" ] ]
+    ],
+    [
+      "[]()",
+      [ [ 0, "[]()", "[]", "()" ] ]
+    ],
+    [
+      "[l](d)",
+      [ [ 0, "[l](d)", "[l]", "(d)" ] ]
+    ],
+    [
+      "Text [li[nk](dest) text",
+      [ [ 8, "[nk](dest)", "[nk]", "(dest)" ] ]
+    ],
+    [
+      "Text [li\\[nk](dest) text",
+      [ [ 5, "[li\\[nk](dest)", "[li\\[nk]", "(dest)" ] ]
+    ],
+    [
+      "Text [li]nk](dest) text",
+      [ [ 5, "[li]", "[li]", undefined ] ]
+    ],
+    [
+      "Text [li\\]nk](dest) text",
+      [ [ 5, "[li\\]nk](dest)", "[li\\]nk]", "(dest)" ] ]
+    ],
+    [
+      "Text [l[in]k](dest) text",
+      [ [ 5, "[l[in]k](dest)", "[l[in]k]", "(dest)" ] ]
+    ],
+    [
+      "Text [li(nk](dest) text",
+      [ [ 5, "[li(nk](dest)", "[li(nk]", "(dest)" ] ]
+    ],
+    [
+      "Text [li)nk](dest) text",
+      [ [ 5, "[li)nk](dest)", "[li)nk]", "(dest)" ] ]
+    ],
+    [
+      "Text [l(in)k](dest) text",
+      [ [ 5, "[l(in)k](dest)", "[l(in)k]", "(dest)" ] ]
+    ],
+    [
+      "Text [link](de(st) text",
+      [ [ 5, "[link]", "[link]", undefined ] ]
+    ],
+    [
+      "Text [link](de\\(st) text",
+      [ [ 5, "[link](de\\(st)", "[link]", "(de\\(st)" ] ]
+    ],
+    [
+      "Text [link](de)st) text",
+      [ [ 5, "[link](de)", "[link]", "(de)" ] ]
+    ],
+    [
+      "Text [link](de\\)st) text",
+      [ [ 5, "[link](de\\)st)", "[link]", "(de\\)st)" ] ]
+    ],
+    [
+      "Text [link](d(es)t) text",
+      [ [ 5, "[link](d(es)t)", "[link]", "(d(es)t)" ] ]
+    ],
+    [
+      "Text [link]() text",
+      [ [ 5, "[link]()", "[link]", "()" ] ]
+    ],
+    [
+      "Text [link](#) text",
+      [ [ 5, "[link](#)", "[link]", "(#)" ] ]
+    ],
+    [
+      "Text [link](<de) text",
+      [ [ 5, "[link]", "[link]", undefined ] ]
+    ],
+    [
+      "Text [link](<de)st> text",
+      [ [ 5, "[link]", "[link]", undefined ] ]
+    ],
+    [
+      "Text [link](<>) text",
+      [ [ 5, "[link](<>)", "[link]", "(<>)" ] ]
+    ],
+    [
+      "Text [link](<dest>) text",
+      [ [ 5, "[link](<dest>)", "[link]", "(<dest>)" ] ]
+    ],
+    [
+      "Text [link](<de st>) text",
+      [ [ 5, "[link](<de st>)", "[link]", "(<de st>)" ] ]
+    ],
+    [
+      "Text [link](<de)st>) text",
+      [ [ 5, "[link](<de)st>)", "[link]", "(<de)st>)" ] ]
+    ],
+    [
+      "Text [<link](dest) text",
+      [ [ 5, "[<link](dest)", "[<link]", "(dest)" ] ]
+    ],
+    [
+      "Text [<link>](dest) text",
+      [ [ 5, "[<link>](dest)", "[<link>]", "(dest)" ] ]
+    ],
+    [
+      "Text [<link>](<dest) text",
+      [ [ 5, "[<link>]", "[<link>]", undefined ] ]
+    ],
+    [
+      "Text [<link>](<dest>) text",
+      [ [ 5, "[<link>](<dest>)", "[<link>]", "(<dest>)" ] ]
+    ],
+    [
+      "Text [[[[l[i]n[k]](dest) text",
+      [ [ 8, "[l[i]n[k]](dest)", "[l[i]n[k]]", "(dest)" ] ]
+    ],
+    [
+      "Text [link](d(e(st))) text",
+      [ [ 5, "[link](d(e(st)))", "[link]", "(d(e(st)))" ] ]
+    ],
+    [
+      "Text [link](d(e(st)) text",
+      [ [ 5, "[link]", "[link]", undefined ] ]
+    ],
+    [
+      "Text [link](<d(e(st)>) text",
+      [ [ 5, "[link](<d(e(st)>)", "[link]", "(<d(e(st)>)" ] ]
+    ],
+    [
+      "Text [link][reference] text",
+      [ [ 5, "[link][reference]", "[link]", "[reference]" ] ]
+    ],
+    [
+      "Text [link][refer]ence] text",
+      [ [ 5, "[link][refer]", "[link]", "[refer]" ] ]
+    ]
+  ];
+  for (const testCase of testCases) {
+    const [ markdown, matches ] = testCase;
+    helpers.forEachLink(String(markdown), (idx, lnk, txt, des) => {
+      // @ts-ignore
+      const match = matches.shift();
+      const [ index, link, text, destination ] = match;
+      t.is(idx, index, String(markdown));
+      t.is(lnk, link, String(markdown));
+      t.is(txt, text, String(markdown));
+      t.is(des, destination, String(markdown));
+    });
+    t.is(matches.length, 0, "Missing match");
+  }
+});