initial support for staging individual lines

pkg/git/patch_parser.go

@@ -0,0 +1,35 @@
+package git
+
+import (
+	"strings"
+
+	"github.com/sirupsen/logrus"
+)
+
+type PatchParser struct {
+	Log *logrus.Entry
+}
+
+// NewPatchParser builds a new branch list builder
+func NewPatchParser(log *logrus.Entry) (*PatchParser, error) {
+	return &PatchParser{
+		Log: log,
+	}, nil
+}
+
+func (p *PatchParser) ParsePatch(patch string) ([]int, []int, error) {
+	lines := strings.Split(patch, "\n")
+	hunkStarts := []int{}
+	stageableLines := []int{}
+	headerLength := 4
+	for offsetIndex, line := range lines[headerLength:] {
+		index := offsetIndex + headerLength
+		if strings.HasPrefix(line, "@@") {
+			hunkStarts = append(hunkStarts, index)
+		}
+		if strings.HasPrefix(line, "-") || strings.HasPrefix(line, "+") {
+			stageableLines = append(stageableLines, index)
+		}
+	}
+	return hunkStarts, stageableLines, nil
+}