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