github.com/vescale/zgraph@v0.0.0-20230410094002-959c02d50f95/expression/expression.go (about)

     1  // Copyright 2023 zGraph Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package expression
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/vescale/zgraph/datum"
    21  	"github.com/vescale/zgraph/parser/model"
    22  	"github.com/vescale/zgraph/stmtctx"
    23  	"github.com/vescale/zgraph/types"
    24  )
    25  
    26  type Expression interface {
    27  	fmt.Stringer
    28  	ReturnType() types.T
    29  	Eval(stmtCtx *stmtctx.Context, input datum.Row) (datum.Datum, error)
    30  }
    31  
    32  // Assignment represents an assignment in INSERT/UPDATE statements.
    33  //
    34  // e.g:
    35  // INSERT VERTEX x LABELS ( Male ) PROPERTIES ( x.age = 22 )
    36  // UPDATE x SET ( x.age = 42 ) FROM MATCH (x:Person) WHERE x.name = 'John'
    37  type Assignment struct {
    38  	VariableRef *VariableRef
    39  	PropertyRef *PropertyRef
    40  	Expr        Expression
    41  }
    42  
    43  // VariableRef represents a variable referenced by other scope.
    44  //
    45  // e.g:
    46  // INSERT VERTEX x LABELS ( Male ) PROPERTIES ( x.age = 22 )
    47  // --------------^------------------------------^----------
    48  type VariableRef struct {
    49  	Name model.CIStr
    50  }
    51  
    52  func (v *VariableRef) String() string {
    53  	return v.Name.O
    54  }
    55  
    56  // PropertyRef represents the accessor of vertex/edge's property.
    57  type PropertyRef struct {
    58  	Property *model.PropertyInfo
    59  }
    60  
    61  func (f *PropertyRef) Clone() *PropertyRef {
    62  	fc := *f
    63  	return &fc
    64  }
    65  
    66  // String implements the fmt.Stringer interface
    67  func (f *PropertyRef) String() string {
    68  	return f.Property.Name.O
    69  }