570 lines
15 KiB
Go
570 lines
15 KiB
Go
package memdb
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import (
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"reflect"
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"strings"
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)
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// Indexer is an interface used for defining indexes
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type Indexer interface {
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// ExactFromArgs is used to build an exact index lookup
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// based on arguments
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FromArgs(args ...interface{}) ([]byte, error)
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}
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// SingleIndexer is an interface used for defining indexes
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// generating a single entry per object
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type SingleIndexer interface {
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// FromObject is used to extract an index value from an
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// object or to indicate that the index value is missing.
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FromObject(raw interface{}) (bool, []byte, error)
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}
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// MultiIndexer is an interface used for defining indexes
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// generating multiple entries per object
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type MultiIndexer interface {
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// FromObject is used to extract index values from an
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// object or to indicate that the index value is missing.
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FromObject(raw interface{}) (bool, [][]byte, error)
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}
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// PrefixIndexer can optionally be implemented for any
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// indexes that support prefix based iteration. This may
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// not apply to all indexes.
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type PrefixIndexer interface {
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// PrefixFromArgs returns a prefix that should be used
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// for scanning based on the arguments
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PrefixFromArgs(args ...interface{}) ([]byte, error)
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}
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// StringFieldIndex is used to extract a field from an object
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// using reflection and builds an index on that field.
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type StringFieldIndex struct {
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Field string
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Lowercase bool
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}
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func (s *StringFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
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v := reflect.ValueOf(obj)
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v = reflect.Indirect(v) // Dereference the pointer if any
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fv := v.FieldByName(s.Field)
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if !fv.IsValid() {
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return false, nil,
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fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
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}
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val := fv.String()
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if val == "" {
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return false, nil, nil
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}
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if s.Lowercase {
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val = strings.ToLower(val)
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}
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// Add the null character as a terminator
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val += "\x00"
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return true, []byte(val), nil
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}
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func (s *StringFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
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if len(args) != 1 {
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return nil, fmt.Errorf("must provide only a single argument")
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}
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arg, ok := args[0].(string)
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if !ok {
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return nil, fmt.Errorf("argument must be a string: %#v", args[0])
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}
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if s.Lowercase {
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arg = strings.ToLower(arg)
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}
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// Add the null character as a terminator
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arg += "\x00"
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return []byte(arg), nil
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}
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func (s *StringFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
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val, err := s.FromArgs(args...)
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if err != nil {
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return nil, err
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}
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// Strip the null terminator, the rest is a prefix
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n := len(val)
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if n > 0 {
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return val[:n-1], nil
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}
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return val, nil
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}
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// StringSliceFieldIndex is used to extract a field from an object
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// using reflection and builds an index on that field.
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type StringSliceFieldIndex struct {
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Field string
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Lowercase bool
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}
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func (s *StringSliceFieldIndex) FromObject(obj interface{}) (bool, [][]byte, error) {
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v := reflect.ValueOf(obj)
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v = reflect.Indirect(v) // Dereference the pointer if any
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fv := v.FieldByName(s.Field)
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if !fv.IsValid() {
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return false, nil,
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fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
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}
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if fv.Kind() != reflect.Slice || fv.Type().Elem().Kind() != reflect.String {
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return false, nil, fmt.Errorf("field '%s' is not a string slice", s.Field)
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}
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length := fv.Len()
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vals := make([][]byte, 0, length)
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for i := 0; i < fv.Len(); i++ {
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val := fv.Index(i).String()
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if val == "" {
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continue
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}
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if s.Lowercase {
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val = strings.ToLower(val)
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}
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// Add the null character as a terminator
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val += "\x00"
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vals = append(vals, []byte(val))
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}
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if len(vals) == 0 {
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return false, nil, nil
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}
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return true, vals, nil
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}
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func (s *StringSliceFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
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if len(args) != 1 {
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return nil, fmt.Errorf("must provide only a single argument")
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}
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arg, ok := args[0].(string)
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if !ok {
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return nil, fmt.Errorf("argument must be a string: %#v", args[0])
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}
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if s.Lowercase {
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arg = strings.ToLower(arg)
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}
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// Add the null character as a terminator
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arg += "\x00"
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return []byte(arg), nil
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}
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func (s *StringSliceFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
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val, err := s.FromArgs(args...)
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if err != nil {
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return nil, err
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}
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// Strip the null terminator, the rest is a prefix
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n := len(val)
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if n > 0 {
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return val[:n-1], nil
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}
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return val, nil
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}
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// StringMapFieldIndex is used to extract a field of type map[string]string
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// from an object using reflection and builds an index on that field.
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type StringMapFieldIndex struct {
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Field string
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Lowercase bool
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}
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var MapType = reflect.MapOf(reflect.TypeOf(""), reflect.TypeOf("")).Kind()
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func (s *StringMapFieldIndex) FromObject(obj interface{}) (bool, [][]byte, error) {
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v := reflect.ValueOf(obj)
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v = reflect.Indirect(v) // Dereference the pointer if any
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fv := v.FieldByName(s.Field)
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if !fv.IsValid() {
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return false, nil, fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
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}
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if fv.Kind() != MapType {
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return false, nil, fmt.Errorf("field '%s' is not a map[string]string", s.Field)
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}
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length := fv.Len()
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vals := make([][]byte, 0, length)
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for _, key := range fv.MapKeys() {
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k := key.String()
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if k == "" {
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continue
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}
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val := fv.MapIndex(key).String()
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if s.Lowercase {
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k = strings.ToLower(k)
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val = strings.ToLower(val)
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}
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// Add the null character as a terminator
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k += "\x00" + val + "\x00"
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vals = append(vals, []byte(k))
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}
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if len(vals) == 0 {
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return false, nil, nil
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}
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return true, vals, nil
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}
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func (s *StringMapFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
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if len(args) > 2 || len(args) == 0 {
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return nil, fmt.Errorf("must provide one or two arguments")
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}
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key, ok := args[0].(string)
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if !ok {
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return nil, fmt.Errorf("argument must be a string: %#v", args[0])
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}
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if s.Lowercase {
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key = strings.ToLower(key)
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}
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// Add the null character as a terminator
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key += "\x00"
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if len(args) == 2 {
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val, ok := args[1].(string)
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if !ok {
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return nil, fmt.Errorf("argument must be a string: %#v", args[1])
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}
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if s.Lowercase {
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val = strings.ToLower(val)
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}
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// Add the null character as a terminator
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key += val + "\x00"
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}
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return []byte(key), nil
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}
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// UintFieldIndex is used to extract a uint field from an object using
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// reflection and builds an index on that field.
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type UintFieldIndex struct {
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Field string
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}
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func (u *UintFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
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v := reflect.ValueOf(obj)
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v = reflect.Indirect(v) // Dereference the pointer if any
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fv := v.FieldByName(u.Field)
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if !fv.IsValid() {
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return false, nil,
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fmt.Errorf("field '%s' for %#v is invalid", u.Field, obj)
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}
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// Check the type
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k := fv.Kind()
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size, ok := IsUintType(k)
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if !ok {
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return false, nil, fmt.Errorf("field %q is of type %v; want a uint", u.Field, k)
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}
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// Get the value and encode it
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val := fv.Uint()
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buf := make([]byte, size)
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binary.PutUvarint(buf, val)
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return true, buf, nil
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}
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func (u *UintFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
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if len(args) != 1 {
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return nil, fmt.Errorf("must provide only a single argument")
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}
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v := reflect.ValueOf(args[0])
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if !v.IsValid() {
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return nil, fmt.Errorf("%#v is invalid", args[0])
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}
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k := v.Kind()
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size, ok := IsUintType(k)
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if !ok {
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return nil, fmt.Errorf("arg is of type %v; want a uint", k)
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}
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val := v.Uint()
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buf := make([]byte, size)
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binary.PutUvarint(buf, val)
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return buf, nil
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}
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// IsUintType returns whether the passed type is a type of uint and the number
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// of bytes needed to encode the type.
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func IsUintType(k reflect.Kind) (size int, okay bool) {
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switch k {
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case reflect.Uint:
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return binary.MaxVarintLen64, true
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case reflect.Uint8:
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return 2, true
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case reflect.Uint16:
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return binary.MaxVarintLen16, true
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case reflect.Uint32:
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return binary.MaxVarintLen32, true
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case reflect.Uint64:
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return binary.MaxVarintLen64, true
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default:
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return 0, false
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}
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}
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// UUIDFieldIndex is used to extract a field from an object
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// using reflection and builds an index on that field by treating
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// it as a UUID. This is an optimization to using a StringFieldIndex
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// as the UUID can be more compactly represented in byte form.
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type UUIDFieldIndex struct {
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Field string
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}
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func (u *UUIDFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
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v := reflect.ValueOf(obj)
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v = reflect.Indirect(v) // Dereference the pointer if any
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fv := v.FieldByName(u.Field)
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if !fv.IsValid() {
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return false, nil,
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fmt.Errorf("field '%s' for %#v is invalid", u.Field, obj)
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}
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val := fv.String()
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if val == "" {
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return false, nil, nil
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}
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buf, err := u.parseString(val, true)
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return true, buf, err
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}
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func (u *UUIDFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
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if len(args) != 1 {
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return nil, fmt.Errorf("must provide only a single argument")
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}
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switch arg := args[0].(type) {
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case string:
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return u.parseString(arg, true)
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case []byte:
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if len(arg) != 16 {
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return nil, fmt.Errorf("byte slice must be 16 characters")
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}
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return arg, nil
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default:
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return nil,
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fmt.Errorf("argument must be a string or byte slice: %#v", args[0])
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}
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}
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func (u *UUIDFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
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if len(args) != 1 {
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return nil, fmt.Errorf("must provide only a single argument")
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}
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switch arg := args[0].(type) {
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case string:
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return u.parseString(arg, false)
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case []byte:
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return arg, nil
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default:
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return nil,
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fmt.Errorf("argument must be a string or byte slice: %#v", args[0])
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}
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}
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// parseString parses a UUID from the string. If enforceLength is false, it will
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// parse a partial UUID. An error is returned if the input, stripped of hyphens,
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// is not even length.
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func (u *UUIDFieldIndex) parseString(s string, enforceLength bool) ([]byte, error) {
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// Verify the length
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l := len(s)
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if enforceLength && l != 36 {
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return nil, fmt.Errorf("UUID must be 36 characters")
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} else if l > 36 {
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return nil, fmt.Errorf("Invalid UUID length. UUID have 36 characters; got %d", l)
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}
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hyphens := strings.Count(s, "-")
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if hyphens > 4 {
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return nil, fmt.Errorf(`UUID should have maximum of 4 "-"; got %d`, hyphens)
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}
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// The sanitized length is the length of the original string without the "-".
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sanitized := strings.Replace(s, "-", "", -1)
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sanitizedLength := len(sanitized)
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if sanitizedLength%2 != 0 {
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return nil, fmt.Errorf("Input (without hyphens) must be even length")
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}
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dec, err := hex.DecodeString(sanitized)
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if err != nil {
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return nil, fmt.Errorf("Invalid UUID: %v", err)
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}
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return dec, nil
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}
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// FieldSetIndex is used to extract a field from an object using reflection and
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// builds an index on whether the field is set by comparing it against its
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// type's nil value.
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type FieldSetIndex struct {
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Field string
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}
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func (f *FieldSetIndex) FromObject(obj interface{}) (bool, []byte, error) {
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v := reflect.ValueOf(obj)
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v = reflect.Indirect(v) // Dereference the pointer if any
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fv := v.FieldByName(f.Field)
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if !fv.IsValid() {
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return false, nil,
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fmt.Errorf("field '%s' for %#v is invalid", f.Field, obj)
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}
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if fv.Interface() == reflect.Zero(fv.Type()).Interface() {
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return true, []byte{0}, nil
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}
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return true, []byte{1}, nil
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}
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func (f *FieldSetIndex) FromArgs(args ...interface{}) ([]byte, error) {
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return fromBoolArgs(args)
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}
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// ConditionalIndex builds an index based on a condition specified by a passed
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// user function. This function may examine the passed object and return a
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// boolean to encapsulate an arbitrarily complex conditional.
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type ConditionalIndex struct {
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Conditional ConditionalIndexFunc
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}
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// ConditionalIndexFunc is the required function interface for a
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// ConditionalIndex.
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type ConditionalIndexFunc func(obj interface{}) (bool, error)
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func (c *ConditionalIndex) FromObject(obj interface{}) (bool, []byte, error) {
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// Call the user's function
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res, err := c.Conditional(obj)
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if err != nil {
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return false, nil, fmt.Errorf("ConditionalIndexFunc(%#v) failed: %v", obj, err)
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}
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if res {
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return true, []byte{1}, nil
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}
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return true, []byte{0}, nil
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}
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func (c *ConditionalIndex) FromArgs(args ...interface{}) ([]byte, error) {
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return fromBoolArgs(args)
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}
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// fromBoolArgs is a helper that expects only a single boolean argument and
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// returns a single length byte array containing either a one or zero depending
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// on whether the passed input is true or false respectively.
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func fromBoolArgs(args []interface{}) ([]byte, error) {
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if len(args) != 1 {
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return nil, fmt.Errorf("must provide only a single argument")
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}
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if val, ok := args[0].(bool); !ok {
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return nil, fmt.Errorf("argument must be a boolean type: %#v", args[0])
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} else if val {
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return []byte{1}, nil
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}
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return []byte{0}, nil
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}
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// CompoundIndex is used to build an index using multiple sub-indexes
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// Prefix based iteration is supported as long as the appropriate prefix
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// of indexers support it. All sub-indexers are only assumed to expect
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// a single argument.
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type CompoundIndex struct {
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Indexes []Indexer
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// AllowMissing results in an index based on only the indexers
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// that return data. If true, you may end up with 2/3 columns
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// indexed which might be useful for an index scan. Otherwise,
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// the CompoundIndex requires all indexers to be satisfied.
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AllowMissing bool
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}
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func (c *CompoundIndex) FromObject(raw interface{}) (bool, []byte, error) {
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var out []byte
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for i, idxRaw := range c.Indexes {
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idx, ok := idxRaw.(SingleIndexer)
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if !ok {
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return false, nil, fmt.Errorf("sub-index %d error: %s", i, "sub-index must be a SingleIndexer")
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}
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ok, val, err := idx.FromObject(raw)
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if err != nil {
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return false, nil, fmt.Errorf("sub-index %d error: %v", i, err)
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}
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if !ok {
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if c.AllowMissing {
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break
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} else {
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return false, nil, nil
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}
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}
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out = append(out, val...)
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}
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return true, out, nil
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}
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func (c *CompoundIndex) FromArgs(args ...interface{}) ([]byte, error) {
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if len(args) != len(c.Indexes) {
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return nil, fmt.Errorf("less arguments than index fields")
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}
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var out []byte
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for i, arg := range args {
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val, err := c.Indexes[i].FromArgs(arg)
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if err != nil {
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return nil, fmt.Errorf("sub-index %d error: %v", i, err)
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}
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out = append(out, val...)
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}
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return out, nil
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}
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func (c *CompoundIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
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if len(args) > len(c.Indexes) {
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return nil, fmt.Errorf("more arguments than index fields")
|
|
}
|
|
var out []byte
|
|
for i, arg := range args {
|
|
if i+1 < len(args) {
|
|
val, err := c.Indexes[i].FromArgs(arg)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
|
|
}
|
|
out = append(out, val...)
|
|
} else {
|
|
prefixIndexer, ok := c.Indexes[i].(PrefixIndexer)
|
|
if !ok {
|
|
return nil, fmt.Errorf("sub-index %d does not support prefix scanning", i)
|
|
}
|
|
val, err := prefixIndexer.PrefixFromArgs(arg)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
|
|
}
|
|
out = append(out, val...)
|
|
}
|
|
}
|
|
return out, nil
|
|
}
|