func (this *EliminateDuplicates) afterItems() {
// write the output
for pos, item := range this.buffer {
// we will nil out duplicates and then skip over those entries in the buffer
if item != nil {
if pos < len(this.buffer) {
// look to see if the exact same item appears later in the buffer
for nextpos, nextitem := range this.buffer[pos+1:] {
itemProj, ok := item.GetAttachment("projection").(*dparval.Value)
if ok {
itemVal := itemProj.Value()
if nextitem != nil {
nextItemProj, ok := nextitem.GetAttachment("projection").(*dparval.Value)
if ok {
nextItemVal := nextItemProj.Value()
comp := ast.CollateJSON(itemVal, nextItemVal)
if comp == 0 {
this.buffer[pos+nextpos+1] = nil
}
}
}
}
}
}
clog.To(DEBUG_DUP_CHANNEL, "distinct: %v", item)
this.Base.SendItem(item)
}
}
}
func (this *Order) Less(i, j int) bool {
left := this.buffer[i]
right := this.buffer[j]
for _, oe := range this.OrderBy {
leftVal, lerr := this.Base.Evaluate(oe.Expr, left)
if lerr != nil {
switch lerr := lerr.(type) {
case *dparval.Undefined:
default:
clog.Error(lerr)
return false
}
}
rightVal, rerr := this.Base.Evaluate(oe.Expr, right)
if rerr != nil {
switch rerr := rerr.(type) {
case *dparval.Undefined:
default:
clog.Error(rerr)
return false
}
}
// at this point, the only errors left should be MISSING/UNDEFINED
if oe.Ascending && lerr != nil && rerr == nil {
// ascending, left missing, right not, left is less
return true
} else if !oe.Ascending && rerr != nil && lerr == nil {
// descending right missing, left not, left is more
return true
} else if !oe.Ascending && lerr != nil && rerr == nil {
// descending, left missing, right not, left is less
return false
} else if oe.Ascending && rerr != nil && lerr == nil {
//ascending, left not, left is more
return false
} else if lerr == nil && rerr == nil {
lv := leftVal.Value()
rv := rightVal.Value()
// both not missing, compare values
result := ast.CollateJSON(lv, rv)
if result != 0 {
if oe.Ascending && result < 0 {
return true
} else if !oe.Ascending && result > 0 {
return true
} else {
return false
}
}
}
// at this level they are the same, keep going
}
// if we go to this point the order expressions could not differentiate between the elements
return false
}
func compareTheLookupValues(left, right catalog.LookupValue) int {
for i, l := range left {
if i >= len(right) {
// left array has more elements, right sorts first
return 1
}
r := right[i]
comp := ast.CollateJSON(l.Value(), r.Value())
if comp != 0 {
return comp
}
}
if len(right) > len(left) {
return -1
}
return 0
}
func compareLookupValues(left, right catalog.LookupValue, nilHighLow int) int {
if left == nil && right == nil {
return 0
} else if left == nil {
return nilHighLow
} else if right == nil {
return -nilHighLow
}
for i, l := range left {
if i >= len(right) {
// left array has more elements, right sorts first
return 1
}
r := right[i]
comp := ast.CollateJSON(l.Value(), r.Value())
if comp != 0 {
return comp
}
}
if len(right) > len(left) {
return -1
}
return 0
}