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flux_predicate.go
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flux_predicate.go
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package influxdb
import (
"fmt"
"github.com/influxdata/flux/ast"
"github.com/influxdata/flux/semantic"
"github.com/influxdata/influxdb/models"
"github.com/influxdata/influxdb/storage/reads/datatypes"
"github.com/pkg/errors"
)
const (
fieldKey = "_field"
measurementKey = "_measurement"
valueKey = "_value"
)
func ToStoragePredicate(n semantic.Expression, objectName string) (*datatypes.Predicate, error) {
root, err := toStoragePredicateHelper(n, objectName)
if err != nil {
return nil, err
}
return &datatypes.Predicate{
Root: root,
}, nil
}
func MergePredicates(op ast.LogicalOperatorKind, predicates ...*datatypes.Predicate) (*datatypes.Predicate, error) {
if len(predicates) == 0 {
return nil, errors.New("at least one predicate is needed")
}
var value datatypes.Node_Logical
switch op {
case ast.AndOperator:
value = datatypes.Node_LogicalAnd
case ast.OrOperator:
value = datatypes.Node_LogicalOr
default:
return nil, fmt.Errorf("unknown logical operator %v", op)
}
// Nest the predicates backwards. This way we get a tree like this:
// a AND (b AND c)
root := predicates[len(predicates)-1].Root
for i := len(predicates) - 2; i >= 0; i-- {
root = &datatypes.Node{
NodeType: datatypes.Node_TypeLogicalExpression,
Value: &datatypes.Node_Logical_{Logical: value},
Children: []*datatypes.Node{
predicates[i].Root,
root,
},
}
}
return &datatypes.Predicate{
Root: root,
}, nil
}
func toStoragePredicateHelper(n semantic.Expression, objectName string) (*datatypes.Node, error) {
switch n := n.(type) {
case *semantic.LogicalExpression:
left, err := toStoragePredicateHelper(n.Left, objectName)
if err != nil {
return nil, errors.Wrap(err, "left hand side")
}
right, err := toStoragePredicateHelper(n.Right, objectName)
if err != nil {
return nil, errors.Wrap(err, "right hand side")
}
children := []*datatypes.Node{left, right}
switch n.Operator {
case ast.AndOperator:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLogicalExpression,
Value: &datatypes.Node_Logical_{Logical: datatypes.Node_LogicalAnd},
Children: children,
}, nil
case ast.OrOperator:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLogicalExpression,
Value: &datatypes.Node_Logical_{Logical: datatypes.Node_LogicalOr},
Children: children,
}, nil
default:
return nil, fmt.Errorf("unknown logical operator %v", n.Operator)
}
case *semantic.BinaryExpression:
left, err := toStoragePredicateHelper(n.Left, objectName)
if err != nil {
return nil, errors.Wrap(err, "left hand side")
}
right, err := toStoragePredicateHelper(n.Right, objectName)
if err != nil {
return nil, errors.Wrap(err, "right hand side")
}
children := []*datatypes.Node{left, right}
op, err := toComparisonOperator(n.Operator)
if err != nil {
return nil, err
}
return &datatypes.Node{
NodeType: datatypes.Node_TypeComparisonExpression,
Value: &datatypes.Node_Comparison_{Comparison: op},
Children: children,
}, nil
case *semantic.StringLiteral:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLiteral,
Value: &datatypes.Node_StringValue{
StringValue: n.Value,
},
}, nil
case *semantic.IntegerLiteral:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLiteral,
Value: &datatypes.Node_IntegerValue{
IntegerValue: n.Value,
},
}, nil
case *semantic.BooleanLiteral:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLiteral,
Value: &datatypes.Node_BooleanValue{
BooleanValue: n.Value,
},
}, nil
case *semantic.FloatLiteral:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLiteral,
Value: &datatypes.Node_FloatValue{
FloatValue: n.Value,
},
}, nil
case *semantic.RegexpLiteral:
return &datatypes.Node{
NodeType: datatypes.Node_TypeLiteral,
Value: &datatypes.Node_RegexValue{
RegexValue: n.Value.String(),
},
}, nil
case *semantic.MemberExpression:
// Sanity check that the object is the objectName identifier
if ident, ok := n.Object.(*semantic.IdentifierExpression); !ok || ident.Name.Name() != objectName {
return nil, fmt.Errorf("unknown object %q", n.Object)
}
switch n.Property.Name() {
case fieldKey:
return &datatypes.Node{
NodeType: datatypes.Node_TypeTagRef,
Value: &datatypes.Node_TagRefValue{
TagRefValue: []byte(models.FieldKeyTagKey),
},
}, nil
case measurementKey:
return &datatypes.Node{
NodeType: datatypes.Node_TypeTagRef,
Value: &datatypes.Node_TagRefValue{
TagRefValue: []byte(models.MeasurementTagKey),
},
}, nil
case valueKey:
return &datatypes.Node{
NodeType: datatypes.Node_TypeFieldRef,
Value: &datatypes.Node_FieldRefValue{
FieldRefValue: valueKey,
},
}, nil
}
return &datatypes.Node{
NodeType: datatypes.Node_TypeTagRef,
Value: &datatypes.Node_TagRefValue{
TagRefValue: []byte(n.Property.Name()),
},
}, nil
case *semantic.DurationLiteral:
return nil, errors.New("duration literals not supported in storage predicates")
case *semantic.DateTimeLiteral:
return nil, errors.New("time literals not supported in storage predicates")
default:
return nil, fmt.Errorf("unsupported semantic expression type %T", n)
}
}
func toComparisonOperator(o ast.OperatorKind) (datatypes.Node_Comparison, error) {
switch o {
case ast.EqualOperator:
return datatypes.Node_ComparisonEqual, nil
case ast.NotEqualOperator:
return datatypes.Node_ComparisonNotEqual, nil
case ast.RegexpMatchOperator:
return datatypes.Node_ComparisonRegex, nil
case ast.NotRegexpMatchOperator:
return datatypes.Node_ComparisonNotRegex, nil
case ast.StartsWithOperator:
return datatypes.Node_ComparisonStartsWith, nil
case ast.LessThanOperator:
return datatypes.Node_ComparisonLess, nil
case ast.LessThanEqualOperator:
return datatypes.Node_ComparisonLessEqual, nil
case ast.GreaterThanOperator:
return datatypes.Node_ComparisonGreater, nil
case ast.GreaterThanEqualOperator:
return datatypes.Node_ComparisonGreaterEqual, nil
default:
return 0, fmt.Errorf("unknown operator %v", o)
}
}