Fix code span parser in GFM

src/commonMain/kotlin/org/intellij/markdown/flavours/gfm/GFMGeneratingProviders.kt

@@ -1,7 +1,6 @@
 package org.intellij.markdown.flavours.gfm
 
 import org.intellij.markdown.MarkdownElementTypes
-import org.intellij.markdown.MarkdownTokenTypes.Companion.ESCAPED_BACKTICKS
 import org.intellij.markdown.ast.*
 import org.intellij.markdown.ast.impl.ListCompositeNode
 import org.intellij.markdown.ast.impl.ListItemCompositeNode
@@ -93,16 +92,7 @@ open class TableAwareCodeSpanGeneratingProvider : GeneratingProvider {
     override fun processNode(visitor: HtmlGenerator.HtmlGeneratingVisitor, text: String, node: ASTNode) {
         val isInsideTable = isInsideTable(node)
         val nodes = collectContentNodes(node)
-        val output = nodes.withIndex().joinToString(separator = "") { (i, it) ->
-            if (i == nodes.lastIndex && it.type == ESCAPED_BACKTICKS) {
-                // Backslash escapes do not work in code spans.
-                // Yet, a code span like `this\` is recognized as "BACKTICK", "TEXT", "ESCAPED_BACKTICKS"
-                // So if the last node is ESCAPED_BACKTICKS, we need to manually render it as "\"
-                return@joinToString "\\"
-            }
-
-            processChild(it, text, isInsideTable).replaceNewLines()
-        }.trimForCodeSpan()
+        val output = nodes.joinToString(separator = "") { processChild(it, text, isInsideTable).replaceNewLines() }.trimForCodeSpan()
         visitor.consumeTagOpen(node, "code")
         visitor.consumeHtml(output)
         visitor.consumeTagClose("code")
@@ -130,14 +120,6 @@ open class TableAwareCodeSpanGeneratingProvider : GeneratingProvider {
 
     protected fun collectContentNodes(node: ASTNode): List<ASTNode> {
         check(node.children.size >= 2)
-
-        // Backslash escapes do not work in code spans.
-        // Yet, a code span like `this\` is recognized as "BACKTICK", "TEXT", "ESCAPED_BACKTICKS"
-        // Let's keep the last ESCAPED_BACKTICKS and manually render it as "\"
-        if (node.children.last().type == ESCAPED_BACKTICKS) {
-            return node.children.drop(1)
-        }
-
         return node.children.subList(1, node.children.size - 1)
     }
 

src/commonMain/kotlin/org/intellij/markdown/flavours/gfm/lexer/gfm.flex

@@ -24,6 +24,8 @@ import org.intellij.markdown.lexer.GeneratedLexer;
 
   private boolean isHeader = false;
 
+  private int codeSpanBacktickslength = 0;
+
   private ParseDelimited parseDelimited = new ParseDelimited();
 
   private static class ParseDelimited {
@@ -79,8 +81,8 @@ import org.intellij.markdown.lexer.GeneratedLexer;
 
     parseDelimited.exitChar = last;
     parseDelimited.returnType = contentsType;
-//    parseDelimited.inlinesAllowed = allowInlines;
-    parseDelimited.inlinesAllowed = true;
+    parseDelimited.inlinesAllowed = allowInlines;
+//    parseDelimited.inlinesAllowed = true;
 
     yybegin(PARSE_DELIMITED);
 
@@ -133,7 +135,7 @@ import org.intellij.markdown.lexer.GeneratedLexer;
   }
 
   private boolean canInline() {
-    return yystate() == AFTER_LINE_START || yystate() == PARSE_DELIMITED && parseDelimited.inlinesAllowed;
+    return yystate() == AFTER_LINE_START || yystate() == PARSE_DELIMITED && parseDelimited.inlinesAllowed || yystate() == CODE_SPAN && parseDelimited.inlinesAllowed;
   }
 
   private IElementType getReturnGeneralized(IElementType defaultType) {
@@ -244,7 +246,7 @@ PATH=({PATH_PART}+ | ("(" {PATH_PART}* ")"? {PATH_PART}*)) ("(" {PATH_PART}* ")"
 // See pushbackAutolink method
 GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {HOST_PART})* (":" [0-9]+)? ("/" {PATH})? "/"?
 
-%state TAG_START, AFTER_LINE_START, PARSE_DELIMITED, CODE
+%state TAG_START, AFTER_LINE_START, PARSE_DELIMITED, CODE_SPAN
 
 %%
 
@@ -266,13 +268,7 @@ GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {
   }
 }
 
-
 <AFTER_LINE_START, PARSE_DELIMITED> {
-  // The special case of a backtick
-  \\"`"+ {
-    return getReturnGeneralized(MarkdownTokenTypes.ESCAPED_BACKTICKS);
-  }
-
   // Escaping
   \\[\\\"'`*_{}\[\]()#+.,!:@#$%&~<>/-] {
     return getReturnGeneralized(MarkdownTokenTypes.TEXT);
@@ -281,6 +277,9 @@ GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {
   // Backticks (code span)
   "`"+ {
     if (canInline()) {
+      codeSpanBacktickslength = yylength();
+      stateStack.push(yystate());
+      yybegin(CODE_SPAN);
       return MarkdownTokenTypes.BACKTICK;
     }
     return parseDelimited.returnType;
@@ -293,6 +292,19 @@ GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {
     }
     return parseDelimited.returnType;
   }
+}
+
+<CODE_SPAN> {
+  "`"+ {
+    if (yylength() == codeSpanBacktickslength) {
+      codeSpanBacktickslength = 0;
+      popState();
+    }
+    return MarkdownTokenTypes.BACKTICK;
+  }
+}
+
+<AFTER_LINE_START, PARSE_DELIMITED, CODE_SPAN> {
 
   // Emphasis
   {WHITE_SPACE}+ ("*" | "_") {WHITE_SPACE}+ {
@@ -314,7 +326,7 @@ GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {
 
 }
 
-<AFTER_LINE_START> {
+<AFTER_LINE_START, CODE_SPAN> {
 
   {WHITE_SPACE}+ {
     return MarkdownTokenTypes.WHITE_SPACE;
@@ -341,6 +353,9 @@ GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {
       return MarkdownTokenTypes.WHITE_SPACE;
     }
 
+    if (yystate() == CODE_SPAN) {
+      popState();
+    }
     processEol();
     return MarkdownTokenTypes.EOL;
   }
@@ -363,11 +378,14 @@ GFM_AUTOLINK = (("http" "s"? | "ftp" | "file")"://" | "www.") {HOST_PART} ("." {
 
 }
 
-<PARSE_DELIMITED> {
+<PARSE_DELIMITED, CODE_SPAN> {
   {EOL} { resetState(); }
 
   {EOL} | {ANY_CHAR} {
     if (yycharat(0) == parseDelimited.exitChar) {
+      if (yystate() == CODE_SPAN) {
+        stateStack.pop();
+      }
       yybegin(stateStack.pop());
       return getDelimiterTokenType(yycharat(0));
     }

src/commonTest/kotlin/org/intellij/markdown/GfmSpecTest.kt

@@ -2101,7 +2101,6 @@ class GfmSpecTest : SpecTest(org.intellij.markdown.flavours.gfm.GFMFlavourDescri
     )
 
     @Test
-    @Ignore
     fun testCodeSpansExample343() = doTest(
             markdown = "` b `\n",
             html = "<p><code> b </code></p>\n"

src/fileBasedTest/kotlin/org/intellij/markdown/MarkdownParsingTest.kt

@@ -146,11 +146,12 @@ class MarkdownParsingTest : TestCase() {
     @Test
     fun testCodeFence() {
         defaultTest()
+        defaultTest(GFMFlavourDescriptor())
     }
 
     @Test
     fun testCodeSpan() {
-        defaultTest()
+        defaultTest(GFMFlavourDescriptor())
     }
 
     @Test

src/fileBasedTest/resources/data/parser/codeSpan.txt

@@ -24,8 +24,8 @@ Markdown:MARKDOWN_FILE
   Markdown:PARAGRAPH
     Markdown:CODE_SPAN
       Markdown:BACKTICK('`')
-      Markdown:TEXT('foo')
-      Markdown:ESCAPED_BACKTICKS('\`')
+      Markdown:TEXT('foo\')
+      Markdown:BACKTICK('`')
     Markdown:TEXT('bar')
     Markdown:CODE_SPAN
       Markdown:BACKTICK('`')
@@ -50,9 +50,7 @@ Markdown:MARKDOWN_FILE
   Markdown:PARAGRAPH
     Markdown:AUTOLINK
       Markdown:<('<')
-      Markdown:AUTOLINK('http://foo.bar.')
-      Markdown:BACKTICK('`')
-      Markdown:AUTOLINK('baz')
+      Markdown:AUTOLINK('http://foo.bar.`baz')
       Markdown:>('>')
     Markdown:BACKTICK('`')
   Markdown:EOL('\n')