func patch(c *object.Commit, path string) ([]diffmatchpatch.Diff, error) {
// get contents of the file in the commit
file, err := c.File(path)
if err != nil {
return nil, err
}
content, err := file.Contents()
if err != nil {
return nil, err
}
// get contents of the file in the first parent of the commit
var contentParent string
iter := c.Parents()
parent, err := iter.Next()
if err != nil {
return nil, err
}
file, err = parent.File(path)
if err != nil {
contentParent = ""
} else {
contentParent, err = file.Contents()
if err != nil {
return nil, err
}
}
// compare the contents of parent and child
return diff.Do(content, contentParent), nil
}
// blobHash returns the hash of a path in a commit
func blobHash(path string, commit *object.Commit) (hash plumbing.Hash, found bool) {
file, err := commit.File(path)
if err != nil {
var empty plumbing.Hash
return empty, found
}
return file.Hash, true
}
// Recursive traversal of the commit graph, generating a linear history of the
// path.
func walkGraph(result *[]*object.Commit, seen *map[plumbing.Hash]struct{}, current *object.Commit, path string) error {
// check and update seen
if _, ok := (*seen)[current.Hash]; ok {
return nil
}
(*seen)[current.Hash] = struct{}{}
// if the path is not in the current commit, stop searching.
if _, err := current.File(path); err != nil {
return nil
}
// optimization: don't traverse branches that does not
// contain the path.
parents := parentsContainingPath(path, current)
switch len(parents) {
// if the path is not found in any of its parents, the path was
// created by this commit; we must add it to the revisions list and
// stop searching. This includes the case when current is the
// initial commit.
case 0:
*result = append(*result, current)
return nil
case 1: // only one parent contains the path
// if the file contents has change, add the current commit
different, err := differentContents(path, current, parents)
if err != nil {
return err
}
if len(different) == 1 {
*result = append(*result, current)
}
// in any case, walk the parent
return walkGraph(result, seen, parents[0], path)
default: // more than one parent contains the path
// TODO: detect merges that had a conflict, because they must be
// included in the result here.
for _, p := range parents {
err := walkGraph(result, seen, p, path)
if err != nil {
return err
}
}
}
return nil
}