Documentation
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Index ¶
- func CommonValue(x interface{}, y interface{}) (interface{}, error)
- func Convert(r Record, template Record) error
- func ConvertSkipUnknown(r Record, template Record) error
- func IsKey(k string) bool
- func IsValue(x interface{}) (ok bool)
- func Scan(dest Record, src Record)
- type BufferedIterator
- type ConversionFunc
- type CountIterator
- type DurationIterator
- type Iterator
- func EmptyIterator() Iterator
- func LimitIterator(itr Iterator, N int64) Iterator
- func LimitSizeIterator(itr Iterator, N int) Iterator
- func NewIterator(resC <-chan Record, errC <-chan error, doneC chan<- struct{}) Iterator
- func SliceIterator(S []Record) Iterator
- func SliceIteratorWithConversionFunc[T any](S []T, f ConversionFunc[T]) Iterator
- type Record
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func CommonValue ¶
func CommonValue(x interface{}, y interface{}) (interface{}, error)
CommonValue returns a (zero-valued) value z that covers the types of x and y, where x, y, z are valid Record types. For example, if x is an int16 and y is an int32, then z will be an int32; if x is a bool and y is a string, then z will be a string.
func Convert ¶
Convert deletes any keys from r not in template, and converts the values in r to types matching those in template.
func ConvertSkipUnknown ¶
ConvertSkipUnknown converts the values in r to types matching those in template. Any key in r that is not in template is ignored.
func IsKey ¶
IsKey returns true if and only if the string k has the format required for a key. Namely, k matches [a-zA-Z]+[a-zA-Z0-9_]*.
Types ¶
type BufferedIterator ¶
type BufferedIterator interface {
Iterator
// Buffered returns true iff the next call to Next or NextContext is
// guaranteed not to block.
Buffered() bool
}
BufferedIterator described an Iterator with buffer.
func NewBufferedIterator ¶
func NewBufferedIterator(itr Iterator, bufSize int) BufferedIterator
NewBufferedIterator returns an iterator wrapping 'itr' that buffers the records. Calling Close on the returned iterator will Close the wrapped iterator 'itr'.
type ConversionFunc ¶
ConversionFunc returns a record for the given object x.
type CountIterator ¶
type CountIterator struct {
Iterator
// contains filtered or unexported fields
}
CountIterator wraps an Iterator, counting the number of entries iterated over.
func NewCountIterator ¶
func NewCountIterator(itr Iterator) *CountIterator
NewCountIterator returns an iterator that will count the number of entries iterated over. Calling Close on the returned iterator will Close the underlying iterator.
func (*CountIterator) Count ¶
func (s *CountIterator) Count() int64
Count returns the number of entries iterated over. This is safe for concurrent access.
func (*CountIterator) Next ¶
func (s *CountIterator) Next() bool
Next advances the iterator. Returns true on successful advance of the iterator; false otherwise. Next or NextContext must be called before the first call to Scan.
func (*CountIterator) NextContext ¶
func (s *CountIterator) NextContext(ctx context.Context) (bool, error)
NextContext advances the iterator. Returns true on successful advance of the iterator; false otherwise. Next or NextContext must be called before the first call to Scan.
type DurationIterator ¶ added in v0.2.8
type DurationIterator struct {
Iterator
// contains filtered or unexported fields
}
DurationIterator wraps an Iterator, limiting the total duration over which Records are returned.
func NewDurationIterator ¶ added in v0.2.8
func NewDurationIterator(itr Iterator, d time.Duration) *DurationIterator
NewDurationIterator returns an iterator that will return records from itr until either itr is exhausted, or duration d has passed since the iterator was created. Calling Close on the returned iterator will Close the underlying iterator.
func (*DurationIterator) Close ¶ added in v0.2.8
func (s *DurationIterator) Close() error
Close closes the underlying iterator and prevents future iteration.
func (*DurationIterator) Next ¶ added in v0.2.8
func (s *DurationIterator) Next() bool
Next advances the iterator. Returns true on successful advance of the iterator; false otherwise. Next or NextContext must be called before the first call to Scan.
func (*DurationIterator) NextContext ¶ added in v0.2.8
func (s *DurationIterator) NextContext(ctx context.Context) (bool, error)
NextContext advances the iterator. Returns true on successful advance of the iterator; false otherwise. Next or NextContext must be called before the first call to Scan.
func (*DurationIterator) Scan ¶ added in v0.2.8
func (s *DurationIterator) Scan(dest Record) error
Scan copies the current record into "dest". Any previously set keys or values in "dest" will be deleted or overwritten.
func (*DurationIterator) Stop ¶ added in v0.2.8
func (s *DurationIterator) Stop()
Stop releases resources used by the duration iterator and prevents further iteration, but does not close the underlying iterator.
type Iterator ¶
type Iterator interface {
// Close closes the iterator, preventing further iteration.
Close() error
// Err returns the last error, if any, encountered during iteration. Err
// may be called after Close.
Err() error
// Next advances the iterator. Returns true on successful advance of the
// iterator; false otherwise. Next or NextContext must be called
// before the first call to Scan.
Next() bool
// NextContext advances the iterator. Returns true on successful
// advance of the iterator; false otherwise. Next or NextContext
// must be called before the first call to Scan.
NextContext(ctx context.Context) (bool, error)
// Scan copies the current record into "dest". Any previously set keys
// or values in "dest" will be deleted or overwritten.
Scan(dest Record) error
}
Iterator defines the interface satisfied by a Record iterator.
func EmptyIterator ¶
func EmptyIterator() Iterator
EmptyIterator returns an empty iterator. Err and Close will always return nil.
func LimitIterator ¶
LimitIterator returns an iterator that will return at most N records. Calling Close on the returned iterator will Close the underlying iterator.
func LimitSizeIterator ¶ added in v0.2.8
LimitSizeIterator returns an iterator that will return records from itr until either itr is exhausted, or the total size of the returned records exceeds N bytes. Calling Close on the returned iterator will Close the underlying iterator.
func NewIterator ¶
NewIterator returns an iterator that reads from the channel resC. Iteration will halt when resC closes. Any error in errC will be returned to the user. Iteration should stop if doneC is closed. A typical implementation looks like:
// Create the communication channels
resC := make(chan record.Record) // Buffer this channel if required
errC := make(chan error)
doneC := make(chan struct{})
// Start the background worker running
go func() {
// Feed resC with records
var err error
for {
r := record.Record{}
// ...
// Handle any errors
if err != nil {
break
}
// Pass the record down the channel
select {
case <-doneC:
break // We've been asked to exit
case resC <- r:
}
}
// Iteration has finished, so tidy up
close(resC)
if err != nil {
errC <- err
}
close(errC)
}()
// Create the iterator
itr := record.NewIterator(resC, errC, doneC)
func SliceIterator ¶
SliceIterator returns an iterator for the given slice. There is no need to call Close on the returned iterator. Err and Close will always return nil.
func SliceIteratorWithConversionFunc ¶
func SliceIteratorWithConversionFunc[T any](S []T, f ConversionFunc[T]) Iterator
SliceIteratorWithConversionFunc returns an iterator for the slice S, where the function f is used to convert the elements in S to records.
type Record ¶
type Record map[string]interface{}
Record is the type defining a record in a table. The keys of the map are the keys of the record, and the values of the map are the values of the record. The values must take one of the following types:
int, int8, int16, int32, int64 uint, uint8, uint16, uint32, uint64 float64 bool string []byte
func IteratorToSliceMaxLen ¶
IteratorToSliceMaxLen reads from itr attempting to populate a slice of maximum length n. Returns the slice created, along with any errors.
func (*Record) GobDecode ¶
GobDecode overwrites the receiver, which must be a pointer, with the value represented by the byte slice, which was written by GobEncode.
func (Record) IsValid ¶
IsValid returns true if and only if the keys in the record satisfy IsKey, and the values in the record satisfy IsValue.
func (Record) Keys ¶
Keys returns a slice of keys in this record. The keys are returned sorted using sort.Strings.
func (Record) Size ¶ added in v0.2.8
Size returns the size, in bytes, of this record.
The size is defined to be the sum of the number of bytes for each key, plus the sum of the number of bytes of storage used by each value. The size is only defined if the record is valid. We define an int and uint as requiring 8 bytes of storage, regardless of whether this is a 32- or 64-bit system.
Source Files