Subversion Dump file Revisionist

Revisionist is a library to read and write Subversion dump files. Versions 2 and 3 of the dump file format are supported.

Revisionist is designed with correctness in mind. It is designed to fail promptly and loudly when reality doesn't match its expectations. It asserts profusely in the parser and the writer.

Originally, I wrote Revisionist to help me migrate Subversion repositories from one server to another. These repositories had used svn:externals to refer to themselves and to each other. These had to be rewritten to refer to repositories at their new location on the new server. Also, some EOL-style bungles had snuck in through Subclipse on Windows.

The script, revisionist-fixprops, can perform simple string substitutions and EOL-style normalization on property values.

Installation

Install revisionist using the usual procedure:

python setup.py install

This will install the revisionist package among your site-packages and deposit revisionist-fixprops.py in the corresponding bin directory.

Using revisionist-fixprops

The script revisionist-fixprops.py performs string replacements and newline normalization on arbitrary properties in a dump file.

revisionist-fixprops.py OPTIONS < dumpfile.in > dumpfile.out

Legal option combinations are described by this BNF:

OPTIONS         = HelpOpt | PropertyClause* 
HelpOpt         = -h | --help
PropertyClause  = PropertyOpt PropertyName EditClause*
PropertyOpt     = -p | --property
PropertyName    = text (unix-style glob syntax accepted)
EditClause      = NormalizeOpt | ReplaceClause
NormalizeOpt    = -n | --normalize-line-breaks
ReplaceClause   = ReplaceOpt OldText NewText
ReplaceOpt      = -r | --replace
OldText         = text
NewText         = text

e.g.

revisionist-fixprops.py --property svn:externals \
     --replace svn://old.com/repos/ svn://new.com/repos/ -n

1. Replace every occurance of the string svn://old.com/repos/ with svn://new.com/repos in every svn:externals property in the dump file.

2. Normalize the line breaks in every svn:externals property.

Using the revisionist package

Once it has been installed, you should be able to import revisionist like this:

import revisionist

Parsing

revisionist.pull() is a generator consuming an Subversion dump file and delivering a sequence of parse events as objects. These objects are of the following classes: BeginDumpfile, EndDumpfile, BeginRevision, EndRevisionHeader, EndRevisionNodes, BeginNode, EndNode, UserProperties, TextContent, BlankLine. See the doc-string for pull for more information.

Editing

revisionist.edit_properties(events, edit): Modifies parse events. Consumes a stream of parse events, invoking the function edit on BeginRevsion, BeginNode and UserProperties events before yielding the events to its caller.

Changes to UserProperties will automatically cause re-computation of Content-length and Prop-content-length of the owning Node or Revision.

Writing

revisionist.write_events_to_dumpfile(events, dstFile) consumes a sequence of parse events while writing them to dstFile (a file-like object that's opened for writing) in Subversion's dump file format.