Update MD037/no-space-in-emphasis to handle multiple embedded underscores separated by a single character (fixes #804).

demo/markdownlint-browser.js

@@ -5186,11 +5186,12 @@ var _require2 = __webpack_require__(/*! ./cache */ "../lib/cache.js"),
   htmlElementRanges = _require2.htmlElementRanges,
   lineMetadata = _require2.lineMetadata;
 var emphasisRe = /(^|[^\\]|\\\\)(?:(\*{1,3})|(_{1,3}))/g;
-var embeddedUnderscoreRe = /([A-Za-z\d])_([A-Za-z\d])/g;
+var embeddedUnderscoreRe = /([A-Za-z\d])(_([A-Za-z\d]))+/g;
 var asteriskListItemMarkerRe = /^([\s>]*)\*(\s+)/;
 var leftSpaceRe = /^\s+/;
 var rightSpaceRe = /\s+$/;
 var tablePipeRe = /\|/;
+var allUnderscoresRe = /_/g;
 module.exports = {
   "names": ["MD037", "no-space-in-emphasis"],
   "description": "Spaces inside emphasis markers",
@@ -5256,7 +5257,9 @@ module.exports = {
         // Emphasis has no meaning here
         return;
       }
-      var patchedLine = line.replace(embeddedUnderscoreRe, "$1 $2");
+      var patchedLine = line.replace(embeddedUnderscoreRe, function (match) {
+        return match.replace(allUnderscoresRe, " ");
+      });
       if (onItemStart) {
         // Trim overlapping '*' list item marker
         patchedLine = patchedLine.replace(asteriskListItemMarkerRe, "$1 $2");

lib/md037.js

@@ -7,11 +7,12 @@ const { addErrorContext, emphasisMarkersInContent, forEachLine, isBlankLine,
 const { htmlElementRanges, lineMetadata } = require("./cache");
 
 const emphasisRe = /(^|[^\\]|\\\\)(?:(\*{1,3})|(_{1,3}))/g;
-const embeddedUnderscoreRe = /([A-Za-z\d])_([A-Za-z\d])/g;
+const embeddedUnderscoreRe = /([A-Za-z\d])(_([A-Za-z\d]))+/g;
 const asteriskListItemMarkerRe = /^([\s>]*)\*(\s+)/;
 const leftSpaceRe = /^\s+/;
 const rightSpaceRe = /\s+$/;
 const tablePipeRe = /\|/;
+const allUnderscoresRe = /_/g;
 
 module.exports = {
   "names": [ "MD037", "no-space-in-emphasis" ],
@@ -102,7 +103,10 @@ module.exports = {
           // Emphasis has no meaning here
           return;
         }
-        let patchedLine = line.replace(embeddedUnderscoreRe, "$1 $2");
+        let patchedLine = line.replace(
+          embeddedUnderscoreRe,
+          (match) => match.replace(allUnderscoresRe, " ")
+        );
         if (onItemStart) {
           // Trim overlapping '*' list item marker
           patchedLine = patchedLine.replace(asteriskListItemMarkerRe, "$1 $2");

test/snapshots/markdownlint-test-scenarios.js.md

@@ -43625,6 +43625,9 @@ Generated by [AVA](https://avajs.dev).
       Emphasis <img alt="inside * attribute * content"/> {MD033}␊
       ␊
       Emphasis <p data="* attribute *">*HTML*</p> {MD033} {MD037}␊
+      ␊
+      Embedded underscore is okay:␊
+      Text _emphas_i_s_ text _emphasis_␊
       `,
     }
 

test/spaces_inside_emphasis_markers.md

@@ -369,3 +369,6 @@ Emphasis <p data="inside * attribute * content"></p> {MD033}
 Emphasis <img alt="inside * attribute * content"/> {MD033}
 
 Emphasis <p data="* attribute *">* HTML *</p> {MD033} {MD037}
+
+Embedded underscore is okay:
+Text _emphas_i_s_ text _emphasis_