Refactor to use core.ObjectReader and core.ObjectWriter

* New function signatures provide the necessary interface to stream data from disk when using filesystem-based storage in the future
* New function signatures provide proper error handling
* ObjectReader and ObjectWriter interfaces added to avoid future refactoring, currently are type aliases for io.ReadCloser and io.WriteCloser respectively
* Object.Reader now returns (ObjectReader, error)
* Object.Writer now returns (ObjectWriter, error)
* File.Contents now returns (string, error)
* File.Lines now returns ([]string, error)
* Blob.Reader now returns (core.ObjectReader, error)
* Added internal close helper function for deferred calls to Close that need to check the return value

1 files changed, 18 insertions, 7 deletions

diff --git a/file.go b/file.go
index 72a7145..0ec524e 100644
--- a/file.go
+++ b/file.go
@@ -18,24 +18,35 @@ func newFile(name string, b *Blob) *File {
 }
 
 // Contents returns the contents of a file as a string.
-func (f *File) Contents() string {
+func (f *File) Contents() (content string, err error) {
+	reader, err := f.Reader()
+	if err != nil {
+		return "", err
+	}
+	defer close(reader, &err)
+
 	buf := new(bytes.Buffer)
-	buf.ReadFrom(f.Reader())
+	buf.ReadFrom(reader)
 
-	return buf.String()
+	return buf.String(), nil
 }
 
 // Lines returns a slice of lines from the contents of a file, stripping
 // all end of line characters. If the last line is empty (does not end
 // in an end of line), it is also stripped.
-func (f *File) Lines() []string {
-	splits := strings.Split(f.Contents(), "\n")
+func (f *File) Lines() ([]string, error) {
+	content, err := f.Contents()
+	if err != nil {
+		return nil, err
+	}
+
+	splits := strings.Split(content, "\n")
 	// remove the last line if it is empty
 	if splits[len(splits)-1] == "" {
-		return splits[:len(splits)-1]
+		return splits[:len(splits)-1], nil
 	}
 
-	return splits
+	return splits, nil
 }
 
 type FileIter struct {