executors/python: add coloring for compileall error messages

dmoj/executors/PY2.py

@@ -4,6 +4,7 @@
 class Executor(PythonExecutor):
     command = 'python'
     command_paths = ['python2.7', 'python2', 'python']
+    pygments_traceback_lexer = 'pytb'
     test_program = """
 import sys
 if sys.version_info.major == 2:

dmoj/executors/PY3.py

@@ -4,6 +4,7 @@
 class Executor(PythonExecutor):
     command = 'python3'
     command_paths = [f'python{i}' for i in ['3.6', '3.5', '3.4', '3.3', '3.2', '3.1', '3']]
+    pygments_traceback_lexer = 'py3tb'
     test_program = """
 import sys
 if sys.version_info.major == 3:

dmoj/executors/PYPY.py

@@ -6,6 +6,7 @@
 
 class Executor(PythonExecutor):
     command = 'pypy'
+    pygments_traceback_lexer = 'pytb'
     test_program = """
 import sys
 if sys.version_info.major == 2:

dmoj/executors/PYPY3.py

@@ -3,6 +3,7 @@
 
 class Executor(PYPYExecutor):
     command = 'pypy3'
+    pygments_traceback_lexer = 'py3tb'
     test_program = """
 import sys
 if sys.version_info.major == 3:

dmoj/executors/python_executor.py

@@ -1,7 +1,11 @@
 import builtins
 import re
 from collections import deque
-from typing import List
+from typing import List, Optional
+
+from pygments import highlight
+from pygments.formatters import Terminal256Formatter
+from pygments.lexers import get_lexer_by_name
 
 from dmoj.cptbox import TracedPopen
 from dmoj.executors.base_executor import VersionFlags
@@ -28,6 +32,7 @@ class PythonExecutor(CompiledExecutor):
     address_grace = 131072
     data_grace = 2048
     ext = 'py'
+    pygments_traceback_lexer: Optional[str] = None
 
     def get_compile_args(self) -> List[str]:
         command = self.get_command()
@@ -48,6 +53,12 @@ def get_executable(self) -> str:
         assert command is not None
         return command
 
+    def handle_compile_error(self, output: bytes) -> None:
+        if self.pygments_traceback_lexer:
+            lexer = get_lexer_by_name(self.pygments_traceback_lexer)
+            output = utf8bytes(highlight(utf8text(output), lexer, Terminal256Formatter()))
+        super().handle_compile_error(output)
+
     def create_files(self, problem_id: str, source_code: bytes, *args, **kwargs) -> None:
         super().create_files(problem_id, source_code, **kwargs)
         self._loader = self._file('-loader.py')