1 files changed, 98 insertions, 0 deletions
diff --git a/tools/cru-py/cru/parsing.py b/tools/cru-py/cru/parsing.py
new file mode 100644
index 0000000..1d2fa7f
--- /dev/null
+++ b/tools/cru-py/cru/parsing.py
@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+from abc import ABCMeta, abstractmethod
+from typing import NamedTuple, TypeAlias, TypeVar, Generic, NoReturn, Callable
+
+from ._error import CruException
+from ._iter import CruIterable
+
+_T = TypeVar("_T")
+
+
+class ParseError(CruException, Generic[_T]):
+    def __init__(
+        self,
+        message,
+        parser: Parser[_T],
+        text: str,
+        line_number: int | None = None,
+        *args,
+        **kwargs,
+    ):
+        super().__init__(message, *args, **kwargs)
+        self._parser = parser
+        self._text = text
+        self._line_number = line_number
+
+    @property
+    def parser(self) -> Parser[_T]:
+        return self._parser
+
+    @property
+    def text(self) -> str:
+        return self._text
+
+    @property
+    def line_number(self) -> int | None:
+        return self._line_number
+
+
+class Parser(Generic[_T], metaclass=ABCMeta):
+    def __init__(self, name: str) -> None:
+        self._name = name
+
+    @property
+    def name(self) -> str:
+        return self._name
+
+    @abstractmethod
+    def parse(self, s: str) -> _T:
+        raise NotImplementedError()
+
+    def raise_parse_exception(
+        self, text: str, line_number: int | None = None
+    ) -> NoReturn:
+        a = line_number and f" at line {line_number}" or ""
+        raise ParseError(f"Parser {self.name} failed{a}.", self, text, line_number)
+
+
+class SimpleLineConfigParserEntry(NamedTuple):
+    key: str
+    value: str
+    line_number: int | None = None
+
+
+class SimpleLineConfigParserResult(CruIterable.IterList[SimpleLineConfigParserEntry]):
+    pass
+
+
+class SimpleLineConfigParser(Parser[SimpleLineConfigParserResult]):
+    """
+    The parsing result is a list of tuples (key, value, line number).
+    """
+
+    Entry: TypeAlias = SimpleLineConfigParserEntry
+    Result: TypeAlias = SimpleLineConfigParserResult
+
+    def __init__(self) -> None:
+        super().__init__(type(self).__name__)
+
+    def _parse(self, text: str, callback: Callable[[Entry], None]) -> None:
+        for ln, line in enumerate(text.splitlines()):
+            line_number = ln + 1
+            # check if it's a comment
+            if line.strip().startswith("#"):
+                continue
+            # check if there is a '='
+            if line.find("=") == -1:
+                self.raise_parse_exception("There is even no '='!", line_number)
+            # split at first '='
+            key, value = line.split("=", 1)
+            key = key.strip()
+            value = value.strip()
+            callback(SimpleLineConfigParserEntry(key, value, line_number))
+
+    def parse(self, text: str) -> Result:
+        result = SimpleLineConfigParserResult()
+        self._parse(text, lambda item: result.append(item))
+        return result