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// Copyright 2017 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 chunk
var (
_ Iterator = (*Iterator4Chunk)(nil)
_ Iterator = (*iterator4RowPtr)(nil)
_ Iterator = (*iterator4List)(nil)
_ Iterator = (*iterator4Slice)(nil)
)
// Iterator is used to iterate a number of rows.
//
// for row := it.Begin(); row != it.End(); row = it.Next() {
// ...
// }
type Iterator interface {
// Begin resets the cursor of the iterator and returns the first Row.
Begin() Row
// Next returns the next Row.
Next() Row
// End returns the invalid end Row.
End() Row
// Len returns the length.
Len() int
// Current returns the current Row.
Current() Row
// ReachEnd reaches the end of iterator.
ReachEnd()
}
// NewIterator4Slice returns a Iterator for Row slice.
func NewIterator4Slice(rows []Row) Iterator {
return &iterator4Slice{rows: rows}
}
type iterator4Slice struct {
rows []Row
cursor int
}
// Begin implements the Iterator interface.
func (it *iterator4Slice) Begin() Row {
if it.Len() == 0 {
return it.End()
}
it.cursor = 1
return it.rows[0]
}
// Next implements the Iterator interface.
func (it *iterator4Slice) Next() Row {
if len := it.Len(); it.cursor >= len {
it.cursor = len + 1
return it.End()
}
row := it.rows[it.cursor]
it.cursor++
return row
}
// Current implements the Iterator interface.
func (it *iterator4Slice) Current() Row {
if it.cursor == 0 || it.cursor > it.Len() {
return it.End()
}
return it.rows[it.cursor-1]
}
// End implements the Iterator interface.
func (it *iterator4Slice) End() Row {
return Row{}
}
// ReachEnd implements the Iterator interface.
func (it *iterator4Slice) ReachEnd() {
it.cursor = it.Len() + 1
}
// Len implements the Iterator interface.
func (it *iterator4Slice) Len() int {
return len(it.rows)
}
// NewIterator4Chunk returns a iterator for Chunk.
func NewIterator4Chunk(chk *Chunk) *Iterator4Chunk {
return &Iterator4Chunk{chk: chk}
}
// Iterator4Chunk is used to iterate rows inside a chunk.
type Iterator4Chunk struct {
chk *Chunk
cursor int32
numRows int32
}
// Begin implements the Iterator interface.
func (it *Iterator4Chunk) Begin() Row {
it.numRows = int32(it.chk.NumRows())
if it.numRows == 0 {
return it.End()
}
it.cursor = 1
return it.chk.GetRow(0)
}
// Next implements the Iterator interface.
func (it *Iterator4Chunk) Next() Row {
if it.cursor >= it.numRows {
it.cursor = it.numRows + 1
return it.End()
}
row := it.chk.GetRow(int(it.cursor))
it.cursor++
return row
}
// Current implements the Iterator interface.
func (it *Iterator4Chunk) Current() Row {
if it.cursor == 0 || int(it.cursor) > it.Len() {
return it.End()
}
return it.chk.GetRow(int(it.cursor) - 1)
}
// End implements the Iterator interface.
func (it *Iterator4Chunk) End() Row {
return Row{}
}
// ReachEnd implements the Iterator interface.
func (it *Iterator4Chunk) ReachEnd() {
it.cursor = int32(it.Len() + 1)
}
// Len implements the Iterator interface
func (it *Iterator4Chunk) Len() int {
return it.chk.NumRows()
}
// GetChunk returns the chunk stored in the Iterator4Chunk
func (it *Iterator4Chunk) GetChunk() *Chunk {
return it.chk
}
// NewIterator4List returns a Iterator for List.
func NewIterator4List(li *List) Iterator {
return &iterator4List{li: li}
}
type iterator4List struct {
li *List
chkCursor int
rowCursor int
}
// Begin implements the Iterator interface.
func (it *iterator4List) Begin() Row {
if it.li.NumChunks() == 0 {
return it.End()
}
chk := it.li.GetChunk(0)
row := chk.GetRow(0)
if chk.NumRows() == 1 {
it.chkCursor = 1
it.rowCursor = 0
} else {
it.chkCursor = 0
it.rowCursor = 1
}
return row
}
// Next implements the Iterator interface.
func (it *iterator4List) Next() Row {
if it.chkCursor >= it.li.NumChunks() {
it.chkCursor = it.li.NumChunks() + 1
return it.End()
}
chk := it.li.GetChunk(it.chkCursor)
row := chk.GetRow(it.rowCursor)
it.rowCursor++
if it.rowCursor == chk.NumRows() {
it.rowCursor = 0
it.chkCursor++
}
return row
}
// Current implements the Iterator interface.
func (it *iterator4List) Current() Row {
if (it.chkCursor == 0 && it.rowCursor == 0) || it.chkCursor > it.li.NumChunks() {
return it.End()
}
if it.rowCursor == 0 {
curChk := it.li.GetChunk(it.chkCursor - 1)
return curChk.GetRow(curChk.NumRows() - 1)
}
curChk := it.li.GetChunk(it.chkCursor)
return curChk.GetRow(it.rowCursor - 1)
}
// End implements the Iterator interface.
func (it *iterator4List) End() Row {
return Row{}
}
// ReachEnd implements the Iterator interface.
func (it *iterator4List) ReachEnd() {
it.chkCursor = it.li.NumChunks() + 1
}
// Len implements the Iterator interface.
func (it *iterator4List) Len() int {
return it.li.Len()
}
// NewIterator4RowPtr returns a Iterator for RowPtrs.
func NewIterator4RowPtr(li *List, ptrs []RowPtr) Iterator {
return &iterator4RowPtr{li: li, ptrs: ptrs}
}
type iterator4RowPtr struct {
li *List
ptrs []RowPtr
cursor int
}
// Begin implements the Iterator interface.
func (it *iterator4RowPtr) Begin() Row {
if it.Len() == 0 {
return it.End()
}
it.cursor = 1
return it.li.GetRow(it.ptrs[0])
}
// Next implements the Iterator interface.
func (it *iterator4RowPtr) Next() Row {
if len := it.Len(); it.cursor >= len {
it.cursor = len + 1
return it.End()
}
row := it.li.GetRow(it.ptrs[it.cursor])
it.cursor++
return row
}
// Current implements the Iterator interface.
func (it *iterator4RowPtr) Current() Row {
if it.cursor == 0 || it.cursor > it.Len() {
return it.End()
}
return it.li.GetRow(it.ptrs[it.cursor-1])
}
// End implements the Iterator interface.
func (it *iterator4RowPtr) End() Row {
return Row{}
}
// ReachEnd implements the Iterator interface.
func (it *iterator4RowPtr) ReachEnd() {
it.cursor = it.Len() + 1
}
// Len implements the Iterator interface.
func (it *iterator4RowPtr) Len() int {
return len(it.ptrs)
}
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