implement config begin and end macros to drop config at beginning of file

PyTeX/format/default_macros.py

@@ -14,5 +14,7 @@ def make_simple_macro(name: str, arg):
 def get_default_macros():
     return [
         make_simple_macro('!', FormatterProperty.file_prefix),
-        make_simple_macro('name', FormatterProperty.name)
+        make_simple_macro('name', FormatterProperty.name),
+        ConfigEndMacro(),
+        ConfigBeginMacro()
     ]

PyTeX/format/macros.py

@@ -2,7 +2,7 @@ import re
 from typing import List, Union, Tuple, Dict
 
 from .constants import *
-from .enums import FormatterProperty, Argument
+from .enums import FormatterProperty, Argument, FormatterMode
 from abc import ABC, abstractmethod
 
 
@@ -98,6 +98,42 @@ class SimpleMacro(Macro):
             ))
 
 
+class SingleLineMacro(Macro, ABC):
+    def __init__(
+            self,
+            chars: str,
+            strip: str = ' %\n'
+    ):
+        self.chars = chars
+        self.strip = strip
+    def matches(self, line: str) -> bool:
+        if line.find(self.chars) != -1:
+            if not line.strip(self.strip) == self.chars:
+                raise NotImplementedError
+            return True
+        else:
+            return False
+
+class ConfigBeginMacro(SingleLineMacro):
+    def __init__(self):
+        super(ConfigBeginMacro, self).__init__(FORMATTER_PREFIX + INFILE_CONFIG_BEGIN_CONFIG)
+
+    def apply(self, line: str, formatter) -> Union[str, List[str]]:
+        if not formatter.mode == FormatterMode.normal:
+            raise NotImplementedError  # invalid config begin
+        formatter.mode = FormatterMode.drop
+        return []
+
+class ConfigEndMacro(SingleLineMacro):
+    def __init__(self):
+        super(ConfigEndMacro, self).__init__(FORMATTER_PREFIX + INFILE_CONFIG_END_CONFIG)
+
+    def apply(self, line: str, formatter) -> Union[str, List[str]]:
+        if not formatter.mode == FormatterMode.drop:
+            raise NotImplementedError  # invalid
+        formatter.mode = FormatterMode.normal
+        return []
+
 class ArgumentMacro(Macro):
     def __init__(
             self,

PyTeX/format/tex_formatter.py

@@ -135,6 +135,14 @@ class TexFormatter(PyTeXFormatter, ABC):
     def format_pre_header(self) -> None:
         pass
 
+    @property
+    def mode(self) -> FormatterMode:
+        return self._mode
+
+    @mode.setter
+    def mode(self, mode: FormatterMode) -> None:
+        self._mode = mode
+
     def format_header(self):
         if self._output_file is None:
             raise NotImplementedError