Script/utility to rewrite all svn:externals in repository trunk

Say that one wishes to convert all absolute svn:externals URLS to relative URLS throughout their repository.

Alternatively, if heeding the tip in the svn:externals docs ("You should seriously consider using explicit revision numbers..."),开发者_开发技巧 one might find themselves needing to periodically pull new revisions for externals in many places throughout the repository.

What's the best way to programmatically update a large number of svn:externals properties?

My solution is posted below.

Here's my class to extract parts from a single line of an svn:externals property:

from urlparse import urlparse
import re
class SvnExternalsLine:
    '''Consult https://subversion.apache.org/docs/release-notes/1.5.html#externals for parsing algorithm.
    The old svn:externals format consists of:
        <local directory> [revision] <absolute remote URL>

    The NEW svn:externals format consists of:
        [revision] <absolute or relative remote URL> <local directory>

    Therefore, "relative" remote paths always come *after* the local path.
    One complication is the possibility of local paths with spaces.
    We just assume that the remote path cannot have spaces, and treat all other
    tokens (except the revision specifier) as part of the local path.
    '''

    REVISION_ARGUMENT_REGEXP = re.compile("-r(\d+)")

    def __init__(self, original_line):
        self.original_line = original_line

        self.pinned_revision_number = None
        self.repo_url = None
        self.local_pathname_components = []

        for token in self.original_line.split():

            revision_match = self.REVISION_ARGUMENT_REGEXP.match(token)
            if revision_match:
                self.pinned_revision_number = int(revision_match.group(1))
            elif urlparse(token).scheme or any(map(lambda p: token.startswith(p), ["^", "//", "/", "../"])):
                self.repo_url = token
            else:
                self.local_pathname_components.append(token)

    # ---------------------------------------------------------------------
    def constructLine(self):
        '''Reconstruct the externals line in the Subversion 1.5+ format'''

        tokens = []

        # Update the revision specifier if one existed
        if self.pinned_revision_number is not None:
            tokens.append( "-r%d" % (self.pinned_revision_number) )

        tokens.append( self.repo_url )
        tokens.extend( self.local_pathname_components )

        if self.repo_url is None:
            raise Exception("Found a bad externals property: %s; Original definition: %s" % (str(tokens), repr(self.original_line)))

        return " ".join(tokens)

I use the pysvn library to iterate recursively through all of the directories possessing the svn:externals property, then split that property value by newlines, and act upon each line according to the parsed SvnExternalsLine.

The process must be performed on a local checkout of the repository. Here's how pysvn (propget) can be used to retrieve the externals:

client.propget( "svn:externals", base_checkout_path, recurse=True)

Iterate through the return value of this function, and and after modifying the property on each directory,

client.propset("svn:externals", new_externals_property, path)