Bugfix: Lua escaped quotes now parsing (#2155)

* Lua Lexer: Better handle escaped single/double quotes

* Lua Lexer: alter gsub parsing to handle single-quoted input strings

* Lua Lexer: Add specific states for SQ and DQ regex

---------

Co-authored-by: Nicholas Reaves <[email protected]>

Author: zanderman112

lib/rouge/lexers/lua.rb

@@ -105,7 +105,26 @@ def builtins
         rule %r/\)/, Punctuation, :pop!
         rule %r/[(,]/, Punctuation
         rule %r/\s+/, Text
-        rule %r/"/, Str::Regex, :regex
+        rule %r/'/, Str::Regex, :regex_sq
+        rule %r/"/, Str::Regex, :regex_dq
+      end
+
+      state :regex_sq do
+        rule %r(') do
+          token Str::Regex
+          goto :regex_end
+        end
+
+        mixin :regex
+      end
+
+      state :regex_dq do
+        rule %r(") do
+          token Str::Regex
+          goto :regex_end
+        end
+
+        mixin :regex
       end
 
       state :regex do
@@ -151,13 +170,15 @@ def builtins
       end
 
       state :sqs do
+        rule %r(\\'), Str::Escape
         rule %r('), Str::Single, :pop!
-        rule %r([^']+), Str::Single
+        rule %r([^'\\]+), Str::Single
       end
 
       state :dqs do
+        rule %r(\\"), Str::Escape
         rule %r("), Str::Double, :pop!
-        rule %r([^"]+), Str::Double
+        rule %r([^"\\]+), Str::Double
       end
     end
   end

spec/visual/samples/lua

@@ -258,6 +258,8 @@ end
 acc = Account.create(1000)
 acc:withdraw(100)
 
+-- gsub examples
 if
    url = url:gsub("^['\"]", ""):gsub("['\"]$", "")
+   local pattern = attr_name .. '=[\'"]' .. attr_value:gsub('([%.%+%-%*%?%[%]%^%$%(%)%%])', '%%%1') .. '[\'"]'
 end