intercom_test.augmentation.origin_mapping_stream module

class intercom_test.augmentation.origin_mapping_stream.OriginMapper(mapper)

Bases: object

corrections

discontinuities

tell_of_chr(n)

Given a character index, compute the byte index in the source file

Due to character encodings and line-ending conventions, each character produced from a stream comes from one or more bytes in the input file. Partial-reading a YAML file requires knowing the exact byte offset into the file at which to start. This function allows “back mapping” from the index in a YAML event’s start_mark to the byte offset within the file.

intercom_test.augmentation.origin_mapping_stream.open(path: os.PathLike, *, buffer_size: int = 8192) → io.TextIOBase

Open a UTF-8 encoded file for reading with origin-byte tracking

Parameters:

• path – file path to open, like io.open()
• buffer_size – size of buffer to use for io.BufferedReader

Returns:

text reader with an origin_mapper

To correctly jump to the starting point of a test case, intercom_test needs the byte offset in the file, while the YAML parser reports position in terms of characters. This requires taking the text encoding into account. To do this efficiently, the object returned by this function provides an origin_mapper, which is an OriginMapper instance.

As a consequence of needing to start in the middle of the file, the only Unicode encoding that can be supported is UTF-8.

The stream does not currently support seeking forward.