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type.go
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type.go
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// Copyright 2021 FerretDB Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package operators provides aggregation operators.
package operators
import (
"errors"
"fmt"
"strings"
"time"
"github.com/FerretDB/FerretDB/internal/handlers/common/aggregations"
"github.com/FerretDB/FerretDB/internal/handlers/commonparams"
"github.com/FerretDB/FerretDB/internal/types"
"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
)
// typeOp represents `$type` operator.
type typeOp struct {
param any
}
// newType returns `$type` operator.
func newType(args ...any) (Operator, error) {
if len(args) != 1 {
return nil, newOperatorError(
ErrArgsInvalidLen,
"$type",
fmt.Sprintf("Expression $type takes exactly 1 arguments. %d were passed in.", len(args)),
)
}
return &typeOp{
param: args[0],
}, nil
}
// Process implements Operator interface.
func (t *typeOp) Process(doc *types.Document) (any, error) {
typeParam := t.param
var paramEvaluated bool
var res any
for !paramEvaluated {
paramEvaluated = true
switch param := typeParam.(type) {
case *types.Document:
if !IsOperator(param) {
res = param
break
}
operator, err := NewOperator(param)
if err != nil {
var opErr OperatorError
if !errors.As(err, &opErr) {
return nil, lazyerrors.Error(err)
}
if opErr.Code() == ErrInvalidExpression {
opErr.code = ErrInvalidNestedExpression
}
return nil, opErr
}
if typeParam, err = operator.Process(doc); err != nil {
var opErr OperatorError
if !errors.As(err, &opErr) {
return nil, lazyerrors.Error(err)
}
return nil, err
}
// the result of nested operator needs to be evaluated
paramEvaluated = false
case *types.Array, float64, types.Binary, types.ObjectID, bool, time.Time,
types.NullType, types.Regex, int32, types.Timestamp, int64:
res = param
case string:
if strings.HasPrefix(param, "$") {
expression, err := aggregations.NewExpression(param, nil)
if err != nil {
return nil, err
}
value, err := expression.Evaluate(doc)
if err != nil {
return "missing", nil
}
res = value
continue
}
res = param
default:
panic(fmt.Sprint("wrong type of value: ", typeParam))
}
}
return commonparams.AliasFromType(res), nil
}
// check interfaces
var (
_ Operator = (*typeOp)(nil)
)