index: add doc, notes, reverse time, start of tests.

Change-Id: I13bae252be9616f39decbfb4cc60eaa92c0f3db9

lib/go/camli/index/doc.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2011 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/*
+Package index provides a generic indexing system on top of an abstract
+index storage system (IndexStorage).
+
+The following keys & values are populated by receiving blobs and queried
+for search operations:
+
+* Recent Permanodes
+  "recpn:<signer-blobref>:<reverse-modtime>:<claim-blobref>" == "<permanode-blobref>"
+   where reverse-modtime flips each digit to '9'-<digit> and prepends "rt" (for reverse time)
+          "2011-11-27T01:23:45Z"
+    ==> "rt7988-88-72T98:76:54Z"
+
+
+*/
+package index

lib/go/camli/index/index_test.go

@@ -0,0 +1,29 @@
+/*
+Copyright 2011 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package index
+
+import (
+	"testing"
+)
+
+func TestReverseTimeString(t *testing.T) {
+	got := reverseTimeString("2011-11-27T01:23:45Z")
+	want := "rt7988-88-72T98:76:54Z"
+	if got != want {
+		t.Errorf("reverseTimeString = %q, want %q", got, want)
+	}
+}

lib/go/camli/index/reversetime.go

@@ -0,0 +1,34 @@
+/*
+Copyright 2011 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package index
+
+import ()
+
+func reverseTimeString(s string) string {
+	b := make([]byte, 0, len(s)+2)
+	b = append(b, 'r')
+	b = append(b, 't')
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if c >= '0' && c <= '9' {
+			b = append(b, '0'+('9'-c))
+		} else {
+			b = append(b, c)
+		}
+	}
+	return string(b)
+}