/
filter.go
143 lines (128 loc) · 3.43 KB
/
filter.go
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package storage
import (
"fmt"
"sort"
"google.golang.org/protobuf/types/known/structpb"
)
// A FilterExpression describes an AST for record stream filters.
type FilterExpression interface {
isFilterExpression()
}
// FilterExpressionFromStruct creates a FilterExpression from a protobuf struct.
func FilterExpressionFromStruct(s *structpb.Struct) (FilterExpression, error) {
if s == nil {
return nil, nil
}
return filterExpressionFromStruct(nil, s)
}
func filterExpressionFromValue(path []string, v *structpb.Value) (FilterExpression, error) {
switch vv := v.GetKind().(type) {
case *structpb.Value_ListValue:
var or OrFilterExpression
for _, vvv := range vv.ListValue.Values {
e, err := filterExpressionFromValue(path, vvv)
if err != nil {
return nil, err
}
or = append(or, e)
}
return or, nil
case *structpb.Value_StructValue:
return filterExpressionFromStruct(path, vv.StructValue)
}
return filterExpressionFromEq(path, v)
}
func filterExpressionFromStruct(path []string, s *structpb.Struct) (FilterExpression, error) {
var and AndFilterExpression
var fs []string
for f := range s.GetFields() {
fs = append(fs, f)
}
sort.Strings(fs)
for _, f := range fs {
v := s.GetFields()[f]
switch f {
case "$and":
expr, err := filterExpressionFromValue(path, v)
if err != nil {
return nil, err
}
or, ok := expr.(OrFilterExpression)
if !ok {
return nil, fmt.Errorf("$and must be an array")
}
if len(or) == 1 {
and = append(and, or[0])
} else {
and = append(and, AndFilterExpression(or))
}
case "$or":
expr, err := filterExpressionFromValue(path, v)
if err != nil {
return nil, err
}
or, ok := expr.(OrFilterExpression)
if !ok {
return nil, fmt.Errorf("$or must be an array")
}
if len(or) == 1 {
and = append(and, or[0])
} else {
and = append(and, or)
}
case "$eq":
expr, err := filterExpressionFromEq(path, v)
if err != nil {
return nil, err
}
and = append(and, expr)
default:
expr, err := filterExpressionFromValue(append(path, f), v)
if err != nil {
return nil, err
}
and = append(and, expr)
}
}
if len(and) == 1 {
return and[0], nil
}
return and, nil
}
func filterExpressionFromEq(path []string, v *structpb.Value) (FilterExpression, error) {
switch vv := v.GetKind().(type) {
case *structpb.Value_BoolValue:
return EqualsFilterExpression{
Fields: path,
Value: fmt.Sprintf("%v", vv.BoolValue),
}, nil
case *structpb.Value_NullValue:
return EqualsFilterExpression{
Fields: path,
Value: fmt.Sprintf("%v", vv.NullValue),
}, nil
case *structpb.Value_NumberValue:
return EqualsFilterExpression{
Fields: path,
Value: fmt.Sprintf("%v", vv.NumberValue),
}, nil
case *structpb.Value_StringValue:
return EqualsFilterExpression{
Fields: path,
Value: vv.StringValue,
}, nil
}
return nil, fmt.Errorf("unsupported struct value type for eq: %T", v.GetKind())
}
// An OrFilterExpression represents a logical-or comparison operator.
type OrFilterExpression []FilterExpression
func (OrFilterExpression) isFilterExpression() {}
// An AndFilterExpression represents a logical-and comparison operator.
type AndFilterExpression []FilterExpression
func (AndFilterExpression) isFilterExpression() {}
// An EqualsFilterExpression represents a field comparison operator.
type EqualsFilterExpression struct {
Fields []string
Value string
}
func (EqualsFilterExpression) isFilterExpression() {}