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result_columns.go
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/
result_columns.go
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// Copyright 2017 The Cockroach Authors.
//
// 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 sqlbase
import (
"fmt"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
)
// ResultColumn contains the name and type of a SQL "cell".
type ResultColumn struct {
Name string
Typ parser.Type
// If set, this is an implicit column; used internally.
Hidden bool
// If set, a value won't be produced for this column; used internally.
Omitted bool
}
// ResultColumns is the type used throughout the sql module to
// describe the column types of a table.
type ResultColumns []ResultColumn
// ResultColumnsFromColDescs converts ColumnDescriptors to ResultColumns.
func ResultColumnsFromColDescs(colDescs []ColumnDescriptor) ResultColumns {
cols := make(ResultColumns, 0, len(colDescs))
for _, colDesc := range colDescs {
// Convert the ColumnDescriptor to ResultColumn.
typ := colDesc.Type.ToDatumType()
if typ == nil {
panic(fmt.Sprintf("unsupported column type: %s", colDesc.Type.SemanticType))
}
hidden := colDesc.Hidden
cols = append(cols, ResultColumn{Name: colDesc.Name, Typ: typ, Hidden: hidden})
}
return cols
}
// TypesEqual returns whether the length and types of r matches other. If
// a type in other is NULL, it is considered equal.
func (r ResultColumns) TypesEqual(other ResultColumns) bool {
if len(r) != len(other) {
return false
}
for i, c := range r {
// NULLs are considered equal because some types of queries (SELECT CASE,
// for example) can change their output types between a type and NULL based
// on input.
if other[i].Typ == parser.TypeNull {
continue
}
if !c.Typ.Equivalent(other[i].Typ) {
return false
}
}
return true
}