/
block.go
executable file
·180 lines (157 loc) · 4.41 KB
/
block.go
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// Copyright 2020-2021 Dolthub, 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package plan
import (
"io"
"github.com/Rock-liyi/p2pdb-store/sql"
)
// Block represents a collection of statements that should be executed in sequence.
type Block struct {
statements []sql.Node
rowIterSch sql.Schema // This is set during RowIter, as the schema is unknown until iterating over the statements.
}
var _ sql.Node = (*Block)(nil)
var _ sql.DebugStringer = (*Block)(nil)
// NewBlock creates a new *Block node.
func NewBlock(statements []sql.Node) *Block {
return &Block{statements: statements}
}
// Resolved implements the sql.Node interface.
func (b *Block) Resolved() bool {
for _, s := range b.statements {
if !s.Resolved() {
return false
}
}
return true
}
// String implements the sql.Node interface.
func (b *Block) String() string {
p := sql.NewTreePrinter()
_ = p.WriteNode("BLOCK")
var children []string
for _, s := range b.statements {
children = append(children, s.String())
}
_ = p.WriteChildren(children...)
return p.String()
}
// DebugString implements the sql.DebugStringer interface.
func (b *Block) DebugString() string {
p := sql.NewTreePrinter()
_ = p.WriteNode("BLOCK")
var children []string
for _, s := range b.statements {
children = append(children, sql.DebugString(s))
}
_ = p.WriteChildren(children...)
return p.String()
}
// Schema implements the sql.Node interface.
func (b *Block) Schema() sql.Schema {
return b.rowIterSch
}
// Children implements the sql.Node interface.
func (b *Block) Children() []sql.Node {
return b.statements
}
// WithChildren implements the sql.Node interface.
func (b *Block) WithChildren(children ...sql.Node) (sql.Node, error) {
return NewBlock(children), nil
}
// RowIter implements the sql.Node interface.
func (b *Block) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter, error) {
var returnRows []sql.Row
var returnNode sql.Node
var returnSch sql.Schema
selectSeen := false
for _, s := range b.statements {
err := func() error {
rowCache, disposeFunc := ctx.Memory.NewRowsCache()
defer disposeFunc()
var isSelect bool
subIter, err := s.RowIter(ctx, row)
if err != nil {
return err
}
subIterNode := s
subIterSch := s.Schema()
if blockSubIter, ok := subIter.(BlockRowIter); ok {
subIterNode = blockSubIter.RepresentingNode()
subIterSch = blockSubIter.Schema()
}
if isSelect = nodeRepresentsSelect(subIterNode); isSelect {
selectSeen = true
returnNode = subIterNode
returnSch = subIterSch
} else if !selectSeen {
returnNode = subIterNode
returnSch = subIterSch
}
for {
newRow, err := subIter.Next(ctx)
if err == io.EOF {
err := subIter.Close(ctx)
if err != nil {
return err
}
if isSelect || !selectSeen {
returnRows = rowCache.Get()
}
break
} else if err != nil {
return err
} else if isSelect || !selectSeen {
err = rowCache.Add(newRow)
if err != nil {
return err
}
}
}
return nil
}()
if err != nil {
return nil, err
}
}
b.rowIterSch = returnSch
return &blockIter{
internalIter: sql.RowsToRowIter(returnRows...),
repNode: returnNode,
sch: returnSch,
}, nil
}
// blockIter is a sql.RowIter that iterates over the given rows.
type blockIter struct {
internalIter sql.RowIter
repNode sql.Node
sch sql.Schema
}
var _ BlockRowIter = (*blockIter)(nil)
// Next implements the sql.RowIter interface.
func (i *blockIter) Next(ctx *sql.Context) (sql.Row, error) {
return i.internalIter.Next(ctx)
}
// Close implements the sql.RowIter interface.
func (i *blockIter) Close(ctx *sql.Context) error {
return i.internalIter.Close(ctx)
}
// RepresentingNode implements the sql.BlockRowIter interface.
func (i *blockIter) RepresentingNode() sql.Node {
return i.repNode
}
// Schema implements the sql.BlockRowIter interface.
func (i *blockIter) Schema() sql.Schema {
return i.sch
}