From 7ffb3fb66cb8de7a6041c4c838aa6d7792321083 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <brad@danga.com>
Date: Sun, 27 Nov 2011 11:41:20 -0500
Subject: [PATCH] index: unreverse time

Change-Id: I1ae6a0c0695e0dfa6626999879dfbb9a05c787df
---
 lib/go/camli/index/index_test.go  |  9 +++++++--
 lib/go/camli/index/reversetime.go | 23 +++++++++++++++++++++--
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/lib/go/camli/index/index_test.go b/lib/go/camli/index/index_test.go
index 514795963..f157a0c1d 100644
--- a/lib/go/camli/index/index_test.go
+++ b/lib/go/camli/index/index_test.go
@@ -21,9 +21,14 @@ import (
 )
 
 func TestReverseTimeString(t *testing.T) {
-	got := reverseTimeString("2011-11-27T01:23:45Z")
+	in := "2011-11-27T01:23:45Z"
+	got := reverseTimeString(in)
 	want := "rt7988-88-72T98:76:54Z"
 	if got != want {
-		t.Errorf("reverseTimeString = %q, want %q", got, want)
+		t.Fatalf("reverseTimeString = %q, want %q", got, want)
+	}
+	back := unreverseTimeString(got)
+	if back != in {
+		t.Fatalf("unreverseTimeString = %q, want %q", back, in)
 	}
 }
diff --git a/lib/go/camli/index/reversetime.go b/lib/go/camli/index/reversetime.go
index 1cbd555d3..848ec7ce0 100644
--- a/lib/go/camli/index/reversetime.go
+++ b/lib/go/camli/index/reversetime.go
@@ -16,12 +16,29 @@ limitations under the License.
 
 package index
 
-import ()
+import (
+	"fmt"
+	"strings"
+)
+
+func unreverseTimeString(s string) string {
+	if !strings.HasPrefix(s, "rt") {
+		panic(fmt.Sprintf("can't unreverse time string: %q", s))
+	}
+	b := make([]byte, 0, len(s)-2)
+	b = appendReverseString(b, s[2:])
+	return string(b)
+}
 
 func reverseTimeString(s string) string {
 	b := make([]byte, 0, len(s)+2)
 	b = append(b, 'r')
 	b = append(b, 't')
+	b = appendReverseString(b, s)
+	return string(b)
+}
+
+func appendReverseString(b []byte, s string) []byte {
 	for i := 0; i < len(s); i++ {
 		c := s[i]
 		if c >= '0' && c <= '9' {
@@ -30,5 +47,7 @@ func reverseTimeString(s string) string {
 			b = append(b, c)
 		}
 	}
-	return string(b)
+	return b
 }
+
+