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arithmetic_operators.go
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/
arithmetic_operators.go
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package engine
import (
"fmt"
"math"
"strconv"
"github.com/influxdb/influxdb/common"
"github.com/influxdb/influxdb/parser"
"github.com/influxdb/influxdb/protocol"
)
type ArithmeticOperator func(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error)
var registeredArithmeticOperator map[string]ArithmeticOperator
func init() {
registeredArithmeticOperator = make(map[string]ArithmeticOperator)
registeredArithmeticOperator["+"] = PlusOperator
registeredArithmeticOperator["-"] = MinusOperator
registeredArithmeticOperator["*"] = MultiplyOperator
registeredArithmeticOperator["/"] = DivideOperator
}
func GetValue(value *parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
switch value.Type {
// if a value is of type ValueTableName then this is probably a
// joined time series and the names of the columns have the format
// series.column
case parser.ValueSimpleName, parser.ValueTableName:
for idx, f := range fields {
if f == value.Name {
return point.Values[idx], nil
}
}
return nil, fmt.Errorf("Invalid column name %s", value.Name)
case parser.ValueExpression:
operator := registeredArithmeticOperator[value.Name]
return operator(value.Elems, fields, point)
case parser.ValueInt:
v, _ := strconv.ParseInt(value.Name, 10, 64)
return &protocol.FieldValue{Int64Value: &v}, nil
case parser.ValueFloat:
v, _ := strconv.ParseFloat(value.Name, 64)
return &protocol.FieldValue{DoubleValue: &v}, nil
}
return nil, fmt.Errorf("Value cannot be evaluated for type %v", value)
}
func PlusOperator(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
leftValue, err := GetValue(elems[0], fields, point)
if err != nil {
return nil, err
}
rightValues, err := GetValue(elems[1], fields, point)
if err != nil {
return nil, err
}
left, right, valueType := common.CoerceValues(leftValue, rightValues)
switch valueType {
case common.TYPE_DOUBLE:
value := left.(float64) + right.(float64)
return &protocol.FieldValue{DoubleValue: &value}, nil
case common.TYPE_INT:
value := left.(int64) + right.(int64)
return &protocol.FieldValue{Int64Value: &value}, nil
}
return nil, fmt.Errorf("+ operator doesn't work with %v types", valueType)
}
func MinusOperator(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
leftValue, err := GetValue(elems[0], fields, point)
if err != nil {
return nil, err
}
rightValues, err := GetValue(elems[1], fields, point)
if err != nil {
return nil, err
}
left, right, valueType := common.CoerceValues(leftValue, rightValues)
switch valueType {
case common.TYPE_DOUBLE:
value := left.(float64) - right.(float64)
return &protocol.FieldValue{DoubleValue: &value}, nil
case common.TYPE_INT:
value := left.(int64) - right.(int64)
return &protocol.FieldValue{Int64Value: &value}, nil
}
return nil, fmt.Errorf("- operator doesn't work with %v types", valueType)
}
func MultiplyOperator(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
leftValue, err := GetValue(elems[0], fields, point)
if err != nil {
return nil, err
}
rightValues, err := GetValue(elems[1], fields, point)
if err != nil {
return nil, err
}
left, right, valueType := common.CoerceValues(leftValue, rightValues)
switch valueType {
case common.TYPE_DOUBLE:
value := left.(float64) * right.(float64)
return &protocol.FieldValue{DoubleValue: &value}, nil
case common.TYPE_INT:
value := left.(int64) * right.(int64)
return &protocol.FieldValue{Int64Value: &value}, nil
}
return nil, fmt.Errorf("* operator doesn't work with %v types", valueType)
}
func DivideOperator(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
leftValue, err := GetValue(elems[0], fields, point)
if err != nil {
return nil, err
}
rightValues, err := GetValue(elems[1], fields, point)
if err != nil {
return nil, err
}
left, right, valueType := common.CoerceValues(leftValue, rightValues)
switch valueType {
case common.TYPE_DOUBLE:
value := left.(float64) / right.(float64)
return &protocol.FieldValue{DoubleValue: &value}, nil
case common.TYPE_INT:
r := right.(int64)
// prevent integer division by zero (i.e., panic)
if r == 0 {
l := left.(int64)
var value float64
if l == 0 {
value = math.NaN()
} else {
value = math.Inf(1)
}
return &protocol.FieldValue{DoubleValue: &value}, nil
} else {
value := left.(int64) / r
return &protocol.FieldValue{Int64Value: &value}, nil
}
}
return nil, fmt.Errorf("/ operator doesn't work with %v types", valueType)
}