64 lines
1.4 KiB
Go
64 lines
1.4 KiB
Go
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package commands
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func newCallFromToBlockProvider(isBackwards bool, callFromProvider, callToProvider BlockProvider) BlockProvider {
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var nextFrom, nextTo uint64
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var hasMoreFrom, hasMoreTo bool
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initialized := false
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return func() (uint64, bool, error) {
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if !initialized {
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initialized = true
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var err error
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if nextFrom, hasMoreFrom, err = callFromProvider(); err != nil {
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return 0, false, err
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}
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hasMoreFrom = hasMoreFrom || nextFrom != 0
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if nextTo, hasMoreTo, err = callToProvider(); err != nil {
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return 0, false, err
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}
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hasMoreTo = hasMoreTo || nextTo != 0
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}
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if !hasMoreFrom && !hasMoreTo {
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return 0, false, nil
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}
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var blockNum uint64
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if !hasMoreFrom {
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blockNum = nextTo
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} else if !hasMoreTo {
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blockNum = nextFrom
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} else {
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blockNum = nextFrom
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if isBackwards {
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if nextTo < nextFrom {
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blockNum = nextTo
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}
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} else {
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if nextTo > nextFrom {
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blockNum = nextTo
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}
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}
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}
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// Pull next; it may be that from AND to contains the same blockNum
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if hasMoreFrom && blockNum == nextFrom {
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var err error
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if nextFrom, hasMoreFrom, err = callFromProvider(); err != nil {
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return 0, false, err
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}
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hasMoreFrom = hasMoreFrom || nextFrom != 0
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}
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if hasMoreTo && blockNum == nextTo {
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var err error
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if nextTo, hasMoreTo, err = callToProvider(); err != nil {
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return 0, false, err
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}
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hasMoreTo = hasMoreTo || nextTo != 0
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}
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return blockNum, hasMoreFrom || hasMoreTo, nil
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}
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}
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