41 lines
1.4 KiB
Go
41 lines
1.4 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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"github.com/pingcap/tidb/context"
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)
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// Expression is an interface for expression.
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// See https://dev.mysql.com/doc/refman/5.7/en/expressions.html
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type Expression interface {
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// Clone clones another Expression.
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Clone() Expression
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// Eval evaluates expression.
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Eval(ctx context.Context, args map[interface{}]interface{}) (v interface{}, err error)
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// IsStatic returns whether this expression can be evaluated statically or not.
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// A Static expression can be evaluated without ctx and args.
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IsStatic() bool
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// String returns the presentation of the expression.
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String() string
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// Accept calls visitor's specific function for its type.
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// It represents a visitor pattern.
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Accept(v Visitor) (Expression, error)
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}
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