/*
Perform either case-sensitive or case-insensitive field lookup.
*/
func (this *Field) Apply(context Context, first, second value.Value) (value.Value, error) {
switch second.Type() {
case value.STRING:
s := second.Actual().(string)
v, ok := first.Field(s)
if !ok && this.caseInsensitive {
s = strings.ToLower(s)
fields := first.Fields()
for f, val := range fields {
if s == strings.ToLower(f) {
return value.NewValue(val), nil
}
}
}
return v, nil
case value.MISSING:
return value.MISSING_VALUE, nil
default:
if first.Type() == value.MISSING {
return value.MISSING_VALUE, nil
} else {
return value.NULL_VALUE, nil
}
}
}
/*
This method takes in an object, a name and a value
and returns a new object that contains the name /
attribute pair. If the type of input is missing
then return a missing value, and if not an object
return a null value.
If the key is found, an error is thrown
*/
func (this *ObjectAdd) Apply(context Context, first, second, third value.Value) (value.Value, error) {
// First must be an object, or we're out
if first.Type() == value.MISSING {
return value.MISSING_VALUE, nil
} else if first.Type() != value.OBJECT {
return value.NULL_VALUE, nil
}
// second must be a non empty string
if second.Type() != value.STRING || second.Actual().(string) == "" {
return first, nil
}
field := second.Actual().(string)
// we don't overwrite
_, exists := first.Field(field)
if exists {
return value.NULL_VALUE, nil
}
// SetField will remove if the attribute is missing, but we don't
// overwrite anyway, so we might just skip now
if third.Type() != value.MISSING {
rv := first.CopyForUpdate()
rv.SetField(field, third)
return rv, nil
}
return first, nil
}
/*
Compute the Final. Compute the sum and the count. If these
arent numbers throw an error. Compute the avg as sum/count.
Check for divide by zero, and return a NULL value if true.
*/
func (this *Avg) ComputeFinal(cumulative value.Value, context Context) (value.Value, error) {
if cumulative == value.NULL_VALUE {
return cumulative, nil
}
sum, _ := cumulative.Field("sum")
count, _ := cumulative.Field("count")
if sum.Type() != value.NUMBER || count.Type() != value.NUMBER {
return nil, fmt.Errorf("Missing or invalid sum or count in AVG: %v, %v.",
sum.Actual(), count.Actual())
}
if count.Actual().(float64) > 0.0 {
return value.NewValue(sum.Actual().(float64) / count.Actual().(float64)), nil
} else {
return value.NULL_VALUE, nil
}
}
func doGetPrepared(prepared_stmt value.Value, track bool) (*Prepared, errors.Error) {
switch prepared_stmt.Type() {
case value.STRING:
prepared := cache.get(prepared_stmt, track)
if prepared == nil {
return nil, errors.NewNoSuchPreparedError(prepared_stmt.Actual().(string))
}
return prepared, nil
case value.OBJECT:
name_value, has_name := prepared_stmt.Field("name")
if has_name {
if prepared := cache.get(name_value, track); prepared != nil {
return prepared, nil
}
}
prepared_bytes, err := prepared_stmt.MarshalJSON()
if err != nil {
return nil, errors.NewUnrecognizedPreparedError(err)
}
return unmarshalPrepared(prepared_bytes)
default:
return nil, errors.NewUnrecognizedPreparedError(fmt.Errorf("Invalid prepared stmt %v", prepared_stmt))
}
}
/*
Aggregate input partial values into cumulative result number value
for sum and count. If the partial results are not numbers, then
return an error.
*/
func (this *Avg) cumulatePart(part, cumulative value.Value, context Context) (value.Value, error) {
if part == value.NULL_VALUE {
return cumulative, nil
} else if cumulative == value.NULL_VALUE {
return part, nil
}
psum, _ := part.Field("sum")
pcount, _ := part.Field("count")
csum, _ := cumulative.Field("sum")
ccount, _ := cumulative.Field("count")
if psum.Type() != value.NUMBER || pcount.Type() != value.NUMBER ||
csum.Type() != value.NUMBER || ccount.Type() != value.NUMBER {
return nil, fmt.Errorf("Missing or invalid partial sum or count in AVG: %v, %v, %v, v.",
psum.Actual(), pcount.Actual(), csum.Actual(), ccount.Actual())
}
cumulative.SetField("sum", psum.Actual().(float64)+csum.Actual().(float64))
cumulative.SetField("count", pcount.Actual().(float64)+ccount.Actual().(float64))
return cumulative, nil
}
/*
Evaluate this as a top-level identifier.
*/
func (this *Identifier) Evaluate(item value.Value, context Context) (value.Value, error) {
rv, _ := item.Field(this.identifier)
return rv, nil
}