67 lines
1.7 KiB
Go
67 lines
1.7 KiB
Go
// Copyright 2013 The ql Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSES/QL-LICENSE file.
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// 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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"fmt"
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"github.com/pingcap/tidb/context"
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)
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var (
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_ Expression = (*Value)(nil)
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)
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// Value is the expression holding simple value.
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type Value struct {
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// Val holds simple value.
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Val interface{}
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}
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// Clone implements the Expression Clone interface.
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func (l Value) Clone() Expression {
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return Value{Val: l.Val}
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}
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// IsStatic implements the Expression IsStatic interface, always returns true.
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func (l Value) IsStatic() bool {
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return true
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}
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// String implements the Expression String interface.
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func (l Value) String() string {
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switch x := l.Val.(type) {
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case nil:
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return "NULL"
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case string:
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return fmt.Sprintf("%q", x)
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default:
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return fmt.Sprintf("%v", l.Val)
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}
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}
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// Eval implements the Expression Eval interface.
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func (l Value) Eval(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
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return l.Val, nil
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}
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// Accept implements Expression Accept interface.
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func (l Value) Accept(v Visitor) (Expression, error) {
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return v.VisitValue(l)
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}
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