Plumbing: object, Add support for Log with filenames. Fixes #826 (#979)

plumbing: object, Add support for Log with filenames. Fixes #826

4 files changed, 271 insertions, 6 deletions

diff --git a/options.go b/options.go
index b572770..b8bc1e9 100644
--- a/options.go
+++ b/options.go
@@ -330,6 +330,10 @@ type LogOptions struct {
 	// set Order=LogOrderCommitterTime for ordering by committer time (more compatible with `git log`)
 	// set Order=LogOrderBSF for Breadth-first search
 	Order LogOrder
+
+	// Show only those commits in which the specified file was inserted/updated.
+	// It is equivalent to running `git log -- <file-name>`.
+	FileName *string
 }
 
 var (
diff --git a/plumbing/object/commit_walker_file.go b/plumbing/object/commit_walker_file.go
new file mode 100644
index 0000000..84e738a
--- /dev/null
+++ b/plumbing/object/commit_walker_file.go
@@ -0,0 +1,115 @@
+package object
+
+import (
+	"gopkg.in/src-d/go-git.v4/plumbing/storer"
+	"io"
+)
+
+type commitFileIter struct {
+	fileName      string
+	sourceIter    CommitIter
+	currentCommit *Commit
+}
+
+// NewCommitFileIterFromIter returns a commit iterator which performs diffTree between
+// successive trees returned from the commit iterator from the argument. The purpose of this is
+// to find the commits that explain how the files that match the path came to be.
+func NewCommitFileIterFromIter(fileName string, commitIter CommitIter) CommitIter {
+	iterator := new(commitFileIter)
+	iterator.sourceIter = commitIter
+	iterator.fileName = fileName
+	return iterator
+}
+
+func (c *commitFileIter) Next() (*Commit, error) {
+	if c.currentCommit == nil {
+		var err error
+		c.currentCommit, err = c.sourceIter.Next()
+		if err != nil {
+			return nil, err
+		}
+	}
+	commit, commitErr := c.getNextFileCommit()
+
+	// Setting current-commit to nil to prevent unwanted states when errors are raised
+	if commitErr != nil {
+		c.currentCommit = nil
+	}
+	return commit, commitErr
+}
+
+func (c *commitFileIter) getNextFileCommit() (*Commit, error) {
+	for {
+		// Parent-commit can be nil if the current-commit is the initial commit
+		parentCommit, parentCommitErr := c.sourceIter.Next()
+		if parentCommitErr != nil {
+			// If the parent-commit is beyond the initial commit, keep it nil
+			if parentCommitErr != io.EOF {
+				return nil, parentCommitErr
+			}
+			parentCommit = nil
+		}
+
+		// Fetch the trees of the current and parent commits
+		currentTree, currTreeErr := c.currentCommit.Tree()
+		if currTreeErr != nil {
+			return nil, currTreeErr
+		}
+
+		var parentTree *Tree
+		if parentCommit != nil {
+			var parentTreeErr error
+			parentTree, parentTreeErr = parentCommit.Tree()
+			if parentTreeErr != nil {
+				return nil, parentTreeErr
+			}
+		}
+
+		// Find diff between current and parent trees
+		changes, diffErr := DiffTree(currentTree, parentTree)
+		if diffErr != nil {
+			return nil, diffErr
+		}
+
+		foundChangeForFile := false
+		for _, change := range changes {
+			if change.name() == c.fileName {
+				foundChangeForFile = true
+				break
+			}
+		}
+
+		// Storing the current-commit in-case a change is found, and
+		// Updating the current-commit for the next-iteration
+		prevCommit := c.currentCommit
+		c.currentCommit = parentCommit
+
+		if foundChangeForFile == true {
+			return prevCommit, nil
+		}
+
+		// If not matches found and if parent-commit is beyond the initial commit, then return with EOF
+		if parentCommit == nil {
+			return nil, io.EOF
+		}
+	}
+}
+
+func (c *commitFileIter) ForEach(cb func(*Commit) error) error {
+	for {
+		commit, nextErr := c.Next()
+		if nextErr != nil {
+			return nextErr
+		}
+		err := cb(commit)
+		if err == storer.ErrStop {
+			return nil
+		} else if err != nil {
+			return err
+		}
+	}
+}
+
+func (c *commitFileIter) Close() {
+	c.sourceIter.Close()
+}
diff --git a/repository.go b/repository.go
index be1f057..62e22a6 100644
--- a/repository.go
+++ b/repository.go
@@ -965,19 +965,26 @@ func (r *Repository) Log(o *LogOptions) (object.CommitIter, error) {
 		return nil, err
 	}
 
+	var commitIter object.CommitIter
 	switch o.Order {
 	case LogOrderDefault:
-		return object.NewCommitPreorderIter(commit, nil, nil), nil
+		commitIter = object.NewCommitPreorderIter(commit, nil, nil)
 	case LogOrderDFS:
-		return object.NewCommitPreorderIter(commit, nil, nil), nil
+		commitIter = object.NewCommitPreorderIter(commit, nil, nil)
 	case LogOrderDFSPost:
-		return object.NewCommitPostorderIter(commit, nil), nil
+		commitIter = object.NewCommitPostorderIter(commit, nil)
 	case LogOrderBSF:
-		return object.NewCommitIterBSF(commit, nil, nil), nil
+		commitIter = object.NewCommitIterBSF(commit, nil, nil)
 	case LogOrderCommitterTime:
-		return object.NewCommitIterCTime(commit, nil, nil), nil
+		commitIter = object.NewCommitIterCTime(commit, nil, nil)
+	default:
+		return nil, fmt.Errorf("invalid Order=%v", o.Order)
+	}
+
+	if o.FileName == nil {
+		return commitIter, nil
 	}
-	return nil, fmt.Errorf("invalid Order=%v", o.Order)
+	return object.NewCommitFileIterFromIter(*o.FileName, commitIter), nil
 }
 
 // Tags returns all the tag References in a repository.
diff --git a/repository_test.go b/repository_test.go
index 2710d9d..bf02933 100644
--- a/repository_test.go
+++ b/repository_test.go
@@ -1143,6 +1143,145 @@ func (s *RepositorySuite) TestLogError(c *C) {
 	c.Assert(err, NotNil)
 }
 
+func (s *RepositorySuite) TestLogFileNext(c *C) {
+	r, _ := Init(memory.NewStorage(), nil)
+	err := r.clone(context.Background(), &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+
+	c.Assert(err, IsNil)
+
+	fileName := "vendor/foo.go"
+	cIter, err := r.Log(&LogOptions{FileName: &fileName})
+
+	c.Assert(err, IsNil)
+
+	commitOrder := []plumbing.Hash{
+		plumbing.NewHash("6ecf0ef2c2dffb796033e5a02219af86ec6584e5"),
+	}
+
+	for _, o := range commitOrder {
+		commit, err := cIter.Next()
+		c.Assert(err, IsNil)
+		c.Assert(commit.Hash, Equals, o)
+	}
+	_, err = cIter.Next()
+	c.Assert(err, Equals, io.EOF)
+}
+
+func (s *RepositorySuite) TestLogFileForEach(c *C) {
+	r, _ := Init(memory.NewStorage(), nil)
+	err := r.clone(context.Background(), &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+
+	c.Assert(err, IsNil)
+
+	fileName := "php/crappy.php"
+	cIter, err := r.Log(&LogOptions{FileName: &fileName})
+
+	c.Assert(err, IsNil)
+
+	commitOrder := []plumbing.Hash{
+		plumbing.NewHash("918c48b83bd081e863dbe1b80f8998f058cd8294"),
+	}
+
+	expectedIndex := 0
+	cIter.ForEach(func(commit *object.Commit) error {
+		expectedCommitHash := commitOrder[expectedIndex]
+		c.Assert(commit.Hash.String(), Equals, expectedCommitHash.String())
+		expectedIndex += 1
+		return nil
+	})
+	c.Assert(expectedIndex, Equals, 1)
+}
+
+func (s *RepositorySuite) TestLogInvalidFile(c *C) {
+	r, _ := Init(memory.NewStorage(), nil)
+	err := r.clone(context.Background(), &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+	c.Assert(err, IsNil)
+
+	// Throwing in a file that does not exist
+	fileName := "vendor/foo12.go"
+	cIter, err := r.Log(&LogOptions{FileName: &fileName})
+	// Not raising an error since `git log -- vendor/foo12.go` responds silently
+	c.Assert(err, IsNil)
+
+	_, err = cIter.Next()
+	c.Assert(err, Equals, io.EOF)
+}
+
+func (s *RepositorySuite) TestLogFileInitialCommit(c *C) {
+	r, _ := Init(memory.NewStorage(), nil)
+	err := r.clone(context.Background(), &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+	c.Assert(err, IsNil)
+
+	fileName := "LICENSE"
+	cIter, err := r.Log(&LogOptions{
+		Order:    LogOrderCommitterTime,
+		FileName: &fileName,
+	})
+
+	c.Assert(err, IsNil)
+
+	commitOrder := []plumbing.Hash{
+		plumbing.NewHash("b029517f6300c2da0f4b651b8642506cd6aaf45d"),
+	}
+
+	expectedIndex := 0
+	cIter.ForEach(func(commit *object.Commit) error {
+		expectedCommitHash := commitOrder[expectedIndex]
+		c.Assert(commit.Hash.String(), Equals, expectedCommitHash.String())
+		expectedIndex += 1
+		return nil
+	})
+	c.Assert(expectedIndex, Equals, 1)
+}
+
+func (s *RepositorySuite) TestLogFileWithOtherParamsFail(c *C) {
+	r, _ := Init(memory.NewStorage(), nil)
+	err := r.clone(context.Background(), &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+	c.Assert(err, IsNil)
+
+	fileName := "vendor/foo.go"
+	cIter, err := r.Log(&LogOptions{
+		Order:    LogOrderCommitterTime,
+		FileName: &fileName,
+		From:     plumbing.NewHash("35e85108805c84807bc66a02d91535e1e24b38b9"),
+	})
+	c.Assert(err, IsNil)
+	_, iterErr := cIter.Next()
+	c.Assert(iterErr, Equals, io.EOF)
+}
+
+func (s *RepositorySuite) TestLogFileWithOtherParamsPass(c *C) {
+	r, _ := Init(memory.NewStorage(), nil)
+	err := r.clone(context.Background(), &CloneOptions{
+		URL: s.GetBasicLocalRepositoryURL(),
+	})
+	c.Assert(err, IsNil)
+
+	fileName := "LICENSE"
+	cIter, err := r.Log(&LogOptions{
+		Order:    LogOrderCommitterTime,
+		FileName: &fileName,
+		From:     plumbing.NewHash("35e85108805c84807bc66a02d91535e1e24b38b9"),
+	})
+	c.Assert(err, IsNil)
+	commitVal, iterErr := cIter.Next()
+	c.Assert(iterErr, Equals, nil)
+	c.Assert(commitVal.Hash.String(), Equals, "b029517f6300c2da0f4b651b8642506cd6aaf45d")
+
+	_, iterErr = cIter.Next()
+	c.Assert(iterErr, Equals, io.EOF)
+}
+
 func (s *RepositorySuite) TestCommit(c *C) {
 	r, _ := Init(memory.NewStorage(), nil)
 	err := r.clone(context.Background(), &CloneOptions{