/
explain.go
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/
explain.go
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// Copyright 2016 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package executor
import (
"github.com/cznic/mathutil"
"github.com/pingcap/tidb/util/chunk"
"golang.org/x/net/context"
)
// ExplainExec represents an explain executor.
type ExplainExec struct {
baseExecutor
rows [][]string
cursor int
}
// Close implements the Executor Close interface.
func (e *ExplainExec) Close() error {
e.rows = nil
return nil
}
// Next implements the Executor Next interface.
func (e *ExplainExec) Next(ctx context.Context, chk *chunk.Chunk) error {
chk.Reset()
if e.cursor >= len(e.rows) {
return nil
}
numCurRows := mathutil.Min(e.maxChunkSize, len(e.rows)-e.cursor)
for i := e.cursor; i < e.cursor+numCurRows; i++ {
for j := range e.rows[i] {
chk.AppendString(j, e.rows[i][j])
}
}
e.cursor += numCurRows
return nil
}