feat(Go-Tool)：2020/11/12:新增linq包使用示例(未完成)

vendor/github.com/ahmetalpbalkan/go-linq/concat.go

@@ -0,0 +1,74 @@
+package linq
+
+// Append inserts an item to the end of a collection,
+// so it becomes the last item.
+func (q Query) Append(item interface{}) Query {
+	return Query{
+		Iterate: func() Iterator {
+			next := q.Iterate()
+			appended := false
+
+			return func() (interface{}, bool) {
+				i, ok := next()
+				if ok {
+					return i, ok
+				}
+
+				if !appended {
+					appended = true
+					return item, true
+				}
+
+				return nil, false
+			}
+		},
+	}
+}
+
+// Concat concatenates two collections.
+//
+// The Concat method differs from the Union method because the Concat method
+// returns all the original elements in the input sequences.
+// The Union method returns only unique elements.
+func (q Query) Concat(q2 Query) Query {
+	return Query{
+		Iterate: func() Iterator {
+			next := q.Iterate()
+			next2 := q2.Iterate()
+			use1 := true
+
+			return func() (item interface{}, ok bool) {
+				if use1 {
+					item, ok = next()
+					if ok {
+						return
+					}
+
+					use1 = false
+				}
+
+				return next2()
+			}
+		},
+	}
+}
+
+// Prepend inserts an item to the beginning of a collection,
+// so it becomes the first item.
+func (q Query) Prepend(item interface{}) Query {
+	return Query{
+		Iterate: func() Iterator {
+			next := q.Iterate()
+			prepended := false
+
+			return func() (interface{}, bool) {
+				if prepended {
+					return next()
+				}
+
+				prepended = true
+				return item, true
+			}
+		},
+	}
+}