From e9bde01cb1424c5c5c12b33788b21fe5962644bd Mon Sep 17 00:00:00 2001
From: Tobie Morgan Hitchcock <tobie@abcum.com>
Date: Thu, 16 Nov 2017 19:10:39 +0000
Subject: [PATCH] Put index diffing code into a separate package

---
 util/indx/indx.go | 79 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 util/indx/indx.go

diff --git a/util/indx/indx.go b/util/indx/indx.go
new file mode 100644
index 00000000..6e9d9407
--- /dev/null
+++ b/util/indx/indx.go
@@ -0,0 +1,79 @@
+// Copyright © 2016 Abcum Ltd
+//
+// 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 indx
+
+import (
+	"reflect"
+
+	"github.com/abcum/surreal/sql"
+	"github.com/abcum/surreal/util/data"
+)
+
+func Diff(old, now [][]interface{}) {
+
+	var d bool
+
+	for i := len(old) - 1; i >= 0; i-- {
+		o := old[i]
+		for j := len(now) - 1; j >= 0; j-- {
+			n := now[j]
+			if reflect.DeepEqual(o, n) {
+				d = true
+				copy(now[j:], now[j+1:])
+				now[len(now)-1] = nil
+				now = now[:len(now)-1]
+			}
+		}
+		if d {
+			d = false
+			copy(old[i:], old[i+1:])
+			old[len(old)-1] = nil
+			old = old[:len(old)-1]
+		}
+	}
+
+}
+
+func Build(cols sql.Idents, item *data.Doc) (out [][]interface{}) {
+
+	if len(cols) == 0 {
+		return [][]interface{}{nil}
+	}
+
+	col, cols := cols[0], cols[1:]
+
+	sub := Build(cols, item)
+
+	if arr, ok := item.Get(col.ID).Data().([]interface{}); ok {
+		for _, s := range sub {
+			for _, a := range arr {
+				idx := []interface{}{}
+				idx = append(idx, a)
+				idx = append(idx, s...)
+				out = append(out, idx)
+			}
+		}
+	} else {
+		for _, s := range sub {
+			idx := []interface{}{}
+			idx = append(idx, item.Get(col.ID).Data())
+			idx = append(idx, s...)
+			out = append(out, idx)
+		}
+	}
+
+	return
+
+}