fix: fix em and strong starting with special char (#1832)

src/Lexer.js

@@ -328,12 +328,13 @@ module.exports = class Lexer {
   /**
    * Lexing/Compiling
    */
-  inlineTokens(src, tokens = [], inLink = false, inRawBlock = false, prevChar = '') {
+  inlineTokens(src, tokens = [], inLink = false, inRawBlock = false) {
     let token;
 
     // String with links masked to avoid interference with em and strong
     let maskedSrc = src;
     let match;
+    let keepPrevChar, prevChar;
 
     // Mask out reflinks
     if (this.tokens.links) {
@@ -352,6 +353,10 @@ module.exports = class Lexer {
     }
 
     while (src) {
+      if (!keepPrevChar) {
+        prevChar = '';
+      }
+      keepPrevChar = false;
       // escape
       if (token = this.tokenizer.escape(src)) {
         src = src.substring(token.raw.length);
@@ -444,6 +449,7 @@ module.exports = class Lexer {
       if (token = this.tokenizer.inlineText(src, inRawBlock, smartypants)) {
         src = src.substring(token.raw.length);
         prevChar = token.raw.slice(-1);
+        keepPrevChar = true;
         tokens.push(token);
         continue;
       }

test/specs/new/em_after_inline.html

@@ -0,0 +1,15 @@
+<p>a<br><em>@</em></p>
+
+<p>a<em>a</em><em>a</em><em>@</em></p>
+
+<p>a<strong>a</strong><em>a</em><em>@</em></p>
+
+<p>a<del>a</del><em>@</em></p>
+
+<p>a<code>a</code><em>@</em></p>
+
+<p>a<a href="http://a.com">http://a.com</a><em>@</em></p>
+
+<p>a<a href="a">a</a><em>@</em></p>
+
+<p>a<a><em>@</em></p>

test/specs/new/em_after_inline.md

@@ -0,0 +1,16 @@
+a\
+*@*
+
+a*a*_a_*@*
+
+a**a**_a_*@*
+
+a~a~*@*
+
+a`a`*@*
+
+a<http://a.com>*@*
+
+a[a](a)*@*
+
+a<a>*@*