1 files changed, 42 insertions, 0 deletions
diff --git a/subv.py b/subv.py
index 0615159..a280e77 100644
--- a/subv.py
+++ b/subv.py
@@ -288,3 +288,45 @@ def dump(line):
 def join_all(gen):
     res = '\n'.join(gen)
     return res
+
+
+class SubVException(Exception):
+    pass
+
+class LineIterator(object):
+    def __init__(self, stream):
+        self.stream = stream
+        self.iter = enumerate(self.stream, start=1)
+        self.i, self.raw_line, self.line = 0, None, None
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        self.i, self.raw_line = next(self.iter)
+        self.line = None
+        try:
+            self.line = parse(self.raw_line)
+        except Exception as e:
+            raise self.exception("failed to parse line") from e
+        return self.line
+
+    def exception(self, msg):
+        if self.line:
+            msg = msg + "\n{}:{}:  {}".format(self.stream.name, self.i, format(self.line))
+            msg = msg + "\nparsed as {}".format(dump(self.line))
+        elif self.raw_line:
+            msg = msg + "\n{}:{}:  {}".format(self.stream.name, self.i, self.raw_line.strip())
+        return SubVException(msg)
+
+def with_parsed_lines(process_fn):
+    def _wrapped(iter):
+        iterator = LineIterator(iter)
+        try:
+            yield from process_fn(iterator)
+        except SubVException:
+            raise
+        except Exception as e:
+            raise iterator.exception("failed to {} line".format(process_fn.__name__)) from e
+
+    return _wrapped