Expand diff parsing for additional metadata and multiple changes.

Review Request #11744 — Created July 26, 2021 and submitted

chipx86
Review Board
release-4.0.x
reviewboard

Historically, our diff parsing infrastructure was built around a base
set of manual line-by-line parsing rules, which could be specialized.
The result would be a list of files. This was expanded a bit in 4.0 and
subsequent releases to collect and handle additional data (such as being
able to populate FileDiff.extra_data), but the core design remained.

With DiffX coming, we need more. This change expands our diff parsing
support.

New ParsedDiff and ParsedDiffChange classes were added, which
represent information on a diff as a whole, and a change within it,
respectively. These both provide support for populating extra_data,
which will be set in DiffSet and DiffCommit when parsing a diff.

A new BaseDiffParser has been introduced as the new base class, which
DiffParser subclasses. The new base class does very little, and is
more of an interface. It contains no built-in parsing logic. This will
allow for more specialized parsers with their own logic.

BaseDiffParser and DiffParser now provide a parse_diff() method,
which is the new method to call to parse a diff. This replaces
parse(), which still exists in DiffParser.

For new subclasses of BaseDiffParser, a parse_diff() implementation
will be responsible for parsing into a series of ParsedDiff,
ParsedDiffChange, and ParsedDiffFile objects.

For subclasses of DiffParser, parse() can still be overridden. The
new default DiffParser.parse_diff() will set up the new objects as
parsed_diff and parsed_diff_change attributes.

This new model will make it easier to implement DiffX, and will give us
some good capabilities down the road. For the moment, there are still
limitations based on our existing process of uploading and parsing
diffs. The main one being that, while a ParsedDiff (and later a DiffX)
can in theory have multiple changes, it's not actually allowed through
our parsing. Clients of the API will need to provide diffs with only a
single change, until we're able to implement the appropriate changes
in the diff upload API and related code (probably post-4.0 sometime).

Unit tests pass on Python 2 and 3.

Tested posting diffs for review, without any issues.

Summary
Expand diff parsing for additional metadata and multiple changes.
Description From Last Updated

F821 undefined name 'parser'

reviewbotreviewbot

F821 undefined name 'parsed_diff_file'

reviewbotreviewbot

F401 'reviewboard.scmtools.core.Revision' imported but unused

reviewbotreviewbot

F821 undefined name 'parent_diff_change'

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chipx86
Review request changed

Change Summary:

  • Removed a duplicate assertion.
  • Fixed a variable access.
  • Removed an unused import.

Commits:

Summary
-
Expand diff parsing for additional metadata and multiple changes.
+
Expand diff parsing for additional metadata and multiple changes.

Diff:

Revision 2 (+1164 -156)

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Checks run (1 failed, 1 succeeded)

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JSHint passed.

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chipx86
david
  1. Ship It!
  2. 
      
chipx86
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to release-4.0.x (e2b6dcc)
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