Update MD037/no-space-in-emphasis to handle more scenarios (refs #286).

helpers/helpers.js

@@ -25,8 +25,8 @@ module.exports.bareUrlRe = /(?:http|ftp)s?:\/\/[^\s\]"']*/ig;
 module.exports.listItemMarkerRe = /^([\s>]*)(?:[*+-]|\d+[.)])\s+/;
 module.exports.orderedListItemMarkerRe = /^[\s>]*0*(\d+)[.)]/;
 
-// Regular expression for emphasis markers
-const emphasisMarkersRe = /[_*]+/g;
+// Regular expression for all instances of emphasis markers
+const emphasisMarkersRe = /[_*]/g;
 
 // Regular expression for links
 const linkRe = /\[(?:[^\]]|\[[^\]]*\])*\]\(\S*\)/g;
@@ -255,7 +255,7 @@ module.exports.getLineMetadata = function getLineMetadata(params) {
 // Calls the provided function for each line (with context)
 module.exports.forEachLine = function forEachLine(lineMetadata, handler) {
   lineMetadata.forEach(function forMetadata(metadata) {
-    // Parameters: line, lineIndex, inCode, onFence, inTable, inBreak
+    // Parameters: line, lineIndex, inCode, onFence, inTable, inItem, inBreak
     handler(...metadata);
   });
 };

lib/md037.js

@@ -6,8 +6,8 @@ const { addErrorContext, emphasisMarkersInContent, forEachLine, isBlankLine } =
   require("../helpers");
 const { lineMetadata } = require("./cache");
 
-const emphasisRe = /(^|[^\\])(?:(\*\*?\*?)|(__?_?))/g;
-const asteriskListItemMarkerRe = /^(\s*)\*(\s+)/;
+const emphasisRe = /(^|[^\\]|\\\\)(?:(\*\*?\*?)|(__?_?))/g;
+const asteriskListItemMarkerRe = /^([\s>]*)\*(\s+)/;
 const leftSpaceRe = /^\s+/;
 const rightSpaceRe = /\s+$/;
 
@@ -101,31 +101,38 @@ module.exports = {
             emphasisLength = matchLength;
             emphasisKind = matchKind;
             effectiveEmphasisLength = matchLength;
-          } else if (
-            (matchLength === effectiveEmphasisLength) &&
-            (matchKind === emphasisKind)
-          ) {
-            // Ending an existing run, report any pending error
-            if (pendingError) {
-              addErrorContext(...pendingError);
-              pendingError = null;
+          } else if (matchKind === emphasisKind) {
+            // Matching emphasis markers
+            if (matchLength === effectiveEmphasisLength) {
+              // Ending an existing run, report any pending error
+              if (pendingError) {
+                addErrorContext(...pendingError);
+                pendingError = null;
+              }
+              const error = handleRunEnd(
+                line, lineIndex, effectiveEmphasisLength, match, matchIndex);
+              if (error) {
+                addErrorContext(...error);
+              }
+              // Reset
+              resetRunTracking();
+            } else if (matchLength === 3) {
+              // Swap internal run length (1->2 or 2->1)
+              effectiveEmphasisLength = matchLength - effectiveEmphasisLength;
+            } else if (effectiveEmphasisLength === 3) {
+              // Downgrade internal run (3->1 or 3->2)
+              effectiveEmphasisLength -= matchLength;
+            } else {
+              // Upgrade to internal run (1->3 or 2->3)
+              effectiveEmphasisLength += matchLength;
             }
-            const error = handleRunEnd(
-              line, lineIndex, effectiveEmphasisLength, match, matchIndex);
-            if (error) {
-              addErrorContext(...error);
-            }
-            // Reset
-            resetRunTracking();
-          } else if (matchLength === 3) {
-            // Swap internal run length (1->2 or 2->1)
-            effectiveEmphasisLength = matchLength - effectiveEmphasisLength;
-          } else if (effectiveEmphasisLength === 3) {
-            // Downgrade internal run (3->1 or 3->2)
-            effectiveEmphasisLength -= matchLength;
+            // Back up one character so RegExp has a chance to match the
+            // next marker (ex: "**star**_underscore_")
+            emphasisRe.lastIndex--;
           } else {
-            // Upgrade to internal run (1->3 or 2->3)
-            effectiveEmphasisLength += matchLength;
+            // Back up one character so RegExp has a chance to match the
+            // mis-matched marker (ex: "*text_*")
+            emphasisRe.lastIndex--;
           }
         }
         if (emphasisIndex !== -1) {

test/spaces_inside_emphasis_markers.md

@@ -188,3 +188,69 @@ Mixed `code_span` scenarios are *also* okay.
 Text [Link](under_score) text _underscore_ text [Link](st*ar) text *star* text
 
 [Link [link] link](under_score) followed by _underscore_
+
+**under_score** text *under_score*
+
+*under_score* text **under_score**
+
+__star*star__ text _star*star_
+
+_star*star_ text __star*star__
+
+*_emphasis* text *emphasis*
+
+*emphasis_* text *emphasis*
+
+*emphasis* text *_emphasis*
+
+*emphasis* text *emphasis_*
+
+text \\*emphasis* text *emphasis* text
+
+text *emphasis\\* text *emphasis* text
+
+text *emphasis* text \\*emphasis* text
+
+text *emphasis* text *emphasis\\* text
+
+text *star*_underscore_ text **star**_underscore_ text
+
+text **star**_underscore_ text *star*_underscore_ text
+
+text **star**_underscore_ text **star**_underscore_ text
+
+text *star*_underscore_ text *star*__underscore__ text
+
+text *star*__underscore__ text *star*_underscore_ text
+
+text *star*__underscore__ text *star*__underscore__ text
+
+text _underscore_*star* text __underscore__*star* text
+
+text __underscore__*star* text _underscore_*star* text
+
+text __underscore__*star* text __underscore__*star* text
+
+text _underscore_*star* text _underscore_**star** text
+
+text _underscore_**star** text _underscore_*star* text
+
+text _underscore_**star** text _underscore_**star** text
+
+> * List with *emphasis* in blockquote
+>
+> > * List with *emphasis* in blockquote
+
+`* text *`
+
+`** text **`
+
+`*** text ***`
+
+`**** text ****`
+
+`***** text *****`
+
+`****** text ******`
+
+`******* text *******`