check: stubbing out the entry Type's

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

check.go

@@ -1,8 +1,51 @@
 package mtree
 
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+)
+
 type Result struct {
 }
 
+var ErrNotAllClear = fmt.Errorf("some keyword check failed validation")
+
 func Check(root string, dh *DirectoryHierarchy) (*Result, error) {
+	creator := dhCreator{DH: dh}
+	curDir, err := os.Getwd()
+	if err == nil {
+		defer os.Chdir(curDir)
+	}
+
+	if err := os.Chdir(root); err != nil {
+		return nil, err
+	}
+	sort.Sort(byPos(creator.DH.Entries))
+
+	for _, e := range creator.DH.Entries {
+		switch e.Type {
+		case SpecialType:
+			if e.Name == "/set" {
+				creator.curSet = &e
+			} else if e.Name == "/unset" {
+				creator.curSet = nil
+			}
+		case DotDotType:
+			// TODO step
+		case RelativeType:
+			// TODO determine path, and check keywords
+			//      or maybe to Chdir when type=dir?
+		case FullType:
+			info, err := os.Lstat(filepath.Join(root, e.Name))
+			if err != nil {
+				return nil, err
+			}
+			// TODO check against keywords present
+			_ = info
+		}
+	}
+
 	return nil, nil
 }