formats/config: Added encoder/decoder for git config files. (#97)

* WIP: Add config format parser.

* add decoder based on gcfg.

Portions of code taken from:
https://github.com/go-gcfg/gcfg/blob/5b9f94ee80b2331c3982477bd84be8edd857df33/read.go

* add git config encoder and config methods.

* use format/config in storage/filesystem for read

* use format/config in storage/filesystem to write

* formats/config: improve docs.

* formats/config: improve tests.

* formats/config: use our fork of gcfg; improve api.

* formats/config: improve api.

* storage/filesystem: fix gofmt

* formats/config: use NoSubsection constant.

* formats/config: add doc.go

* formats/config: requested sytle changes.

* formats/config: do not use *_test packages.

1 files changed, 76 insertions, 0 deletions

diff --git a/formats/config/section.go b/formats/config/section.go
new file mode 100644
index 0000000..6d6a891
--- /dev/null
+++ b/formats/config/section.go
@@ -0,0 +1,76 @@
+package config
+
+import "strings"
+
+type Section struct {
+	Name        string
+	Options     Options
+	Subsections Subsections
+}
+
+type Subsection struct {
+	Name    string
+	Options Options
+}
+
+type Sections []*Section
+
+type Subsections []*Subsection
+
+func (s *Section) IsName(name string) bool {
+	return strings.ToLower(s.Name) == strings.ToLower(name)
+}
+
+func (s *Subsection) IsName(name string) bool {
+	return s.Name == name
+}
+
+func (s *Section) Option(key string) string {
+	return s.Options.Get(key)
+}
+
+func (s *Subsection) Option(key string) string {
+	return s.Options.Get(key)
+}
+
+func (s *Section) AddOption(key string, value string) *Section {
+	s.Options = s.Options.withAddedOption(key, value)
+	return s
+}
+
+func (s *Subsection) AddOption(key string, value string) *Subsection {
+	s.Options = s.Options.withAddedOption(key, value)
+	return s
+}
+
+func (s *Section) SetOption(key string, value string) *Section {
+	s.Options = s.Options.withSettedOption(key, value)
+	return s
+}
+
+func (s *Section) RemoveOption(key string) *Section {
+	s.Options = s.Options.withoutOption(key)
+	return s
+}
+
+func (s *Subsection) SetOption(key string, value string) *Subsection {
+	s.Options = s.Options.withSettedOption(key, value)
+	return s
+}
+
+func (s *Subsection) RemoveOption(key string) *Subsection {
+	s.Options = s.Options.withoutOption(key)
+	return s
+}
+
+func (s *Section) Subsection(name string) *Subsection {
+	for i := len(s.Subsections) - 1; i >= 0; i-- {
+		ss := s.Subsections[i]
+		if ss.IsName(name) {
+			return ss
+		}
+	}
+	ss := &Subsection{Name: name}
+	s.Subsections = append(s.Subsections, ss)
+	return ss
+}