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, 37 insertions, 0 deletions

diff --git a/formats/config/decoder.go b/formats/config/decoder.go
new file mode 100644
index 0000000..0f02ce1
--- /dev/null
+++ b/formats/config/decoder.go
@@ -0,0 +1,37 @@
+package config
+
+import (
+	"io"
+
+	"github.com/src-d/gcfg"
+)
+
+// A Decoder reads and decodes config files from an input stream.
+type Decoder struct {
+	io.Reader
+}
+
+// NewDecoder returns a new decoder that reads from r.
+func NewDecoder(r io.Reader) *Decoder {
+	return &Decoder{r}
+}
+
+// Decode reads the whole config from its input and stores it in the
+// value pointed to by config.
+func (d *Decoder) Decode(config *Config) error {
+	cb := func(s string, ss string, k string, v string, bv bool) error {
+		if ss == "" && k == "" {
+			config.Section(s)
+			return nil
+		}
+
+		if ss != "" && k == "" {
+			config.Section(s).Subsection(ss)
+			return nil
+		}
+
+		config.AddOption(s, ss, k, v)
+		return nil
+	}
+	return gcfg.ReadWithCallback(d, cb)
+}