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