feat(literalMidWordAsterisks): add option for mid word asterisks

Implements feature similar to ignoring midword underscores but with asterisks. The main use case is ignoring cursing.

README.md

@@ -253,6 +253,18 @@ var defaultOptions = showdown.getDefaultOptions();
    ```html
    <p>some text with__underscores__in middle</p>
    ```
+
+ * **literalMidWordAsterisks**: (boolean) [default false] Turning this on will stop showdown from interpreting asterisks in the middle of words as `<em>` and `<strong>` and instead treat them as literal asterisks. 
+
+   Example:
+
+   ```md
+   some text with**underscores**in middle
+   ```
+   will be parsed as
+   ```html
+   <p>some text with**underscores**in middle</p>
+   ```
    
  * **strikethrough**: (boolean) [default false] Enable support for strikethrough syntax.
    `~~strikethrough~~` as `<del>strikethrough</del>`

src/options.js

@@ -51,6 +51,11 @@ function getDefaultOpts (simple) {
       describe: 'Parse midword underscores as literal underscores',
       type: 'boolean'
     },
+    literalMidWordAsterisks: {
+      defaultValue: false,
+      describe: 'Parse midword asterisks as literal asterisks',
+      type: 'boolean'
+    },
     strikethrough: {
       defaultValue: false,
       describe: 'Turn on/off strikethrough support',

src/subParsers/italicsAndBold.js

@@ -39,16 +39,29 @@ showdown.subParser('italicsAndBold', function (text, options, globals) {
   }
 
   // Now parse asterisks
-  text = text.replace(/\*\*\*(\S[\s\S]*?)\*\*\*/g, function (wm, m) {
-    return (/\S$/.test(m)) ? parseInside (m, '<strong><em>', '</em></strong>') : wm;
-  });
-  text = text.replace(/\*\*(\S[\s\S]*?)\*\*/g, function (wm, m) {
-    return (/\S$/.test(m)) ? parseInside (m, '<strong>', '</strong>') : wm;
-  });
-  text = text.replace(/\*([^\s*][\s\S]*?)\*/g, function (wm, m) {
-    // !/^\*[^*]/.test(m) - test if it doesn't start with ** (since it seems redundant, we removed it)
-    return (/\S$/.test(m)) ? parseInside (m, '<em>', '</em>') : wm;
-  });
+  if (options.literalMidWordAsterisks) {
+    text = text.trim().replace(/(?:^| +)\*{3}(\S[\s\S]*?)\*{3}(?: +|$)/g, function (wm, txt) {
+      return parseInside (txt, ' <strong><em>', '</em></strong> ');
+    });
+    text = text.trim().replace(/(?:^| +)\*{2}(\S[\s\S]*?)\*{2}(?: +|$)/g, function (wm, txt) {
+      return parseInside (txt, ' <strong>', '</strong> ');
+    });
+    text = text.trim().replace(/(?:^| +)\*{1}(\S[\s\S]*?)\*{1}(?: +|$)/g, function (wm, txt) {
+      return parseInside (txt, ' <em>', '</em>' + (wm.slice(-1) === ' ' ? ' ' : ''));
+    });
+  } else {
+    text = text.replace(/\*\*\*(\S[\s\S]*?)\*\*\*/g, function (wm, m) {
+      return (/\S$/.test(m)) ? parseInside (m, '<strong><em>', '</em></strong>') : wm;
+    });
+    text = text.replace(/\*\*(\S[\s\S]*?)\*\*/g, function (wm, m) {
+      return (/\S$/.test(m)) ? parseInside (m, '<strong>', '</strong>') : wm;
+    });
+    text = text.replace(/\*([^\s*][\s\S]*?)\*/g, function (wm, m) {
+      // !/^\*[^*]/.test(m) - test if it doesn't start with ** (since it seems redundant, we removed it)
+      return (/\S$/.test(m)) ? parseInside (m, '<em>', '</em>') : wm;
+    });
+  }
+
 
   text = globals.converter._dispatch('italicsAndBold.after', text, options, globals);
   return text;

test/features/enable-literalMidWordAsterisks.html

@@ -0,0 +1,24 @@
+<p>this is a sentence*with*mid asterisks</p>
+<p>this is a sentence**with**two mid asterisks</p>
+<p>this is a sentence***with***three mid asterisks</p>
+<p>this is a sentence with just*one asterisk</p>
+<p>this is a sentence with just**one asterisk</p>
+<p>this is a sentence with just***one asterisk</p>
+<p>this is double**asterisk**mid word</p>
+<p>this has just**one double asterisk</p>
+<p>this has just***one triple asterisk</p>
+<p>this <em>should be parsed</em> as emphasis</p>
+<p>this <strong>should be parsed</strong> as bold</p>
+<p>this <strong><em>should be parsed</em></strong> as bold and emphasis</p>
+<p>emphasis at <em>end of sentence</em></p>
+<p>bold at <strong>end of sentence</strong></p>
+<p>bold and emphasis at <strong><em>end of sentence</em></strong></p>
+<p><em>emphasis at</em> line start</p>
+<p><strong>bold at</strong> line start</p>
+<p><strong><em>bold and emphasis at</em></strong> line start</p>
+<p>multi <em>line emphasis
+yeah it is</em> yeah</p>
+<p>multi <strong>line emphasis
+yeah it is</strong> yeah</p>
+<p>multi <strong><em>line emphasis
+yeah it is</em></strong> yeah</p>

test/features/enable-literalMidWordAsterisks.md

@@ -0,0 +1,46 @@
+this is a sentence*with*mid asterisks
+
+this is a sentence**with**two mid asterisks
+
+this is a sentence***with***three mid asterisks
+
+this is a sentence with just*one asterisk
+
+this is a sentence with just**one asterisk
+
+this is a sentence with just***one asterisk
+
+this is double**asterisk**mid word
+
+this has just**one double asterisk
+
+this has just***one triple asterisk
+
+this *should be parsed* as emphasis
+
+this **should be parsed** as bold
+
+this ***should be parsed*** as bold and emphasis
+
+emphasis at *end of sentence*
+
+bold at **end of sentence**
+
+bold and emphasis at ***end of sentence***
+
+*emphasis at* line start
+
+**bold at** line start
+
+***bold and emphasis at*** line start
+
+multi *line emphasis
+yeah it is* yeah
+
+
+multi **line emphasis
+yeah it is** yeah
+
+
+multi ***line emphasis
+yeah it is*** yeah

test/node/testsuite.features.js

@@ -62,6 +62,8 @@ describe('makeHtml() features testsuite', function () {
         converter = new showdown.Converter({encodeEmails: false, simplifiedAutoLink: true});
       } else if (testsuite[i].name === '#331.allow-escaping-of-tilde') {
         converter = new showdown.Converter({strikethrough: true});
+      } else if (testsuite[i].name === 'enable-literalMidWordAsterisks') {
+        converter = new showdown.Converter({literalMidWordAsterisks: true});
       } else if (testsuite[i].name === 'prefixHeaderId-simple') {
         converter = new showdown.Converter({prefixHeaderId: true});
       } else if (testsuite[i].name === 'prefixHeaderId-string') {
@@ -104,6 +106,8 @@ describe('makeHtml() features testsuite', function () {
         converter = new showdown.Converter({simplifiedAutoLink: true, strikethrough: true});
       } else if (suite[i].name === 'disallow-underscores') {
         converter = new showdown.Converter({literalMidWordUnderscores: true, simplifiedAutoLink: true});
+      } else if (suite[i].name === 'disallow-asterisks') {
+        converter = new showdown.Converter({literalMidWordAsterisks: true, simplifiedAutoLink: true});
       } else {
         converter = new showdown.Converter({simplifiedAutoLink: true});
       }