Huangzj
80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
package linq
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// Except produces the set difference of two sequences. The set difference is
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// the members of the first sequence 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 and
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// produces the set difference of two sequences. The set difference is the
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// members of the first sequence that don't appear in the second sequence.
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func (q Query) ExceptBy(q2 Query,
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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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// ExceptByT is the typed version of ExceptBy.
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//
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// - selectorFn is of type "func(TSource) TSource"
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//
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// NOTE: ExceptBy has better performance than ExceptByT.
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func (q Query) ExceptByT(q2 Query,
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selectorFn interface{}) Query {
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selectorGenericFunc, err := newGenericFunc(
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"ExceptByT", "selectorFn", selectorFn,
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simpleParamValidator(newElemTypeSlice(new(genericType)), newElemTypeSlice(new(genericType))),
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)
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if err != nil {
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panic(err)
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}
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selectorFunc := func(item interface{}) interface{} {
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return selectorGenericFunc.Call(item)
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}
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return q.ExceptBy(q2, selectorFunc)
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}
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