Iterate through all commits and yield file version information or a time series of file changes.

gitseries.py

## Imports
import os
import git


## Module Constants
DATE_TIME_FORMAT = "%Y-%m-%dT%H:%M:%S%z"
EMPTY_TREE_SHA   = "4b825dc642cb6eb9a060e54bf8d69288fbee4904"


def versions(path, branch='master'):
    """
    This function returns a generator which iterates through all commits of
    the repository located in the given path for the given branch. It yields
    file diff information to show a timeseries of file changes.
    """

    # Create the repository, raises an error if it isn't one.
    repo = git.Repo(path)

    # Iterate through every commit for the given branch in the repository
    for commit in repo.iter_commits(branch):
        # Determine the parent of the commit to diff against.
        # If no parent, this is the first commit, so use empty tree.
        # Then create a mapping of path to diff for each file changed.
        parent = commit.parents[0] if commit.parents else EMPTY_TREE_SHA
        diffs  = {
            diff.a_path: diff for diff in commit.diff(parent)
        }

        # The stats on the commit is a summary of all the changes for this
        # commit, we'll iterate through it to get the information we need.
        for objpath, stats in commit.stats.files.items():

            # Select the diff for the path in the stats
            diff = diffs.get(objpath)

            # If the path is not in the dictionary, it's because it was
            # renamed, so search through the b_paths for the current name.
            if not diff:
                for diff in diffs.values():
                    if diff.b_path == path and diff.renamed:
                        break

            # Update the stats with the additional information
            stats.update({
                'object': os.path.join(path, objpath),
                'commit': commit.hexsha,
                'author': commit.author.email,
                'timestamp': commit.authored_datetime.strftime(DATE_TIME_FORMAT),
                'size': diff_size(diff),
                'type': diff_type(diff),
            })

            yield stats


def diff_size(diff):
    """
    Computes the size of the diff by comparing the size of the blobs.
    """
    if diff.b_blob is None and diff.deleted_file:
        # This is a deletion, so return negative the size of the original.
        return diff.a_blob.size * -1

    if diff.a_blob is None and diff.new_file:
        # This is a new file, so return the size of the new value.
        return diff.b_blob.size

    # Otherwise just return the size a-b
    return diff.a_blob.size - diff.b_blob.size


def diff_type(diff):
    """
    Determines the type of the diff by looking at the diff flags.
    """
    if diff.renamed: return 'R'
    if diff.deleted_file: return 'D'
    if diff.new_file: return 'A'
    return 'M'