some better error handling

PyTeX/format/errors.py

@@ -1,6 +1,27 @@
+from typing import Optional
+
 
 class PyTeXError(Exception):
-    pass
+    def __init__(self, msg, explanation: Optional[str] = None):
+        self._msg = msg
+        self._traceback_explanation = []
+        if explanation is not None:
+            self._traceback_explanation.append(explanation)
+        super().__init__(self._dispstr())
+
+    def _dispstr(self):
+        depth = 0
+        ret = [self._msg]
+        for explanation in self._traceback_explanation:
+            ret.append(' ' * 2 * depth + explanation)
+            depth += 1
+        return '\n'.join(ret)
+
+    def add_explanation(self, explanation: str):
+        self._traceback_explanation.append(explanation)
+
+    def __str__(self):
+        return self._dispstr()
 
 
 class PyTeXFormattingError(PyTeXError):

PyTeX/format/macros.py

@@ -158,7 +158,9 @@ class MacroCodeBeginMacro(SingleLineMacro):
 
     def _apply(self, line: str, formatter) -> Union[str, List[str]]:
         if not formatter.mode == FormatterMode.meta:
-            raise PyTeXInvalidBeginMacroCodeUsageError
+            raise PyTeXInvalidBeginMacroCodeUsageError(
+                r"\begin{macrocode} used outside meta context"
+            )
         formatter.mode = FormatterMode.macrocode
         return r'%    \begin{macrocode}'
 
@@ -169,7 +171,9 @@ class MacroCodeEndMacro(SingleLineMacro):
 
     def _apply(self, line: str, formatter) -> Union[str, List[str]]:
         if not formatter.mode == FormatterMode.macrocode:
-            raise PyTeXInvalidEndMacroCodeUsageError
+            raise PyTeXInvalidEndMacroCodeUsageError(
+                r"\end{macrocode} used outside macrocode context"
+            )
         formatter.mode = FormatterMode.meta
         return r'%    \end{macrocode}'
 

PyTeX/format/tex_formatter.py

@@ -7,6 +7,7 @@ from .macros import Macro
 from .pytex_formatter import PyTeXFormatter
 from .enums import *
 from ..logger import logger
+from .errors import *
 
 
 class LineStream:
@@ -15,6 +16,7 @@ class LineStream:
         self._handle = open(filename, 'r')
         self._cached_lines: List[str] = []
         self._file_exhausted: bool = False
+        self._line_number: int = 0
 
     def current_line(self):
         return self.future_line(0)
@@ -47,6 +49,7 @@ class LineStream:
             self._cached_lines.append(
                 self._handle.readline()
             )
+            self._line_number += 1
         if self._cached_lines[-1] == '':
             self._handle.close()
             self._file_exhausted = True
@@ -57,6 +60,10 @@ class LineStream:
         b = len(self._cached_lines) == 0
         return a & b
 
+    @property
+    def line_number(self) -> int:
+        return self._line_number
+
 
 class TexFormatter(PyTeXFormatter, ABC):
     def __init__(self, *args, **kwargs):
@@ -102,13 +109,21 @@ class TexFormatter(PyTeXFormatter, ABC):
         self._macros = macros
 
     def _handle_macro(self, macro: Macro):
+        try:
             replacement, shipout = macro.apply(
                 self.line_stream.current_line(),
                 self
             )
+        except PyTeXMacroError as e:
+            e.add_explanation('While applying macro')
+            raise e
         if shipout:
             self.line_stream.pop_line()
+            if isinstance(replacement, str):
                 self._shipout_line(replacement)
+            else:
+                for line in replacement:
+                    self._shipout_line(line)
         else:
             if isinstance(replacement, str):
                 self.line_stream.set_line(replacement)
@@ -150,13 +165,13 @@ class TexFormatter(PyTeXFormatter, ABC):
     def mode(self, mode: FormatterMode) -> None:
         self._mode = mode
 
-    def _get_provides_text(self) -> str:
+    def _get_provides_text(self, provided_type: str) -> str:
         if self.config.has_description:
             if self.config.tex_flavour == TeXFlavour.LaTeX2e:
                 return  \
                     r'\Provides%s{%s}[%s - %s]' \
                     % (
-                        self.config.tex_type.value.capitalize(),
+                        provided_type,
                         self.name,
                         self.attribute_dict[FormatterProperty.date.value],
                         self.attribute_dict[FormatterProperty.description.value]
@@ -166,7 +181,7 @@ class TexFormatter(PyTeXFormatter, ABC):
                 return \
                     '\\ProvidesExpl%s { %s } { %s } { %s }\n  { %s }' \
                     % (
-                        self.config.tex_type.value.capitalize(),
+                        provided_type,
                         self.name,
                         self.attribute_dict[FormatterProperty.date.value],
                         self.config.version,
@@ -183,14 +198,22 @@ class TexFormatter(PyTeXFormatter, ABC):
 
     def format_document(self) -> None:
         while not self.line_stream.exhausted:
+            try:
                 recent_replacement = True
                 while recent_replacement:
                     recent_replacement = False
                     for macro in self.macros:
                         if macro.matches(self.line_stream.current_line()):
+                            try:
                                 self._handle_macro(macro)
+                            except PyTeXMacroError as e:
+                                e.add_explanation('while handling macro')
+                                raise e
                             recent_replacement = True
                             break
+            except PyTeXMacroError as e:
+                e.add_explanation(f'in line {self.line_stream.line_number} ({self.line_stream.current_line().rstrip()})')
+                pass
             self._shipout_line(self._post_process_line(
                 self.line_stream.pop_line()
             ))