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package mapr
import (
"context"
"fmt"
"sort"
"strconv"
)
// GroupSet represents a map of aggregate sets. The group sets
// are requierd by the "group by" mapr clause, whereas the
// group set map keys are the values of the "group by" arguments.
// E.g. "group by $cid" would create one aggregate set and one map
// entry per customer id.
type GroupSet struct {
sets map[string]*AggregateSet
}
// Internal helper type
type result struct {
groupKey string
values []string
columnWidths []int
orderBy float64
}
// NewGroupSet returns a new empty group set.
func NewGroupSet() *GroupSet {
g := GroupSet{}
g.InitSet()
return &g
}
// String representation of the group set.
func (g *GroupSet) String() string {
return fmt.Sprintf("GroupSet(%v)", g.sets)
}
// InitSet makes the group set empty (initialize).
func (g *GroupSet) InitSet() {
g.sets = make(map[string]*AggregateSet)
}
// GetSet gets a specific aggregate set from the group set.
func (g *GroupSet) GetSet(groupKey string) *AggregateSet {
set, ok := g.sets[groupKey]
if !ok {
set = NewAggregateSet()
g.sets[groupKey] = set
}
return set
}
// Serialize the group set (e.g. to send it over the wire).
func (g *GroupSet) Serialize(ctx context.Context, ch chan<- string) {
for groupKey, set := range g.sets {
set.Serialize(ctx, groupKey, ch)
}
}
// Return a sorted result slice of the query from the group set.
func (g *GroupSet) result(query *Query, gathercolumnWidths bool) ([]result, []int, error) {
var err error
var rows []result
// Helpers for calculating the ASCII table output (output is the terminal and
// not a CSV file).
columnWidths := make([]int, len(query.Select))
var valueStrLen int
for groupKey, set := range g.sets {
result := result{groupKey: groupKey}
for i, sc := range query.Select {
if valueStrLen, err = g.resultSelect(query, &sc, set, &result); err != nil {
return rows, columnWidths, err
}
// Do we want to gather the table withs? This is required to print out a decent
// ASCII formated table (table output is the terminal and not a CSV file).
if !gathercolumnWidths {
continue
}
if columnWidths[i] < len(sc.FieldStorage) {
columnWidths[i] = len(sc.FieldStorage)
}
if columnWidths[i] < valueStrLen {
columnWidths[i] = valueStrLen
}
}
rows = append(rows, result)
}
g.resultOrderBy(query, rows)
return rows, columnWidths, nil
}
func (*GroupSet) resultSelect(query *Query, sc *selectCondition, set *AggregateSet,
result *result) (int, error) {
var valueStr string
var value float64
switch sc.Operation {
case Count:
value = set.FValues[sc.FieldStorage]
valueStr = fmt.Sprintf("%d", int(value))
case Len:
fallthrough
case Sum:
fallthrough
case Min:
fallthrough
case Max:
value = set.FValues[sc.FieldStorage]
valueStr = fmt.Sprintf("%f", value)
case Last:
valueStr = set.SValues[sc.FieldStorage]
value, _ = strconv.ParseFloat(valueStr, 64)
case Avg:
value = set.FValues[sc.FieldStorage] / float64(set.Samples)
valueStr = fmt.Sprintf("%f", value)
default:
return 0, fmt.Errorf("Unknown aggregation method '%v'", sc.Operation)
}
if sc.FieldStorage == query.OrderBy {
result.orderBy = value
}
result.values = append(result.values, valueStr)
return len(valueStr), nil
}
func (*GroupSet) resultOrderBy(query *Query, rows []result) {
if query.OrderBy == "" {
return
}
if query.ReverseOrder {
sort.SliceStable(rows, func(i, j int) bool {
return rows[i].orderBy < rows[j].orderBy
})
} else {
sort.SliceStable(rows, func(i, j int) bool {
return rows[i].orderBy > rows[j].orderBy
})
}
}
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