Fix python call syntax highlighting

lib/rouge/lexers/python.rb

@@ -68,12 +68,34 @@ def self.exceptions
       end
 
       identifier =        /[[:alpha:]_][[:alnum:]_]*/
+      lower_identifier =  /[[:lower:]_][[:alnum:]_]*/
+      upper_identifier =  /[[:upper:]_][[:alnum:]_]*/
       dotted_identifier = /[[:alpha:]_.][[:alnum:]_.]*/
 
       def current_string
         @string_register ||= StringRegister.new
       end
 
+      # Yield a token for an identifier. Handle keywords/builtins, attr accesses
+      def token_for_identifier(word, fallback)
+        if self.class.keywords.include? word
+          token Keyword
+        elsif not in_state?(:dot) and self.class.exceptions.include? word
+          token Name::Builtin
+        elsif not in_state?(:dot) and self.class.builtins.include? word
+          token Name::Builtin
+        elsif not in_state?(:dot) and self.class.builtins_pseudo.include? word
+          token Name::Builtin::Pseudo
+        else
+          token fallback
+        end
+
+        # Reset attr access state
+        if in_state?(:dot)
+          pop!
+        end
+      end
+
       state :root do
         rule %r/\n+/m, Text
         rule %r/^(:)(\s*)([ru]{,2}""".*?""")/mi do
@@ -84,10 +106,16 @@ def current_string
 
         rule %r/[^\S\n]+/, Text
         rule %r(#(.*)?\n?), Comment::Single
-        rule %r/[\[\]{}:(),;.]/, Punctuation
+        rule %r/[\[\]{}:(),;]/, Punctuation
         rule %r/\\\n/, Text
         rule %r/\\/, Text
 
+        # Push the :dot state to the stack to keep track of attr accesses
+        rule %r/\./ do
+          token Punctuation
+          push :dot if not (in_state?(:generic_string) or in_state?(:dot))
+        end
+
         rule %r/@#{dotted_identifier}/i, Name::Decorator
 
         rule %r/(in|is|and|or|not)\b/, Operator::Word
@@ -116,9 +144,6 @@ def current_string
           push :classname
         end
 
-        rule %r/([a-z_]\w*)[ \t]*(?=(\(.*\)))/m, Name::Function
-        rule %r/([A-Z_]\w*)[ \t]*(?=(\(.*\)))/m, Name::Class
-
         # TODO: not in python 3
         rule %r/`.*?`/, Str::Backtick
         rule %r/([rfbu]{0,2})('''|"""|['"])/i do |m|
@@ -127,22 +152,18 @@ def current_string
           push :generic_string
         end
 
-        # using negative lookbehind so we don't match property names
-        rule %r/(?<!\.)#{identifier}/ do |m|
-          if self.class.keywords.include? m[0]
-            token Keyword
-          elsif self.class.exceptions.include? m[0]
-            token Name::Builtin
-          elsif self.class.builtins.include? m[0]
-            token Name::Builtin
-          elsif self.class.builtins_pseudo.include? m[0]
-            token Name::Builtin::Pseudo
-          else
-            token Name
-          end
+        # Identifiers used in a call expr
+        rule %r/#{lower_identifier}(?=[[:blank:]]*\()/m do |m|
+          token_for_identifier m[0], Name::Function
+        end
+        rule %r/#{upper_identifier}(?=[[:blank:]]*\()/m do |m|
+          token_for_identifier m[0], Name::Class
         end
 
-        rule identifier, Name
+        # All other identifiers
+        rule identifier do |m|
+          token_for_identifier m[0], Name
+        end
 
         digits = /[0-9](_?[0-9])*/
         decimal = /((#{digits})?\.#{digits}|#{digits}\.)/
@@ -158,6 +179,10 @@ def current_string
         rule %r/([1-9](_?[0-9])*|0(_?0)*)/, Num::Integer
       end
 
+      state :dot do
+        mixin :root
+      end
+
       state :funcname do
         rule identifier, Name::Function, :pop!
       end

spec/visual/samples/python

@@ -218,3 +218,13 @@ def do_nothing():
 
     app = FastAPI()
     FastAPIInstrumentor.instrument_app(app)
+
+# Keyword shouldn't be read as function call
+def take_first(pairs):
+    for (first, _) in pairs:
+        yield first
+
+    self.for('nonsense')
+
+# Distinguish between builtins and method calls
+self.filter(filter(lambda x: x == 1, items))