63 lines
1.7 KiB
Go
63 lines
1.7 KiB
Go
// Copyright 2015 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expression
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import (
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"github.com/pingcap/tidb/context"
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)
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var _ Expression = (*ParamMarker)(nil)
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// ParamMarker expresion holds a place for another expression.
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// Used in parsing prepare statement.
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type ParamMarker struct {
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// Expr is the expression to be evaluated in this place holder.
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Expr Expression
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}
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// Clone implements the Expression Clone interface.
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func (pm *ParamMarker) Clone() Expression {
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np := &ParamMarker{}
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if pm.Expr != nil {
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np.Expr = pm.Expr.Clone()
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}
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return np
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}
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// Eval implements the Expression Eval interface.
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func (pm *ParamMarker) Eval(ctx context.Context, args map[interface{}]interface{}) (v interface{}, err error) {
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if pm.Expr != nil {
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return pm.Expr.Eval(ctx, args)
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}
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return nil, nil
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}
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// Accept implements Expression Accept interface.
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func (pm *ParamMarker) Accept(v Visitor) (Expression, error) {
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return v.VisitParamMaker(pm)
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}
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// IsStatic implements the Expression IsStatic interface, always returns false.
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func (pm *ParamMarker) IsStatic() bool {
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return false
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}
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// String implements the Expression String interface.
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func (pm *ParamMarker) String() string {
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if pm.Expr != nil {
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return pm.Expr.String()
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}
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return "?"
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}
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