BIML: properly delegate to C# within strings

lib/rouge/lexers/biml.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative 'xml'
+require_relative 'csharp'
 
 module Rouge
   module Lexers
@@ -14,22 +15,48 @@ def self.detect?(text)
         return true if text =~ /<\s*Biml\b/
       end
 
+      start do
+        @csharp = CSharp.new(options)
+      end
+
+      state :biml_interp do
+        rule %r(<#[=]?)m do
+          token Name::Tag
+          push :directive_as_csharp
+        end
+      end
+
       prepend :root do
         rule %r(<#\@\s*)m, Name::Tag, :directive_tag
 
-        rule %r(<#[=]?\s*)m, Name::Tag, :directive_as_csharp
+        mixin :biml_interp
       end
 
       prepend :attr do
-        #TODO: how to deal with embedded <# tags inside a attribute string
-        #rule %r("<#[=]?\s*)m, Name::Tag, :directive_as_csharp
+        rule(%r/"/) { token Str::Double; goto :biml_dq }
+        rule(%r/'/) { token Str::Double; goto :biml_sq }
+
+        mixin :biml_interp
+      end
+
+      state :biml_dq do
+        rule %r/[^<"]+/, Str::Double
+        mixin :biml_interp
+        rule %r/"/, Str::Double, :pop!
+        rule %r/</, Str::Double
+      end
+
+      state :biml_sq do
+        rule %r/[^<']+/, Str::Single
+        mixin :biml_interp
+        rule %r/'/, Str::Single, :pop!
+        rule %r/</, Str::Single
       end
 
       state :directive_as_csharp do
-        rule %r/\s*#>\s*/m, Name::Tag, :pop!
-        rule %r(.*?(?=\s*#>\s*))m do
-          delegate CSharp
-        end
+        rule(/[^#]+/) { delegate @csharp }
+        rule /#>/, Name::Tag, :pop!
+        rule(/[#>]/) { delegate @csharp }
       end
 
       state :directive_tag do