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row.go
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row.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 sql
import (
"fmt"
"io"
"strings"
debug "github.com/favframework/debug"
)
// Row is a tuple of values.
type Row []interface{}
// NewRow creates a row from the given values.
func NewRow(values ...interface{}) Row {
row := make([]interface{}, len(values))
copy(row, values)
return row
}
// Copy creates a new row with the same values as the current one.
func (r Row) Copy() Row {
return NewRow(r...)
}
// Append appends all the values in r2 to this row and returns the result
func (r Row) Append(r2 Row) Row {
debug.Dump("========= Append start ")
row := make(Row, len(r)+len(r2))
for i := range r {
row[i] = r[i]
}
for i := range r2 {
row[i+len(r)] = r2[i]
}
debug.Dump("========= Append end ")
return row
}
// Equals checks whether two rows are equal given a schema.
func (r Row) Equals(row Row, schema Schema) (bool, error) {
if len(row) != len(r) || len(row) != len(schema) {
return false, nil
}
for i, colLeft := range r {
colRight := row[i]
cmp, err := schema[i].Type.Compare(colLeft, colRight)
if err != nil {
return false, err
}
if cmp != 0 {
return false, nil
}
}
return true, nil
}
// FormatRow returns a formatted string representing this row's values
func FormatRow(row Row) string {
var sb strings.Builder
sb.WriteRune('[')
for i, v := range row {
if i > 0 {
sb.WriteRune(',')
}
sb.WriteString(fmt.Sprintf("%v", v))
}
sb.WriteRune(']')
return sb.String()
}
// RowIter is an iterator that produces rows.
type RowIter interface {
// Next retrieves the next row. It will return io.EOF if it's the last row.
// After retrieving the last row, Close will be automatically closed.
Next(*Context) (Row, error)
Closer
}
// RowIter2 is an iterator that produces row2s.
type RowIter2 interface {
RowIter
// Next2 produces the next row, and stores it in the RowFrame provided.
// It will return io.EOF if it's the last row. After retrieving the
// last row, Close will be automatically called.
Next2(*Context, *RowFrame) error
}
// RowIterToRows converts a row iterator to a slice of rows.
func RowIterToRows(ctx *Context, i RowIter) ([]Row, error) {
debug.Dump("========= RowIterToRows start ")
var rows []Row
for {
row, err := i.Next(ctx)
if err == io.EOF {
break
}
if err != nil {
_ = i.Close(ctx)
return nil, err
}
rows = append(rows, row)
}
debug.Dump("========= RowIterToRows end ")
return rows, i.Close(ctx)
}
// NodeToRows converts a node to a slice of rows.
func NodeToRows(ctx *Context, n Node) ([]Row, error) {
debug.Dump("========= NodeToRows start ")
i, err := n.RowIter(ctx, nil)
if err != nil {
return nil, err
}
debug.Dump("========= NodeToRows start ")
return RowIterToRows(ctx, i)
}
// RowsToRowIter creates a RowIter that iterates over the given rows.
func RowsToRowIter(rows ...Row) RowIter {
return &sliceRowIter{rows: rows}
}
type sliceRowIter struct {
rows []Row
idx int
}
func (i *sliceRowIter) Next(*Context) (Row, error) {
debug.Dump("========sliceRowIter row Next start")
if i.idx >= len(i.rows) {
return nil, io.EOF
}
r := i.rows[i.idx]
i.idx++
debug.Dump("======== sliceRowIter row Next end")
return r.Copy(), nil
}
func (i *sliceRowIter) Close(*Context) error {
i.rows = nil
return nil
}