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

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

@@ -0,0 +1,59 @@
+package linq
+
+// Except produces the set difference of two sequences.
+// The set difference is the members of the first sequence
+// that don't appear in the second sequence.
+func (q Query) Except(q2 Query) Query {
+	return Query{
+		Iterate: func() Iterator {
+			next := q.Iterate()
+
+			next2 := q2.Iterate()
+			set := make(map[interface{}]bool)
+			for i, ok := next2(); ok; i, ok = next2() {
+				set[i] = true
+			}
+
+			return func() (item interface{}, ok bool) {
+				for item, ok = next(); ok; item, ok = next() {
+					if _, has := set[item]; !has {
+						return
+					}
+				}
+
+				return
+			}
+		},
+	}
+}
+
+// ExceptBy invokes a transform function on each element of a collection
+// and produces the set difference of two sequences.
+// The set difference is the members of the first sequence
+// that don't appear in the second sequence.
+func (q Query) ExceptBy(
+	q2 Query, selector func(interface{}) interface{}) Query {
+	return Query{
+		Iterate: func() Iterator {
+			next := q.Iterate()
+
+			next2 := q2.Iterate()
+			set := make(map[interface{}]bool)
+			for i, ok := next2(); ok; i, ok = next2() {
+				s := selector(i)
+				set[s] = true
+			}
+
+			return func() (item interface{}, ok bool) {
+				for item, ok = next(); ok; item, ok = next() {
+					s := selector(item)
+					if _, has := set[s]; !has {
+						return
+					}
+				}
+
+				return
+			}
+		},
+	}
+}